Special K – time for a reappraisal ?

2 recent articles highlight the potential benefit of an often overlooked induction agent in critically ill patients.

Etomidate versus ketamine for rapid sequence intubation in acutely ill patients: a multicentre randomised controlled trial. Jabre, P. et al. Lancet. Volume 374, Issue 9686, Pages 293 – 300, 25 July 2009.

This multicentre, randomised, blinded trial in 65 french ICUs & 12 field teams enrolled 655 patients to either etomidate or ketamine for emergent intubation for critical illness. Patients were analysed only if they remained in ICU after day 3 (469). Adequate and reasonable power calculation, including predetermined septic & trauma subgroups. Primary end point was maximal SOFA score within 3 days (chosen as etomidate’s effects on adrenocortical axis thought to last <48 hrs). Secondary end points included intubation conditions, and 28 day ICU stay, catecholamine requirement, mortality & adrenocortical insufficiency. Results: no significant difference in mortality or SOFA scores at 28 days, although there was significantly more adrenocortical insufficency in the etomidate group. Of note only 15% of recruited patients were subsequently found to have sepsis, which was underpowered for this subgroup. The clinical significance of these findings must be questioned since the publication of the CORTICUS trial which has cast doubt as to the significance of adrenocortical failure on ICU. Interestingly subgroup analysis of that trial did suggest excess mortality in etomidate treated patients, a finding not borne out in this randomised trial. Although they failed to show a significant difference in primary end points, this trial adds to the evidence that even single doses of etomidate have lasting effects in critically ill patients. If heamodynamic stability is to be maintained during induction is there a case for a greater role for ketamine?

A recent review article, written by local clinicians in Derby, seeks to answer this question.

Anaesthesia in haemodynamically compromised emergency patients: does ketamine represent the best choice of induction agent? Morris, C et al. Anaesthesia.2009, 64; p 532–539.

An excellent summary of both the pharmacology and evidence base for these 2 induction agents. They question the logic of our reluctance to use ketamine in brain injured patients (making the valid point that secondary injury via hypoxia / hypotension is likely to be of greater significance than theoretical increases in ICP). Interestingly they call for trials of induction agents in compromised patients not dissimilar to that reported above. Our current default induction agent for trauma patients is etomidate, a policy that probably needs review.  Certainly for any patient in whom sepsis is a real or likely diagnosis should not be given etomidate in my opinion, despite the potentially conflicting data on harm from a single dose. Comments from the floor ?

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