Ketamine versus alternate agents to prevent postinduction haemodynamic instability during tracheal intubation of critically ill adults: a systematic review and meta-analysis

BACKGROUND: Postinduction haemodynamic instability is common in critically ill adults undergoing emergency tracheal intubation. Ketamine is frequently used for induction of anaesthesia in patients perceived to be at high risk of haemodynamic instability; however, its haemodynamic effects relative to other induction agents remain uncertain. We sought to evaluate the effect of ketamine compared with alternative induction agents on postinduction haemodynamic instability and other clinically important outcomes during emergency tracheal intubation. METHODS: We conducted a systematic review and meta-analysis according to a prospectively registered International Prospective Register of Systematic Reviews protocol (CRD42024618433) and Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines. Randomised controlled trials enrolling adults undergoing tracheal intubation in the emergency department or intensive care unit were included. Searches of six databases and three trial registries were performed to November 5, 2025, supplemented by pre-publication access to the RSI trial. The primary outcome was postinduction haemodynamic instability harmonised across trials. A random-effects model with Hartung-Knapp adjustment was used. RESULTS: Ten trials (n=4673) met inclusion criteria, of which nine used etomidate as the comparator, and one used a regimen of midazolam and sufentanil. There was a significantly greater risk of postinduction haemodynamic instability (risk ratio 1.28 [1.13-1.45]) with ketamine compared with etomidate. However, when compared with the alternative comparator, ketamine appeared superior (risk ratio 0.51 [0.29-0.89]). No differences in mortality, ventilator-free days, or ICU-free days were shown. CONCLUSIONS: Ketamine appears associated with less haemodynamic stability than etomidate during the peri-intubation period but might perform more favourably than other agents, with no effect on longer-term outcomes.