Incidence of post-induction hypotension following emergency rapid sequence induction with ketamine: a systematic review and meta-analysis.

Introduction: Rapid sequence induction (RSI) is a potentially-life saving intervention in critically ill patients. An important adverse effect of this procedure is post-induction hypotension (PIH), which is associated with worsened patient outcomes. Choice of induction agent can affect incidence of PIH, although the optimal drug has yet to be determined. Ketamine is postulated to reduce PIH incidence in emergency RSI when used instead of alternative agents.

Aims: This systematic review and meta-analysis aims to evaluate the effect on PIH incidence of inducing anaesthesia with ketamine during emergency RSI.

Methods: A systematic search was conducted to identify a sample of studies fulfilling criteria for population (emergency RSI), intervention (ketamine), comparator (any alternative induction agent) and outcome (PIH). No single definition of PIH was required for eligibility. A random-effects model was used to produce a pooled effect size estimate from the extracted data. The study question was also tested in pre-specified subgroups, including by specific comparator induction agent and by indication for RSI (medical vs trauma).

Results: 27 studies, including 6 randomised controlled trials, were eligible for inclusion, with total n = 31,956. There was considerable methodological heterogeneity. The pooled estimate of odds ratio (OR) of PIH when ketamine is used for emergency RSI is 1.10, with 95% confidence interval 0.78-1.56. Excluding data from the 6 studies (1 randomised and 5 observational) at greater risk of bias, the pooled OR is 0.99 (0.69-1.43). There was no significant difference between ketamine and comparators in any subgroup, although significance was approached when comparing ketamine to etomidate, with OR 1.38 (0.99-1.94) and p = 0.058.

Conclusions: Choice of ketamine to carry out emergency RSI did not affect the incidence of PIH incidence in this diverse sample of studies. Given the breadth of inclusion criteria, applicability of this result is not necessarily universal. It is likely that optimal choice of induction agent varies according to specific circumstances in a manner as yet incompletely understood.