Etomidate – misused or misunderstood?

In response to the recent editorial by Morris and McAllister [1] concerning the use of etomidate, which follows other publications questioning its continued use both in anaesthesia and critical care [2, 3], we agree that the use of a single dose of etomidate is associated with suppression of the adreno-cortical axis. However, we dispute the assertion that there has been a proven link between a single dose of etomidate and excess mortality. One previous study published in Anaesthesia, quoted by the authors, showed no significant differences in mortality between critically ill patients given single dose etomidate compared with thiopental. Moreover, the authors commented that the clinical implications of the ACTH suppression were unclear in this group [4]. The Helicopter Emergency Medical Service based at the Royal London Hospital uses etomidate as the standard induction agent in the prehospital environment due to its wide therapeutic index and safe cardiovascular profile. In a small study of 22 such polytrauma patients admitted to the ICU at the Royal London, all had ACTH stimulation tests with baseline and 60 min cortisol levels within 36 h of admission. Impaired adrenal function was seen in 36% of these patients, but the presence of adrenal suppression did not predict mortality [5]. Obviously, this is a small number of patients and a larger study would be required to make categorical conclusions. Another study of 62 patients published this year [6] suggested that a single dose of etomidate for intubation in intensive care may be detrimental on the basis of response to ACTH stimulation; the evidence was by no means absolute. The conclusion was that a larger randomised controlled study is required. We agree and plan to undertake a phase II clinical study which will, hopefully, inform an adequately powered, phase III clinical study with mortality as the primary outcome. To undertake such a multicentre clinical trial will require a critical care clinical trials network, which within the UK and Ireland have been slow to develop compared to other international groups [7]. A rush to judgement in the absence of such evidence would seem premature. Similar advice was given previously about the use of albumin in intensive care, which was later withdrawn following the SAFE study, which performed a randomised, controlled trial comparing albumin with normal saline [7].