Ultrasound Guided Peripheral Vascular Access

Cite this article as:
Trent Calcutt. Ultrasound Guided Peripheral Vascular Access, Don't Forget the Bubbles, 2021. Available at:
https://doi.org/10.31440/DFTB.23253

One of my favourite things in paediatrics is the expanding role of ultrasound guided vascular access.

When I started as a paediatric registrar, I’d just finished an adult ICU term where I’d become spent a majority of time supporting provision of a vascular access service, and as part of this had become a PICC line insertion instructor. Eventually, I got to the point where I dreamt of abstract grey shapes. But then I started a paediatric job in a regional hospital where it seemed that ultrasound was used for vascular access rarely if at all. Initially, I thought there must have been something different about paediatric vascular access that I was unaware of. One day, when looking after a young lady with Rett’s who was known to be difficult to cannulate, I reached for the ultrasound. In the five years since, ultrasound has been a standard part of my practice in achieving vascular access in children, with technique adapted to fit the age of the patient.

Ultrasound-guided vascular access and paediatrics seem like such a natural partnership. The concept of a DIVA (“difficult IV access”) patient is receiving increasing interest and research. Criteria for a DIVA can include prematurity, inability to see or feel a vessel, or an episode of multiple prior attempts. These criteria would be met by a huge number of the kids we care for, in particular toddlers or the previously premature infant. 

Chonky baby arm
Spot the veins

Why is ultrasound not the first-line adjunct in these tricky kids? It’s probably multifactorial, but certainly, ultrasound is more difficult in children than adults. Its utility is varied in the NICU context and for infants under 2.5kg, although can still have a role with a modification to technique. It’s also harder to learn ultrasound in a population who are scared, angry, impatient and poorly tolerant of a prolonged period of needle-through-skin. For these reasons, I think that there is less appeal to replace the familiar (cannulating without an ultrasound), with the unfamiliar (cannulating with an ultrasound). As I’d experienced, this also leads to a culture where ultrasound is infrequently utilized, decreasing the likelihood of implementation by new or more junior staff.

Once the learning investment is made to reach a proficient level of ultrasound competency (about 20 cannulas in adults) the potential benefits are significant. Decreased time spent performing a procedure, decreased number of attempts and subsequent patient trauma, and increased cannula longevity are all achievable.

I’ve spent a lot of time thinking success optimisation in paediatric ultrasound guided cannulation, both during my own development of proficiency and then in an effort to verbalize this skill when educating others. Below are my 5 top tips to enhance your ultrasound-guided cannulation skills:

I’m hoping that some of these words may help avoid some bits of the inevitable trial and error process that comes with learning a new skill.

There is sometimes a general impression of both practical and personal inconvenience in using ultrasound for vascular access. An ultrasound may not be nearby. There is the fear of “looking silly” in front of other people, as turning on, adjusting, and then physically coordinating the use of the ultrasound may be unfamiliar. During the period of establishing proficiency, an approach to decreasing this sense of unfamiliarity is to get in the habit of bringing the ultrasound with you do a cannula. Turn on and optimize the ultrasound to view vessels, and spend a period mapping out candidates for cannulation using your non-cannulating hand. Draw on the patient with a skin pen if you want to keep track of the best sites. Then, discard the ultrasound and cannulate using whatever technique is most familiar to you, but with the added knowledge of vessel location, depth, size, and direction. If this becomes a routine and almost ritualistic process, the mental barrier created by a lack of familiarity with ultrasound settings and holding the transducer should decrease over time. It is a relatively small step from performing vascular mapping to placing a cannula under real-time ultrasound guidance.

The preparation otherwise is quite straightforward. In addition to the set up that you use for all other cannulas, you need the following four things:

  • An ultrasound with a linear array probe (the smaller the footprint and the higher the frequency, the better)
  • Sterile lubricating gel and some form of sterile barrier to cover your probe (this varies institutionally)
  • Cavilon wipe or skin prep (securement devices / dressings / tape doesn’t like to stick to ultrasound gel so will need some encouragement)
  • An extra person (one of your hands is out of action, so you need an additional person to perform the task that your non-dominant hand would normally do; this is typically stabilization of the distal limb)

The ultrasound sits on the opposite side of the bed to the operator, so as to minimize truncal movement in looking from the puncture site to screen. Aside from making sure the correct probe is selected, the only 3 settings you need to know how to adjust are depth (typically as shallow as possible), gain (similar to a ‘brightness’ setting to highlight blood-filled vessels), and a midline marker (for physical-digital landmark referencing).

As alluded to above, pre-scanning is a useful skill even in the absence of cannulating under real-time ultrasound guidance. It’s a good idea to scope out the most appropriate vessels and puncture sites prior to picking up your cannula. Essentially the objective is to place a cannula within a vessel with as few attempts as possible, as quickly as possible, with as little pain as possible, and in a site that will provide the greatest longevity. Characteristics of vessels that tend to correlate with these outcomes are:

  • long and straight stretches
  • vessel 6mm or less below the surface
  • vessels greater than 2mm in diameter
  • vessels that don’t cross a joint (provides freedom of movement and less extravasation)
  • vessels without upstream thrombosis or obstruction

Mid-forearm vessels often meet the above criteria.

The greater length of cannula able to be placed within the vessel can correlate with longevity, however larger cannula diameter may increase the phlebitis and decrease longevity. This requires consideration of the balance between length and diameter of device. Of the commonly available devices, a good balance is a blue cannula (22G). There are several specialised less widely available devices that are longer versions of small diameter cannulae (24G and 22G).

In practical terms, to find these vessels you can start in the antecubital fossa (more familiar area for most of us) and track them down, or plonk down on the forearm and pan circumferentially. Scanning in the short axis / transverse axis / cross-sectional view tends to work best in kids. To assess suitability, translate the probe up and down along a vessel to get an idea of the direction. If it’s running diagonally, rotate your probe until it’s running along the same plane as the vessel to act as a mental reminder of the angle/direction that you need to insert your cannula. Pick the specific spot on the vessel that you’d like to puncture, bearing in mind that you will be puncturing the skin millimetres back from that point. Pick the patch of the vein that is the longest, straightest, shallowest, and biggest. Have a second fallback site planned out elsewhere for if required. Lastly, make sure to track the vein proximally as far as you can to ensure that it doesn’t run into a large thrombosed/occluded/recannalizing patch of vessel.

Obscure angles make things more challenging, in my experience. Right angles and parallel lines are your friends because they assist in mental unburdening and allow you to devote energy to troubleshooting issues. As mentioned above, map the vessel prior to puncture. Part or all of a vein will often wander diagonally along its journey, so approaching from the wrong direction increases the likelihood of punching through the side of the vessel. The centre of the image corresponds to the arrow/marker along the long edge of the probe, so you have a reference point between digital (screen) and physical (skin). Use the ultrasound as a mental reminder of your plane of approach; rotate the probe until the vessel is consistently sitting in the very centre of your image as you plane up and down. In other words, the ultrasound image is perfectly perpendicular to the plane of the vessel.

Speaking of right angles, I prefer to keep the ultrasound at right angles to the surface that you’re scanning. Angling back and forth creates a loss of contact and a distorted image as the ultrasound bounces of structures and does not return to the transducer. This creates a less clear image where vessels artificially look larger. If you need to change your view, translate/glide the probe along the skin, rather than introducing angle. It can be useful to temporarily angle the transducer perpendicular to the shaft of the cannula if you lose sight of it as this will light it up more clearly.

This is a big one. Thinking of your cannulation as a two-phase puncture process is something that I find extremely helpful. Your objective is not to puncture the skin and end up inside the vessel in a single action, and in fact, attempting to do this seems decrease the likelihood of success. 

 

Puncture Phase 1

Puncture 1 is the process from skin puncture to positioning the tip of your cannula on the superficial wall of the vessel. To achieve this, align your probe to achieve a view with the vessel in the centre of the image. Puncture the skin with the cannula a few millimetres distal to the probe. This bit is painful, so do this with a decisive action so that 2-3 mm of the cannula is within the soft tissue. Increase your angle of insertion to 30-45°. Your next objective is to find the tip of the cannula. Moving your non-dominant (ultrasound) hand, translate/slide the probe towards the puncture site until a glimmering white dot becomes apparent in your image. Once you are convinced that you are viewing your cannula, you need to ensure that you are viewing the tip at all times.

The most important thing to remember is the only way to be certain that you are viewing the tip of your cannula is when the glimmering dot disappears when you move the probe 1mm proximally (away). It is frustratingly easy to think that you are viewing your cannula tip when instead you are halfway along the shaft, with the tip out the deep wall of the vessel. Maintain this view via a “walking” approach. For each 1-2mm advancement (step) of the cannula, make an equivalent proximal movement with your ultrasound probe (step). Move the ultrasound away so that you cannot see cannula tip anymore, and then advance the cannula into view. If needed, intermittently stop advancing your cannula and check your tip position as described above. I find advancing at 30-45° until you reach the vessel works well as minimal cannula is wasted on the journey there.

If you find yourself wandering off track, keep the ultrasound focused around the vessel as the centre of your image (as this is your target). Correcting if off centre is slightly counterintuitive. Move your cannulating hand away from the direction that you want to move your cannula tip (ie- moving right will move the tip left). Continue inserting until your cannula tip is sitting at 12 o’clock on top of your vessel. As you reach this point, the tip of the cannula may gently tent the roof of the vessel, turning an “O” shape into a “❤️” shape. This is a good test of correct positioning. Once you’ve reached this point, you’re ready for puncture phase 2!!

 Puncture Phase 2

Puncture 2 is the process of entering the vessel to feeding your cannula fully in. With the tip of your cannula in view and the roof of the vessel tented (❤️), continue incrementally advancing your cannula with tiny movement, walking the ultrasound forward to ensure the tip remains in view (as above). Gently decrease your angle of insertion so that the superficial wall is not tenting towards the deep wall but rather into the potential space of the proximal vessel. Eventually, your tented vessel (❤️) will suddenly encompass the cannula and return to a circular shape (O). This may be associated with a tactile pop. You can check for flashback for additional confirmation of vessel puncture, but I prefer to not take my eyes off the ultrasound screen at this point.

Continue decreasing your angle of insertion to maintain the tip of the cannula in the top 50% of the vessel (keep the sharp bevel away from the deep wall). This may eventually require you be pushing the cannula into the skin, which really requires your assistant to get out of the way. Don’t lose site of your tip! Continue to step forward; cannula then ultrasound. To check whether you are in the vessel and not in soft tissue or dragging on the vessel wall, waggle the tip of the cannula around gently (left, right, up, down). There should be absolutely no distortion of the soft tissue surrounding the vessel; completely free cannula tip movement. I tend to leave the metal stylet in until the plastic catheter is fully inserted to the hub because of greater visibility and added rigidity. This does, however, carry the risk of puncturing the back or sidewall of the vessel if you don’t keep a close eye on your cannula tip. At the very least, ensure 3-4mm of the cannula is inside the vessel lumen prior to gliding the plastic catheter off (to avoid tissuing / tearing the vessel roof). Once this is done, you’ve just successfully place a real-time ultrasound-guided cannula! Well done!

I think it’s reasonable with each healthcare interaction to measure success both in the resolution of issue (beneficence) and in minimization of harm / traumatic experience (non-maleficence). Vascular access is our commonest painful procedure, hence representing a significant potential burden of pain, anxiety, and trauma. Undertaking steps to minimize vascular access attempts, maximize speed/efficiency, and maximize cannula longevity are important considerations in the healthcare interaction. Even if we manage to achieve the elusive goal of a single puncture hospital admission, this still requires a single puncture. 

This discussion is not really directed towards addressing the specifics of analgesia and sedation but suffice to say that time permitting these should be used and optimized readily. A topical anaesthetic is valuable, although in the case of an ultrasound-guided cannula application by the operator is useful in ensuring good placement. Evidence is increasingly suggesting that topical anaesthetic is appropriate in all ages including neonates.

The power of social stories, rehearsal, music therapy, and just general distraction cannot be undervalued. There is a multitude of approaches to this. 

Unfortunately, it is not an uncommon experience to be in a situation where vascular access is required with a degree of clinical urgency. In this circumstance, oral/intranasal/topical medication may have not had time to work, and a specialist in distraction may not be readily available.

In this circumstance, I have found that playing calm and quiet music more useful than positioning a video in front of a child. Maintaining a minimum of people speaking, and using quiet calm voices is valuable. I have had some success using the ultrasound itself as a distraction modality while telling the child a story of the “doughnut that has lost its hole” (vein and cannula tip respectively) as the tip tracks toward the vessel. A variant is the “star that fell from the sky into the lake” (cannula tip and vein respectively). There are many approaches to pain reduction through distraction.

It is my sincere hope that these tips are of some practical and clinical value in your cannulating endeavours. If it makes a difference for a single child, then surely it’s worth it. Good luck!

Sepsis 2020

Cite this article as:
Emma Lim. Sepsis 2020, Don't Forget the Bubbles, 2021. Available at:
https://doi.org/10.31440/DFTB.32392

Where do we start?

Fever and suspected sepsis is our bread and butter. This post will take you through a whirlwind 2020 sepsis update. We’ll cover what sepsis is, how to recognize deterioration and the recent management updates in light of the new 2020 International Surviving Sepsis Campaign Guidelines1.

For me, it is all about “What keeps me up at night?” and there are two things I worry about. The first is missing cases of suspected sepsis.  Think back to all those hot, miserable children you sent home over your career and the heart sink you feel when someone says, “Remember that child you sent home yesterday?”.  My second worry is making bad choices; making mistakes about how much fluid to give or which antibiotics to choose or when to start inotropes.

What is sepsis?

Let’s start at the beginning. How do you get sepsis? A bacterial or viral infection causes a systemic, inflammatory response syndrome (SIRS). We are used to seeing children who have a fever and a fast heart rate or respiratory rate and a raised white cell count, for example with bronchiolitis. A certain proportion of those children will go on to get sepsis but not a lot.

Spotting sepsis in the paediatric ED is like a game of Where’s Wally: there are a whole lot of hot febrile children with accompanying hot cross parents. Fever is common but sepsis is rare – at a quick glance they all look like Wally, but, of course, there is actually only one real one and it takes a bit of time and patience to find him. It is the same with all those children with fever: around 55% have self-limiting viral infections, only 7-13% have serious bacterial infection (SBI)2-4 and only 1% have sepsis. The picture’s different in PICU; 10% of PICU admissions are for sepsis. The 2015 SPROUT study5 looked at 569 children in PICU with sepsis (8.2% point prevalence). 40% were caused by respiratory infections and 19% percent by bloodstream infections. A quarter (25%) of them died.

That quote “7-13% of febrile children have a serious bacterial infection” seems high. There are predefined criteria (such as pneumonia, urinary tract infection, meningitis, osteomyelitis, septic arthritis), but in a reductionist sense, sepsis is any infection that makes a child so unwell that they are admitted to hospital for more than 72 hours and need IV antibiotics. But, the need for admission is very subjective and dependent on the experience of the doctor and the parents’ level of concern.  The goal posts are constantly shifting.  Ten years ago, we would admit children with osteoarticular infections for 6 weeks of IV antibiotics. Now they can be in and out within 72 hours (with most of their course given orally). That doesn’t mean the infections have got less severe, it’s just that our treatments have changed.  And is a urinary tract infection over a year of age really a serious infection?  Most will get treated with a short course of oral antibiotics, as will children with pneumonia.  Because that’s a whole other controversy; reporting focal consolidation on a X ray is art not science and has been shown to be famously unreliable in double blind studies.  So if we remove children who have simple pneumonia, urinary tract infections in older children,  skin and soft tissue infections that do not have positive cultures, the number of true SBI is quite a lot less than the quoted 1 in 10.

Unbelievably, there is no good definition of ‘sepsis’ in paediatrics6, so we tend to use the adult Sepsis 3 definition7 which states:

“Sepsis is life threatening organ dysfunction caused by a dysregulated host immune response to infection including renal, respiratory, hepatic dysfunction or metabolic acidosis”. A small proportion of children or young people with sepsis will go into septic shock, where shock is defined as hypotension, or impaired perfusion requiring inotropes with a higher risk of death than sepsis.”

This doesn’t really help us spot sepsis early enough to prevent these children going into shock.  So far, there is no reliable way of pinpointing who these children are. However, there is some exciting news. 2020 has brought us new international evidence-based guidelines for the management of septic shock and sepsis associated organ dysfunction in children; the Surviving Sepsis Campaign.

This has been a huge piece of work by an incredible transatlantic consortium, including Mark Peters (for the horse’s mouth listen to our latest RCPCH Paediatric Sepsis Podcasts). I am going to take you through some of these recommendations, but I think everybody should read it themselves.  The consortium took 3 years and reviewed over 500 papers, but you only have to read this one paper, so go on, make your life easy!  

Spotting sepsis

Recommendation number one. In children who present acutely well, “we suggest implementing systematic screening for timely recognition.”

Take note of the word suggest. This means there is some, but not definitive, evidence. We all recognise systematic screening for sepsis is a huge problem for paediatricians. Most children with a fever have a self-limiting viral infection, and many of these children will have fever, tachycardia and tachypnoea. But most do not have sepsis.  However, if we use the UK-based NICE high-risk ‘Red Flag’ criteria, these children are all flagged as potentially having sepsis. They over-trigger, shown by a 2020 paper by Ruud Nijman which showed that 41% of all febrile children in PED present with warning signs of sepsis3. If you look at this paper in some detail, 50% of children aged 1-2 years triggered the NICE red high-risk category for tachycardia alone. This mirrors data from a local audit from the Great North Children’s Hospital Emergency Department, conducted between April and June of 2017. Of 868 patients, 5% had serious bacterial infections, but 50% triggered NICE high-risk criteria. Sam Romaine from Alderhey Children’s Hospital, and part of Enitan Carrol’s group, looked at 12,241 patients and again, 55% triggered NICE high risk criteria8. For a full critical review of Ruud’s paper, take a look at our Searching for Sepsis post.

The NICE high risk criteria have a very high sensitivity but limited specificity, which means although they ‘over-trigger’, if a child doesn’t have any red flags then they are potentially ‘good to go’, helping inform safe discharge.

Is there a better score?

For a long time, adults have used the Q-SOFA score, a quick sepsis related organ failure assessment. Typically, this adult score has performed poorly in children. Enitan Carroll’s group have looked at a modified Q-SOFA score called the LQ-SOFA score (L for Liverpool), modified to predict critical care admission rather than sepsis. Critical care admission is a more common outcome than sepsis, particularly relevant because this helps us understand which children are at risk of deterioration. The modified score, is made up of four simple, straightforward criteria, including capillary refill, AVPU (that’s Alert, Verbal, only to Pain or Unresponsive), heart rate and respiratory rate, purposefully not including blood pressure, making this quick and easy to use as a screening tool. But what did they find? Carroll’s group compared five different scores that could help us predict sepsis or deterioration: lactate, CRP, adult Q-SOFA, NICE and LQ-SOFA. Lactate performed the least well, CRP and Q-SOFA a little bit better, NICE high-risk criteria better again, but best of all was the LQ-SOFA score. 

This work suggests that there are more sensitive tools out there, but these need to be combined with some way of de-escalating children who trigger because most of these children have a SIRS response from a self-limiting viral infection and not sepsis. De-escalation is usually done by ‘a senior review,’ with the intention of differentiating the hot and bothered child who has a viral infection from early sepsis.

Listen to parents

There are many examples of systematic screening protocols, the best being electronic scores. But they are not perfect.  Most importantly, the good ones listen to parents. Parental concern or health professional concern is particularly important for children with complex medical conditions: neurodisability, recurrent chest infections, those with indwelling lines or fed by gastrostomy. These children often don’t have typical signs and symptoms that health care professionals associate with infections or sepsis, often presenting with nothing more than their parents saying that they’re not well or not quite themselves. These children can be hypothermic (due to hypothalamic dysfunction) and run ‘cold’ so when they get an infection, their temperature may goes up to ‘normal’ (37 degrees), not triggering at all. The presenting signs can be very, very subtle like not tolerating their feed, or vomiting, or they may just be miserable and unhappy. This is why any escalation tool or score must in some way include parental concern. The NICE sepsis guidelines from 2017 tells us to pay particular attention to ‘concerns expressed by parents, families or carers’, for example, changes from usual behaviour.’  We must not underestimate the expertise of parents and we should incorporate them into the team of people caring for their children.

Doctors can be wary of parental concern but if we look at a systematic review of family-initiated escalation of care for the deteriorating patients in hospital, we can see that this wariness is unfounded.  Gill et al 20169 looked at a systematic review of ten articles (all descriptive studies) over ten years evaluating response systems for patients and families; five described a triaged response; five reported systems for families to directly activate the rapid response team. There were a total of 426 family-initiated calls, range 0.17 to 11 per month, with no deaths reported. All calls were deemed to be appropriate and three calls resulted in intensive care unit admissions.”

I believe there is evidence that parents only escalate when they need to.  As one of our parents of a child with a complex medical condition said;

Please listen to us when we say something is not right, we can see subtle changes in children, in our children, in their health and behaviour. That may not be apparent to the casual observer or even health professionals like yourselves and children like them cannot speak for themselves. Therefore, as parents, we have to ensure that we advocate for them in the strongest possible terms. We do not think we are better than the team, nor are we full of our own importance. But we are simply trying to give a voice to our children as they don’t have one of their own.”

What do you do next?

The Surviving Sepsis campaign developed a management algorithm for children, and while it is useful, there’s a lot of information, for many different teams in a small space. Firstly, when you look closely, the lower half (in black) is actually all about management in a Paediatric Intensive Care (PICU) setting -treatment of refractory shock and advanced haemodynamic monitoring. For paediatric emergency physicians, there is a lot that has to happen first! Let’s break it down.

The first thing that the international guidelines asks us to do is get intravenous or intraosseous access. Please only have three tries at getting intravenous access and if this isn’t successful, go straight to intraosseous access. It’s a great safe route and can be much easier to get than intravenous especially in children with complex medical conditions whom may be difficult to cannulate. Although it may feel like using an IO in an awake child will be traumatic , flushing with 0.5mg/kg of 2% lignocaine before you infuse fluids, antibiotics and other drugs, will reduce the pain.

Test, tests, tests

Recommendation number two. Get a blood culture.

This should always be your next priority, as long as it does not delay treatment. Let’s just think for a moment about blood cultures. Blood cultures are old technology. They were developed in the 1950s and have not really changed since. Traditionally, blood cultures are read at 48 hours but often don’t give any definitive answer. The European Union Childhood Life-threatening Infectious Disease Study (EUCLIDS)10 was a prospective, multi-centre, cohort study of 2844 children under 18  with sepsis (or suspected sepsis) or severe focal infections, admitted to 98 hospitals across Europe and incredibly in 50% of patients the causative organism remained unidentified! Alasdair Munroe explains more in his blood culture post.

What we really want is a point of care test, a test that takes less than 60 minutes, that can quickly differentiate between viral and bacterial infections at the child’s bedside11. Andreola et al12 (and more recent studies by Ruud Nijman again) looked at febrile children and infants in Emergency Departments and this is what they found:

White cell counts, we know, are not helpful. A raised white cell count has poor sensitivity and specificity, so while CRP is better and PCT better still there is room for improvement.  All these tests have problems with sensitivity which means there is still going to be a worrying number of falsely negative tests.  We know this, for example, in children with diseases that progress quickly like meningococcaemia or sepsis who can have normal inflammatory markers early on.

However, new tests are on the horizon. The PERFORM/IRIS group published a diagnostic test using a two-transcript host RNA signature that can discriminate between bacterial and viral infections in febrile children (Herberg, JAMA 2016), using gene arrays to demonstrate up or down regulation of protein expression. Sensitivity in the validation group was 100% and specificity 96.4%13.  

But we don’t just want to know if a child has a bacterial or viral infection, we really want a clinical predictor of severity that could tell us which children are going to get very ill.  We have a few tests, but they’re not very specific. We often look at blood gases, looking for a metabolic acidosis. But that is very broad. What about a lactate >2mmol/l? The international guidelines did not recommend the use of lactate as the evidence is lacking, although it can give an idea of the trend and whether a child is getting better or worse and is generally considered to be best practice and is already standard in adult sepsis. But this is in direct contrast to a study by Elliot Long and team published earlier this year14 looking at predictors of organ dysfunction in over 6000 children presenting to the ED with fever. A lactate of 4 or higher was one of the best performing ED predictor of new organ dysfunction, the need for inotropic support and the need for mechanical ventilation. Take a look at Deirdre Philbin’s DFTB review of the study.

More new tests are coming.  For example, interleukin 6 and 10 may be able to predict which children with febrile neutropenia have serious infections and mid regional pro-adrenoedullin (MR pro-ADM) may be a promising biomarker to predict sepsis and septic shock15. So, watch this space!

Antibiotics

Recommendation number three. Start broad-spectrum antibiotics.

Moving on from tests to treatment, we now want to look at recommendation number three, when to start broad-spectrum antibiotics. There is a change in timing here.

In children with septic shock, antimicrobial therapy should be started as soon as possible and within one hour of recognition of sepsis.”  But, in children with suspected sepsis (i.e. organ dysfunction, but not shock), most of the children we see, guidelines suggest starting antimicrobial treatment as soon as possible after evaluation – you have 3 hours not 1 hour16.

This is important, because it gives you a chance to do tests and decide whether the child in front of you has sepsis or just a SIRS response due to a viral infection. This has bigger implications than just saving hospital beds, because we know timely initial empirical antibiotics will save lives, but unnecessary antibiotic use for all children with fevers increases antibiotic side effects, antibiotic resistance and cost.

Antibiotic choice

There are other recommendations around antibiotics. Importantly, the new consensus recommends a broad-spectrum antibiotic therapy with one single drug in normal children, such as  cefotaxime or ceftriaxone or, if they are allergic, meropenem.

As a quick aside, let’s think about penicillin allergy.

It’s important to get a history and to understand what a ‘real’ penicillin allergy is. We see a lot of children who present with a vague story of having been given a couple of doses of penicillin many years ago, who developed a rash and have been labelled as ‘penicillin allergic’.  But doing that in the heat of the moment can be tricky.

Zagursky believes “Avoidance of cephalosporins, when they are the drug of choice in a penicillin-allergic individual, results in significant morbidity that outweighs the low risk of anaphylaxis. We conclude that there is ample evidence to allow the safe use of cephalosporins in patients with isolated confirmed penicillin or amoxicillin allergy”17

Studies have found the risk of crossover between penicillin/cephalosporin reactions is <1%, so using cephalosporins as a first line is safe.  If the child also has cephalosporin sensitivity, they may need a carbapenem like meropenem.  Later, please think about referring these children to your local allergy service for penicillin or cephalosporin de-labelling, which entails having an antibiotic challenge under controlled, safe circumstances.

Moving on… antibiotics in immunocompromised children

The guidelines suggest using empiric multi-drug therapy in children with immunocompromise and those at high risk for multi-drug resistant pathogens. In this case, you might choose piperacillin-tazobactam and, if shock is present, amikacin. You can add teicoplanin if you suspect a line infection, with rigors when flushing the line, or a line site infection, with redness around their exit site, or signs of any soft tissue cellulitis.

The recommendations also cover antimicrobial stewardship. Once the pathogen and sensitivities are available, the guidelines recommend narrowing antimicrobial therapy coverage. This means narrowing down the antibiotic to something specific to the clinical presentation, site of infection, or risk factors.  Ask yourself these questions:

  • Is the child is showing clinical improvement?
  • Can they have their antibiotics at home? (via a paediatric out-patient antibiotic service)
  • Can they switch to oral antibiotics?
  • Can they stop their antibiotics?  If you don’t find any bugs, and the child is well, then the guidelines recommend stopping antimicrobial therapy.

Remember to phone a friend

Infectious disease teams or microbiologists; you never need to make decisions alone. The guidelines recommended daily assessment with clinical laboratory assessment for de-escalation of antimicrobial therapy. Assessment includes a review of the ongoing indication for antibiotics after the first 48 hours and should be guided by results from microbiology, signs of clinical improvement and evidence of reducing inflammatory markers, such as a halving of CRP, or if the child’s fever has settled for more than 24 hours.

Fluids

Moving on from antibiotics to fluids. The Surviving Sepsis Campaign has another paediatric management algorithm for fluid and vasoactive drugs. It’s also quite busy, incorporating the results of the FEAST study18.  It’s split into two, a green side and a blue side. The green side is for children who live in healthcare systems without intensive care, while the blue side is healthcare systems with paediatric intensive care. The change boils down to being more cautious with fluids.  The guidelines recommend 10-20 ml/kg boluses. I suggest giving 10 ml/kg and then reassessing for signs of fluid overload with hepatomegaly and listening for basal crackles suggesting pulmonary oedema, repeating a second or third bolus as needed.  I use 10 ml/kg because it’s the same in sepsis, in neonates and in trauma.

If the child needs more volume, give them more volume; you can repeat 10ml/kg boluses up to 40 ml/kg or more as needed just use smaller aliquots.  Remember there may still be children who need big volumes of fluid early on, and we have PICU readily available and the technology to support children’s circulation and ventilation and ‘dry them out’ later.  There isn’t enough evidence to fluid restrict children with sepsis in the ‘resource rich’ world just yet but trials are ongoing. The Squeeze Canadian Critical Care Group19 has started a study, so watch this space for results.

Which fluids should you choose?

Please use crystalloids not colloids. And although historically we have used 0.9% saline, it is better to choose balanced or buffered solutions such as Ringer’s lactate or Plasmalyte. Too much saline can cause hyperchloremic acidosis.   

Inotropes

There has been a real sea change in our approach with inotropes. As we’re being more cautious with fluid resuscitation, we need to start giving inotropes earlier. After giving 40 to 60 ml/kg have your inotrope lined up ready to go.  There is good evidence that the drug of choice should be adrenaline20.  You can give adrenaline via a peripheral intravenous cannula or an intra osseous cannula safely if you don’t have central access. There have also been studies in adults that showed that peripheral adrenaline is also safe, especially when given for less than four hours or in a diluted dose.

Safety netting

Most of the febrile children we see will be discharged; safe discharge is a big priority because that’s what the majority of hot bothered children need: good advice and home care.  Winters (2017)21 looked at 33,000 children who were discharged from Emergency Departments with abnormal vital signs. 27,000 (80%) of them were discharged with normal vital signs, with only one case of potentially preventable permanent disability (a child who presented with tummy pains and came back with torsion of the testes, unlucky). 5,500 children (16%) were discharged with abnormal vital signs; there were no permanent disability or deaths from this group. So, you can send children home with fevers safely. But, the proviso to this is they need good safety netting on discharge, including both verbal and written information. This is one of the NICE recommendations. Our discharge safety netting leaflet22, which (gives some straightforward, practical information about giving anti-pyretic medication like paracetamol and ibuprofen), works like a ‘parent’s PEWS’ chart. It allows parents to see if their child is OK to stay at home or if they’re at some risk and should contact the GP, go to a walk in centre or call 111-advice line if they haven’t got better in 48 hours.  If the child is on the ‘high risk’ side, we want to see them back in the Paediatric Emergency Department.

In summary…

So, in summary, please screen for sepsis, we should all be doing it. I don’t know the best systems to help you but, ideally, you should have electronic observations, protocols and local guidelines.  Be aware that in the ED the incidence of sepsis is rare and that recent surviving sepsis campaign guidance suggests you can safely observe while you make a decision on treatment. Give antibiotics within 60 minutes in septic shock, but in sepsis with no shock you have three hours. If you are treating use fluid cautiously, with 10-20 ml/kg boluses and frequent reassessments.  Start adrenaline early if appropriate, and this can be given safely, peripherally.  Finally, safety netting is essential.

Thank you very much for reading this right through to the end! If you want to hear more, please have a listen to our Paediatric Sepsis podcast, hosted by the RCPCH.

Selected references

  1. Surviving Sepsis Campaign International Guidelines for the Management of Septic Shock and Sepsis-Associated Organ Dysfunction in Children. Weiss SL et al. Pediatr Crit Care Med. 2020 Feb;21(2):e52-e106. doi: 10.1097/PCC.0000000000002198.PMID: 32032273
  2. Craig JC et al. The accuracy of clinical symptoms and signs for the diagnosis of serious bacterial infection in young febrile children: prospective cohort study of 15 781 febrile illnesses. BMJ. 2010;340:c1594 10.1136/bmj.c1594
  3. Nijman RG et al. Clinical prediction model to aid emergency doctors managing febrile children at risk of serious bacterial infections: diagnostic study. BMJ. 2013;346:f1706 10.1136/bmj.f1706
  4. van de Maat J et al. Antibiotic prescription for febrile children in European emergency departments: a cross-sectional, observational study. Lancet Infect Dis. 2019;19:382–91. 10.1016/S1473-3099(18)30672-8
  5. Weiss SL et al. Sepsis Prevalence, Outcomes, and Therapies (SPROUT) Study Investigators and Pediatric Acute Lung Injury and Sepsis Investigators (PALISI) Network. Global epidemiology of pediatric severe sepsis: the sepsis prevalence, outcomes, and therapies study. Am J Respir Crit Care Med. 2015 May 15;191(10):1147-57. doi: 10.1164/rccm.201412-2323OC. Erratum in: Am J Respir Crit Care Med. 2016 Jan 15;193(2):223-4. PMID: 25734408; PMCID: PMC4451622.
  6. International pediatric sepsis consensus conference: definitions for sepsis and organ dysfunction in pediatrics. Goldstein B, Giroir B, Randolph A; International Consensus Conference on Pediatric Sepsis.Pediatr Crit Care Med. 2005 Jan;6(1):2-8. doi: 10.1097/01.PCC.0000149131.72248.E6. PMID: 15636651 Review
  7. Developing a New Definition and Assessing New Clinical Criteria for Septic Shock: For the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). Shankar-Hari M et al. Sepsis Definitions Task Force. JAMA. 2016 Feb 23;315(8):775-87. doi: 10.1001/jama.2016.0289. PMID: 26903336
  8. Romaine ST et al. Accuracy of a Modified qSOFA Score for Predicting Critical Care Admission in Febrile Children. Pediatrics. 2020 Oct;146(4):e20200782. doi: 10.1542/peds.2020-0782. PMID: 32978294; PMCID: PMC7786830.
  9. Gill FJ et al. The Impact of Implementation of Family-Initiated Escalation of Care for the Deteriorating Patient in Hospital: A Systematic Review. Worldviews Evid Based Nurs. 2016 Aug;13(4):303-13. doi: 10.1111/wvn.12168. Epub 2016 Jun 3. PMID: 27258792.
  10. Martinón-Torres F et al. EUCLIDS Consortium. Life-threatening infections in children in Europe (the EUCLIDS Project): a prospective cohort study. Lancet Child Adolesc Health. 2018 Jun;2(6):404-414. doi: 10.1016/S2352-4642(18)30113-5. Epub 2018 Apr 28. PMID: 30169282.
  11. Herberg JA et al. IRIS Consortium. Diagnostic Test Accuracy of a 2-Transcript Host RNA Signature for Discriminating Bacterial vs Viral Infection in Febrile Children. JAMA. 2016 Aug 23-30;316(8):835-45. doi: 10.1001/jama.2016.11236. Erratum in: JAMA. 2017 Feb 7;317(5):538. PMID: 27552617; PMCID: PMC5997174.
  12. Andreola, B et al. Procalcitonin and C-Reactive Protein as Diagnostic Markers of Severe Bacterial Infections in Febrile Infants and Children in the Emergency Department, The Pediatric Infectious Disease Journal: August 2007 – Volume 26 – Issue 8 – p 672-677. doi: 10.1097/INF.0b013e31806215e3
  13. Herberg JA et al. Diagnostic Test Accuracy of a 2-Transcript Host RNA Signature for Discriminating Bacterial vs Viral Infection in Febrile Children. JAMA. 2016 Aug 23-30;316(8):835-45. doi: 10.1001/jama.2016.11236. Erratum in: JAMA. 2017 Feb 7;317(5):538. PMID: 27552617; PMCID: PMC5997174.
  14. Long E, Solan T, Stephens DJ, et al. Febrile children in the Emergency Department: Frequency and predictors of poor outcome. Acta Paediatr. 2020; 00: 1– 10 
  15. Xia T, Xu X, Zhao N, Luo Z, Tang Y. Comparison of the diagnostic power of cytokine patterns and procalcitonin for predicting infection among paediatric haematology/oncology patients. Clin Microbiol Infect. 2016 Dec;22(12):996-1001. doi: 10.1016/j.cmi.2016.09.013. Epub 2016 Sep 22. PMID: 27665705.
  16. Elke G et al. SepNet Critical Care Trials Group. The use of mid-regional proadrenomedullin to identify disease severity and treatment response to sepsis – a secondary analysis of a large randomised controlled trial. Crit Care. 2018 Mar 21;22(1):79. doi: 10.1186/s13054-018-2001-5. PMID: 29562917; PMCID: PMC5863464.
  17. Zagursky RJ, Pichichero ME. Cross-reactivity in β-Lactam Allergy. J Allergy Clin Immunol Pract. 2018 Jan-Feb;6(1):72-81.e1. doi: 10.1016/j.jaip.2017.08.027. Epub 2017 Oct 7. PMID: 29017833.
  18. Maitland K et al. FEAST Trial Group. Mortality after fluid bolus in African children with severe infection. N Engl J Med. 2011 Jun 30;364(26):2483-95. doi: 10.1056/NEJMoa1101549. Epub 2011 May 26. PMID: 21615299.
  19. Parker, M.J., Thabane, L., Fox-Robichaud, A. et al. A trial to determine whether septic shock-reversal is quicker in pediatric patients randomized to an early goal-directed fluid-sparing strategy versus usual care (SQUEEZE): study protocol for a pilot randomized controlled trial. Trials 17, 556 (2016). https://doi.org/10.1186/s13063-016-1689-2
  20. Ramaswamy KN, Singhi S, Jayashree M, Bansal A, Nallasamy K. Double-Blind Randomized Clinical Trial Comparing Dopamine and Epinephrine in Pediatric Fluid-Refractory Hypotensive Septic Shock. Pediatr Crit Care Med. 2016 Nov;17(11):e502-e512. doi: 10.1097/PCC.0000000000000954. PMID: 27673385.
  21. Winter J, Waxman MJ, Waterman G, Ata A, Frisch A, Collins KP, King C. Pediatric Patients Discharged from the Emergency Department with Abnormal Vital Signs. West J Emerg Med. 2017 Aug;18(5):878-883. doi: 10.5811/westjem.2017.5.33000. Epub 2017 Jul 19. PMID: 28874940; PMCID: PMC5576624.
  22. Lim E, Mistry RD, Battersby A, Dockerty K, Koshy A, Chopra MN, Carey MC, Latour JM. “How to Recognize if Your Child Is Seriously Ill” During COVID-19 Lockdown: An Evaluation of Parents’ Confidence and Health-Seeking Behaviors. Front Pediatr. 2020 Nov 17;8:580323. doi: 10.3389/fped.2020.580323. PMID: 33313025; PMCID: PMC7707121.

Febrile Infection-Related Epilepsy Syndrome (FIRES)

Cite this article as:
Jessica Archibald and Catherine Murphy. Febrile Infection-Related Epilepsy Syndrome (FIRES), Don't Forget the Bubbles, 2021. Available at:
https://doi.org/10.31440/DFTB.32716

An 8-year-old presents to the emergency department following a first seizure episode. They had a witnessed generalised tonic-clonic seizure that morning lasting approximately 60 seconds and remain post-ictal. They have a history of being non-specifically unwell yesterday with subjective fever, lethargy and a mild headache. They have no significant past medical history and no family history of seizures. The examination is unremarkable. Whilst in the emergency department they have a further two self-terminating generalised tonic-clonic seizures.

Febrile Infection-Related Epilepsy Syndrome (FIRES) is a rare epileptic encephalopathy that results in prolonged refractory status epilepticus in previously well patients.

Presenting Features

FIRES typically presents in children between the age of 3 to 15 years, with intractable status epilepticus, 2 to 10 days post a febrile illness. The preceding illness is most commonly an upper respiratory tract infection or gastroenteritis. Fevers may have resolved prior to the onset of the acute phase of the condition.

The acute phase of the illness is characterised by frequent seizures, rapidly progressing to status epilepticus. Although the seizures are initially focal in nature, they may evolve into secondary generalised seizures. The acute phase can be prolonged, lasting from weeks to months. An association with rash, liver derangement and arrhythmia has been noted in the literature. There is no latency period.

The chronic phase is denoted by refractory epilepsy, resulting in seizures that may cluster every 2 to 4 weeks. This is often associated with severe neurological impairment and cognitive decline.

FIRES had previously been thought to only occur in children, and New-Onset Refractory Status Epilepticus (NORSE) only in adults, however this theory has been disproven. Although FIRES is more prevalent in children, it has been known to also occur in adults. As such, FIRES is now considered a subtype of NORSE, characterised by a preceding febrile illness. It has previously been known as Acute Encephalitis with Refractory, Bepetitive Partial Seizures (AERRPS) and Devastating Epilepsy in School-age Children (DESC).

Aetiology

The aetiology of FIRES in unknown and as such the pathophysiology remains unclear.

One theory is that FIRES is a form of severe infectious encephalitis, but as yet no infectious agent has been identified, and the refractory nature of the seizures is atypical of encephalitis. Another hypothesis suggests FIRES is the result of an immune response, however, there is not enough evidence to support this theory.

A case identifying anti-GABA A receptor antibodies in the CSF of a patient who presented with severe refractory status epilepticus associated with a fever led to speculation that the condition may be autoimmune-mediated. Again this has not been proven and the case may have been an exception rather than a rule.

Other theories include genetic associations and potential links with metabolic disease, but as yet a cause has not been identified.

Diagnosis and Differentials

The diagnosis of FIRES is essentially clinical, as FIRES is a cryptogenic illness. The work up is initially general, and focused on the exclusion of other treatable causes, such as infectious or autoimmune encephalitis.

A detailed history will identify the preceding febrile illness, and would be focussed on the identification of risk factors for other causes for the presentation, including exposure to animals, drugs and toxins, recent foreign travel and immunosuppression.

Blood sampling will be used to identify an infectious cause for the presentation, through full blood count, blood cultures and a screen for atypical infective agents. Lumbar puncture should be performed for CSF sampling in order to investigate bacterial, viral, fungal or autoimmune causes. CSF may show a mildly elevated white cell count in those with FIRES.

EEGs may show a generalised slowing, in keeping with an encephalopathic picture, but do little in the way of distinguishing between other causes of seizures. However, they are useful in guiding treatment and identifying non-convulsive seizures.

Initial MRI imaging is often normal, however, follow up imaging has been associated with devastating changes. Early MRI, in the first weeks of the acute illness, has shown swelling of the mesial temporal structures and increased T2 weighted signal. Follow up MRI, greater than 6 months after onset, may be associated with bilateral mesial temporal atrophy and increased T2 weighted signal. It should be noted that MRI may be normal in 50% of cases.

Differentials to consider are Dravet Syndrome, which presents with a febrile illness associated with status epilepticus, though this tends to present within the first year of life. Also Alper’s Disease, which presents with refractory seizures in previously well children, and is often associated with liver disease.

The patient is loaded with levetiracetam (40mg/kg) as per hospital guidelines, and admitted under paediatrics locally. A CT head is unremarkable and bloods show mild LFT derangement with normal inflammatory markers. They are treated empirically with intravenous cefotaxime and aciclovir. Later that afternoon they develop a fever of 38.3.

The GCS fluctuates between 11 to 13 with no full recovery to baseline until later that evening. Following two focal seizures the next afternoon, they are transferred to the local tertiary centre for further investigation and management.

Initial Management

Initial management involves treating the seizure, and more often status epilepticus. Local hospitals have their own guideline for managing status epilepticus but the first line is typically benzodiazepines (lorazepam, diazepam, midazolam, clonazepam). Second-line treatment is standard anti-convulsants (levetiracetam, phenytoin, phenobarbitone, sodium valproate), however, FIRES does not typically respond to these medications even in high doses.


The seizure pattern in FIRES is often resistant to multiple anti-epileptics. Alternative treatment options have to be sought although there is limited evidence as to the optimal treatment.

Long-term Management

There is limited data on the treatment of FIRES, however, they all conclude the seizures are very difficult to manage and often require polytherapy. Some of the alternative treatment options include drug-induced burst-suppression comas, immunotherapy, a ketogenic diet, vagus nerve stimulation, therapeutic hypothermia and intravenous magnesium sulfate. The most commonly used and researched options are discussed below.

Burst suppression coma

Burst suppression coma induction is viewed as standard care for refractory status epilepticus. If first and second-line treatments fail the next option involves high doses of anti-convulsants along with anaesthetic agents, for example, an infusion of midazolam, barbiturates or propofol. Unfortunately when the anti-convulsants are weaned the seizures tend to reoccur. Prolonged burst suppression coma has been associated with a significantly worse cognitive outcome and poorer prognosis.

Immunotherapy

Immunotherapy has been trialled due to the suspected role of inflammation in the pathogenesis of FIRES. High dose steroids, intravenous immunoglobulin and plasmapheresis have all been used. There is limited evidence to suggest a beneficial role in the management of refractory epilepsy. A large-scale Japanese study described 2 out of 12 patients responding to steroids, although there is not enough evidence to support this as a treatment option. Treatment with immunotherapy is often associated with significant side effects

Anakinra is a recombinant and modified human interleukin-1 receptor antagonist protein. Recent evidence has shown it to be an effective and promising treatment option in patients with FIRES, though relapse has been reported after withdrawal. It has been shown to decrease the duration of mechanical ventilation and hospital length of stay, and possibly seizure reduction. Future studies are required to understand the optimum dosing regime and safety of anakinra.

Ketogenic diet

A ketogenic diet is a high fat, adequate protein and low carbohydrate diet aimed at imitating the body’s fasting state. The body, therefore, metabolises fat for energy. The early introduction of the ketogenic diet has shown to be beneficial in the management of FIRES in uncontrolled trials. It has been suggested that the ketogenic diet may have an anti-inflammatory, as well as an anti-convulsant effect. Some reports suggest it may also have a positive effect on long term cognition. Currently, it is one of the only management options shown to be effective. Future controlled studies are needed to prove this efficacy.

Vagus nerve stimulation

Vagus nerve stimulation (VNS) involves the implantation of an electrode that produces intermittent electrical stimulation into the left cervical vagus nerve. Case reports have found benefit from VNS in the cessation of seizures in patients with refractory status epilepticus and NORSE. There is limited evidence of its use in FIRES.

Long term effects

The prognosis of FIRES is poor. The outcome varies with the length of the acute phase with mortality rates up to 30%. Of those patients who survive there is 66-100% chance that they will have long term cognitive impairment due to damage of the frontal and temporal lobe functions. Survivors with a normal cognitive function will present with a spectrum of learning disabilities, behavioural disorders, memory issues and sensory changes. There is a high risk of recurrent status epilepticus. Unfortunately, only a small proportion of survivors will have no neurologic sequelae.

The patient required a lengthy PICU admission where they were managed with a burst suppression coma, ketogenic diet, high dose steroids and intravenous immunoglobulin.

They were later diagnosed with Febrile-Infection Related Epilepsy Syndrome after extensive investigations, including a normal brain MRI and a lumbar puncture which showed a mildly elevated white cell count but was otherwise unremarkable.

They are currently seizure free on a combination of oral phenobarbitone, perampanel and levetiracetam but have some cognitive sequelae.

References

  1. Fox K, Wells ME, Tennison M, Vaughn B. Febrile Infection-Related Epilepsy Syndrome (FIRES): A literature Review and Case Study. Neurodiagn J. 2017;57(3):224-233. doi: 10.1080/21646821.2017.1355181. PMID: 28898171
  2. Lee H, Chi C. Febrile infection-related epilepsy syndrome (FIRES): therapeutic complications, long-term neurological and Neuro imaging follow-up. Seizure. 2018;56:53-59.
  3. Serino D, Santarone M, Caputo D, Fusco L. Febrile infection-related epilepsy syndrome (FIRES): prevalence, impact and management strategies. Neuropsychiatric Disease and Treatment. 2019;Volume 15:1897-1903.
  4. NORSE (New Onset Refractory Status Epilepticus) and FIRES (Febrile Infection-Related Epilepsy Syndrome) – NORD (National Organization for Rare Disorders) [Internet]. NORD (National Organization for Rare Disorders). 2021 [cited 20 January 2021]. Available from: https://rarediseases.org/rare-diseases/new-onset-refractory-status-epilepticus-norse
  5. Orphanet: Febrile infection related epilepsy syndrome [Internet]. Orpha.net. 2021 [cited 20 January 2021]. Available from: https://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=EN&Expert=163703
  6. Caputo D, Iorio R, Vigevano F, Fusco L. Febrile infection-related epilepsy syndrome (FIRES) with super-refractory status epilepticus revealing autoimmune encephalitis due to GABA A R antibodies. European Journal of Paediatric Neurology. 2018;22(1):182-185.
  7. Diagnostic Evaluation — NORSE INSTITUTE [Internet]. NORSE INSTITUTE. 2021 [cited 20 January 2021]. Available from: http://www.norseinstitute.org/definitions
  8. Dravet Syndrome – NORD (National Organization for Rare Disorders) [Internet]. NORD (National Organization for Rare Disorders). 2021 [cited 20 January 2021]. Available from: https://rarediseases.org/rare-diseases/dravet-syndrome-spectrum
  9. Alpers Disease – NORD (National Organization for Rare Disorders) [Internet]. NORD (National Organization for Rare Disorders). 2021 [cited 20 January 2021]. Available from: https://rarediseases.org/rare-diseases/alpers-disease
  10. Wheless. J. Treatment of refractory convulsive status epilepticus in children: other therapies. Seminars in Paediatric Neurology (2010) 17 (3) 190-194.
  11. Kramur U et al. Febrile infection-related epilepsy syndrome (FIRES): Pathogenesis, treatment and outcome. Epilepsia (2011) 52: 1956-65.
  12. Gaspard et al. New-onset refractory status epilepticus (NORSE) and febrile infection-related epilepsy syndrome (FIRES): State of the art and perspectives. Epilepsia (2018). 59 (4) 745-752.
  13. Sakuma et al. 2010. Acute encephalitis with refractory, repetitive partial seizures (AERRPS): a peculiar form of childhood encephalitis. Acta Neurol Scand 121:251–256.
  14. Hon et al. Febrile Infection-Related Epilepsy Syndrome (FIRES): An overview of treatment and recent patents. Recent Patents on Inflammation & Allergy Drug Discovery (2018). 12 (2): 128-135
  15. Maniscalco et al. The off-label use of anakinra in pediatric systemic autoinflammatory diseases. The Advance Musculoskeletal Disease (2020)
  16. Shukla N et al. Anakinra (IL-1 blockade) use in children with suspected FIRES: a single institution experience. Neurol 2018; 90: 346
  17. Lai et al. Anakinra usage in febrile infection related epilepsy syndrome: an international cohort. Annals of Clinical and Translational Neurology (2020). 7(12): 2467 – 2474
  18. Dibue-Adjei et al. 2019. Vagus nerve stimulation in refractory and super-refractory status epilepticus – A systematic review. Brain Stimuatlion. 12 (4) 1101-1110.
  19. Kurukumbi et al. 2019. Vagus nerve stimulation (VNS) in super refractory new onset refractory status epilepticus (NORSE). Case Reports in Neu

Treating big people (adults) with COVID…

Cite this article as:
Vicki Currie. Treating big people (adults) with COVID…, Don't Forget the Bubbles, 2021. Available at:
https://doi.org/10.31440/DFTB.32313

Reflections from a Paediatric Registrar

‘I won’t touch the feet- I’ll do ANYTHING else’. Avoiding adult feet was one of the reasons I chose a career in paediatrics was one of my responses when I found out that the PICU I was working in was being converted to an adult COVID ITU. I chose paediatrics as a career for so many other reasons, but this was the first thing that popped into my head. 

The world has been turned upside down by this pesky virus.If one year ago you would have told me that I would be looking after adult ITU patients with this new disease I would have refused to believe it. For so many, working lives have changed, roles have been adapted or learnt at lightning speed and working outside your ‘comfort zone’ has become part of the ‘new normal’. 

After a few weeks of looking after adult COVID ITU patients on a PICU I have had some time to reflect on how different things have been. Some things will change my practice forever, some of the big differences in ways of working between those looking after big and littler people. As a general paediatrician doing a stint on PICU, intensive care was new but the steep learning curve after 6 years of looking after ‘littler people’ was even steeper. 

After working closely with adult ITU team members for the last few weeks, we have had a chance to see how each other works. It has proven an opportunity to learn form each other. There are a lot of similarities, and a few differences. There are also some things which both sides can hopefully take forward into our future practice. 

Handover

As paediatricians we LOVE a handover- in some places I have worked it can feel like handovers take over the entire day. One of the biggest differences is the way the adult team do handover.  It seems so much more business-like – especially at the end of a nightshift. There’s no messing around. Any issues? Who is stable or not\? Salient points only. The paediatrician’s in the room added their own twists ‘Had the family been updated? What had they eaten today? What did their poo look like? And how had they slept?’

After a few weeks a happy medium had been found. There was a nice balance achieved between getting the night team off on time, and reducing information that could be found out easily on the morning round whilst including some of the more holistic aspects of care.

Communication with relatives and patients

Those who look after children are used to having to flip between conversing with patient and family. This is a great advantage. We are constantly thinking about updating relatives and keeping family informed. Using FaceTime allowed us to communicate with relatives. They could see their loved ones when they could not be with them. 

The adult team, who have had much more practice with the difficult conversations, seemed to be so slick, having the same realistic and honest conversations. It was business-like and well-rehearsed. Delivering the information succinctly meant that time could be spent talking to more families. 

Patients told me that the way medical and nursing staff spoke with them was different when they made the move to the PICU. Many patients told me that they could tell we were used to dealing with children. The way we spoke was cheery, informal, and most importantly, personal.  I wonder if this was always what they wanted though, especially when delivering difficult news. With the help of the adult ITU team, a delicate balance was maintained. 

Attachment

The adults with COVID in the ITU seem to be long- stayers.Having the same set of patients for a few weeks is great in some ways; and hard in others. Often, with PICU patients, there can be prolonged stays but one of the things the adult team found hard was the attachment they formed to their patients  from seeing them shift after shift. Couple this with the need to look after so many patients on adult ITU , whilst rotating through different pods. On PICU it was one area with the same patients.

On the plus side, you knew the patients REALLY well. You understood things in detail things, like what ventilation strategies they responded to- or didn’t. You knew what previous infections they had been treated for and you knew what families had been told. The downside: you became more attached. It was harder, emotionally, when a patient you knew deteriorated or didn’t better. I wonder if we carry more of an emotional burden in paediatrics because of this. Any doctor will get emotionally attached to certain patients. But are we more likely to do so by seeing fewer patients but more often than our adult counterparts? 

Teamwork

Without question, the amazing paediatric ITU nurses stepped up to the challenge of looking after grown-ups. The incredible camaraderie, between nursing staff, paediatric doctors and the adult ITU team, proning the most unwell patient at 2 in the morning is something which should be bottled up and stored for reuse when this is all done. Truly working together to pull, not only the patients but also each other through the difficult shifts. 

The adult ITU team helped whenever they were needed. They supported us and also credited us paediatricians on many occasions for out strict attention to detail – with anything from charting blood results to charting fluid balances. 

This has been an eye-opening experience. It has been challenging, terrifying, devastating at times. It has also provided opportunities to work with amazing colleagues and witness teamwork between medical and nursing staff like never before. It has been a unique opportunity for adult and paediatric teams to work side by side and siphon bits of each other’s practices. 

As for the feet- it wasn’t as bad as I expected- but I drew the line at a request for a foot massage!

An excellent resource for those working on the front line who are struggling or just looking for that little bit of extra support…

https://www.rcpch.ac.uk/key-topics/your-wellbeing-during-covid-19-pandemic

PEM adventures chapter 3

Cite this article as:
Team PEM Adventures. PEM adventures chapter 3, Don't Forget the Bubbles, 2021. Available at:
https://doi.org/10.31440/DFTB.31888

It’s time for another PEM adventure. Join us on another journey (with an inbuilt time travel machine) in managing Francesca, a teen who dreams of being a pop star…

Meet Francesca, a 15 year old girl who dreams of being a pop star.  She is making ripples in the world of teen music videos and has a HUGE audition tomorrow for a music video. But for the last 24 hours she’s been feeling a little shaky and pretty nauseous. Putting it down to nerves, her mother (who is also her agent) continued packing for the big trip. But Francesca vomited, had two episodes of diarrhoea and then spiked a fever and her mother knew she needed to get her fixed. Fast.

It’s the middle of a run of the mill shift for you. You’ve just fished a bead from a child’s ear, reduced a decently angulated forearm fracture and admitted a child with a pyelonephritis. When you take a look at Francesca though you know she’s sick. She is agitated, clammy and flushed, and febrile at 39.3°C. She’s tachycardic at 130, with a bounding pulse, blood pressure of 128/74 and normal heart sounds. She tachypnoeic at 24, with sats of 98% in air and a clear chest. Her abdomen is tender in the epigastric region, with no guarding or rigidity. Her GCS is 15 with no focal neurology. Her triage weight is 44kg.

You grab the sepsis trolley. Cannula in you, send some bloods: FBC, coagulation, CRP renal and liver function and blood cultures. You run a venous gas and this is what you see…

That lactate is horrific. You hastily prescribe a 20ml/kg bolus of 0.9% saline and a broad-spectrum third-generation cephalosporin. But, what’s your next step?

You prescribe some paracetamol. Easy enough. And then you go back and think about what to do next.

Close the tab and have a think about some more choices or move on to the next section.

You give another 20ml/kg of 0.9% saline and reassess.

Her heart rate drops down a couple of beats per minute but it bounces up again. So you give more saline. But her heart rate goes up a bit higher. And higher again. She begins to hyperventilate. Heart sinking, you repeat her gas. Her pH has dropped, her lactate has climbed and her potassium looks horribly high. This was NOT supposed to happen. The saline has done exactly the opposite of what you’d like it to do… how could that be? 

You wish you could go back in time and make that choice again. Luckily for you, that’s exactly what the inbuilt time travel machine is for.

Close the tab and take another look at the choices. If there’s nothing else you’d like to do then move on to the next section.

You give another 20ml/kg, but this time, instead of reaching for the saline, you go for Plasmalyte (or Hartmann’s, if that’s your fluid of choice). You reassess. Her heart rate drops down a couple of beats per minute but it bounces up again. Her pulses remain bounding, BP holds and JVP isn’t raised with no rales in her chest so you give another bolus and reassess. Same thing happens: a miniscule response but nothing substantial. You don’t make things worse, but you can’t seem to make things better either. Why isn’t fluid bringing down Francesca’s heart rate?

Close the tab and take another look at the choices. If there’s nothing else you’d like to do then move on to the next section.

Her ECG shows a sinus tachycardia. She’s in sinus rhythm with a p wave before each QRS and a normal p wave axis; her QRS axis is normal and intervals are normal too. There are no voltage criteria for ventricular hypertrophy and you can’t spot any subtle ST changes or delta waves. You use a handy ECG proforma to double check, but apart from the tachycardia, it all looks fine. So you go back to Francesca and have a think about what to do next.

Close the tab and take another look at the choices. If there’s nothing else you’d like to do then move on to the next section.

You have recently been on a POCUS course so you want to try out your ultrasound skills. You ultrasound her abdomen. It looks normal. The eminent professor of ultrasonography wanders by. You ask him to double check your findings. He agrees, ultrasound is normal. 

Close the tab and take another look at the choices. If there’s nothing else you’d like to do then move on to the next section.

While you’re pondering what to do, you receive a phone call from your bank. It’s noisy in ED so you pop into the corridor. The bank tells you they’ve just realised they owe you a couple of hundred pounds (*replace pounds with Euros, Dollars, Australian Dollars or any other local currency). That’s great news! Smiling, you type out a quick text to your best friend. “Epic windfall. Celebrate later in China Town?” You can almost smell the chow mein. Your stomach rumbles. It’s definitely time for some lunch. You let Francesca’s nurse know you’re going for a break.

Just as you’re finishing your sandwich, Francesca’s nurse comes rushing to find you. What with the phone call, the texting and the lunchtime queue in the canteen, it’s been almost three quarters of an hour since you last reviewed Francesca. She is far more agitated. The monitor is alarming. Her temperature is now 40.2°C and she’s very sweaty. She looks a little blue. With a heart rate of 159, BP of 108/72, respiratory rate of 32 and O2 saturations of 93% in air, things are not looking good.

Her mother wails, “Will she be better for her audition?!”

You repeat her gas. It’s not good – her lactate’s now 9.3 and her pH is down to 7.03.

Her nurse hands you an ECG. Scanning it you spy peaked T waves, wide QRS complexes and a prolonged PR.

Hang on! What was the potassium on that gas?! You snatch up her gas – her potassium’s 7.2! How are you going to bring that potassium down? What will you prescribe first?

This is a great first choice. Calcium gluconate stabilises Francesca’s cardiac membrane, buying you some time. The gluconate’s in. But that potassium still needs to come down. How are you going to do that?

Close the tab and choose a second drug or drug combination to bring that potassium down. If you’ve already done that and you’re happy with your choice then move on to the next section.

Fabulous! Sodium bicarbonate is an ideal drug in a child or young person who has hyperkalaemia AND acidosis (but you might want to stabilise the cardiac membrane first, if you haven’t done this already). You prescribe a sodium bicarbonate bolus once Francesca’s had her calcium gluconate and ask your amazing resus nurse to start to prepare for an insulin and dextrose infusion.

Close the tab and move on in the story.

On goes the salbutamol nebuliser while the infusion is drawn up. Up goes the infusion. But then something terrible happens. Francesca’s heart rate climbs higher and higher. And then higher again. Her pulse is thready, she’s more diaphoretic. You didn’t think it was possible but she looks even worse. A repeat ECG confirms your worst fears: she’s in SVT. 

Let’s jump back in that time machine and try that vote again. Close the tab and have a look at your other options.

Insulin and dextrose sounds like a good choice. But do you want to give it as your first line agent to bring Francesca’s potassium down? Or after something else?

You get out your phone – there must be an app there somewhere that tells you how to prescribe insulin dextrose infusions for hyperkalaemia. After much tapping and scrolling you find what you’re looking for and write it up. Your amazing resus nurse starts making up the infusion. 13 minutes later it’s up and running. But it’s too late. Francesca’s potassium has continued to climb and she’s going into a VT arrest. No!

It’s time for the time machine. Close this tab and click on “after something else”

This sounds very sensible. After all, insulin-dextrose infusions can take ages to draw up and you need to give something that will work quickly to stabilise her myocardium as well as something that will help drive the potassium back into the cells.

Close the insulin and dextrose tab and choose two drugs: one to stabilise the myocardium and one to bring down the potassium. Hint: she’s acidotic.

Phew! Francesca’s ECG rhythm is improving. Crisis averted. Or is it?

By now Francesca is so agitated, it’s becoming impossible to keep her in bed. “I have to rule out an intracranial infection”, you think to yourself. She needs a CT.

Her nurse begs you to give her a sedative. This makes you a little anxious (pun totally intended). You know that sedation in a sick child can be lethal. So, how will you manage her agitation?

You don’t want to risk giving her a sedative. You’re quite fond of being a doctor and this is a high stakes situation – you don’t want to lose your medical licence if she arrests. Her nurse rolls his eyes – you’re not the one trying to hold her in bed. But as Francesca rips out her cannula and throws herself against the wall you come to the realisation that you are going to have to prescribe something.

Close this tab and go back to choose a sedative.

You like ketamine, you use it a lot and it’s got an excellent safety profile, right? You give Francesca 1mg/kg. She drifts off into a dissociative state. Unfortunately you weren’t as right as you thought. Because it inhibits reuptake of catecholamines it tends to push heart rates up. Francesca becomes extremely tachycardic. After 20 minutes she starts to develop emergence phenomena and becomes even more agitated. She arrests. But don’t worry, we’ve given you a time travel machine for this very reason.

Close the tab and go back to make a different choice.

Unfortunately haloperidol, like Olanzepine, lowers seizure thresholds. You remember this just as it’s infused. Francesca starts fitting. And to make matters worse, it has also prolonged Francesca’s QTc. Her cardiac rhythm becomes unstable and she arrests. Not what you intended. You hop in your time travel machine and go back to make that choice again.

Close the tab and go back to make a different choice.

Unfortunately Olanzepine, like Haloperidol, lowers seizure thresholds. You remember this just as it’s infused. Francesca starts fitting. And to make matters worse, it has also further prolonged Francesca’s QTc. Her cardiac rhythm becomes unstable and she arrests. Not what you intended. You hop in your time travel machine and go back to make that choice again.

Close the tab and go back to make a different choice.

You give Francesca a nice calming benzodiazepine. She settles, buying you some time.

Close the tab and read on to the next part of the story.

You want Francesca out of ED – this is too stressful! Thankfully PICU have a bed. You compassionately explain to Francesca’s mum that the PICU team will work very hard to treat Francesca but she’s very, very sick. Her mum starts crying, “She’s such a beautiful girl! She was going to be famous! She’s worked so hard to lose weight for her audition!”

Internal alarm bells start ringing. “Hang on! How has she lost weight?” Eyes wide, you ask her mother, “Has she been taking something?!?”

Just as you garble this, Francesca’s dad arrives. He’s found a bottle of pills in Francesca’s room. The label says DNP. They were next to her exercise bike.

You ask switchboard to put you through to the national toxicology advice line. The toxicologist who answers the phone tells you that DNP, short for dinitrophenol, is a diet pill that’s illegal in most countries but quite freely available over the internet. It’s called a fat burner because DNP short circuits mitochondrial ATP production by uncoupling oxidative phosphorylation. Because ATP can’t be produced, metabolic rate increases and energy is instead released as heat. People who take it literally burn fat. But even a single pill can lead to uncontrolled hyperpyrexia and its toxic effects are increased with exercise.

They tell you that Francesca’s bloods must be monitored closely; her liver function will deteriorate as her liver literally cooks from within; she will become hypoglycaemic as her glycogen stores are consumed; and she’ll become hyperkalaemic. Monitor her methaemoglobin and if it reaches 30% or if there are signs of tissue hypoxia, give methylene blue.

They give you a long list of treatments including…

Cold intravenous fluids…

…ice packs…

…gastric and bladder cold fluid lavage with peritoneal cooling if you can…

…and Dantrolene…

…and if that fails… then a cooling heat-exchange central line… or ECMO if you’re really stuck.

That temperature just has to come down.

You thank toxicology and replace the handset and think to yourself, “Now where will I find Dantrolene?”

But while you’re pondering this, things go from bad to worse. Francesca’s temperature continues to climb. She’s now 41°C. She’s boiling. Sweat drips onto the sheets. She starts to have a generalised tonic-clonic seizure. You give her a dose of IV. Lorazepam but she continues to seize.

What will you give next?

But a second benzo doesn’t do the trick. She continues to seize. What will you give next?

Close the tab and have another look at the options.

Phenytoin seems like a sensible idea. It’s the second line anticonvulsant in APLS after all. You prescribe 20mg/kg and the infusion’s set up. But it wasn’t a sensible idea. In fact, it was a terrible idea. The phenytoin has exacerbated sodium channel blockade, making her QRS becomes extremely wide. Despite your best efforts to manage her arrhythmia she arrests. It’s time for the time machine. Let’s go back in time to try that one again.

Close the tab and take another look at the options.

You decide to avoid phenytoin because in the context of a toxin you were worried it would prolong her QTc and make her arrest. And ECLIPSE and CONSEPT showed it’s non-inferior to phenytoin in the management of seizures. It’s a good choice.  Her seizure stops.  What a relief.

Close the tab and move on in the story.

You decide to avoid phenytoin because you were worried its sodium channel blocking properties will widening her QRS complexes and make her arrest. And you’ve heard phenobarbital remains the second line recommended treatment in seizures secondary to recreational drugs. It’s a good choice.  Her seizure stops.  What a relief.

Close the tab and move on in the story.

Things can’t get any worse, right? Wrong. She is making a funny snoring noise. You’re really worried about her airway. You fast bleep the anaesthetist. Finally something’s going right, he’s just walking past, and he’s in resus in less time than you can say “dinitrophenol.” He’s up to speed in no time, and definitely agrees she needs a tube. Your RSI cocktail of choice is ketamine (1-2mg/kg), fentanyl (1mcg/kg) and rocuronium (1-2mg/kg). It’s the least cardio-unstable combination of drugs and you definitely don’t want to make things worse. (Take a look at ‘The curious incident of the wheeze in the night time’ for more on this.) But, luckily for you, the  anaesthetist is a clever guy and says, “Let’s avoid fentanyl since she’s hyperpyrexic as fentanyl’s serotonergic – we don’t want to raise her body temperature any higher than it is already.”

The resus nurse mishears his instruction and almost makes a fatal mistake. Spying a syringe labelled suxamethonium, the anaesthetist (who you decide is your new best friend) calmly says, “No suxamethonium. Her potassium is high. She’ll arrest with sux.”

He intubates successfully using midazolam, propofol and rocuronium.  She’s easy to ventilate.

Finally Francesca’s ready for PICU. With cold fluids, ice packs and Dantrolene her temperature comes down to 37.9 °C. You hand her over with clear instructions to avoid…

…serotonergic drugs (put away that fentanyl)

… or drugs that prolong QRS (don’t even think about phenytoin if she fits again)

…and to set up ECMO if her temperature climbs again.

18 months later you watch Francesca perform live in Eurovision. She receives “Douze points!” from every country, setting the record for the highest ever Eurovision score. She campaigns for better awareness of body image in girls and is vocal about the dangers of diet pills.

But let’s hop back in that time travel machine one last time and see what your learning was from her case…

You find this review article about DNP.

Grundlingh J, Dargan PI, El-Zanfaly M, Wood DM. 2,4-dinitrophenol (DNP): a weight loss agent with significant acute toxicity and risk of death. J Med Toxicol. 2011;7(3):205-212

Fascinatingly, as well as all the clinical management advice you received from your friendly toxicologist, it also tells you a bit about the history of DNP. You’re intrigued to read that the first death from DNP was over 100 years ago in 1918 secondary to occupational exposure of DNP powder.  It was used in France for the manufacture of munitions during the First World War.  In 1933 it was discovered that human consumption led to significant weight loss. It became very popular as a weight-loss drug but within 5 years it was recognised as being extremely dangerous and was labelled as “not for human consumption” by the FDA in 1938.  Anecdotally, it was prescribed to Russian soldiers during World War II to keep them warm.

It all went wrong in the 80s (didn’t it all?).  An American doctor prescribed DNP tablets to thousands of patients through his private weight loss clinic.  In 1986 he was convicted for drug law violations, fined and prohibited from dispensing DNP to patients.  But this didn’t stop him.  He was eventually jailed for fraud in 2008. But DNP is still out there and sadly widely available on the internet…

So, what has Francesca’s case taught us (aside from reminding us how very cool the Eurovision Song Contest is)?

1. Infection isn’t the only cause of fever

Keep your differentials open. You only need to Google ‘differentials fever + tachycardia’ and the first thing that pops up is a 2013 article titled, ‘Intoxications Associated With Agitation, Tachycardia, Hypertension, and Fever: Differential Diagnosis, Evaluation, and Management.’ (True as of 1st November 2020). Toxicological agents include drugs that cause:

  • Serotonin Syndrome: some antidepressants including SSRIs, SNRIs and lithium, anticonvulsants such as valproate, analgesics such as fentanyl, antiemetics such as ondansetron and street drugs such as cocaine, ecstasy, methamphetamine and LSD.
  • Neuroleptic Malignant Syndrome: ‘typical’ antipsychotics such as haloperidol, newer ‘atypicals’ such as risperidone and olanzepine, antiemetics such as metoclopramide and promethazine.
  • Malignant Hyperthermia: an inherited skeletal muscle disorder triggered by inhaled anaesthetics, succinylcholine, heat or exercise.
  • Sympathomimetics: cocaine, ketamine, ecstasy, amphetamines, synthetic cannabinoids.

Toxicology isn’t where it ends though. In our COVID world we’ll be used to including inflammatory syndromes like PIMS-TS to our list of differentials, but don’t forget other inflammatory syndromes including inflammatory bowel disease and rheumatological; oncological presentations; intracranial causes (bleed, tumour, basically anything that damages the hypothalamus can dysregulate temperature control); endocrine causes like thyroid storm, adrenal crisis… and the list goes on.

2. Engage your toxicology colleagues early

Even if you don’t think the primary cause is toxicological, as soon as it could be then pick up the phone to your regional / national toxicological service. Sedatives, anticonvulsants, anaesthetic induction cocktails… there are many ways things can go wrong. Ask a friend for advice before prescribing drugs in a potentially unstable situation.

3. Familiarise yourself with the management of acute behavioural disturbance

Acute behavioural disturbance can be a very challenging situation to manage. RCEM, the Royal College of Emergency Medicine in the UK, has a short guideline explaining the pros and cons of the different drugs of chemical restraint. Although not specifically tailored to paediatric presentations, the explanation of the drug side effects is a useful guide to frame your management. From a paediatric perspective, NICE (The National Institute of Health and Care Excellence, UK) have a pathway specific for children. If behavioural techniques don’t work and you need to move onto a pharmacological approach, NICE only advocates the use of IM lorazepam. The Royal Children’s Hospital in Melbourne’s ‘Acute Behavioural Disturbance: Acute Management’ CPG has an escalation ladder from behavioural management, to oral, then IM / IV medications, clearly stating antipsychotics should only be given to children who have previously taken antipsychotics or who have a normal ECG. Read it in conjunction with the RCEM guideline to understand the risks of each drug.

4. Think about the approaches to managing fever

We love a bit of paracetamol or ibuprofen to bring down a fever. But do you know how they work? Although paracetamol’s been used for over 100 years, we’re still not entirely sure how it works. Its antipyretic actions are thought to be due to inhibition of prostaglandin synthesis, resulting in a reset of the temperature centre in the hypothalamus. Nonsteroidals, such as ibuprofen, also inhibit prostaglandin production, although via a different cyclooxygenase (COX) pathway (all sounding vaguely familiar?).

However, fever caused by toxins is not caused by prostaglandin or COX inhibition and needs a different approach to resolve.

Start with non-pharmacological measures. Fans, ice packs in the groins and axillae, ice baths and internal techniques such as gastric and bladder cold fluid lavage, or, more invasively, Intravascular Heat Exchange Catheters (the ICY Catheter). The ICY catheter is placed in the inferior vena cava via the femoral vein, acting as an extracorporeal cooling device. Cold saline circulates through the catheter, which is closed so does not infuse saline into the bloodstream, instead returning the now-warmed saline back out of the body. The patient’s core temperature is measured via a thermometer in the bladder and an automated feedback loop between the thermometer and the ICY Catheter ensures the patient’s temperature is brought down to a target range, which can be adjusted by the treating clinician. Add benzodiazepines to prevent shivering and for sedation to help the child or young person tolerate these techniques.

There’s an extremely high mortality in severe hyperthermia – if these measures don’t work then RSI with muscle paralysis (but avoiding suxamethonium), with benzodiazepine infusions.

And reach for the antipyretic drugs. Dantrolene is frequently used in the management of anaesthetic-induced malignant hyperthermia and neuroleptic malignant syndrome. It works as a postsynaptic muscle relaxant, inhibiting calcium ion release and therefore decreasing the amount of excitation-contraction coupling from muscle cells. It’s usually found in theatre, to keep it ready to hand for the treatment of malignant hyperthermia. But, theatre is often far from the ED, and unless you know it’s there, it can take a while to hunt it down in the hospital – don’t let this delay you using it emergently in ED. Although the use of Dantrolene in DNP toxicity is currently under debate with only a few case reports citing its efficacy in DNP toxicity, its use is still recommended to bring down temperatures above 39-40 °C by Toxbase (the UK National Poisons Information Service) because of the high lethality of DNP.

Other options include Cyproheptadine, a first-generation antihistamine with additional anticholinergic properties and antagonist to serotonin, used in the treatment of serotonergic-driven hyperpyrexia (Serotonin Syndrome). To date, there are no case reports of cyproheptadine being used in DNP toxicity.

And don’t forget to monitor CK and renal function.

5. Consider your resuscitation fluid

You may have heard the phrase ‘(ab)normal saline’ before. Sure, one bolus with 0.9% saline is probably fine, but we should be reaching early for a balanced crystalloid like Hartmann’s or Plasmalyte, and probably from the outset.

Francesca has a pure metabolic acidosis and is trying to compensate by dropping her PaCO2. (Ab)normal saline is 0.9% NaCl – that’s one chloride ion for every sodium ion. Chloride binds with hydrogen to form HCl, hydrochloric acid. Giving Francesca more acid in the form of chloride will plunge her pH lower. This will cause her to hyperventilate to compensate further, which will tire her out faster.

And then Francesca becomes hyperkalaemic. Worsening Francesca’s acidosis by giving more saline will only serve to make the hyperkalaemia worse for a number of reasons, the simplest one being that acidosis drives intracellular potassium to the extracellular (intravascular) space. ‘Why is that?’ you might wonder. Remember, we use alkaline sodium bicarbonate to treat hyperkalaemia by driving potassium into the intracellular space. Giving acidic sodium chloride does the opposite: the hydrogen potassium pump exchanges extracellular hydrogen for intracellular potassium, pushing potassium out of the cell into the intravascular space. Giving acid, makes hyperkalaemia worse. Have a look at this Paediatric FOAM post, ‘Hartmanns in hyperkalaemia: Is that (O)K?’, for a more detailed account as to why we shouldn’t use saline in hyperkalaemic patients.

6. Have a strategy for your emergency treatment of hyperkalaemia

The treatment of life-threatening hyperkalaemia has three facets. All three are important but there is physiological and clinical  merit in doing these in order:

1) Membrane stabilisation

2) Shifting K+ into the cells

3) Reducing total body K+

The first two are the quick fix solutions for the ED. The last solution involves potassium diuresis and haemodialysis or haemofiltration and will traditionally be dealt with on the renal unit or PICU – we will expand on these in a separate blog.

IV Calcium Gluconate

Calcium is vital for stabilising the myocardium. Avoidance of a lethal arrhythmia is our primary concern in life threatening hyperkalemia and so giving calcium first is a priority.

Initial dose: Assuming we have peripheral access the dose is 0.1-0.3 ml/kg IV calcium gluconate 10%  over 10 minutes, diluted fivefold to 20mg/ml. Aim for an ionised calcium >1.15  and repeat if required, remembering that a one-off dose will usually last between 30 minutes to an hour. In the case of persistent arrhythmias or particularly resistant hypocalcaemic state further doses of calcium may be indicated or an infusion can be considered (0.2ml/kg/hr of calcium gluconate 10% diluted as above).

Bicarbonate

It is important to understand that bicarbonate will only work in hyperkalaemia if the patient is in an acidotic state. In this context not all bicarbonate solutions have been created equal.  8.4% bicarbonate is very hypertonic and a number of RCT’s suggest that, if given neat, it will not work in reducing serum potassium levels in hyperkalemic patients. This is thought to be due  to the phenomenon of solvent drag; the hypertonic fluid drags potassium ions to the extracellural compartment due to an osmotic shift. This essentially neutralises the effect a neutral or alkali pH has in the direction of movement of the K+ ions making the overall net shift minimal.

On the other hand, isotonic bicarbonate works in patients in an acidotic hyperkalemic state. Isotonic bicarbonate isn’t commercially available in most UK based hospitals but can be made by diluting each milliliter of 8.4% sodium bicarbonate with 4.6 ml of sterile water for injection or 5% dextrose.  A 1.5% solution of sodium bicarbonate is approximately isotonic. Isotonic bicarbonate can rapidly improve hyperkalemia if the patient is acidotic in three ways: a) by shifting potassium intro the intracellular compartment, b) by increasing potassium diuresis due to alkalosis and c) due to a dilutional effect.  1mmol/kg of isotonic bicarbonate can be given to alkalinise the pH and cause a K+ shift.

Insulin

Insulin shifts potassium into cells by stimulating the activity of the Na+– H+ channel on cell membranes. This in turn promotes the entry of sodium into cells, which leads to activation of the Na+– K+ ATPase, causing an influx of potassium. The decline in serum potassium levels by insulin is dose dependent. Due care must be taken to avoid hypoglycaemia, especially in infants and children with nephropathies.  The doses of IV insulin are as follows:

Neonates: 0.3 – 0.6 units/kg/hour

Children > 1 month: 0.05 – 0.2 units/kg/hour 

Run with glucose 0.5 – 1 g/kg/hour (5-10 ml/kg of glucose 10% via peripheral administration)

Salbutamol

Salbutamol causes a small shift of potassium into cells but a high dose is needed for an adequate effect, around 10-20mg on average. This equates to 4 to 8 back to back nebulised doses depending on the patient’s age. Salbutamol use comes with a caution however; it can both worsen a pre-existing acidosis by driving up lactate (essentially having a neutral effect  on potassium clearance) and will also cause a tachycardia, and in patients prone to arrhythmias, it can cause SVT’s or even VF. It should not be first line treatment, and certainly not before the membrane has been stabilised with calcium nor before the pH has been made less acidotic.

7. And DNP?

DNP toxicity is a well reported presentation to the ED, including a case report of a fatality in a teenage girl, using it as a weight-loss drug

Features usually occur within 4 hours, with agitation, flushing, hyperthermia and diaphoresis. As with Francesca, there may be abdominal pain, vomiting and diarrhoea. There may be yellow discolouration to the skin and urine, which can be confused with jaundice, and rash and desquamation can be a feature, (mis)leading you down the path of toxic shock. The deterioration can be very rapid with grossly elevated temperatures, heart rates and respiratory rates.

And the investigations? A metabolic acidosis secondary to raised lactate, methaemoglobinaemia, hyperkalaemia, hypocalcaemia and hyperglycaemia (at least until glycogen stores become depleted, when the blood sugar will drop).

Have a read of the letter to the editor in response to this case report, two case reports from the States, and a further report from London and decide for yourself whether you’ll be reaching for Dantrolene to treat DNP toxicity.

But, let’s finish on a cautionary tale. Dantrolene can be hepatotoxic so monitor liver function closely. This case report describes a child who developed hepatitis after dantrolene at a pretty low dose.

We would LOVE your feedback about these DFTB PEM adventures so if you can spare a minute, please complete our survey at www.tiny.cc/DFTBpemadventure or use your smartphone to let the QR code take you straight there. We timed ourselves completing it and it takes less than a minute. Thank you.

A HUGE thank you to Dr Laura Hunter, EM and Toxicology consultant at Guy’s and St Thomas’ NHS Foundation Trust in London, UK. As well as a wicked sense of humour, Laura has an encyclopedic knowledge of all things toxicological. Thank you Laura.

And we are absolutely delighted to announce that our friend, Costas Kanaris, has joined the PEM adventures team, bringing with him his wisdom of all things critical care and general brilliance.

References

Keary CJ, Nejad SH, Rasimas JJ, Stern TA. Intoxications associated with agitation, tachycardia, hypertension, and Fever: differential diagnosis, evaluation, and management. Prim Care Companion CNS Disord. 2013;15(3):PCC.12f01459. doi:10.4088/PCC.12f01459

Blumberg A, Weidmann P, Ferrari P. Effect of prolonged bicarbonate administration on plasma potassium in terminal renal failure. Kidney Int. 1992;41(2):369-374.

Kim H. Acute therapy for hyperkalemia with the combined regimen of bicarbonate and beta(2)-adrenergic agonist (salbutamol) in chronic renal failure patients. J Korean Med Sci. 1997;12(2):111-116.

Kim H. Combined effect of bicarbonate and insulin with glucose in acute therapy of hyperkalemia in end-stage renal disease patients. Nephron. 1996;72(3):476-482.

Conte G, Dal C, Imperatore P, et al. Acute increase in plasma osmolality as a cause of hyperkalemia in patients with renal failure. Kidney Int. 1990;38(2):301-307.]

Fraley D, Adler S. Correction of hyperkalemia by bicarbonate despite constant blood pH. Kidney Int. 1977;12(5):354-360.

end-stage renal disease. Miner Electrolyte Metab. 1991;17(5):297-302.

Gutierrez R, Schlessinger F, Oster J, Rietberg B, Perez G. Effect of hypertonic versus isotonic sodium bicarbonate on plasma potassium concentration in patients with

DeFronzo RA, Felig P, Ferrannini E, et al. Effect of graded doses of insulin on splanchnic and peripheral potassium metabolism in man. Am J Physiol. 1980;238(5):E421–E427

Grundlingh J, Dargan PI, El-Zanfaly M, Wood DM. 2,4-dinitrophenol (DNP): a weight loss agent with significant acute toxicity and risk of death. J Med Toxicol. 2011;7(3):205-212. doi:10.1007/s13181-011-0162-6

Allen L. Hsiao, Karen A. Santucci, Patricia Seo-Mayer, M. Rajan Mariappan, Michael E. Hodsdon, Kenneth J. Banasiak & Carl R. Baum (2005) Pediatric Fatality Following Ingestion of Dinitrophenol: Postmortem Identification of a “Dietary Supplement”, Clinical Toxicology, 43:4, 281-285, DOI: 10.1081/CLT-58946

Kim Barker, Donna Seger & Suparna Kumar (2006) Letter To The Editor: “Comment on “Pediatric Fatality Following Ingestion of Dinitrophenol: Postmortem Identification of a ‘Dietary Supplement’””, Clinical Toxicology, 44:3, 351, DOI: 10.1080/15563650600584709

Siegmueller C, Narasimhaiah R. Fatal 2,4-dinitrophenol poisoning… coming to a hospital near you. Emergency Medicine Journal 2010;27:639-640.

Kopec KT, Kim T, Mowry J, Aks S, Kao L. Role of dantrolene in dinitrophenol (DNP) overdose: A continuing question? Am J Emerg Med. 2019 Jun;37(6):1216.e1-1216.e2. doi: 10.1016/j.ajem.2019.03.035. Epub 2019 Mar 23. PMID: 30948257.

Divij Pasrija, Shilpi Gupta, Amanda Hassinger. Dantrolene-Induced Hepatitis: A Rare Culprit in the PICU. J Pediatr Intensive Care 2020. DOI: 10.1055/s-0040-1710496

Van Schoor J, Khanderia E, Thorniley A. Dantrolene is not the answer to 2,4-dinitrophenol poisoning: more heated debate. BMJ Case Rep. 2018 Dec 19;11(1):e225323. doi: 10.1136/bcr-2018-225323. PMID: 30573533; PMCID: PMC6303589.

PEM Adventures Chapter 2

Cite this article as:
Team PEM Adventures. PEM Adventures Chapter 2, Don't Forget the Bubbles, 2020. Available at:
https://doi.org/10.31440/DFTB.30926

Are you ready for another PEM adventure? This time the stakes are a little higher. Join us on another journey (with an inbuilt time travel machine) as we manage Grace…

Teenager holding mobile phone

Meet Grace. Grace is a 15-year-old vegetarian environmental activist. She’s thrilled because she’s recently hit a TikTok following of 10,000 – social media is SO the way to spread the word.

She spent yesterday at an illegal climate strike rally outside parliament. Buoyed up on the adrenaline of a thrilling protest, she and some buddies went back to her friend, Zak’s house where they celebrated in style with vodka pops. But this morning, horrified by the fact Grace was impossible to wake, Zak called the emergency services.

Meanwhile, you’ve just fished a pea out of a child’s ear when the red phone rings. Hearing the pre-alert, you mobilise the team and prep a bay in resus. Minutes later, Grace is wheeled in with Zak in tow and she’s transferred to a trolley.

Whiteboard containing vital signs

Your SHO, Lucy, does a primary survey:

  • A: Tolerating an oropharyngeal airway. No stridor or stertor.
  • B: Self-ventilating in 15L O2 via a non-rebreathe mask. Respiratory rate is a bit raised but her chest is clear and she doesn’t have any other signs of respiratory distress.
  • C: Warm and well perfused, heart rate 68 with normal heart sounds and normal pulse volume. Blood pressure is 115/70 and capillary refill time is less than 2 seconds.
  • D: GCS 7, made up of M4, V2, E1. Pupils are size 3 bilaterally and normally reactive to light. Tone is generally low but reflexes are normal and plantars are down going.
  • E: No rashes, no bruises and Grace is currently afebrile.

Lucy gets Grace’s mum’s number from Zak and phones her to get a bit more information. Grace is a healthy adolescent with no significant past medical history. She’s not on any medications, is not allergic to anything and is fully vaccinated. She’s been completely well with no fever, cough, coryza, or any other symptoms. She did have a cold sore a few months ago – could that be relevant?

Grace’s parents, who had gone away for the first time since covid-lockdown lifted, are running to the train station to make their way back home.

Back in resus, you put in a cannula, and send off some bloods: FBC, U&E, LFT, CRP, blood culture and an alcohol level.

Her venous gas shows a pH of 7.47, pCO2 of 2.7, bicarb 14, lactate of 2.7 and normal glucose.

Blood gases showing respiratory alkalosis

That’s odd, you think to yourself, a respiratory alkalosis with some metabolic compensation. You pause for a second and work through your list of possible causes.

  1. Could this be a central cause of hyperventilation? A bleed? A tumour? A meningoencephalitis? You put up a request for CT brain. 
  2. Could this be a respiratory cause? Asthma? Pneumonia? Pneumothorax? Better get a chest x-ray too.
  3. Could this be sepsis? You prescribe ceftriaxone and add acyclovir. There was that coldsore after all…
  4. Pregnancy?
  5. Endocrine or hypermetabolic cause? Maybe DKA? No… her blood sugar’s normal. Or thyrotoxicosis?
  6. Maybe it’s something toxicological? You remember, from your undergraduate days, learning that salicylates cause a respiratory alkalosis.

You add a salicylate level, and paracetamol for good measure, add thyroid function and ask for a catheter urine for beta HCG and a tox screen.  

But her catheter urine doesn’t give you any extra clues. Grace’s urine beta-HCG is negative, her tox screen is negative and her dip is negative.

The resus nurse gently touches your elbow and quietly says, “Do you want to call the anaesthetist?

Good question, you think to yourself. Her GCS is 7 and she’s tolerating the oropharyngeal airway, but she’s breathing well for herself at the moment. What do you want to do?

There are some compelling arguments not to intubate; Grace is maintaining her airway and she’s obtunded and may have seizures – if you give her a paralysing agent as part of her RSI you’ll never be able to tell. Sure, if you really want to monitor for seizure activity, AND you’re in a a tertiary centre with a PICU with capability of CFM or EEG monitoring, you could keep arguing you can monitor for seizure activity while she’s intubated and ventilated, but it takes a while to set up, and time is of the essence.

So you make the brave decision not to intubate. 

You later decide it was less brave and more foolhardy. While Grace is in CT she drops her GCS further and then has a respiratory arrest, which quickly deteriorates into cardiac arrest. The scanner is a terrible place for CPR. While you’re trying to run an arrest on a narrow CT bed you wish you could go back in time and make that choice again. Luckily for you, the inbuilt PEM adventures time travel machine can do just that. In you hop and whizz back to resus.

Close the toggle and this time click on the ‘intubate’ choice.

There are some compelling arguments not to intubate; Grace is maintaining her airway and she’s obtunded and may have seizures – if you give her a paralysing agent as part of her RSI you’ll never be able to tell if she’s seizing. 

But there’s something niggling you… Grace is heading for a CT scan and the LAST thing you need is for her to arrest in the scanner.

And yes, it’s true, there is a risk you could miss a seizure if she was paralysed, but you can give her a long-lasting anticonvulsant to prevent seizures. 

So… you decide to follow your gut and make the decision to intubate.

Thankfully the anaesthetist is nifty with a tube and she’s already drawn up the RSI drugs – fentanyl, ketamine and rocuronium in a 1:1:1 ratio (that’s fentanyl 1mcg/kg, ketamine 1mg/kg and rocuronium 1mg/kg). She’s intubated without difficulty. 

Grace has bilateral equal breath sounds and a mobile chest x-ray shows the tube to be in a good position, with clear lung fields and normal heart size. You mentally cross respiratory causes of an alkalosis off your list.

You’re doing great.

The anaesthetist asks you, “How should I ventilate Grace? Should I match her raised respiratory rate?

That’s a good question, you think to yourself. What should you do?

This is a very good question and you’re not sure you know the answer. Grace is hyperventilating for some reason, and maybe mimicking this is the right thing to do…

But, you’re worried about her ultra low pCO2. At 2.7 it’s likely to be causing cerebral vasoconstriction and hypoperfusion. It’s time to start some simple, proactive neuroprotective measures.

On reflection, you decide it would be better to slow Grace’s breathing so resolutely you turn back to the anaesthetist and ask him to SLOW Grace’s respiratory rate to keep her end tidal CO2 tightly between 4.5 and 5; you want to prevent secondary brain injury.

He nods his assent, while tilting the head of the bed up to 30 degrees.

But, remembering a great DFTB post by Costas Kanaris, you know you can do more than that to neuroprotect. As well as maintaining normocapnia and nursing her at 30 degrees head in line, Grace needs strict normothermia and hypoxia should be avoided at all costs. She needs vigilant glucose monitoring, tight circulatory monitoring and support and an anticonvulsant to prevent seizures. 

Close the toggle and move on to the next part of the story.

You think this through. The alkalotic pH doesn’t matter quite so much, what’s really troubling you is Grace’s pCO2. With a pCO2 of 2.7, there’ll be huge amount of cerebral vasoconstriction and hypoperfusion. It’s time to start some simple, proactive neuroprotective measures.

Resolutely you turn back to the anaesthetist and ask him slow Grace’s respiratory rate to keep her end tidal CO2 tightly between 4.5 and 5; you want to prevent secondary brain injury and so now’s the time to start some neuroprotection.

He nods his assent, while tilting the head of the bed up to 30 degrees.

But, remembering a great DFTB post by Costas Kanaris, you know you can do more than that to neuroprotect. As well as maintaining normocapnia and nursing her at 30 degrees head in line, Grace needs strict normothermia and hypoxia should be avoided at all costs. She needs vigilant glucose monitoring, tight circulatory monitoring and support and an anticonvulsant to prevent seizures. 

Great choice! Close the toggle and move on to the next part of the story.

With fortuitous timing, CT ring down to say they’re ready for Grace.

Satisfied that A, B and C are all stable, you turn to take the brake off the trolley when Lucy, your SHO, asks, “But do we only want a plain non-contrast CT?

That’s a good question, you think to yourself. Is that all I want? What neuroimaging will you choose?

“Yes”, you say to Lucy. “A non-con CT is quick and will show us most tumours and bleeds. She can have an MRI later to get a bit more detail.” 

But,” your SHO counters, “a non-con CT won’t always detect an ischaemic stroke. Perhaps we should ask for a CTA too?

You remember a case from a few weeks ago, a little boy called Tomas. You’d bookmarked the RCPCH Stroke in Childhood guideline on your phone. You quickly bring it up and Lucy’s right, the guideline says to consider stroke in children with focal neurology, speech disturbance, focal seizures, severe headache, cerebellar signs… and unexplained decreased conscious level.

Smiling gratefully at Lucy you pick up the phone and ask the radiologist if you can add a CTA. They say yes.

Minutes later, Grace has her CT with CTA… but it’s normal. No abscess… no tumour… no bleed… and no stroke.

Well that’s good news for Grace, you think to yourself, but it doesn’t give you any much-needed clues.

Great work. Close the toggle and move onto the next part of the story.

You know what”, you say to your SHO, “let’s ask for a contrast-enhanced CT. It’s still quick and will give us a little more detail than a non-con CT.

But,” she counters, “do you think we should be considering stroke in our differential? Perhaps we should ask for a CTA too?

You remember a case from a few weeks ago, a little boy called Tomas. You’d bookmarked the RCPCH Stroke in Childhood guideline on your phone. You quickly bring it up and Lucy’s right, the guideline says to consider stroke in children with focal neurology, speech disturbance, focal seizures, severe headache, cerebellar signs… and unexplained decreased conscious level.

Smiling gratefully at Lucy you pick up the phone and ask the radiologist if you can add a CTA. They say yes.

Minutes later, Grace has her CT with CTA… but it’s normal. No abscess… no tumour… no bleed… and no stroke.

Well that’s good news for Grace, you think to yourself, but it doesn’t give you any much-needed clues.

Great work. Close the toggle and move onto the next part of the story.

You know what”, you say to your SHO, “let’s ask for a CT plus CTA. The CT will show us most tumours and bleeds and she can have an MRI later for a bit more detail, but we should consider stroke in our differential, and to detect that we need to add angiography to our CT.

You think back to a case from a few weeks ago, a little boy called Tomas. You’d read the RCPCH Stroke in Childhood guideline and remember that it says to consider stroke in children with focal neurology, speech disturbance, focal seizures, severe headache, cerebellar signs… and unexplained decreased conscious level.

Smiling gratefully at Lucy you pick up the phone and ask the radiologist if you can add a CTA. They say yes.

Minutes later, Grace has her CT with CTA… but it’s normal. No abscess… no tumour… no bleed… and no stroke.

Well that’s good news for Grace, you think to yourself, but it doesn’t give you any much-needed clues.

Great work. Close the toggle and move onto the next part of the story.

You haven’t ruled out infection. So, when you’re back down in resus, you ask Lucy if she’d like to do the LP.

Really? Is that safe with her low GCS?” she questions. 

What do you think? Should you LP?

It’s fine,” you reply, “she doesn’t have physiological signs of raised ICP: she’s not bradycardic or hypertensive, she’s not posturing and she didn’t have focal neurology. Plus, her CT doesn’t look like there’s cerebral oedema.

Feeling reassured, Lucy picks up the spinal needle and performs an LP. 

But it’s not your finest decision. Grace cones and arrests. 

Luckily for you and Grace, there’s an inbuilt time travel function in your PEM adventure and you return back to resus just as your SHO asks if it’s safe to LP Grace.

You have a strange feeling of déjà vu, while a little voice tells you that although a normal CT is usually reliable for ruling out raised intracranial pressure, this isn’t failsafe and it might be safer to defer the LP for when she’s a little more stable. You’ve already started the ceftriaxone and acyclovir, so this time you decide that the LP can wait until she’s a bit more stable and can have an MRI first. 

Thank goodness for that time machine! Close this toggle and move onto the next part of the story.

Lucy’s right. Although a normal CT is usually reliable for ruling out raised ICP, this isn’t failsafe and there’s no rush to get CSF now. You’ve already started ceftriaxone and acyclovir anyway. And when she’s a bit more stable she can have an MRI to check the LP’s safe. The LP can wait for now.

Great teamwork! Close the toggle and continue the next part of the story.

You’re still not sure what’s causing Grace’s low GCS though. Maybe the bloods will help. So you log in to the computer to check Grace’s results.

Results showing a mild transaminitis

Huh, you think to yourself. Grace’s FBC and CRP are normal; it’s sounding less and less like infection.

Her urea is low and her liver enzymes are raised, with a slightly prolonged INR.

Her salicylate and alcohol levels are undetectable. This isn’t feeling so toxicological anymore.

You mull this over with Lucy. Maybe this is a viral picture. There was that cold sore…

Just then Maureen, the ED cleaner, pops her head into the office. “Might this be of any use?” she asks. She’s holding the RCPCH Decreased Conscious level guideline.

You quickly flick through. Bloods… imaging… you’ve done pretty much everything it suggests. But then you take a closer look at the list of bloods it suggests. And there, in black and white, it says ammonia.

Of course!” you say out loud. “That would explain the respiratory alkalosis!

You draw off an ammonia sample, get it on ice and ask Raymond, the dashing porter, to run it down to the lab. You give the lab a ring so they can get the machine primed.

While you’re waiting for the result to come back, Zak comes running over. He’s just been looking in Grace’s backpack for her mobile and found a high protein Diet book. Apparently she’s been trying to lose weight for TikTok. Could it be relevant?

The cogs begin to whir… Hang on a minute… A high protein diet in a vegetarian environmental activist?

The lab phones with Grace’s ammonia level.

It’s over 500! And normal is less than 40.

It all falls into place. Selective vegetarian… Recent protein load… Raised transaminases… High ammonia… This is all beginning to sound a bit metabolic.

But what should you do about that ammonia? As far as you can see, the DeCon guidance only tells you to take it, not what you do when it comes back at over 10 times the upper limit of normal.

Just a sec,” says Lucy scrolling through her mobile phone, “The British Inherited Metabolic Disease Group have got this covered. They’ve produced a whole range of easy access emergency guidelines, including this one, for the management of an undiagnosed hyperammonaemia.”

It says, turn off protein catabolism by giving a 10% dextrose bolus followed by a dextrose infusion to provide an alternative energy source. If her glucose climbs, add insulin but don’t reduce the dextrose – otherwise, she’ll just start breaking down more protein. And, finally, mop up that ammonia with scavengers like phenylbutyrate and sodium benzoate.

The words ‘ammonia scavengers’ remind you of another post you read on Don’t Forget The Bubbles, about the different types of metabolic conditions, how they present and the various treatment strategies. You make a mental note to read it again later to remind yourself of the differences between an amino acid and organic acid.

Meanwhile, you hastily prescribe…

  •       A 2ml/kg bolus of 10% dextrose
  •       a dextrose infusion
  •       And those ammonia scavengers, sodium benzoate and sodium phenylacetate

Grace is subsequently diagnosed as having a urea cycle disorder. You’re amazed to discover that although most diagnoses are made in neonates, diagnoses are sometimes made in adolescents and adults presenting encephalopathic after a big protein load or when catabolic, such as after trauma, childbirth, major surgery, major haemorrhage, critical illness, rapid weight loss or simply after switching to a high protein diet. This is particularly true for ornithine transcarbamylase (OTC) deficiency, which although is X-linked, can present in symptomatic female OTC carriers. Little diagnostic clues include autoselective vegetarianism (that protein makes them feel a bit ‘ugh’) and subtle or behavioural difficulties from chronic low-level hyperammonaemia.

You bookmark a fantastic review article to read later and flick back through your undergraduate biochemistry textbook to remind yourself about urea cycle defects… and hastily close it again when you remember how little you knew even then, at the prime of your undergrad years.

Wow, what a shift. You pack up your stethoscope and head home, reflecting on your day as you walk to the bus stop.

Grace has taught you the importance of…

Reaching for the RCPCH DeCon guideline when looking after a child with an unexplained low GCS.

Not ever forgetting to send an ammonia in an encephalopathic child, young person or even adult; these tricksy urea cycle disorders can present in adulthood. If the ammonia comes back high, BIMDG have a handy guideline telling you exactly what to do.

And, remembering that a normal CT does not ALWAYS rule out raised ICP. In a child with low GCS, put away that LP needle and neuroprotect instead.

But what happened to Grace? Let’s jump in the time travel machine and find out…

Your epic diagnosis of a late presenting metabolic disorder was the talk of the ED. The RCPCH DeCon poster was put up in the ED staff room and from that point onwards, everyone remembered to check an ammonia in a patient presenting with an unexplained low GCS. 

Lucy was nominated as employee of the month. This shift was a pivotal moment in her career as she decided PEM was her vocation.

The ammonia scavengers did the trick and Grace made a full recovery.

Grace focussed her efforts on reducing plastic waste in hospital and successfully petitioned for the introduction of plastic-free PPE, reducing plastic waste during the COVID-19 pandemic by an incredible 275%.

She hit 3 million TikTok followers (and you’re one of them).

This PEM adventure wouldn’t have been possible without some help from some amazing people. Thank you to Roshni Vara, Consultant in Paediatric Inherited Metabolic Disease at the Evelina London, Costas Kanaris, PICU and retrieval consultant at the Royal Manchester Children’s Hospital and Jon Lillie, PICU and retrieval consultant at the Evelina London Children’s Hospital.

Here are some of their wise words of advice…

As Costas says in The N of 1 matters, we’ve outlined our take on Grace’s case and how we’d manage her in our own resus bays. Medicine’s not always so clear cut and there are often different approaches to the same problem, but this is our consensus on minimising risk using, as Costas says, a rational, evidence-based and pharmacologically prudent approach (I love that phrase Costas!)

Should we intubate Grace?

Grace is self-ventilating but the fact that she is tolerating an oropharyngeal airway means some of her airway reflexes have gone. Scanning a child with a GCS of 8 or less, without securing the airway, puts them at risk. If they vomit, they aspirate. If they stop breathing and arrest in the scanner, the CT room is one of the least fun places to run an arrest, perhaps second only to an elevator. Are there any counter-arguments? Yes, and they’re soft.  One is “this patient is encephalopathic/obtunded and may have seizures; if the child starts fitting we won’t be able to tell as they’ll be paralysed”.  Costas says he usually stands his ground and says that if someone is worried about seizures then the child can be given a long-acting antiepileptic. Levetiracetam is his preference, although phenytoin would work just as well unless there’s suspicion of an overdose of an arrhythmogenic agent. The last thing you need is to tip this child into an arrhythmia.

When should a lumbar puncture be performed in a child with a decreased conscious level?

CT is a useful tool for ruling out raised intracranial pressure before proceeding to lumbar puncture. And we’d agree. But Grace has a low GCS and this changes the picture.

If we take a look at the full RCPCH DeCon guideline it dedicates a whole section to answering the question about LP in decreased conscious level. So, let’s start there.

The DeCon guideline advises a lumbar puncture if your differentials are viral encephalitis or tuberculous meningitis and advises that we consider lumbar puncture when our differentials are bacterial meningitis, sepsis, or the cause of the low GCS is not known. This is cloaked with the phrase “when no acute contraindications exist” and this is key. So what are those contraindications?

  • Signs of raised intracranial pressure: dilated pupil(s), abnormal pupil reaction to light, bradycardia, hypertension or abnormal breathing pattern.
  • A GCS equal to or less than 8, or a deteriorating GCS
  • Focal neurology
  • A seizure lasting more than 10 minutes with a GCS less than 13
  • Shock or clinical evidence of meningococcal disease
  • CT or MRI suggesting obstruction of the CSF pathways by blood, pus, tumour or coning.

What’s the evidence? Well, it’s mostly been derived by expert opinion, and there aren’t many people who’d dispute them.

But what about when you have a normal CT? The radiologists can look for midline shift and for signs of impending herniation by assessing the position of the cerebellar tonsils. So, surely that can rule out raised ICP, allowing an LP to be done?

The DeCon guideline quotes a study published in 2000 that showed that in 124 CT scans from 65 children with traumatic brain injury, CT had an excellent sensitivity of detecting raised ICP of 99.1%, with a specificity of 78.1%. But, a 2019 revision to the guideline says that no further evidence about the sensitivity or specificity of CT in detecting raised ICP in children has been found. None. Although the sensitivity in the one quoted study was very high, it was felt that one study, in children with traumatic brain injury, could not be extrapolated to all children with a decreased conscious level. And so the guideline states that a normal CT scan does not exclude raised ICP. If other contraindications are present, don’t use a normal CT to justify LP.

What does this mean in practice? Well, in a child with a GCS of 8 or less, like Grace, there’s no rush to do an LP. It’s unlikely to change your management acutely in the ED. Her infection can be treated empirically and once she’s more stable, and you have more information including, potentially, an MRI, she can then have an LP for PCR.

What neuroimaging should we do?

That’s a good question, answered beautifully by an article by Hayes et al, published in 2018. Although this article focuses on neuroimaging for headaches, it has a great section on when you might choose each type of scan.

We’d all agree that the ideal imaging to look for a brain tumour is an MRI. It gives excellent detail about the brain tissue as well as other intracranial soft tissues and the extra-axial CSF spaces.

But, if you want a quick answer, or your access to MR is difficult, a non-contrast CT can be performed easily from the ED. If there’s no possibility of a later MR, then contrast-enhanced CT might be better as it gives more detail, but it’s more radiation – this is one for discussion with the radiologist.

CT is very sensitive in detecting blood, and it can be done quickly, in an emergent setting from the ED. So, in children with thunderclap headache, when you want to exclude subarachnoid hemorrhage, a non-contrast CT will be your first choice scan. If blood is detected, then add in arterial imaging: CT or MR angiography (CTA or MRA). Contrast is injected and images taken in the arterial phase.

CTA or MRA are also useful in the investigation of suspected stroke. In practice, you need an answer fast, particularly if the child’s within the thrombolysis window and could be a candidate if there’s evidence of ischaemic stroke, so a CTA is a more practical scan. The CT component looks for blood or large areas of parenchymal infarct, while the angiography looks for filling defects in the arteries that could indicate a thrombus.

If you’re looking for intracranial extension of infection, such as from an orbital cellulitis, mastoiditis or a brain abscess, then a contrast-enhanced CT will highlight suppurative collections.

And if you suspect a venous sinus thrombosis, such as in children with coagulopathies, sickle cell disease, infective spread from meningitis / mastoiditis / sinusitis, or secondary to dehydration or renal failure? Then you need to look at the venous spaces. CT or MR venography (CTV or MRV), when contrast is injected and images obtained in the venous phase, will give you the answers you need.

And what ARE the causes of a respiratory alkalosis?

There are a few! Here are the main ones:

  • Central: brain tumours, meningoencephalitis; stroke
  • Respiratory: asthma, pneumonia, pneumothorax, PE
  • Sepsis
  • Pregnancy
  • Endocrine and hypermetabolic cause: DKA, thyrotoxicosis
  • Toxicology: salicylates 
  • Hyperammonemia: liver and metabolic disorders 
infographic of causes of respiratory alklosis

We would LOVE your feedback about these DFTB PEM adventures so if you can spare a minute, please complete our survey at www.tiny.cc/DFTBpemadventure or use your smartphone to let the QR code take you straight there. We timed ourselves completing it and it takes less than a minute. Thank you.

Select references

The management of children and young people with an acute decrease in conscious level. A nationally developed evidence-based guideline for practitioners. RCPCH. 2015 update, with 2019 revisions. Management of children and young people with an acute decrease in conscious level – Clinical guideline | RCPCH

Undiagnosed Hyperammonaemia. Diagnosis and Immediate Management. British Inherited Metabolic Disease Group. Last reviewed 2017. The major causes are as follows (bimdg.org.uk)

Hirsch, W., Beck, R., Behrmann, C. et al. Reliability of cranial CT versus intracerebral pressure measurement for the evaluation of generalised cerebral oedema in children. Pediatric Radiology 30, 439–443 (2000). https://doi.org/10.1007/s002470000255

Expert Panel on Pediatric Imaging:, Hayes LL, Palasis S, Bartel TB, Booth TN, Iyer RS, Jones JY, Kadom N, Milla SS, Myseros JS, Pakalnis A, Partap S, Robertson RL, Ryan ME, Saigal G, Soares BP, Tekes A, Karmazyn BK. ACR Appropriateness Criteria® Headache-Child. J Am Coll Radiol. 2018 May;15(5S):S78-S90. doi: 10.1016/j.jacr.2018.03.017. PMID: 29724429.

Mitani H, Mochizuki T, Otani N, Tanaka H, Ishimatsu S. Ornithine transcarbamylase deficiency that developed at the age of 19 years with acute brain edema. Acute Med Surg. 2016;3(4):419-423. doi:10.1002/ams2.214

Summar ML, Barr F, Dawling S, Smith W, Lee B, Singh RH, Rhead WJ, Sniderman King L, Christman BW. Unmasked adult-onset urea cycle disorders in the critical care setting. Crit Care Clin. 2005 Oct;21(4 Suppl):S1-8. doi: 10.1016/j.ccc.2005.05.002. PMID: 16227111.

Kanaris C, Ghosh A, Partington CG389(P) A case for early ammonia testing in all encephalopathic patients: female patients with x-linked ornithine transcarbamylase deficiency. Archives of Disease in Childhood 2015;100:A158-A159. http://dx.doi.org/10.1136/archdischild-2015-308599.343

Summar, Marshall. (2005). Presentation and management of urea cycle disorders outside the newborn period. Critical Care Clinics. 21. IX-IX. 10.1016/j.jccc.2005.08.004.

Petechiae in Children – the PiC Study

Cite this article as:
Tessa Davis. Petechiae in Children – the PiC Study, Don't Forget the Bubbles, 2020. Available at:
https://doi.org/10.31440/DFTB.30782

Today the Lancet has published the long-awaited results of the Petechiae in Children (PiC) study. Team DFTB got our hands on a pre-publication copy to read, summarise, and analyse for you. So let’s get to it.

This PERUKI study by Waterfield et al. is a prospective, multicentre cohort study:

Waterfield T, Maney J-A, Fairley D, Lyttle MD, McKenna JP, Roland D, Corr M, McFetridge L, Mitchell H, Woolfall K, Lynn F, Patenall B, Shields MD, Validating clinical practice guidelines for the management of children with non-blanching rashes in the UK (PiC): a prospective, multicentre cohort study, The Lancet, 2020

Why is this study needed?

We are all somewhat terrified of children with fever and a non-blanching rash. We don’t want to miss meningococcal sepsis. Current guidelines are based on data from before the introduction of the Meningococcal B (2015) and C (1999) vaccines and consider a prevalence of 10-20% of meningococcal infection in children with fever and non-blanching rash.

Who were the patients?

The paper looked at children under 18 years old presenting to 37 Paediatric Emergency Departments in the UK over a 16 month period. Children were included if they had a fever (>38oC) and new onset of a non-blanching rash or features suggestive of meningococcal infection. Children were excluded if they had a pre-existing haematological condition or if they already had a diagnosis of Henoch-Schonlein purpura.

1513 patients were screened. 179 were excluded due to not meeting the criteria, not consenting, or a language barrier. Five that were enrolled had incomplete data leaving 1329 children were enrolled and included – the median age was 24 months, and 59% were male. Most children were vaccinated with 73% having had at least one dose of the Meningococcal B vaccine, and 77% having had at least one dose of the Meningococcal C vaccine.

What was the intervention?

There was no intervention here. Included patients were recruited at the point of meeting the criteria, using ‘recruitment prior to consent‘ and then consent was obtained soon after (usually within 24 hours). Data were collected contemporaneously: patient symptoms, blood test results, and treatment. A positive case was identified by being positive on PCR, or with a positive growth from another body sample (e.g. blood culture, or CSF). Patients were also checked for re-attendance to the hospital within 7 days. Results were also confirmed with the Public Health Agency – as meningococcal disease is a notifiable condition, this was a good method of picking up any missed cases.

What were the outcomes measured?

The primary outcome was assessing the performance of eight clinical guidelines on identifying children with invasive meningococcal disease (NICE meningitis (CG102); NICE sepsis (NG51); London; Chester; Bristol; Nottingham; Newcastle-Birmingham-Liverpool; and Glasgow).

The secondary outcomes were: performance of the eight guidelines in identifying children with other bacterial infections; and also looking at a cost comparison of each of the eight guidelines.

What were the results?

Of all 1334 children, 86% had a blood test and 45% had antibiotics. For patients admitted to hospital, the median length of stay was one night. 11 patients were admitted to PICU (2%) and two patients died (<1%).

Eight of these 11 PICU patients had N. meningitidis as did both of the patients who died. Seven patients had invasive bacterial infection (five with pneumococcal infection, one with E. Coli, and one with Group A Strep).

19 (1%) of patients in the cohort had meningococcal disease. 17 of these had N. meningitidis B, one had N. meningitidis C, and one had N. meningitidis W. Overall there were 26 patients (2%) with invasive bacterial infection (19 with meningococcal disease and 7 with an invasive bacterial infection).

346 patients (26%) did not have standard testing, and of these 19 patients (5%) had one unplanned re-attendance within seven days. However, none of these required readmission, antibiotics, or bacterial infection.

And how did the guidelines do?

All eight guidelines identified all of the 19 cases of meningococcal disease and all 26 cases of invasive bacterial infection (so the sensitivity of all of them is 100%). Specificity varied though. The NICE sepsis guideline stratified every patient as having a bacterial infection and therefore had a specificity of zero, making it the lowest specificity out of all the guidelines (closely followed by NICE meningitis guidelines with a specificity of 1%). This strategy clearly has cost implications too which is why the two NICE guidelines were also the most expensive per patient (£660.41 for the NICE sepsis guidelines).

Coming out top of the guideline ranking was the Barts Health NHS Trust guideline with a sensitivity of 100%, a specificity of 36%, and a cost of £490.29. This makes it the most accurate and also the cheapest.

Here’s the Barts Health NHS Trust guideline:

What about when we don’t follow the guidelines?

In practice, the guidelines were adhered to in 46% of the patients in the cohort. Deviation from guidelines resulted in fewer antibiotics being given. However, it also resulted in two patients being discharged with early meningococcal disease (they were subsequently treated and did not need PICU admission). Clinician decision-making increased the specificity (i.e. clinicians treated fewer people with antibiotics who didn’t have an invasive bacterial infection), but unfortunately reduced the sensitivity to 89%. Clinician decision-making did have the lowest cost per patient.

You’ve heard the facts, but how good was the paper?

As Ken Milne says…let’s get nerdy (and consider the CASP checklist for cohort studies)

Yes.

Research without prior consent was used to avoid recruitment delaying any treatment plans. However consent was obtained as soon as possible after inclusion in the study (usually within 24 hours).

Yes. Objective measurements were used for a blood test and PCR results. Risk factors for meningococcal disease are subjective and were based on contemporaneous clinical assessment – but this is what we do in practice so is a good reflection.

Yes. Note, however, that two patients with meningococcal disease were not included – one was not enrolled and the other was deemed by local staff to be inappropriate for inclusion.

Yes.

Yes, and also results were also checked with the Public Health Agency which would have allowed pick up of any missed meningococcal positive results.

There is a 1% prevalence of meningococcal disease in a mainly immunised population of children with fever and a non-blanching rash. The Barts Health NHS Trust guideline was the most accurate out of all the guidelines and with the lowest cost per patient.

Yes.

Yes. However, they would not be transferrable to populations with lower rates of vaccine uptake or a higher disease prevalence. The data was not shared on whether those with meningococcal disease were unimmunised or not, and therefore it would be prudent to be more cautious if your patient is not vaccinated.

Previous data was from prior to the meningococcal vaccination so this is the first and largest study since then.

What did the authors conclude and what can we take away from this study?

Since the advent of a vaccination programme and increased vaccine uptake, the rates of meningococcal disease are lower. Although previous data suggested 10-20% of children with fever and a non-blanching rash had meningococcal disease, in fact this study shows that only 1% had meningococcal disease.

Using a cautious guideline like NICE results in a lower specificity and higher cost. Tailored guidelines can increase the specificity and reduce the cost per patient without compromising on 100% sensitivity. The Barts Health NHS Trust guideline was the top performing guideline.

And finally, a comment from the authors themselves:

From Tom Waterfield:

The Petechiae in Children study represents the best available evidence regarding the assessment and management of febrile children with non-blanching rashes in the UK and clearly demonstrates that a lighter touch, tailored approach, is favourable to a test/treat all approach as currently advised by NICE. Moving to a tailored approach will reduce the need for invasive procedures, improve antimicrobial stewardship and save money. 

In vaccinated populations where the prevalence of invasive meningococcal disease is low the presence of Petechiae alone should no longer be viewed as a red flag and should not be used to justify immediate treatment with broad spectrum antibiotics. The emphasis and teaching should shift away from worrying about all non-blanching rashes with greater emphasis on the importance of identifying purpuric rashes as they confer the greatest risk of invasive meningococcal disease. 

Finally the PiC study demonstrates the importance of well designed prospective research studies in identifying risk factors for sepsis. Traditional approaches utilising retrospective reporting of symptoms from convenience samples of children with sepsis results in an over estimation the risks. This in turn leads to the development of overly aggressive clinical practice guidelines that are poorly adhered to. 

Note from Tessa: I am an employee of Barts Health but was not involved in the PiC study or in writing the Barts Health NHS Trust guideline.

Post ROSC care

Cite this article as:
Costas Kanaris. Post ROSC care, Don't Forget the Bubbles, 2020. Available at:
https://doi.org/10.31440/DFTB.29109

Or some pointers on clinical management following the successful return of spontaneous circulation in children. 

It’s 5:40 am at Bubblesville ED. The red phone rings. The paramedic crew informs you that they are five minutes away with a 7 kg, 6-month-old, previously thriving, baby boy called Tarquin. He has had a witnessed out of hospital cardiac arrest at home and there was no prodromal illness according to the family. He choked during a breastfeed, turned blue, and stopped breathing. He had 5 minutes of CPR by the parents by the time the ambulance arrived and had ROSC by the paramedic team after a further 8 minutes. The rhythm strip was consistent with a PEA arrest. They are hand-ventilating him through an LMA.

This is his capillary gas on arrival in the ED
  1. What are your clinical priorities?
  2. What clinical problems do you anticipate in the immediate post-arrest phase?
  3. Who do you call for help?
  4. What do you do with the family whilst you’re managing the patient?
  5. What investigations do you need?

A systematic, collaborative, well-led approach to advanced paediatric life support can maximize the chances of the clinical team achieving a return of spontaneous circulation in a child that has arrested. We’ve seen the drill be before. We can go through our algorithms expertly and the 5-H’s and 5-T’s roll off the tongue, even under duress. The return of a pulse is heralded as the “hallelujah moment”, almost as if the patient is now healthy and safe and all we have to do is wait for the paediatric critical care retrieval team to arrive.

Whilst traditional APLS teachings are vital for the dissemination of knowledge and it’s application in everyday clinical life, their main focus is on the initial phase of achieving a pulse with very little attention placed on the all-important post-resuscitation phase.  This part of care is crucial, not only if we are to minimize secondary brain injury to the child but also to improve the chances of permanent returns of spontaneous circulation. Good short and long term outcomes rely heavily on how well we manage the post-resuscitation stage. 

There are four phases of cardiac arrest:-

Phase one: Prevention. This is the pre-arrest phase. Child safety and injury prevention strategies are in place to recognize deterioration. Adequate monitoring by using early warning systems and a pro-active approach to management is likely to contribute to avoiding an arrest.

Phase two: No flow arrest. This is a period of cardiac arrest prior to us commencing CPR. Our aim here is to minimize the time it takes to start life support. It is key that we involve the cardiac arrest team quickly, we start chest compressions early, and that we do not delay defibrillation if this is needed. 

Phase three: Low flow resuscitation. This phase describes when CPR is in progress. The aim is to achieve high-quality CPR in order to allow adequate coronary and cerebellar perfusion. Maintaining good ventilation and oxygenation whilst avoiding aggressive over-ventilation is paramount. It is during this phase that we systematically approach and threaten the reversible causes of cardiac arrest. 

Phase four: This is the post-resuscitation phase after ROSC has been achieved. Our aim here is to optimize coronary and cerebral perfusion. Neuroprotection and treatment of arrhythmias as well as treatment of post-cardiac arrest syndrome come under this phase. 

Adult v paediatric arrest: What’s the difference?

Out of hospital cardiac arrests in children >16 years of age are relatively rare – reported at 8-20/100000/ year. The incidence is only comparable to that of the adult population, estimated at 70/100000/year. The incidence of in-hospital paediatric arrests is much higher, with a nearly one-hundred-fold increase, compared to the out-of-hospital incidence for the <16’s. 

Survival, and especially a “good” survival from a neurological perspective still remain poor. Out of hospital survival rates are estimated to be 5 – 12%. Only 0.3 to 4% of those that survive have no long-term neurological insult.

Children have cardiac arrests due to severe respiratory insult or circulatory collapse, in the main. Either can lead to a respiratory arrest coupled with hypoxia, which then results in a cardiac arrest. The overwhelming majority of cardiac arrests present with a non-shockable rhythm.  It is also worth noting that almost half of the paediatric population that have a cardiac arrest have other chronic comorbidities such as respiratory conditions e.g. asthma, congenital cardiac disorders, or neurodisability. 

In the adult population, cardiac arrest is more likely due to long-term comorbidities such as ischaemic heart disease. This contributes to the development of an acute myocardial insult and (usually) a shockable rhythm. Understanding the difference in pathology leading to a cardiac arrest between adults and children is vital. Reversing the cause of the respiratory compromise can make the impalpable pulse palpable, allowing us to perfuse our patient once again. 

The recommended CPR ratio of 15:2 for children aims to provide adequate ventilation for oxygenation as well as satisfactory cardiac compressions to maintain sufficient perfusion of the coronary and cerebral circulation. Adult studies looking at compression-only CPR in patients with VF arrest have shown that success in achieving ROSC is due to pre-existing pre-arrest aortic blood oxygen and pulmonary oxygen stores.  As a mere 14% of cardiac arrests are due to a shockable rhythm, combining ventilation and compressions is vital. 

What is the Post Cardiac Arrest Syndrome (PCAS)? 

PCAS describes the period in which our patients are at the highest risk of developing ventricular arrhythmias and reperfusion injuries after ROSC. This is secondary to prolonged ischaemia then reperfusion of vital organs, primarily the myocardium and central nervous system. Its systemic effects are not dissimilar to those encountered in severe sepsis. There are four stages to PCAS:

  • Immediate post-arrest – First 20 minutes. 
  • Early post-arrest – 20 minutes to 6-12 hours. 
  • Intermediate phase – 6-12 hours up to 72 hours.
  • Recovery phase – From 72h onwards. 

Neuroprotection

Even high-quality closed-chest CPR can only achieve 50% of normal cerebral blood flow at best. It is not a secret that the brain does not tolerate hypoxia or ischaemia, the effects on both of these processes are exponential during a cardiac arrest, the longer the downtime, the worse the neurological hit

The pathophysiological cascade for neurodegeneration following cardiac arrest is complex and multi-factorial. Following a hypoxic or ischaemic period the brain develops cerebral oedema and cerebral hyperaemia. There is impaired cerebral vascular reactivity and like any other organ trying to reperfuse, the post-ischaemic biochemical cascade is activated. All these factors contribute to a secondary brain injury. Of course, the duration of hypoxia will in large part dictate how severe the primary brain injury is and whether the patient is likely to survive or not. Brain injury can manifest as myoclonus, stroke, seizures, coma, or brain death. 

We can minimize the extent of secondary brain injury with simple proactive, neuroprotective measures:

  • Strict normothermia
  • Aggressive seizure prophylaxis
  • Avoiding hypoxia and hyperoxia
  • Tight circulatory monitoring and support
  • Patient position
  • Eucapnia and normoventilation
  • Vigilant glucose monitoring
  • Frequent neurological assessment, especially before the administration of anaesthetic agents and paralysis

Strict normothermia

Therapeutic hypothermia following a cardiac arrest during the intermediate phase (after VF in adults), as well as newborns with birth asphyxia, has shown some correlation with better neurological outcomes and reduced neurodisability.  Similarly, there is strong evidence linking core temperature above 38° with worse neurological outcomes in patients following cardiac arrest. There is a wide variation in practice in relation to therapeutic hypothermia.  Mild hypothermia after paediatric cardiac arrest is in the policy of some PICU’s. Patients are cooled to 33-34°C for 1 – 2 days and are then gradually rewarmed. Paralysis can be used as an adjunct to stop shivering. Temperatures below 32°C should be avoided as they are associated with worse survival, immunosuppression, arrhythmias, coagulopathies, and infections.  The decision to “cool” must be made early and in conjunction with your critical care transport team. You have many tools at your disposal to achieve this such as cold IV fluids, cooling blankets, and catheters. 

What is, and should be, more aggressively targeted is strict normothermia (temperatures between 36-37°C), and depending on local practice hypothermia can be targeted to 33-36°C. Avoidance of pyrexia is crucial. Fever can result in an increased metabolic demand of the brain. This contributes to more ischemic injury and more infarcts as the threshold for ischemia in the injured brain is lower than that of the normal brain. The brain can no longer auto-regulate the mismatch between cerebral blood flow and metabolic demand.

Aggressive seizure prophylaxis

Seizures after paediatric cardiac arrest can occur in up to 47% of cases. 35% of these can lead to refractory status epilepticus.  Whilst CFAM/EEG monitoring is unlikely to be available in your local PED, it is important to have a low threshold to administer a long-acting anti-epileptic or a continuous infusion of a short-acting medicine to prevent/avoid this from happening. Ideally, a continuous infusion of midazolam +/- levetiracetam (less arrhythmogenic than phenytoin but both will work) and standard national guidelines should be followed. 

Clues as to whether a patient is still fitting include:

  • Unexpected changes in the pupillary size (beware of the child that had atropine on induction with the “fixed dilated pupils”).
  • Sudden changes in BP or heart rate.  

If you have given a paralytic for intubation, do not fall into the trap of thinking that the patient is not seizing, only an EEG or CFAM can tell you that. It is better to err on the side of caution.

Avoiding hypoxia and hyperoxia

Avoiding hypoxia and hyperoxia are also key components in minimizing secondary brain injury.  Whilst hypoxia will further exacerbate secondary brain injury, hyperoxia  (PaO2 > 40 kPa) is also be associated with worse survival due to oxygen free-radical formation that can inactivate intracellular enzymes, damage DNA, and destroy lipid membranes. It is reasonable to have high concentration oxygen therapy during the low-flow resuscitation and early post-resuscitation phases (as the commonest causes are respiratory). In the subsequent phases, we should target oxygen saturations between 94 and 96% and be proactive in how we reduce the FiO2 whilst avoiding hypoxia. There is a caveat in cases of severe anaemia or carbon monoxide poisoning. Then it is clinically appropriate for the highest concentration of oxygen to be administered.

Tight circulatory monitoring and support

Inotropic support may also be needed early. A degree of myocardial dysfunction/stunning is expected following CPR. To ensure adequate cerebral perfusion we need to target an age-specific, physiologically normal blood pressure. Both hypo and hypertension can exacerbate secondary brain injury. Because of this, monitoring the blood pressure through an arterial line is preferred. If the local set-up or skillset does not allow for arterial line placement, especially in smaller children, having non invasive blood pressure on 1-2 minute cycles can be a useful proxy.  

The paediatric myocardium is much more resilient than its adult counterpart.  If the arrest is not secondary to congenital heart disease the paediatric heart can regain normal function within 12-24 hours.  During the first 20 minutes following ROSC poor cardiac function is due to profound systemic vasoconstriction and cellular acidosis. We can support the myocardium by supplying adequate fluid resuscitation, targeting normal (age-appropriate) blood pressure and inotropic support. Point of care ultrasound, CVP monitoring, or assessing for hepatomegaly/rales if there is no access to the former, can help us prevent fluid overload

Inotrope choice is usually made with the help of the critical care team and depends on the balance between the need for inotropy and vasoconstriction.  Adrenaline is preferred for inotropy, noradrenaline for vasoconstriction.  Be aware that severe acidosis can cause catecholamine resistance, so giving some bicarbonate if the pH <7 may help your inotropes work better. Routine administration of bicarbonate has not been shown to improve clinical outcomes. There are some special circumstances in which we should consider its use such as cases of hyperkalaemia or hypermagnesaemia and arrests due to tricyclic antidepressant overdose. 

Patient position

The patient position that can achieve optimum cerebral perfusion is with the patient semi-sat up at a 30-45 degree angle.

Eucapnia and normoventilation

Avoidance of hypercapnia or hypocapnia is important in preventing secondary brain injury. It is, therefore, recommended that eucapnia is achieved by targeting a PaCO2 between 4.5 and 5.5 kPa. Hyperventilation can cause hypoxia and increase intracranial pressure due to hyperaemia, it can also cause further cerebral ischemia. As the intrathoracic pressures increase, cardiac venous return is impaired. Since the myocardium is already injured this can have catastrophic effects causing the BP to plummet and subsequently impair cerebral perfusion.

Vigilant glucose monitoring 

Following ROSC, children are also at risk of developing hypoglycemia (glucose <3 mmol/L). There is good evidence to suggest that hypoglycaemia negatively impacts neurological outcome and cause hypoglycaemic seizures, especially in the younger ages. Vigilant glucose monitoring and correction as per APLS guidelines is important. If regular dextrose boluses are needed, consider a continuous glucose infusion. If the patient mounts an adequate stress response, they may become hyperglycaemic.  There is no evidence to suggest that aggressive glucose control with insulin in the non-diabetic patient is beneficial; wait with watchful deliberation and the glucose will usually return to normal levels with no intervention.

Frequent neurological assessment

It is important to frequently assess neurological status frequently after ROSC as this can help us prognosticate. Take the time to do a very quick assessment ideally before the administration of anaesthetic agents and paralysis. Document clearly pupillary size/reactivity, GCS (and its break down) and any respiratory effort or gasping. 

Adjunctive investigations

Following ROSC a number of investigations will be needed to guide diagnosis and therapy. Routine bloods such as renal function, electrolytes, liver function tests, full blood count, and clotting are a basic standard. In cases of lactaemia and/or severe metabolic acidosis ammonia and toxicology is useful. Arterial blood sampling is invaluable to allow quick correction of any electrolyte abnormalities and help titrate ventilation settings and (in part) guide inotropic support. Arterial samples will also help uncover any exposure to carbon monoxide, especially in burns cases. 

From an imaging perspective, a chest X-ray is vital in ascertaining tube positioning and lung pathology as well as cardiac contours in case a congenital or acquired heart disease is suspected. Head CT is obviously useful in cases in keeping with traumatic arrest and NAI but timing of the CT and whether it should take place pre-departure to PICU or after depends largely on local trauma network protocols so should ideally be discussed with the regional trauma team lead and paediatric critical care transport team. 

Children that die or arrest unexpectedly in the UK are subject to a sudden unexpected death in infancy investigation (SUDI) so the appropriate referrals need to be made to the child protection team, police and social care. It is important to clarify that even near-miss cases merit triggering the same SUDI process to ensure that any NAI cases don’t slip through the net. 

Transport pearls

After ROSC the patients will need stabilisation and transfer to PICU for on-going management. Depending on the geographical location of your hospital and the availability of a critical care retrieval service you may have to transfer the patient yourselves or look after them until he/she is retrieved by transport team. A good transport and adequate neuroprotection can be achieved by applying these simple pearls: 

  1. Aggressive temperature monitoring and control between 33°C and 37°C.
  2. Monitor for seizures and pre-empt with long-acting antiepileptic accordingly.
  3. Correct electrolytes and hypoglycaemia and monitor frequently.
  4. Nurse the patient a 45° degree angle.
  5. Aim for a higher end of normal BP and use inotropes to achieve this. If you can’t insert an arterial line, have the NIVBP cycle every couple of minutes. 
  6. In cases of trauma, blood products should be used for volume. In an atraumatic arrest, balanced solution boluses are less harmful than 0.9% saline; don’t forget that you are still likely to need blood products. 
  7. Aim for a pCO2 of 4.5-5.5 kPa; use your continuous EtCO2 monitor to titrate ventilation. 
  8. Vigilant and through history/examination to rule out NAI. Free up a member of the team to do a thorough history from the family, always suspect NAI until proven otherwise especially in children under 6 months. 
  9. Know your anaesthetic drug side-effects (atropine dilates pupils for example so impairs our ability to monitor for seizures). Primum non nocere. 
  10. Intraosseous access can be used instead of a central line, have a low threshold to insert one and do it early.
  11. Have a member of the team check-in with the family every 10-15 minutes to explain what is happening, this is a bad day at work for you but probably the worst day of their lives. 

Conclusion

Achieving ROSC is an important step to give our patients a shot at survival. In some cases, achieving ROSC can only give us enough time to prognosticate and understand that survival is not possible. In some other cases ROSC can be the stepping-stone for a good, meaningful survival with a good quality of life. To achieve that, we must be able to apply good quality post–ROSC care and aggressive, pre-emptive neuroprotection. Learn the PCAS disease process to beat the PCAS disease process.  The APLS algorithm has become the bread and butter of anyone that is involved in paediatric care. Understanding and applying the principles of post-cardiac arrest syndrome is equally vital in improving survival outcomes for our patients. Learn the pearls, use them, teach them and I guarantee that it will make a difference.

Haemolytic Uraemic Syndrome

Cite this article as:
Jennifer Watt. Haemolytic Uraemic Syndrome, Don't Forget the Bubbles, 2020. Available at:
https://doi.org/10.31440/DFTB.26233

What is HUS?

Haemolytic Uraemic Syndrome is a combination of findings which involves the triad of:

  • Microangiopathic haemolytic anaemia with red blood cell fragmentation on blood film
  • Acute renal failure
  • Thrombocytopenia

 What causes HUS?

About 90% of cases follow an infection, most commonly with entero-haemorrhagic E. Coli (EHEC). Other infective causes to be considered include Shigella and Streptococcus pneumoniae.

These infections are commonly contracted by the ingestion of contaminated food or water sources. In the US and UK, E. Coli 0.157 forms part of the natural intestinal microflora of cattle and sheep, therefore infection can be caused by direct contact with animal faeces. This can take place at farms or petting zoos, or via undercooked contaminated meat or dairy products.

The other 10-15% of cases represent atypical HUS and are due to a variety of causes, which will not be discussed here.

How do children present?

In children infected with EHEC about 10-15% of them will go on to develop HUS.

The common presentation includes bloody diarrhoea +/- cramping abdominal pain, fever and/or vomiting. The average onset of HUS after development of diarrhoea is about 7-10 days, with children under the age of 5 at highest risk.

Dependent on the extent of HUS progression, children may present with pallor, oedema, lethargy, or reduced urine output.

How to approach the examination

As with any unwell child, an A to E assessment is critical to rule out any immediate, life threatening complications.

Specific attention should be paid to assessing their fluid status, especially for evidence of dehydration.

*Although they may be oedematous, it is important to assess if they are intra-vascularly dry.

Things to examine for:

  • Prolonged capillary refill time
  • Observations: Tachycardia; hypotension or hypertension
  • Are they are cool peripherally?
  • Assess fontanelle tension (if applicable)
  • Dry mucus membranes/reduced skin turgor
  • Oedema (common locations in children include lower limbs, sacral and peri-orbital)

Is there evidence of neurological sequelae?

  • Irritable/restlessness
  • Confusion
  • Reduced GCS

Key investigations to perform

A. Initial blood samples:

  • Full blood count with blood film to assess for RBC fragmentation
  • Coagulation
  • Group and Save +/- cross match if haemoglobin low
  • Biochemistry: U&Es, calcium, phosphate, magnesium, bicarbonate
  • Glucose
  • CRP
  • Liver function including albumin
  • Amylase/Lipase (hospital dependent)
  • LDH
  • Blood gas
  • Blood cultures

B. Stool MC&S + E. Coli PCR

C. Urinalysis + MC&S

How to approach the management of HUS

Management should always be discussed with your local paediatric nephrologist in order to individualise/optimise management.

This is a generalised framework for the approach to management. Treatment involves supportive therapy to allow time for the infection to clear and the HUS process to cease.

1. Fluid Management:

  • IV access
  • Assess fluid status
  • Monitor for electrolyte disturbances and correct as per local guidelines
  • Daily weight, In/Out fluid balance, close monitoring of patient observations

*Fluid rehydration should be administered cautiously and in the setting of oliguria/anuria and oedema, fluids given should not exceed insensible loss + urine output.

*Evidence has shown that children presenting to hospital with dehydration in the prodromal phase of EHEC-induced HUS have a higher risk of developing an oliguric AKI and the requirement for dialysis. The administration of isotonic fluid in this phase has shown to be nephroprotective. 

2. Hypertension:

  • Can be secondary to fluid overload or as a result of the HUS process
  • Trial of diuretics or if receiving dialysis, fluid can be offloaded
  • If unresponsive to diuretics, consider a vasodilator (For example, amlodipine/ nifedipine *hospital dependent)

3. Anaemia:

  • Target Haemoglobin: 70-100g/L
  • Avoid excessive transfusion due to the associated risk of development of hyperkalaemia or fluid overload

4. Thrombocytopenia:

  • Consideration for platelet transfusion if platelets <10 x109
  • If undergoing surgery may require platelets > 50 x 109

5. Abdominal pain/vomiting:

  • Secondary to colitis
  • Regular paracetamol for pain relief
  • Avoid opiates if possible due to constipating side effects

*NSAIDS like Ibuprofen should not be prescribed*

6. Nutrition:

  • All patients should be reviewed by a dietician
  • NG tube and feeding regime

7. Dialysis (Peritoneal Dialysis or Haemodialysis) Indications:

  • Intractable acidosis
  • Diuretic resistant fluid overload
  • Electrolyte abnormalities Hyperkalaemia
  • Symptoms of uraemia

In children with HUS, peritoneal dialysis is the preferred treatment option as it is a gentler form of dialysis.

Haemodialysis is indicated for children with severe colitis, severe electrolyte abnormalities and those with neurological complications.

 HUS Complications

  • AKI:  Oliguria/anuria; hyperkalaemia; hypertension
  • Neurological: Irritable, confusion, seizures
  • Bleeding Risk
  • Cardiac: Hypertensive cardiomyopathy/myocarditis
  • Gastrointestinal: Severe colitis with bleeding/perforation
  • Pancreatitis
  • Pulmonary oedema

Selected references

Mayer CL, Leibowitz CS, Kurosawa S and Stearns-Kurosawa DJ. Shiga Toxins and the Pathophysiology of Hemolytic Uremic Syndrome in Humans and Animals. Toxins (Basel). Nov 2012. [Cited June 2020]; 4 (11): 1261-1287. doi: 10.3390/toxins4111261

Kausman. J 517 Haemolytic uraemia syndrome. Royal Hospital for Children- Nephrology. Dec 2013. [Cited June 2020]; Available from:  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3509707/

Hughes D. Management and investigation of bloody diarrhoea and haemolytic uraemic syndrome [draft].  GG&C Paediatric Guidelines- Kidney Diseases. Oct 30 2019. [Cited June 2020]; Available from: https://www.clinicalguidelines.scot.nhs.uk/ggc-paediatric-guidelines/ggc-guidelines/kidney-diseases/management-and-investigation-of-bloody-diarrhoea-and-haemolytic-uraemic-syndrome-draft/

Balestracci A et al. Dehydration at admission increased the need for dialysis in hemolytic uremic syndrome children. Pediatr Nephrol. 2012. [ Cited June 2020];27: 1407-1410. Doi: 10.1007/s00467-012-2158-0

Scheiring J. Andreoli SP. Zimmerhackl LB. Treatment and outcome of Shiga-toxin-associated hemolytic uremic syndrome (HUS). Ped Neprhrol. 2008. [Cited June 2020]; 23: 1749-1760. Doi: 10.1007/s00467-008-0935-6

Grisaru Silviu. Management of hemolytic-uremic syndrome in children. Int J Nephrol Renovasc Dis. 2014 [Cited June 2020]; 7: 231-239. Doi: 10.2147/IJNRD.S41837.

Metabolic presentations part 1: neonates

Cite this article as:
Taciane Alegra. Metabolic presentations part 1: neonates, Don't Forget the Bubbles, 2020. Available at:
https://doi.org/10.31440/DFTB.28423

You are working in the Paediatric Emergency Department and are called in to see a neonate with a history of irritability and seizures. You enter the room and are told the following: “Emma is a 3 day old, term baby who has been refusing feeds and crying excessively. Her mother says she has been irritable since birth. There has been no history of fever or cough. At home she had seizure-like activity with tonic posturing”. When you examine her, you find an awake, extremely irritable baby with flexed upper limbs flexed, extended lower limbs and global hyperreflexia. She is not dysmorphic and has no cardiac murmurs, respiratory distress or abdominal organomegaly.

Babies cry (a lot!) and we all know that, however Emma is presenting some red flags: she’s irritable and has an acute onset of seizures, without any obvious trigger.

The basics

In this post we will discuss some acute metabolic presentations in the neonatal period, how to identify potential problems and emergency treatment in the ED. You don’t need to make a diagnosis (bonus points if you do) but do need to remember that spotting the zebra will lead to more favourable outcomes. Metabolic diseases / disorders are also called inborn errors of metabolism (IEM).

How common are metabolic conditions?

Individually, metabolic conditions are rare, most having an incidence of less than 1 per 100,000 births. However, when considered collectively, the incidence may reach 1 in 800 to 1 in 2500 births (Applegarth et. al, 2000; Sanderson et.al, 2006). 

Remember: some symptoms can be unspecific and can mimic sepsis; or a child with an undiagnosed metabolic condition can decompensate with an intercurrent infection. 

An easy-to-understand classification by Saudubray divides the IEM in three groups of disorders, depending on how they present. 

Intoxication disorders

An acute or progressive intoxication from the accumulation of toxic compounds, usually small molecules. 

These usually present with a symptom-free interval and clinical signs of ‘intoxication’, which may be acute, although can be intermittent.

  • disorders of amino acid catabolism: e.g. phenylketonuria, maple syrup urine disease, homocystinuria, tyrosinemia 
  • most organic acidurias: e.g. methylmalonic, propionic, isovaleric acidaemia
  • urea cycle defects: e.g. Ornithine transcarbamylase deficiency (OTC deficiency), Citrullinemia type I (ASS1 deficiency).
  • sugar intolerances: galactosemia
  • metals: Wilson’s, Menkes, hemochromatosis
  • porphyrias

Disorders involving energy metabolism

A deficiency in energy production or utilization, within the liver, myocardium, muscle, brain or other tissues. 

Common symptoms include hypoglycemia, hyperlactatemia, hepatomegaly, failure to thrive and cardiac failure. 

  • Mitochondrial defects: congenital lactic acidemias (defects of pyruvate transporter, pyruvate carboxylase, pyruvate dehydrogenase, and the Krebs cycle), mitochondrial respiratory chain disorders and the fatty acid oxidation defects (MCAD deficiency).
  • Cytoplasmic energy defects: disorders of glycogen metabolism (collectively known as glycogen storage diseases), hyperinsulinism.  

Complex molecules disorders

Problems in the synthesis or catabolism of complex molecules, leading to storage of big molecules. 

Symptoms are chronic, progressive and independent of intercurrent events or food intake. 

  • Mucopolysaccharidosis (I-IV, VI and VII). The eponymous names are used less frequently now, particularly in the literature, but you might come across them in clinical practice (MPS I, Hurler’s Syndrome; MPS II, Hunter’s Syndrome; MPS VI, Maroteaux- Lamy) 
  • Gaucher disease
  • Peroxisomal disorders: e.g. X-linked adrenoleukodystrophy (X-ALD) and Zellweger’s Syndrome.

Treatment strategies

Remember your biochemistry: a substrate is transformed by an enzyme into a product .

If there is a problem with the enzyme, the substrate will accumulate. If this substrate accumulation is a problem, we eliminate it, like avoiding protein in the diet or removing toxins with treatments such as ammonia scavengers.  If a lack of the product is the problem, we can supplement it (for example the administration of carbohydrate in glycogen storage disease). And for some diseases the  enzyme can be “corrected” with organ transplantation or enzyme replacement therapy.

A bonus on smells

Due to accumulation of “unusual” products in their body fluids, people with certain metabolic conditions have distinctive odours (better observed in urine, for practical reasons):

  • Maple syrup, burnt sugar, curry: Maple syrup urine disease
  • Sweaty feet: glutaric aciduria type II, isovaleric acidaemia
  • Cabbage: tyrosinemia
  • Mousy, musty: phenylketonuria
  • Rotting fish: trimethylaminuria
  • Swimming pool: Hawkinsinuria 

Back to Emma. You explain to Emma’s mother that there are lots of things that could be making her unwell so you’re going to send some tests to help work out what the problem is. You put in a cannula, take a gas, send some bloods to the lab and set her and her mother up to collect a urine.

Seeing that Emma has a metabolic acidosis on her gas you send a metabolic screen: plasma amino acids, urine organic acids, acylcarnitine profile. Her urine dip has some ketones but is otherwise unremarkable, except for a strange smell of sweaty feet…

Remembering a fabulous infographic about the importance of calculating the anion gap in children with a metabolic acidosis (and how to interpret them!), you get out your pen and paper and do the following calculations: 

Just as you’re pondering the causes of a raised anion gap, the lab phones with Emma’s blood results… Her ammonia is 184!

Emma has an acute neurological presentation, with metabolic acidosis, increased anion gap and mildly elevated ammonia, suggestive of an organic acidaemiaIn the context of a sick neonate with a raised anion gap, a normal lactate and normal ketones, think organic acids.

Are you familiar with ammonia?

A normal ammonia level is <50 mol/l but mildly raised values are common, up to 80 mol/l.

In neonates, any illness may be responsible for values up to 180 mol/l.

Artifactually high values can be caused by muscle activity, haemolysis or delay in separating the sample. Capillary samples are often haemolysed or contaminated and therefore should not be used.

There’s debate as to whether a level of >100 or 200 should be discussed with a metabolic specialist, but if in doubt, follow the RCPCH DeCon guideline and seek advice for any patient presenting with a level >100 mmol/l.

Urine organic acids and blood acylcarnitines will also be sent as part of this baby’s metabolic work-up. Although the results won’t be available in ED, the urine organic acid profile will confirm a diagnosis of an organic acidaemia, while the blood acylcarnitine profile will support the diagnosis as the organic acids conjugate with carnitines creating compounds such as isovalerylcarnitine.

The emergency treatment of suspected organic acidaemias

It’s important to think about your differentials. Sepsis is the most common – these conditions can mimic sepsis, or decompensation can be triggered by an infection, always cover with broad spectrum antibiotics. But don’t forget non-accidental injury and other differentials – the baby is likely to need a CT head if presenting encephalopathic or with seizures. If she continues to seize, load with an anticonvulsant.

 Specific emergency treatment of her metabolic presentation requires:

  • stopping sources of protein (milk)
  • avoiding catabolism (by giving glucose IV – 2mL/kg 10% glucose) 
  • rehydration (IV fluids resuscitation and maintenance)

What about that urine?

The “sweaty feet” smell of the urine points towards the diagnosis of Isovaleric Acidaemia. Remember that this condition can be part of the Newborn Screening in some countries (Ireland, UK, Australia, New Zealand).

Isovaleric acidaemia is a type of organic acidemia, inherited in an autosomal recessive way. It is caused by a problem with the enzyme that usually breaks down the amino acid leucine. This amino acid accumulates and is toxic at high levels, causing an ‘intoxication’ encephalopathy. The sweaty feet smell is stronger without treatment or  during acute exacerbations.

Maple Syrup Urine Disease (MSUD) is another organic acidaemia, associated with sweet smelling urine during decompensation. These children cannot break down leucine, valine and isoleucine. They may not have hypoglycaemia, hyperammonemia or acidosis and, if not picked up on newborn screening, can be diagnosed late, resulting in neurological sequelae.

Organic acidaemias: the take homes

  • Always measure the anion gap and send an ammonia sample in any sick neonate.
  • Sick neonates with metabolic acidosis, increased anion gap and mildly elevated ammonia may have an organic acidemia.
  • Treatment is to stop feeds, prevent catabolism with 10% dextrose (and standard electrolytes for IV maintenance) and cover for sepsis with IV antibiotics, whilst considering other differentials.

The next case feels like déjà vu…

The next baby you see is remarkably like Emma but with a subtle difference. Lucy is a 3 day old baby, presenting with poor feeding, irritability and seizures at home. There has been no fever, cough, coryza, or sick contacts. On examination she’s awake, extremely irritable, with upper limbs, extended lower limbs extended and global hyperreflexia. She has no dysmorphic features, cardiac murmur or abdominal organomegaly. You notice that she seems tachypnoeic at 70, although her lungs are clear. The rest of her observations are normal. 

The key differences between Emma and Lucy’s presentations is that Lucy is tachypnoeic and has a respiratory alkalosis; this should make you suspicious of hyperventilation. Always check an ammonia level in sick babies, but particularly in this case as hyperammonemia stimulates the brain stem respiratory centre, causing hyperventilation and, as consequence, respiratory alkalosis. 

The lab phones you with Lucy’s ammonia result…

Acute neurological presentations, with respiratory alkalosis and extremely elevated ammonia point towards a urea cycle disorder. Respiratory alkalosis is a common early finding caused by hyperventilation secondary to the effect of hyperammonemia on the brain stem, although later the respiratory rate slows as cerebral oedema develops and an acidosis is seen. Lucy also has a low urea and mildly deranged liver enzymes and INR, all of which support the diagnosis of a urea cycle disorder.

The emergency treatment of suspected urea cycle disorders

Overall the acute treatment is similar to the first case: cover for sepsis, manage seizures and consider differentials.

And as in the first suspected metabolic case:

  • stop sources of protein – stop feeds 
  • avoid catabolism – giving glucose IV – 2mL/kg 10% glucose 
  • rehydrate – IV fluids resuscitation and maintenance

In urea cycle disorders, the toxic metabolite is ammonia, so ammonia scavengers are used, all given intravenously:

  • sodium benzoate
  • phenylbutyrate 
  • arginine

A nice guideline on the management of hyperammonemia secondary to an undiagnosed cause can be found on the British Inherited and Metabolic Disease Group website.

Urea cycle disorders are autosomal recessive inborn errors of metabolism. A defect in one of the enzymes of the urea cycle, which is responsible for the metabolism of nitrogen waste from the breakdown of proteins, leads to an accumulation of ammonia as it cannot be metabolised to urea. The urea cycle is also the only endogenous source of the amino acids arginine, ornithine and citrulline.   The most common urea cycle disorder is Ornithine Transcarbamylase (OTC) deficiency. Unlike the other urea cycle disorders (which are autosomal recessive), OTC deficiency is x-linked recessive, meaning most cases occur in male infants. Female carriers tend to be asymptomatic.

CPSI: Carbomoyl Phosphate Synthetase; OTC: Ornithine Transcarbamylase; ASS: Arginosuccinate Acid Synthase; ASL: Arginosuccinate; ARG: Arginase

Classically, urea cycle disorders present in the neonatal period with vomiting, anorexia and lethargy that rapidly progresses to encephalopathy, coma and death if untreated. In these circumstances, ammonia accumulates leading to a very high plasma ammonia. 

Children presenting in infancy generally have less acute and more variable symptoms than in the neonatal period and include anorexia, lethargy, vomiting and failure to thrive, with poor developmental progress. Irritability and behavioural problems are also common. The liver is often enlarged but, as the symptoms are rarely specific, the illness is initially attributed to many different causes that include gastrointestinal disorders. The correct diagnosis is often only established when the patient develops a more obvious encephalopathy with changes in consciousness level and neurological signs. 

Adolescents and adults can present with encephalopathy and or chronic neurological signs. 

What are ammonia scavengers?

In urea cycle defects, ammonia cannot be converted to urea so instead is converted to glutamine and glycine. 

Ammonia scavengers phenylbutyrate and sodium benzoate offer alternative pathways for ammonia excretion through urinary pathways.

Phenylglutamine and hippurate are produced and are excreted in urine.

Urea cycle disorders: the take homes

  • Always measure the anion gap and send an ammonia sample in any sick neonate.
  • Sick neonates with respiratory alkalosis, normal anion gap and very elevated ammonia may have a urea cycle defect. 
  • Emergency treatment of urea cycle disorders is the same as for an organic acidaemia (stopping feeds, starting dextrose and rehydrating) PLUS intravenous ammonia scavengers.

Thank you to Dr Roshni Vara, Consultant in Paediatric Inherited Metabolic Disease at the Evelina London Children’s Hospital for her help with this post.

References

Adam , HH. Ardinger, RA. Pagon, S. E. Wallis, L. J. H. Bean, K. Stephens, & A. Amemiya (Eds.), GeneReviews® [online book].

Applegarth DA, Toone JR, Lowry RB. Incidence of inborn errors of metabolism in British Columbia, 1969-1996. Pediatrics. 2000 Jan;105(1):e10.

Sanderson S, Green A, Preece MA, Burton H. The incidence of inherited metabolic disorders in the West Midlands, UK.Arch Dis Child. 2006 Nov;91(11):896-9. 

Saudubray J-M, Baumgartner MR, Walter JH. (editors) Inborn Metabolic Diseases. Diagnosis and treatment. 6th Edition. Springer 2016. 

Neonatal ventilation basics

Cite this article as:
Jasmine Antoine. Neonatal ventilation basics, Don't Forget the Bubbles, 2020. Available at:
https://doi.org/10.31440/DFTB.19875

A term infant is admitted to the intensive care nursery with severe respiratory distress. They are currently on CPAP 8cm H2O and FiO2 0.50  with no signs of improvement. You begin preparing for intubation. The nurse looking after the baby is setting up the ventilator. “What ventilator setting would you like, doctor”?

Before listing off some ventilator settings, there are several decisions that we need to make. What type of ventilation should we be using for this baby? What settings will we start them on? What do we need to do post ventilation? This post will begin to answer some of these questions, but as always, it is advisable to be guided by your unit policies and senior staff members.

Ventilation modes

This post will discuss the basics of conventional ventilation. High-frequency oscillatory ventilation (HFOV) is also commonly used in the nursery, particularly for extremely preterm infants or those with persistent pulmonary hypertension. Stay tuned for an upcoming post on HFOV.

Synchronized intermittent mandatory ventilation (SIMV)

This type of ventilation administers a set amount of mechanical breaths that are synchronized with the patient’s own inspiration. When the infant breaths above the set ventilator respiratory rate, these additional breaths do not receive a ventilator breath. This mode can be useful when weaning ventilation.

Synchronized intermittent positive pressure ventilation (SIPPV) or patient triggered ventilation (PTV) or Assist Control (AC)

This form of ventilation confusingly has many different names. It supports every breath the infant makes. The set ventilator respiratory rate is the backup number of breaths that will be mechanically administered if the infant makes no spontaneous breaths. Each mechanical breath is synchronized with the patient’s own inspiration.

Pressure support ventilation (PSV)

Similar to SIPPV in that every breath is supported with mechanical ventilation. However, the inspiratory time is limited depending on the infant’s own inflation. The infant sets their own mechanical breath rate and inspiratory time.

Volume controlled (VC) or volume guarantee

This mode of ventilation can be used with SIMV or SIPPV. The ventilator aims to deliver tidal volumes (VT) set by the clinician. A maximum peak inspiratory pressure (PIP) is set, the ventilator’s PIP will vary to reach the target volume.

So, which is better for our infant?

There have been no large prospective trials that have determined if SIMV or SIPPV is the superior format of ventilation. The choice of ventilation will largely depend on unit preference. Studies have illustrated that volume-controlled ventilation reduces the duration of ventilation, risk of pneumothorax, grade 3/4 intraventricular haemorrhage, and chronic neonatal lung disease.

So what’s on your ventilator screen?

Peak end expiratory pressure (PEEP): The maximum pressure that provides continuous distension of the lungs. Usually between 6-8cmH20 Peak inspiratory pressure (PIP): Maximum pressure used during inspiration. Consider the tidal volumes achieved to determine a suitable PIP. VT are usually around 4-5ml/kg. Respiratory rate (RR): Set number of mechanical breaths administered in a minute. Usually between 40-60. In SIMV the set RR is both the maximum and minimum rate while in SIPPV the RR is the minimum but not the maximum rate. Inspiratory time (Ti): Set time for inspiration during a breath. Usually between 0.3-0.5s Patient Circuit Flow Rate or Rise Time or Rise Slope: Depending on the manufacturer or the unit policy, one of these options will be available. If only the patient circuit flow rate is available then this is set 6 – 10 L/min. If rise time or slope is available then this is set to 30 – 50% of the Ti. Pmax: In the volume-controlled mode this is the maximum peak inspiratory pressure you wish the ventilator to administer to reach target tidal volumes. Usually set 5 cmH2O higher than the average PIP used to achieve the set tidal volume. FiO2: The amount of supplementary oxygen. Target saturations will depend on the gestational age and the underlying condition affecting the infant. Your unit’s policy on SpO2 targets should guide the FiO2 setting.

Many other ventilators exist

What are the ventilator measurements we should be aware of?

Minute volume (MV): Amount of gaseous exchange in one minute. MV= VT x RR Tidal volume (VT): The amount of gas in an expiration. Usually around 4-5ml/kg. Leak: Traditionally in neonates, uncuffed tubes are used for intubation due to concerns regarding subglottic stenosis and pressure necrosis. As a result, most infants will have a percentage of leak. It will change during an infant’s respiratory cycle, it is usually greater in inspiration.

What do we need to do next?

After attaching our infant to the ventilator, clinical checks should once again be undertaken to ensure adequate ventilation. Review the infant, is there misting of ETT, equal air entry by auscultation, symmetrical chest rise, stable observations and adequate tidal volumes being achieved. A post-intubation chest x-ray should be taken as early as possible to check the placement of the endotracheal tube. The ideal placement is between T1-3,  just above the carina. An arterial gas should be undertaken post-intubation to check adequate ventilation, within an hour. The timing of the next gas will depend on the results, clinical condition and how old the patient is. Your boss will be able to give you some guidance.

Take-home messages

  • Avoiding mechanical ventilation using early continuous positive airway pressure (CPAP) with, or without, surfactant administration is the most effective way to reduce the risk of lung injury.
  • Using volume-controlled ventilation reduces the risk of chronic neonatal lung disease.
  • If you’re not sure where to start or how to alter ventilation, ask for your boss’ help.

Resources

Keszler M. State of the art in conventional mechanical ventilation. Journal of Perinatology. 2009 Apr;29(4):262. Mechanical ventilation of the premature neonate. Respir Care. 2011 Sep;56(9):1298-311; discussion 1311-3. doi: 10.4187/respcare.01429

Aerosol Generating Procedures

Cite this article as:
Tagg, A. Aerosol Generating Procedures, Don't Forget the Bubbles, 2020. Available at:
https://dontforgetthebubbles.com/aerosol-generating-procedures/

As more cases of Covid19 present to health care facilities across the world, there seems to be some confusion as to what is an aerosol-generating procedure. Turning up to work is not without risk with a large number of healthcare workers in Italy and Ireland. diagnosed with COVID19. There is a case report of asymptomatic carriage lasting up to 16 days so we need to be careful whether the child in front of us has been diagnosed with COVID19 or not.

A lot of the data we have comes from the 2003 SARS epidemic and the H5N1 influenza outbreaks. There are always going to be a number of confounding variables when looking at these reports – whether the HCW was wearing appropriate PPE (or had access to it), how good their hand-washing was, how close together patients are – but nosocomial infections do occur.

First off,  we are going to take a look at what an aerosol is, then how aerosols and droplets relate to some common, and uncommon, things we do in paediatrics.

 

Aerosol or droplet?

Let’s define some terms before we get started – not as easy as it sounds, it turns out.

A  respiratory droplet is a fluid bundle of infectious particles that travels from the respiratory tract of the infected individual onto the mucosal surface of another, rather than floating down the respiratory tract. Small droplets are between 5-20μm and tend to hang up around the glottis. Large droplets are > 20μm and are probably too big to follow airflow. They tend to obey the laws of gravity and so settle on nearby surfaces when you sneeze. If you inadvertently touch the same surface then touch your face you can potentially transmit the infection. This is why we wash our hands. In healthcare, droplet precautions include a surgical mask, eyewear, disposable gown, and gloves. The surgical mask acts as a physical barrier to droplets that are too large to be inhaled.

A droplet nucleus is what is left once the liquid rapidly evaporates from a droplet. They are in the order of 10μm in diameter and are in the respirable range. This is generally defined as any particle less than 10μm. The inspirable range is defined as anything between 10 – 100μm in size.

An aerosol is a liquid (or solid) suspended in the air – think mist and fog. These small particles are less than 5μm and so are in the respirable range (rather than the inspirable range like droplets) and can enter the lower respiratory tract. They are affected by diffusion rather than gravity so tend to hang around for a while.  Measles is one such airborne disease. A recent letter in the NEJM suggests that SARS-CoV-2 can remain viable in aerosols for at least 3 hours, though the WHO’s guidance is clear that it should be managed with droplet and contact precautions UNLESS you are performing an aerosolising procedure.

Consider them on the continuum of aerosol -> small droplets -> large droplets -> puddles. Aerosols and small droplets have the ability to travel fair distances, especially if powered by a blast of oxygen or expired air. Larger droplets tend to obey the laws of gravity and settle on surfaces.

 

Just breathing, coughing and sneezing

But even putting an oxygen mask on the patient may not protect you. Hui et al. (2006) used fancy laser beams and smoke to detect just how far a single breath might travel.  With a standard oxygen mask on the patient and a flow rate of 4l/min, a tidal volume of 500mls, and 12 breaths a minute the smoke plume traveled approximately 0.45m. In most experiments, scientists use smoke as a stand-in for the more nebulous breath of air. Non-biological aerosols will behave differently depending on the airflow and ventilation in the room and have a constant density. Mathematical modelling would suggest that the further from the source a sample is taken then the lower the potential infectivity until a state of equilibrium is reached. Fortunately, the air is exchanged in most hospital rooms on a regular basis.

A patient that is coughing and sneezing can produce large, short-range droplets and small, long-range aerosols. The aerosols produced by coughing are heavier than the smoke used in experiments so hopefully, they may not be able to travel as far. Experimental data will tend to over-estimate the spread of droplets.

Thompson et al (2013) took 99 air samples around presumptive AGPs. 26.1% of them contained viral RNA. But the baseline level of contamination, when no AGPs (as defined by WHO 2009) were performed was 10.5%. Just because a procedure might generate an aerosol, it does not hold true that the aerosol can cause an infection.

Most of the data we have comes from the fast SARS-CoV epidemic in 2002-2003. Tran et al. tried to find all of the papers related to HCW infection and aerosol-generating procedures. They found 10 – 5 non-randomized cohort studies and 5 retrospective cohort studies. They then created pooled estimates of odds ratios.

Judson and Munster usefully categorized AGPs into those that mechanically create and disperse aerosols and those that make the patient wriggle and cough. Or you could think of them, as suggested by Brewster et al. (2020) as those procedures that require gas flow and those that require no extrinsic gas flow.

 

 

Bag-valve-mask ventilation and CPR

High risk 

A paediatric cardiac arrest is uncommon. When it occurs your first move* should be to open the airway and provide rescue breaths. In this time of COVID19, I doubt anyone is going to be doing mouth-to-mouth/nose ventilation. They are going to reach for an appropriately sized bag-valve-mask. Just like when placing a standard oxygen mask, there is a transverse movement of droplets even with a reasonable seal. The addition of an HME filter does appear to attenuate some of this, as demonstrated by Chan et al.(2018).

Adapted from Chan MT, Chow BK, Lo T, Ko FW, Ng SS, Gin T, Hui DS. Exhaled air dispersion during bag-mask ventilation and sputum suctioning-Implications for infection control. Scientific reports. 2018 Jan 9;8(1):1-8.

 

Adult CPR guidelines are advocating for chest compression-only CPR in the community and rapid intubation pre-compressions if circumstances allow. There has been little guidance on paediatric CPR from the ALSG but a number of enterprising teams are looking at it.

Possible cases of SARS transmission by CPR have been reported (Christian et al. 2004) but BVM ventilation took place during the cases and this may be the most important factor for possible viral transmission.

 

Intubation

High risk 

Anything, where the clinician is inches away from the respiratory tract of the patient, is going to be a high-risk procedure. There have been huge collaborative efforts worldwide creating COVID intubation algorithms. They share a lot of commonalities.

  • The most experienced operator performs the procedure – this is not a time for learning
  • No bag-valve-mask ventilation prior to intubation
  • Use of videolaryngoscopy to maximize the distance between intubator and patient
  • Minimum number of staff present

This is my favourite paediatric intubation resource from Queensland Children’s Hospital.

 

Nebulizing a medication

High risk / Unclear evidence

There are few indications for nebulizing medication. Bronchodilators are best delivered by MDI and spacer when possible but in cases of severe asthma or perhaps, more commonly, in croup, a nebulizer chamber may be the way to go. The UK guidelines do not consider the delivery of nebulized medications as an AGP. The rationale behind this is that the aerosol is derived from a non-patient source. Even if they do have the disease the medication sticks to the mucus membranes and so will not get released into the general environs. There seems to be a lack of global consensus on this.

Nebulizers generate small particles, between 1-5microns in diameter, in order to get down into the bronchioles and not just be deposited in the oropharynx. Viable COVID19 viral RNA has been detected in aerosol form 3 hours after delivery by nebulizer in experimental conditions but this does not prove infectivity, just infectious potential.

In 2009 O’Neill et al. performed air sampling studies for common patient activities, including making the bed and providing nebulized therapy, as well as some more invasive treatments (bronchoscopy and suctioning). Although small numbers they found an increase in influenza particle numbers (from baseline) of up to 70,000/cm³.

 

High Flow Nasal Cannula

High risk 

In adult practice, high flow oxygen delivery is anything over 6l/min. In paediatrics, it is 2l/kg/min up to the adult maximum of 60l/min. In one of my favourite studies to date (and certainly in keeping with the DFTB ethos) five anaesthetists gargled 10mls of red food dye, inhaled to their vital capacity and then coughed. They then repeated the experiment using blue food dye and HFNC at 60l/min and compared the distance traveled. They showed a baseline cough distance of 2.48m increasing up to 2.91m with high flow. Of course, children have a much smaller vital capacity.

This is in contradiction to the data from Hui et al. (2019). They used a human-patient-simulator (as opposed to humans in the above study), smoke and lasers. With a properly fitted mask flow forward flow was increased to ~26 cm with 5cm of CPAP and to around 33cm with 20cm of CPAP. With HFNC the exhalation distance increased from 6.5cm (10l/min) to ~17cm (60l/min). When the mask became loose or disconnected smoke was detected up to ~62cm laterally.  So why the big difference in the studies? It is the cough that causes the problem.

This video from Sick Kids in Toronto says more than any words ever could.

Whether you believe in the benefits of high-flow or not, pushing oxygen through the nose at 2l/kg/min and out through the mouth can create an aerosol spread of snot and virus. We would advise that it is only be used in cases where low flow oxygen therapy has failed. It also makes sense then, that it should only be started in the place where the patient is going to end up. It would not be wise to start a patient on HFNCO2 then wheel them through the hospital leaving a cloud of viral particles in their wake like some overactive Bisto Kid. And if you are going to do it with a coughing patient then it would be sensible to put a standard face mask on first.

 

Non-invasive ventilation (CPAP or BiPAP)

High risk 

High flow nasal cannula seems to have superseded non-invasive ventilation in many cases, though CPAP is regularly used in neonatal practice. There is very little evidence for maternal transmission of COVID19 and one might suppose that full PPE is then not warranted. However, you need to consider where the baby has come from.

Open suctioning and chest physiotherapy

High risk 

Removal of nasal foreign body

Medium to high risk

There are lots of ways to remove a nasal foreign body but all of them will generate snot. The old standby – the mother’s kiss – is, realistically, no more dangerous for the parent than living in close proximity. If your pre-encounter probability of infection with SARS-CoV-2 is low, i.e. there is little community transmission, then the risk to the provider is probably low.

Nitrous oxide

Medium to high risk 

Respiratory illness is a contra-indication to nitrous sedation but given that there is a degree of asymptomatic carriage it is not impossible that we might need to use it. With children not going to school and being told to stay away from their friends, there is going to be a spike in trampoline and bunk-bed related injuries. Again consideration should be made as to the possibility of community transmission. Logically holding a continuous flow mask on an uncooperative toddler would expose a HCW to higher risk than being a room Sith a cooperative patient using a demand system with appropriately attached to suction.

Examining the throat

Medium to high risk 

In normal times, no paediatric examination is complete without looking in the ears, nose, and throat, no matter how hard it might be. You can argue that looking at tonsils might not be overly helpful, given that the inter-rate variability is pretty high but there are other things to look for too – emerging teeth, Koplik spots, ulcers. But does a look in the throat put us at risk?

The Royal College of Paediatric and Child Health concurs, and in a statement put out on the 24th of March suggest that we only look in the throat if it is essential. If we have to do it we should be wearing appropriate protection (glove, gown, surgical face mask). If a child is at particularly high risk then they recommend empiric antibiotics.

Even ENT experts, like Eric Levi, recognize the unique risks that fiddling around near the upper respiratory tract hold.

Inserting a nasogastric tube

Medium to high risk

The combined Colleges of Surgeons of Great Britain and Ireland suggest that insertion of a nasogastric tube in an adult is an AGP, probably as it may induce coughing.

Taking a nasopharyngeal swab

Low to moderate risk 

The CDC state that collecting a nasopharyngeal swab doesn’t need to take place in an isolation room but should at least be performed in a single room with a closed door. The health care practitioner should wear an N95 mask or equivalent, coupled with eye protection, gloves, and gown. Given how far the swab has to travel up the nasopharynx nobody should be surprised that it might make someone sneeze.

The current Australian guidance contains slightly different advice.

 

We can also add things like IV access, suprapubic aspiration and performance of a lumbar puncture to this list of LOW-risk procedures.

And let’s not forget our surgical and dental colleagues

Surgical procedures

Clearly, some surgical procedures are more dangerous than others. Eric Levi. advocates for a risk assessment before any procedure takes place, starting with ‘Does it need to be done now?” Take a look at his post on how he is modifying his operative technique in order to reduce risk to himself and his colleagues.

On the 25th of March, the combined Colleges of Surgeons of Great Britain and Ireland recommended against laparoscopic surgery due to the potential for aerosol formation. Endoscopy, at either end, also has the potential for the creation of fomites and aerosolizing droplets and so should be carried out with extreme caution.

Dental procedures

There are very few dental procedures that need to be performed as an emergency but given that high-speed drills can lead to aerosolization have a care for our dental colleagues that may also be exposed in the course of duty.

The guidance for these procedures is common sense. Don’t perform them if you don’t have to. This is not the time for some minor dental procedures. If they have to be carried out then it should happen in the appropriate space with the appropriate staff. This means in a single room (ideally) with the minimum number of staff wearing appropriate PPE.

 

These are our thoughts, based on the current evidence, and we’d love you to persuade us otherwise in the comments below.

*Clearly the first step of the algorithm is D for Danger. That means putting on your PPE.

Selected references

Bourouiba L. Turbulent Gas Clouds and Respiratory Pathogen Emissions: Potential Implications for Reducing Transmission of COVID-19. JAMA. 2020 Mar 26.

Brewster DJ, Chrimes NC, Do TB, Fraser K, Groombridge CJ, Higgs A, Humar MJ, Leeuwenburg TJ, McGloughlin S, Newman FG, Nickson CP. Consensus statement: Safe Airway Society principles of airway management and tracheal intubation specific to the COVID-19 adult patient group.

Brown JS, Gordon T, Price O, Asgharian B. Thoracic and respirable particle definitions for human health risk assessment. Particle and fibre toxicology. 2013 Dec 1;10(1):12.

Davies A, Thompson G, Walker J, Bennett A. A review of the risks and disease transmission associated with aerosol generating medical procedures. J Infect Prev 2009; 10:122–6.

van Doremalen N, Bushmaker T, Morris D, Holbrook M, Gamble A, Williamson B, Tamin A, Harcourt J, Thornburg N, Gerber S, Lloyd-Smith J. Aerosol and surface stability of HCoV-19 (SARS-CoV-2) compared to SARS-CoV-1. medRxiv. 2020 Jan 1.

Hui DS, Ng SS. Recommended hospital preparations for future cases and outbreaks of novel influenza viruses. Expert Review of Respiratory Medicine. 2020 Jan 2;14(1):41-50.

Hui DS, Ip M, Tang JW, Wong AL, Chan MT, Hall SD, Chan PK, Sung JJ. Airflows around oxygen masks: A potential source of infection. Chest. 2006 Sep 1;130(3):822-6.

Judson SD, Munster VJ. Nosocomial Transmission of Emerging Viruses via Aerosol-Generating Medical Procedures. Viruses. 2019 Oct;11(10):940.

Kam KQ, Yung CF, Cui L, Lin Tzer Pin R, Mak TM, Maiwald M, Li J, Chong CY, Nadua K, Tan NW, Thoon KC. A well infant with coronavirus disease 2019 (COVID-19) with high viral load. Clinical Infectious Diseases. 2020 Feb 28.

Liu Y, Ning Z, Chen Y, Guo M, Liu Y, Gali NK, Sun L, Duan Y, Cai J, Westerdahl D, Liu X. Aerodynamic Characteristics and RNA Concentration of SARS-CoV-2 Aerosol in Wuhan Hospitals during COVID-19 Outbreak. bioRxiv. 2020 Jan 1

Macintyre CR, Seale H, Yang P, Zhang Y, Shi W, Almatroudi A, Moa A, Wang X, Li X, Pang X, Wang Q. Quantifying the risk of respiratory infection in healthcare workers performing high-risk procedures. Epidemiology & Infection. 2014 Sep;142(9):1802-8.

Noti JD, Lindsley WG, Blachere FM, Cao G, Kashon ML, Thewlis RE, McMillen CM, King WP, Szalajda JV, Beezhold DH. Detection of infectious influenza virus in cough aerosols generated in a simulated patient examination room. Clinical Infectious Diseases. 2012 Jun 1;54(11):1569-77.

Seto WH. Airborne transmission and precautions: facts and myths. Journal of Hospital Infection. 2015 Apr 1;89(4):225-8.

Shiu EY, Leung NH, Cowling BJ. Controversy around airborne versus droplet transmission of respiratory viruses: implication for infection prevention. Current opinion in infectious diseases. 2019 Aug 1;32(4):372-9.

Somogyi R, Vesely AE, Azami T, Preiss D, Fisher J, Correia J, Fowler RA. Dispersal of respiratory droplets with open vs closed oxygen delivery masks: implications for the transmission of severe acute respiratory syndrome. Chest. 2004 Mar 1;125(3):1155-7.

Tang JW, Li Y, Eames I, Chan PKS, Ridgway GL. Factors involved in the aerosol transmission of infection and control of ventilation in healthcare premises. J Hosp Infect 2006;64:100-14.

Tellier, R., Li, Y., Cowling, B.J. et al. Recognition of aerosol transmission of infectious agents: a commentary. BMC Infect Dis 19, 101 (2019). https://doi.org/10.1186/s12879-019-3707-y

Thompson KAPappachan JVBennett AM, et al. EASE study consortium. Influenza aerosols in UK hospitals during the H1N1 (2009) pandemic–the risk of aerosol generation during medical procedures. PLoS One. 2013;8:e56278.

Tran K, Cimon K, Severn M, Pessoa-Silva CL, Conly J. Aerosol generating procedures and risk of transmission of acute respiratory infections to healthcare workers: a systematic review. PloS one. 2012;7(4).

World Health Organization. Infection prevention and control during health care when novel coronavirus (‎‎‎ nCoV)‎‎‎ infection is suspected: interim guidance, January 2020. World Health Organization; 2020

Intubation

Cheung JC, Ho LT, Cheng JV, Cham EY, Lam KN. Staff safety during emergency airway management for COVID-19 in Hong Kong. The Lancet Respiratory Medicine. 2020 Feb 24.

Nebulizing a medication

O’Neil CA, Li J, Leavey A, Wang Y, Hink M, Wallace M, Biswas P, Burnham CA, Babcock HM. Characterization of aerosols generated during patient care activities. Clinical Infectious Diseases. 2017 Oct 1.

Amirav I, Newhouse MT. RE: Transmission of Corona Virus by Nebulizer-a serious, underappreciated risk!.

High Flow Nasal Cannula

Hui DS, Chow BK, Lo T, Tsang OT, Ko FW, Ng SS, Gin T, Chan MT. Exhaled air dispersion during high-flow nasal cannula therapy versus CPAP via different masks. European Respiratory Journal. 2019 Apr 1;53(4):1802339.

Leung CCJoynt GMGomersall CD, et al. Comparison of high-flow nasal cannula versus oxygen face mask for environmental bacterial contamination in critically ill pneumonia patients: a randomized controlled crossover trial. J Hosp Infect. 2019;101(1):8487.

Loh NH, Tan Y, Taculod J, Gorospe B, Teope AS, Somani J, Tan AY. The impact of high-flow nasal cannula (HFNC) on coughing distance: implications on its use during the novel coronavirus disease outbreak. Canadian Journal of Anesthesia/Journal canadien d’anesthésie. 2020 Mar 18:1-2.

Non-invasive ventilation

Singh A, Sterk PJ. Noninvasive ventilation and the potential risk of transmission of infection. European Respiratory Journal. 2008 Sep 1;32(3):816-.

Bag-Valve-Mask Ventilation

Chan MT, Chow BK, Lo T, Ko FW, Ng SS, Gin T, Hui DS. Exhaled air dispersion during bag-mask ventilation and sputum suctioning-Implications for infection control. Scientific reports. 2018 Jan 9;8(1):1-8.

Christian MD, Loutfy M, McDonald LC, Martinez KF, Ofner M, Wong T, Wallington T, Gold WL, Mederski B, Green K, Low DE. Possible SARS coronavirus transmission during cardiopulmonary resuscitation. Emerging infectious diseases. 2004 Feb;10(2):287.

Suctioning

Inserting a nasogastric tube

Nitrous oxide

Taking a naso-pharyngeal swab

Examining the throat

Lu D, Wang H, Yu R, Zhao Y. Integrated infection control strategy to minimize nosocomial infection of corona virus disease 2019 among ENT healthcare workers. Journal of Hospital Infection. 2020 Feb 27.

Tang JW, Nicolle AD, Klettner CA, Pantelic J, Wang L, Suhaimi AB, Tan AY, Ong GW, Su R, Sekhar C, Cheong DD. Airflow dynamics of human jets: sneezing and breathing-potential sources of infectious aerosols. PLoS One. 2013;8(4).

Removal of foreign bodies

Surgical spread

Ong J, Cross GB, Dan YY. The prevention of nosocomial SARS-CoV2 transmission in endoscopy: a systematic review of recommendations within gastroenterology to identify best practice. medRxiv. 2020 Jan 1.

Dental spread

Divya R, Senthilnathan KP, Kumar MP, Murugan PS. Evaluation of aerosol and splatter contamination during minor oral surgical procedures. Drug Invention Today. 2019 Sep 1;12(9).

Sabino-Silva R, Jardim AC, Siqueira WL. Coronavirus COVID-19 impacts to dentistry and potential salivary diagnosis. Clinical Oral Investigations. 2020 Feb 20:1-3.