Hemodynamic Effects of Prophylactic Vasopressors During Anesthetic Induction and Emergency Tracheal Intubation in Adults: A Systematic Review

Hemodynamic instability is the most frequent serious complication of tracheal intubation in critically ill adults, and prophylactic vasopressors are increasingly used to prevent it.This systematic review assessed comparative evidence on adrenergic vasopressors given before or during anesthetic induction in adults, with emergency tracheal intubation analyzed as a clinically distinct subgroup.Applicability was examined according to clinical determinants of hemodynamic risk, with procedural location, including urgent radiology, considered as one contextual factor.No protocol was registered.Eligibility was broadened from a radiology-specific population to adult induction and emergency intubation in any setting after preliminary searching found no direct comparative studies.PubMed/MEDLINE, Embase, CENTRAL, and Scopus were searched for studies published from August 2021 to 15 August 2026, with supplementary searching to 26 September 2026.Risk of bias was assessed with risk-of-bias tool for randomized trials (RoB 2) and Risk of Bias in Non-randomised Studies of Interventions (ROBINS-I), and the narrative synthesis followed the Synthesis Without Meta-analysis (SWiM) guideline.Of 341 database records, 205 were screened, and 67 full texts were assessed; 13 studies were included (eight randomized, five nonrandomized), one of which was published after the primary database search date.Two studies addressed emergency intubation and 11 addressed planned induction.In planned induction, point estimates mostly favored prophylaxis, but effect sizes ranged from large reductions in moderate hypotension to no difference in severe hypotension (mean arterial pressure below 55 mmHg) in the cardiac surgery trial.The two emergency intubation cohorts were observational and gave discordant results, and no study evaluated intubation for urgent radiology.Benefits for kidney injury and mortality were not shown, and pressure benefits were accompanied in some trials by hypertension or dose-related bradycardia.Prophylactic vasopressors can reduce induction-related hypotension in selected planned-induction populations, but evidence for emergency intubation is limited and conflicting.Emergency status, baseline shock and vasopressor requirement, cardiovascular reserve, and induction technique are more plausible determinants of benefit than procedural location.No universal agent, dose, or regimen can be recommended.