Induction Agents for Tracheal Intubation in Critically Ill Patients

OBJECTIVES: Concise definitive review of the use of induction agents in critically ill patients undergoing tracheal intubation and their association with outcomes. DATA SOURCES: Original publications were retrieved through a PubMed search with search terms related to induction agents for tracheal intubation in critically ill patients. STUDY SELECTION: We included randomized controlled trials and observational studies that reported patient outcomes. DATA EXTRACTION: Data from included studies, including choice of induction agents and clinically relevant outcomes, were extracted. DATA SYNTHESIS: Etomidate and ketamine have been the most studied induction agents in critical care during last years. Recent studies on etomidate investigated the clinical impact of its recognized adrenal suppression in terms of morbidity and mortality. Etomidate may carry a non-negligible mortality risk without definitive hemodynamic benefits compared with ketamine. Available data then support the use of ketamine over etomidate, since the difference in the hemodynamic profile seems to be of minor clinical relevance. No multicenter randomized studies are available comparing propofol to other induction agents but evidence from a large observational study identified an association of propofol with post-intubation cardiovascular instability in critically ill patients. Despite the observational nature of these findings cannot exclude the role of confounders, the association of propofol with post-induction cardiovascular instability is pharmacologically plausible, justifying its avoidance in favor of drugs with a better safety profile in critical care such as ketamine. CONCLUSIONS: Although no definitive conclusions can be drawn based on the available evidence, recent evidence pointed out the potential negative effect of etomidate on survival and the association of propofol with cardiovascular instability. Ketamine may be considered the drug with a safer profile, widespread availability and low cost but future research should provide definitive data on optimal drug selection, its dosage in the context of critical illness and concomitant interventions to minimize the risk of peri-intubation complications.