In this episode, I’ll discuss ketamine vs etomidate for RSI.
Countless journal articles, podcast episodes, blog posts, and social media posts have been filled up comparing and contrasting the pros and cons of ketamine vs etomidate for sedation prior to rapid sequence intubation (RSI). While there are differences between these two medications, it is hard to argue that there is a compelling, clinically important difference to choose one over the other.
A recent article published in the journal Intensive Care Medicine examined this issue.
The study was a prospective, randomized, open-label, parallel assignment, single-center clinical trial of 801 patients. RSI was performed by an anesthesiology-based Airway Team under emergent circumstances at one high-volume medical center in the United States.
Patients were randomized to receive etomidate 0.2–0.3 mg/kg or ketamine 1–2 mg/kg for sedation prior to intubation.
The primary endpoint of the trial was survival at day 7. Secondary endpoints included survival at day 28, SOFA score, duration of mechanical ventilation, duration of catecholamine vasopressor use, length of stay in the ICU, and development of new adrenal insufficiency.
At day 7 the survival rate in the etomidate group was 77.3% vs 85.1% for ketamine. This difference was statistically significant with a p value of 0.005.
Unfortunately, by day 28 the survival benefit of ketamine disappeared and mortality rates were 64.1% and 66.8%, a non-significant difference.
Contrary to what would be predicted, patients who received ketamine had a higher rate of rescue vasopressor use and post-induction cardiovascular collapse than those receiving etomidate. This may be from ketamine’s known side effect of causing a paradoxical decrease in blood pressure when given to patients with depleted catecholamine reserves.
New development of adrenal insufficiency was numerically higher in the etomidate group at 2.8% vs 1% however this was not statistically significant.
A higher rate of survival is certainly clinically meaningful and if it persisted at 28 days is a compelling reason to choose ketamine over etomidate. However, the authors stopped short of recommending ketamine over etomidate based on this study alone because the survival benefit was not apparent at 28 days. They point out that the 7-day survival benefit could be based on practices at their center rather than due to ketamine. The possibility does remain that a small difference at 28 days in favor of ketamine exists but the study was underpowered to detect it. A future multicenter study might be able to clarify this, however this study did take about 6 years from start to publication so there is not likely going to be a definitive answer anytime soon and the debate over whether to use etomidate over ketamine will continue.
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