Effect of esketamine on postinduction hypotension in elderly patients undergoing elective noncardiac surgery: a secondary analysis of a randomized clinical trial.

Postinduction hypotension (PIH) increases the risk of perioperative adverse events. This study aimed to test if low-dose esketamine could significantly decrease the incidence of PIH in elderly patients undergoing elective noncardiac surgery. This was a post hoc analysis of a randomized clinical trial in university-affiliated academic tertiary hospital. Patients (65 to 85 years, ASA physical status classification II or III) randomly received esketamine (0.2 mg/kg) or normal saline intravenous injection before general anesthesia induction. The primary outcome was the incidence of PIH. The secondary outcomes were the profiles of induction and adverse events during postinduction period. Several different definitions of hypotension and postinduction period were prespecified as the sensitivity analysis. The baseline characteristics were comparable between esketamine group (n = 211) and normal saline group (n = 213). The incidence of PIH was significantly lower in esketamine group than that in normal saline group (44.1 vs. 64.8%, P < 0.01). Esketamine pretreatment significantly decreased the consumption of propofol (P < 0.01) and the rate of vasoconstrictor utilization (P = 0.02). There were no significant differences in the incidence of postinduction adverse events between two groups (all P > 0.05). And, no other severe adverse events were observed. The sensitivity analysis displayed the robustness of the conclusion, though the effect size was lower than 0.2 under certain definition of PIH. A low dose of esketamine treatment before general anesthesia induction for elderly patients undergoing noncardiac surgery could significantly reduce the risk of PIH.Trial registration: www.chictr.org.cn (ChiCTR2100051179); registered 15 September 2021. Date of enrolment of the first participant to the trial: 24 February 2022.