Hot Garbage: Mythbusting fever in children

Cite this article as:
Alasdair Munro. Hot Garbage: Mythbusting fever in children, Don't Forget the Bubbles, 2020. Available at:
https://doi.org/10.31440/DFTB.22916

Juniper is a 3yr old girl brought in with her mother, with a 48hr history of fever. Her mum is particularly concerned because her fever was up to 39.8°C, didn’t come down with paracetamol and she describes an episode which sounds like a rigor. On examination, she has a temperature of 39.3°C, a runny nose and bright red tonsils, and looks otherwise well. You go to discharge her, but your colleague asks if you should wait to see if her temperature comes down with ibuprofen before sending her home?

 

Introduction

Febrile illnesses are the most common cause of presentation to acute paediatric medical services. This means that fever is the most common presenting symptom seen by paediatricians, and it is clearly a huge cause of concern for parents. Despite this fact, it is clear that in day-to-day practice that there is a widespread misunderstanding about fever, its purpose, and its clinical interpretation.

Well, no longer! Once you have finished reading, you will be a master of all things related to fevers in children. We will start with some basic understanding of the processes surrounding fever, and finish off with some mega myth-busting!

What is fever?

Fever is an elevated core body temperature, as part of a physiological response to infection regulated by the hypothalamus. This is crucial to understand – your body is in control of your temperature. This is not something an infection is doing to your body; it is something your body is doing to the infection. This is different from pathological hyperthermia, where your temperature is elevated by either hypothalamic dysfunction or external heat. These are extremely rare.

Note: there are other, non-infectious causes of fever, such as cancer, Kawasakis, and autoinflammatory conditions, but these are rare in comparison to infectious fever and are covered elsewhere.

 

What temperature counts as a fever?

At what threshold do we say a child has an elevated body temperature? This is more controversial than one might think, as actually the data from which we derive “normal” body temperature is extremely poor. The most common cut off for defining a fever is 38°C – but it is important to remember that there is nothing magic about 38°C compared to 37.9°C, and temperature is better taken in context or a trend, if possible.

How do we get fevers?

The process of developing fever is extremely complex, and our understanding is still developing. At present, our best explanation is that the process is triggered by the presence of chemicals referred to as pyrogens. Pyrogens can either be exogenous (such as parts of the microbe itself, like the lipopolysaccharide on the outside of bacteria), or endogenous, such as cytokines like IL1, TNF, Prostaglandin E2 and importantly IL6, which are released by immune cells when they detect an invader. These pyrogens act to increase body temperature peripherally, but importantly also trigger receptors in the preoptic nucleus in the brain. This releases PGE2 into the hypothalamus, which then sets a new target temperature. This target is met by many facets designed to increase heat, including:

  • Release of noradrenaline by the sympathetic nervous system, increasing thermogenesis in brown adipose tissue and causing peripheral vasoconstriction and piloerection (reducing heat loss)
  • Acetylcholine release stimulating muscle myocytes to induce shivering
  • Feeling cold”, inducing heat-seeking behaviours (warm clothes and blankets)

It is important to remember that the body is trying to get hotter. If you intervene with non-medicinal efforts to cool it down, it will work even harder to try to heat up.

Why do we get fevers?

The process of having a fever has been conserved across species from lizards to mammals, and even plants! This is because it is a beneficial response to an infection. The mechanisms by which a fever helps protect you from infection include:

  1. Higher temperatures inhibiting growth/replication of pathogens
  2. Higher temperatures promoting the immune response to infection

It is also worth noting that bacteria are killed more easily by antibiotics at higher temperatures, so there is also a potential third mechanism.

 

Summary

Fever is beneficial. When a pathogen causes infection, pyrogens stimulate the hypothalamus to increase the body temperature through several mechanisms, and this increased temperature helps inhibit the growth of the pathogen AND stimulates the immune system to fight it.

That was a lot of science. Don’t worry – it’s time to get clinical! All this science stuff is lovely, but what does this mean for our patients?

Clinical significance of fever

As we have ascertained, fever is beneficial. For this reason, when a child presents with fever, the fever itself is actually of no concern. What we are interested in is the reason for the fever. Is this fever the result of a benign, self-limiting, childhood infection – or is it associated with a serious bacterial infection? Trying to determine this is enough for its own blog article (the most important thing is the end of the bed assessment – see Andy Tagg’s excellent breakdown of the paediatric assessment triangle).

Ignore the fever itself – what’s important is ascertaining its cause.

Now, let’s get on and bust some myths that persist surrounding fever in children!

 

Myth 1 – Higher temperature indicates a serious infection

This is one of the most common concerns amongst parents. The particular height of temperature may be what prompts them to come to hospital, or even what prompts the health care provider to initiate more aggressive management or investigations.

The truth is that the relationship between the height of temperature and risk of serious illness is at best complicated, and at worst a dangerous distraction. There is a very poor correlation, with such woeful sensitivity and specificity that it will both grossly over and under-call serious infections (either if the high temperature is used to rule in, or lower temperature to rule out). The caveat to this is in younger infants (particularly under 60 or 90 days), who have a higher baseline risk of serious infections (and more to the point – once they spike a temperature will be managed aggressively regardless of how high it was). Some studies have shown an extremely weak association in older children, but not enough for it to have any meaningful influence on our management. A fever is a fever – higher temperatures should not be managed any differently than lower ones.

 

Myth 2 – Temperature not relieved by antipyretics indicates a serious infection

Another common misconception also linked to the myth above. Some fevers respond well to antipyretics, and some do not. We do not understand why this is the case, however, studies have not demonstrated that failure to respond to antipyretics is a useful indicator of a more serious infection. It is not very pleasant for the child to remain hot, but it does not mean they are at any higher risk. A child whose temperature does not respond to antipyretics should not be treated any differently to one that does.

Myth 3 – Rigors indicated a serious infection

This has been covered in-depth in a separate blog post – but to summarise; there is extremely weak evidence that rigors are associated with an increased risk of bacterial infection in children, which is irrelevant when factors that are more important are taken into account. There is also evidence of no increased risk. The presence or absence of rigors should not be a deciding factor in the management of febrile children.

Myth 4 – You must wait for a fever to come down before discharge

This may seem common practice for many of you working in acute paediatrics. If a child is febrile on arrival, people often want to wait to see the temperature come down before allowing them to be discharged (this should be differentiated from seeing observations normalize in the absence of fever – which is a more understandable if still slightly questionable practice). As we have seen, a fever merely indicates the presence of an infection. If you have ascertained the cause of the fever, or at least ruled out any red flags for serious causes, the ongoing presence or absence of a fever means nothing for the child. If it comes down before discharge, it will probably just go up again once they are home! There is no need to make them wait around for hours for no reason.

Myth 5 – Fever should be treated with antipyretics

We have established that fever is beneficial. Therefore, there is essentially no reason to treat a fever in and of itself. It will not cause harm, and it is probably helping. Some children tolerate having higher temperatures extremely well, so if they are playing happily or do not seem terribly bothered about their temperature of 39°C then you leave them well alone.

Treat the child, not the fever.

Myth 6 – Fever should not be treated with antipyretics

There is an opposing school of thought, which says that since fevers are beneficial, we should not treat them at all. Given how absolutely dreadful it can feel to have a fever (which many of us adults should be able to vouch for), many of us give medicines to try to bring the temperature down and make the child more comfortable. This is the right thing to do. Despite the potential benefits having a fever confers, there is no evidence of any clinically meaningful harms to treating temperatures in unwell children, or even in adults in ICU. If the child is distressed by the temperature, they should have antipyretics to make them feel more comfortable.

Summary

  • Fever helps your body to fight infection and is not dangerous (no matter how high)
  • The fever itself is not important. The cause of the fever is what matters
  • There is little to no evidence that higher temperatures, temperatures that don’t respond to antipyretics, or rigors indicate an increased risk of serious infection
  • Persisting fever on its own is not a reason to postpone discharge
  • Only treat fevers if they are causing distress. Treat the child, not the fever

 

Postscript: Febrile convulsions

When I posted my initial thread on twitter about fevers, there were many comments asking why I didn’t address febrile convulsions. This was mainly because these are worth a post to themselves (which they have here). In brief, febrile convulsions are extremely distressing for parents to observe, but they are common and they are very benign. We do not advise treating fevers to prevent febrile convulsions, and until recently, this was because there was no evidence that they had any effect in preventing them. A recent study from Japan did demonstrate a decrease in recurrence of febrile convulsions in children who had already had one if given regular PR paracetamol, however, there are major caveats to this study discussed in depth here.

 

For the more visual oriented, the talented Emma Buxton has created an infographic of the key reminders from this blog post:

Are rigors a sign of serious bacterial infection?

Cite this article as:
Alasdair Munro. Are rigors a sign of serious bacterial infection?, Don't Forget the Bubbles, 2019. Available at:
https://doi.org/10.31440/DFTB.18150

Noah is an 18m old boy who presents with fever since yesterday evening. He’s been eating and drinking a little less than usual but wetting nappies regularly. He’s been miserable when hot, but settles when his temperature comes down. His mum presented to A&E because whilst febrile this morning, he had an episode of shivering which lasted several minutes. He was conscious during the episode.

CVADs – a survival guide

Cite this article as:
Amanda Ullman. CVADs – a survival guide, Don't Forget the Bubbles, 2016. Available at:
https://doi.org/10.31440/DFTB.10530

This guest post is from Amanda Ullman, Tricia Kleidon, Anna Dean and the Paediatric Vascular Assessment and Management Service, Lady Cilento Children’s Hospital, Brisbane.

We all love reliability. Central venous access devices (CVADs) are everywhere – across disciplines and departments, and we just want them to work reliably, without complication.

But every day, somewhere in your hospital, we are problem solving CVADs gone awry. And in many hospitals no specialist vascular access teams are there to help you. 

Being a CVAD survivalist will help you – most likely at 3am. Some situations will need escalating to specialists, but many can be quickly and effectively managed with simple, evidence-based techniques.

 

Needling a totally implanted device (ports)

Some totally implanted devices – or ports – are a pain. This is especially a problem in children with large amounts of adipose tissue, or poorly positioned ports.

But when problem solving this – everyone is different. Ask the child to sit up in the bed (or on their parent), and take off any restrictive clothing (e.g. bras for teenage girls). Use a rolled up towel under their back/shoulder blade and ask the patient to push their chest out, allowing less tissue to cover the port – making it become more prominent.  Make sure you have a firm grip of the port and stretch the skin out over it to reduce the amount of tissue you have to go through – this cannot be overemphasised.  There should be no slack in the skin.  You may need to change your grip a couple of times to get this just right. Also consider your own position when inserting, often placing yourself at the head of the bed is helpful.

 

Post CVAD insertion bleeding

Bleeding after the insertion of CVADs can require frequent dressing changes – not the easiest task on a post-anaesthetic child or toddler.

The application of small drops of medical-grade superglue, or tissue adhesive (cyanoacrylate), directly on the CVAD insertion site results in immediate haemostasis, without resulting in significant skin injury [1, 2]. Most practical on peripherally inserted central catheters (PICCs) and non-tunnelled CVADs, make sure the site is completely dry before applying the glue, try not to stick yourself to the child or the CVAD, and allow the glue to dry completely before covering it with the usual CVAD dressing.

 

Lumens that won’t aspirate or flush

Many factors can result in blocked CVAD lumens. A step-by-step approach is necessary…

  1. Don’t over complicate matters! Check for external occlusion due to a kinked line etc.
  2. Change the needleless access device (i.e. the bung) – these frequently dysfunction and result in blockage.
  3. Try small, pulsatile aspirates, and then flushes of normal saline using a 10mL syringe. Never use a syringe smaller than 10mL or be tempted to use excessive force – this can result in catheter breakage. Ask the patient to cough, breathe deeply, or change their position while aspirating and flushing.
  4. Assess for correct placement (chest x-ray, angiography).
  5. Instil a thrombolytic agent, such as Urokinase or Alteplase (unless contraindicated), allow it to dwell for at least 60 minutes, and then aspirate and/or flush with normal saline. This may need to be repeated several times.
  6. In the case of total occlusion where you can’t administer a thrombolytic agent by a simple push – use a 3-way tap and additional empty 10mL syringe.  Turn the 3-way tap off to the thrombolytic agent, pull back on the empty 10mL syringe to create a vacuum.  Turn the tap so it is open to the drug and patient, and the drug should infuse under negative pressure.
  7. If the blockage is a result of drug precipitation or build of lipid products; talk to the pharmacist for an appropriate dissolving agent such as hydrochloric acid or sodium bicarbonate.
  8. Phone a friend, preferably someone who can insert a replacement device.

 

Local CVAD site irritation vs local infection

Identification is of the issue is key.

If there are any signs of inflammation or infection (e.g., raised red area, ooze ) take a swab for microscopy, culture and sensitivity (MC&S).

Early libe sire infection

For uncomplicated exit site infections (i.e., no signs of systemic infection, purulent drainage or positive blood cultures) in long-term CVADs, the Infectious Diseases Society of America recommends the use of topical antimicrobial agents specific to the MC&S results, (i.e. mupirocin ointment for S. aureus infection and ketoconazole or lotrimin ointment for Candida infection). If it is a short-term CVAD (e.g. PICC) take it out and organise a replacement device.

If infection doesn’t seem likely, identify what is causing the skin irritation.

Contact dermatitis

Most frequently it will be the decontaminant (2% CHG in alcohol) that has not been left to dry adequately.  Some patients have a reaction to the fibres in the decontaminant stick. If this is a possibility use bottled (2% CHG in alcohol) with gauze and forceps.  Additionally, consider the use of a barrier film product, provide symptom relief (i.e. itch, pain), and if symptoms persist recommend changing to a less-irritating silicone-based dressing product.

 

Broken lumens

Oh God, it snapped. This happens – a lot it seems.

Broken lumens don’t always result in the end of the entire CVAD, but it does depend on the type of CVAD. Silicone CVADs, such as HickmansTM, have catheter repair kits that sit with skilled clinicians, such as paediatric oncology and haematology. Peripherally inserted central catheters vary by brand and catheter material in their ability to be repaired. This is definitely a phone a friend situation. When repairing a broken catheter, always consider the circumstances in which it fractured and environmental exposure. Blood cultures and prophylactic antibiotics might reduce the risk of subsequent infection.

References

1. Rickard, C.M., et al., A 4-arm randomized controlled pilot trial of innovative solutions for jugular central venous access device securement in 221 cardiac surgical patients. Journal of Critical Care, 2016. 36: p. 35-42.

2. Ullman, A.J., et al., Central venous Access device SeCurement And Dressing Effectiveness (CASCADE) in paediatrics: protocol for pilot randomised controlled trials. BMJ Open, 2016. 6(6).

3. Simcock, L., Managing occlusion in central venous catheters. Nurs Times, 2001. 97(21): p. 36-8.

4. Mermel, et al., Clinical practice guidelines for the diagnosis and management of intravascular catheter-related infection: 2009 update by the Infectious Diseases Society of America. Clin Infect Dis, 2009. 49: p. 1-45.

Infection

Cite this article as:
Marc Anders. Infection, Don't Forget the Bubbles, 2013. Available at:
https://doi.org/10.31440/DFTB.3764

Surgical site infection (superficial/deep/organ):

  • Prevalence 5-10%
  • Within 10-14 days post surgery
  • Most common: Staphylococcus aureus
  • Risk factors: neonate, HLHS, hospitalization prior surgery, TPN, emergency procedures, long CPB

Blood stream infection:

  • Prevalence 5-10%
  • Within 10-14 days post surgery
  • Most common: gram negative organism (Pseudomonas, Enterobacter)
  • Risk factors: surgical complexity, open sternum, low body weight, longer duration of central line, prolonged ICU stay

Pulmonary infection:

  • Prevalence 10%
  • Risk factors: prolonged mechanical ventilation, surgical complexity, low cardiac output syndrome, failed extubation

Current recommendation for antimicrobial prophylaxis in cardiac surgery: cefazolin up to 72 hrs (prolonged use may increase antimicrobial resistance). In the setting of either a presumed or known Staphylococcal colonisation, the hospital presence of a high incidence of MRSA, patients susceptible to colonisation, or an operation for a patient having prosthetic valve or vascular graft insertion, it would be reasonable to combine the beta-lactam with a glycopeptide (vancomycin) for prophylaxis.

Special considerations in immunodeficient syndromes (DiGeorge Syndrome, postoperative – see chylothorax).

See also sepsis and fever.


References:

[1] Am J Infect Control 2010 Nov;38(9):706-710: Sohn et al: Risk factors and risk adjustement for surgical site infections in pediatric cardiothoracic surgery patients

[2] Pediatr Cardiol 2010 May;31(4): 483-9: Abou Elella et al: Impact of bloodstream infection on the outcome of children undergoing congenital heart surgery

[3] Am J Health Syst Pharm 2008 Nov 1;65(21): 2008, 2010: Survey of congenital heart surgeons’ preferences for antimicrobial prophylaxis for pediatric cardiac surgery patients

[4] Ann Thorac Surg 2007 Apr; 83(4): 1569-76: Engelman et al: The Society of thoracic surgeons practice guideline series: Antibiotic prophylaxis in cardiac surgery, Part II: Antibiotic Choice


All Marc’s PICU cardiology FOAM can be found on PICU Doctor and can be downloaded as a handy app for free on iPhone or AndroidA list of contributors can be seen here.