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Question 3 Ketamine or midazolam: does it matter which?
  1. Elisabeth Jameson
  1. Elisabeth Jameson, Biochemical Genetics Unit, Royal Manchester Children's Hospital, Manchester, UK; elisabeth.jameson{at}cmft.nhs.uk

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Scenario

A 7-year-old boy presents to the emergency department having sustained a laceration to his forearm after playing pirates with his brother using kitchen knives. He has no other injuries but the laceration requires suturing. He is, unsurprisingly, not keen on the idea of stitches and is very upset and won't co-operate. Midazolam and ketamine are commonly used sedative agents; which would be preferable in this emergency room scenario?

Structured clinical question

In children with simple lacerations requiring suturing [patient], is midazolam [intervention] more effective than ketamine [comparison] in achieving adequate sedation [outcome]?

Search strategy and outcome

Primary sources

MEDLINE was searched from 1950 to November 2008 and EMBASE from 1980 to week 51 2008 via the OVID interface. The advanced search mode was used with the terms (‘midazolam’ and ‘ketamine’) and (‘suturing’ or ‘laceration’). Limits were: MEDLINE, ‘all child 0–18 years’ and EMBASE, ‘child <unspecified>‘.

Secondary sources

The Cochrane Library was searched using the search terms ‘midazolam’ and ‘ketamine’.

Outcome

The search of MEDLINE revealed 15 papers, three of which were relevant. EMBASE yielded 24 articles with one additional relevant article. No other papers were identified in The Cochrane Library, but all four relevant papers were listed on the Cochrane register of trials (see table 1).

Commentary

Emergency departments are often presented with children requiring minor procedures, for example, wound closure, wound exploration or incision and drainage of minor collections. These children are often scared, tired and in pain, which can make these procedures difficult. In order to facilitate treatment, a two-part approach should be taken. The first part is non-pharmacological, relevant to all aspects of paediatric services and involves provision of the following:

  • Child-friendly environment

  • Distraction with use of play specialists where available

  • Experienced paediatric medical and nursing staff who can reassure the child and perform any interventions in a timely fashion

  • Analgesia

  • Consideration of Entonox; this can be particularly useful in the older child.

If these measures do not facilitate the procedure, then sedation can be considered. The aims of sedation should be to produce reliable sedation, minimal side effects and a quick onset and offset times (thus allowing procedures to be conducted in a time efficient manner). If sedation can be performed within the emergency department, it can prevent admission and the need for a general anaesthetic and its associated risks.

Clinical bottom line

  • Ketamine is an alternative to midazolam for the effective sedation of children requiring minor procedures and can prevent unnecessary admission and general anaesthesia.

  • In children with difficult venous access, intramuscular ketamine is an option and is preferable to intranasal midazolam.

  • The guidelines published by the College of Emergency Medicine provide an excellent summary of ketamine use.1

Midazolam is classically the sedative agent of choice with a fast recovery time and low toxicity. There are oral, intranasal and intravenous preparations, with the oral preparation generally being well tolerated. In addition to being a sedative it is also a good anxiolytic, amnesic and hypnotic, which are all useful features in this scenario. Midazolam, like all drugs, does have undesirable side-effects. The one that causes the most concern in this scenario is that it often has the opposite effect and results in hyperactivity in approximately 2% of children, thus leading to the need for general anaesthesia. Other side-effects occurring in children include vomiting in 11% and nausea in 5%. As with any sedative there is the risk of respiratory depression, which can potentially lead to the need for respiratory support; however, flumazanil is an effective antidote.

Ketamine is an alternative sedative agent that comes in the same forms as midazolam but there is also an intramuscular preparation. It produces a ‘dissociative’ anaesthesia and the resultant preservation of laryngeal reflexes, respiratory drive and muscle tone means that there is less risk of respiratory depression, and thus reduced need for ventilatory support. Its other main advantage is that it does not produce a paradoxical hyperactivity. In terms of disadvantages, there is a 0.3% risk of laryngospasm1 and occurrence of emergence phenomena. The latter is experienced as hallucinations and nightmares as the ketamine wears off. Emergence phenomena are not commonly seen in the paediatric population, although incidence increases with age.2 This, however, may be a reflection of a pre-verbal child's inability to report these phenomena and any behavioural changes being attributed to the stress of the situation. Other side-effects include emesis (again this increases with age), flushing and increased oral secretions, the latter clearly posing a possible risk to the airway.2 A recent meta-analysis reviewed the predictors of adverse events with ketamine and these included use in children aged less than 2 years or those aged 13 or above.3

It should be noted that both sedatives have the potential to cause respiratory depression. It is therefore advisable that the person administering either agent should be competent in basic airway management, that is, be able to perform a jaw thrust and bag-mask ventilation to maintain oxygenation while awaiting anaesthetic support.

Age is always a prime consideration in paediatric patients. Three of the trials included children aged from 1 to 7 years, while the fourth paper included children aged 6 months to 12 years. In accordance with the Children's British National Formulary, ketamine and midazolam can both be used from the neonatal period. The papers, however, did not review the effectiveness of either medication in terms of the age of the child.

The papers summarised in table 3 suggest ketamine should be considered as the potential sedative of choice as it offers quick, reliable sedation with minimal side effects and has a rapid onset and offset time. For children with difficult venous access, intramuscular ketamine can provide an alternative to intranasal midazolam, which despite popular belief, is unpleasant for all involved and is less effective. All four papers commented on the views of both doctors and parents, the overall opinion being that ketamine is the preferred agent. This review leads on to the question: ‘Could ketamine be used for children undergoing MRI, dimercaptosuccinic acid scan, metaiodobenzylguanidine scan, lumbar puncture, etc?’

Table 3

Ketamine or midazolam: does it mater which?

References

View Abstract

Footnotes

  • Competing interests None.

  • Provenance and peer review Not commissioned; not externally peer reviewed.

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