Comparative effects of remimazolam and propofol on intraoperative redistribution hypothermia in urologic surgery: a retrospective propensity-matched cohort study.

Abstract

Background: Redistribution hypothermia, characterized by rapid core-to-peripheral heat transfer after anesthetic induction, is a major cause of perioperative hypothermia and is linked to adverse outcomes. Propofol, widely used for induction, impairs thermoregulatory vasoconstriction. Remimazolam, a novel ultra-short-acting benzodiazepine, provides greater hemodynamic stability, but its thermoregulatory effects remain unclear. This study compared remimazolam and propofol on intraoperative hypothermia in patients undergoing urologic surgery.

Methods: This retrospective observational study included adult patients (≥ 19 years) who underwent elective urologic surgery under general anesthesia between February 2024 and February 2025. Patients receiving remimazolam (0.2 mg/kg) or propofol (1.5-2.5 mg/kg) for induction were classified into respective groups. Propensity score matching (PSM) was performed (1:1 ratio) using demographic and perioperative covariates. The primary outcome was the incidence of redistribution hypothermia, defined as core temperature < 36.0°C within the first hour after induction. Secondary outcomes included severity of hypothermia, maximum temperature decrease, perioperative temperature trends, and predictors of hypothermia.

Results: Among 181 patients analyzed, 71 per group were matched after PSM. Hypothermia incidence was significantly lower with remimazolam than propofol both before (16.5% vs. 50.0%, P < 0.001) and after matching (15.5% vs. 47.9%, P < 0.001). Propofol use was an independent risk factor (adjusted OR: 7.31; 95% CI: 2.81-21.58; P < 0.001). Female sex, higher BMI, and higher baseline temperature were protective factors.

Conclusion: Compared with propofol, remimazolam was associated with lower incidence and severity of redistribution hypothermia in urologic surgery. These findings suggest thermoregulatory benefits of remimazolam, warranting confirmation in prospective trials.