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Ketamine

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You can keep staring at the 3-year-old’s deep eyebrow laceration, desperate to glue it, but you know it needs to be sutured. Now what?

Injured or distressed children present us with difficulties in the emergency department. Children experience a more intense physical and emotional reaction to painful or threatening procedures than adults. The goals of sedation of children in the emergency department include minimizing pain, anxiety, movement which may jeopardize the procedure, and maximizing the chances of success for the procedure performed, returning the patient to his or her pre-sedated state as quickly as possible while assuring the patient’s safety. In addition to minimizing the negative psychological experience for the child, sedation will reduce fear and distress in subsequent presentations to healthcare facilities.

Paediatric procedural sedation has become a domain of expertise in emergency medicine. As emergency physicians, we should be aware of the pros and cons of the different options within paediatric sedation and not only skilled in the technicalities of each but in the non-clinical aspect of ensuring both the child and the caregiver have as pleasant an experience as possible.

Choice of sedation

There are no hard and fast rules on what sedation to use. One must take into account many variables, including the age (and temperament) of the child, the proposed procedure, fasting time, co-morbidities, and levels of parental anxiety. If a patient or a parent is extremely anxious, or if the procedure has the potential to be very long, complex or painful, it may be more appropriate or kinder for the child to have their procedure done in theatre under general anaesthetic. In a compliant child with a laceration away from the face needing sutures, nitrous oxide may be ideal.

Prior to any form of sedation

  • Take time to discuss the options with the parents.
  • Remember to consider systemic pain relief. If using ketamine, the patient must be comfortable before administering the drug. If they are uncomfortable or agitated during administration, they are more likely to have nightmares or a scary emergence.
  • ALA (or similar) should be used around wound edges and AnGel/LMX on potential cannulation sites.
  • Local anaesthetics should be used where appropriate as the analgesic effect will outlast the ketamine.

Ketamine sedation

Ketamine has been described as the “ideal” agent for paediatric sedation. It has rapidly become the drug of choice for short, painful procedures in the ED due to its rapid onset of action and anxiolytic, analgesic and amnesic properties. Ketamine dissociation results in a lack of response to painful or noxious stimuli whilst preserving respiratory and cardiovascular stability.

Ketamine use has previously been restricted to anaesthetists, but emergency physicians are using it more and more frequently; ACEM and ACEP both have formal guidelines for emergency physicians, especially for ketamine sedations, and most departments will have a local protocol. It should, however, only ever be used in a resuscitation area by an airway-trained doctor in case of laryngospasm. It is mandatory to have a separate doctor performing the procedure itself and a nurse credentialed in ketamine sedation. Local policies may specify PLS/APLS certification or similar. This may mean delaying the procedure until daylight hours or calling in the consultant if there is an urgent clinical need.

Absolute contraindication

Infants less than six months (due to increased risk of airway compromise and recent animal studies which have found that ketamine is involved in neuronal degeneration within the developing brain)

Relative contraindications

  • age less than 12 months
  • high risk of laryngospasm (e.g. asthma, active URTI)
  • significant cardiac disease
  • reduced level of consciousness or recent head injury
  • previous psychosis
  • prior adverse reaction to ketamine

Examples of appropriate procedures

For the parents

For successful sedation, it is integral to involve the parents or caregivers and keep them on side. Take the time to explain the procedure to them and gain informed consent. I often give them a leaflet to read about ketamine sedation and then come back ten minutes later to answer any questions they may have. Ensure to go over what will happen, what they will see and what the child will experience.

Your child may seem to be awake after receiving ketamine, their eyes might flicker from side to side or they might twitch – this is normal

They may develop a rash

They may vomit

They may drool

Sometimes as your child wakes up they may be agitated or appear to be having hallucinations or nightmares. These can normally be helped by minimizing sensory input (e.g. talking softly and dimming the lights), but if required we can give a drug that will help to minimize these.

In very few cases, we may have to give extra Oxygen or extra drugs

Be reassured that your child will not remember the procedure

How parents can help

They can keep calm, reassure the child, talk softly and smoothly and describe a pleasant scene to them as they are given the drug. Remain with the child throughout the procedure and provide positive

Routes of administration

Ketamine can be used intravenously or intra-muscularly if access is likely to be a problem. Studies have concluded that IV ketamine is similar to IM ketamine in efficacy and safety, with no significant difference in the rates of adverse respiratory events. However, higher rates of vomiting were found following intramuscular administration.

IM has also been found to last slightly longer, and time to discharge was, therefore, longer (129 minutes from administration to discharge with intra-muscular ketamine, versus 80 minutes with IV).

Dose

Dissociation can usually be achieved with:

1-1.5mg/kg iv (given over 1-2 mins to avoid apnoea); top up dose of 0.5mg/kg iv can be given if required

4mg/kg im, a repeat dose of 2-4mg/kg can be given after 10 minutes if sedation inadequate

Note – Several studies have shown that higher ketamine doses are required for smaller children

It usually is good practice to site a cannula when the child is dissociated if using the IM route, in case the procedure takes longer or any other drugs are required, and to titrate any top-up doses more accurately.

Dosing in obese children

Whilst ketamine is widely used in children of all ages, studies (Green et al., 2009) have shown that adverse events associated with ketamine are more common in adolescents (including airway adverse events and vomiting).

Additionally, there is a lack of clarity for calculating the ketamine dose in obese adolescent patients – should it be based on ideal body weight  (Wulfsohn, 1972) or standard mg/kg doses as most guidelines suggest? Standard paediatric guidelines don’t tend to include a max dose – so what are we supposed to do?

This study investigated the dose of ketamine required to achieve adequate sedation in adolescents.

Street MH, Gerard JM, A fixed-dose ketamine protocol for adolescent sedations in a pediatric emergency department, Journal of Pediatrics, 2014

Who was studied?

This was a prospective, observational cohort study.

The study included patients presenting to the Emergency Department aged between 12 and 18 years old and weighing greater than 35kg, who required procedural sedation. They had to meet the criteria for ASA Class I or II.

Patients were excluded if they had: craniofacial, airway, and cardiorespiratory abnormalities, previous sedation-related events, neurological masses, or were undergoing an oral procedure.

There were 43 patients – mean age 13.9 years, mean weight 68.8kg, and mean BMI 24.4.

39.5% had a BMI greater than 25.

What was the intervention?

The normal sedation policy was followed, with pre-oxygenation and ongoing physiological observations. No benzodiazepines or antiemetics were given before sedation.

50mg of IV ketamine was given to each patient (over 30-60 seconds) and then sedation was assessed. Further doses of 25mg IV ketamine were administered until adequate sedation was achieved.

Sedation was measured using the Ramsay Sedation Score (RSS), and ‘adequate sedation’ was when the RSS was 5 or greater.

All patients were managed with the same guidelines. However, for data analysis, the patients were split into those with a BMI over 25 and those with a BMI of 25 or less. Data was collected to record the dose of ketamine required to achieve adequate sedation.

What were the outcomes?

The main outcome was provider satisfaction with sedation which was based on a 0-100 point scale rating.

Adverse events were noted during the procedure, and families were contacted 12-24 hours post-procedure to grade their satisfaction and record any other adverse events.

Heights, weights, and BMIs were calculated for all patients.

What did the results show?

81.4% of the cohort achieved adequate sedation after just 50mg of ketamine. All the remaining subjects achieved adequate sedation following a further 25mg dose.

The mean sedation time was 27.4 minutes and the mean time to discharge was 116.9 minutes. Time to discharge was shorter in the overweight group.

A similar proportion of people from both the overweight and non-overweight groups achieved adequate sedation with the 50mg ketamine dose. Based on actual body weight, the overweight group received less ketamine per kg.

Satisfaction scores were the same between the groups immediately post-procedure, and also on follow-up. 95.3% of families were satisfied or very satisfied with the sedation.

Were there any side effects?

  • 2.3% (one patient) desaturated and this which recovered with repositioning
  • 18.6% developed nausea during the recovery
  • 14% vomited during recovery
  • 2.3% (one patient) developed agitation which required midazolam

There was no difference in adverse events between the two groups.

No patient required over 75mg of ketamine to achieve initial adequate sedation (but bear in mind that patients did require further doses during the procedure as top-ups). Those in the overweight group required a median dose of 0.79 mg/kg to achieve adequate sedation.

Ketamine dosing in obese adolescents is a poorly understood area. This study indicates that there is no need to give the standard 1-2mg/kg ketamine initially. A fixed dose of 50/75mg should be sufficient to achieve adequate sedation in the obese adolescent population.

During the procedure

Talk gently and tell the child to choose a dream as they drift off to sleep. You can also describe (or get the parent to describe) a pleasant scene as you are administering the drug.

A lack of response to verbal stimuli and nystagmus usually indicates adequate sedation. Be patient. The effects of ketamine are usually apparent 1-2 minutes after an intravenous dose and 5 minutes after an intramuscular dose (this can seem a long time with the orthopaedic surgeon staring at you!) Top-up doses can be given as above, but ensure you have waited sufficient time before topping up.

Atropine 0.02mg/kg up to a maximum of 0.6mg can be used to reduce the hypersalivation caused by ketamine which can lead to laryngospasm or aspiration. Recent studies have shown no benefit to routine co-administration of atropine. However, prophylactic administration may be considered in procedures where minimising oral secretions is important, such as lip or tongue wounds. It is worth having it drawn up to be administered in case of concerns surrounding hypersalivation during the procedure.

Midazolam has previously been used for emergence phenomena. Still, it should be noted that unpleasant reactions are uncommon, and there is no benefit from the routine prophylactic administration of midazolam in children. There is significant variation in the literature with regard to dose, ranging from 0.02mg/kg to 0.1mg/kg. I favour a 0.05mg/kg dose, but this can be repeated if necessary. I usually don’t draw this up, but I have the dose required in my head and the vial nearby should unpleasant reactions arise.

Ondansetron 0.15mg/kg would be the drug of choice for the vomiting child; some clinicians opt to give it prophylactically although there is minimal evidence to support routine use.

After the procedure

Ensure to put the lights down, talk in whispers, and leave the child to wake up

Regular observations are required post-procedure until the child is fully awake

Prior to discharge

Ensure the child is fully awake and give them something to eat and drink

Discharge home with parents when able to mobilise and verbalise

Ensure to give appropriate post-procedure advice

References

https://emupdates.com/2011/01/27/taming-the-ketamine-tiger/

https://www.rch.org.au/clinicalguide/guideline_index/Ketamine_use_in_the_emergency_department/

CEM4880-CEC-Guideline-for-Ketamine-sedation-of-children-in-EDs-July-2010-Rev-1.pdf

https://www.rcemlearning.co.uk/references/ketamine-sedation-in-children/

About the authors

  • A London raised and trained ED registrar, she has temporarily swapped breaches for beaches in beautiful Northern Sydney. Passionate about all things EM - especially trauma, critical care and paediatrics - and hugely excited by the #FOAMed movement

  • Tessa Davis is a Consultant in Paediatric Emergency Medicine at the Royal London Hospital and a Senior Lecturer at Queen Mary University of London.

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5 thoughts on “Ketamine”

  1. I see oral is not included in the routes of administration. We find this particularly useful for very short procedures, good option for low resource environment.

    1. Thanks Kat.

      I have to say I have no real experience with oral ketamine in the ED. I’ve seen data regarding its use for painful dressing changes.

      What sort of dosing regime do you use?

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