The effects of active warming on perioperative inadvertent hypothermia in patients undergoing vitreoretinal surgery under local anesthesia.

Purpose Perioperative inadvertent hypothermia (PIH) is the decrease in core temperature below 36°C. We aimed to assess whether PIH develops in patients operated under local anesthesia (ULA) for vitreoretinal surgery in the operating room and investigate active warming efficacy. Methods Seventy-two patients were divided into two groups: Group 1 contained unwarmed patients (n = 36), and Group 2, warmed patients (n = 36). The core temperatures, heart rate (HR), and mean arterial pressure (MAP) of the patients were measured at the beginning of surgery, after 20 min, 40 min, 1 h, at the end of the operation, and during the postoperative period. Results PIH incidence was 44.6% in Group 1, whereas no hypothermia was observed in Group 2. Patient temperatures at 20 min (P = 0.001), 40 min (P < 0.001), 1 h (P < 0.001), the end of the operation (P < 0.001), and the postoperative period (P < 0.001) were significantly higher in Group 2 than in Group 1. Patient HRs at the end of the operation and during the postoperative period were significantly lower in Group 2 (P = 0.005) than in Group 1 (P < 0.001). The intraoperative 40th (P = 0.044) and 60th (P < 0.001) minutes, end of operation (P < 0.001), and postoperative MAP (P < 0.001) values of Group 1 were significantly higher than those of Group 2. Conclusion PIH may develop in patients operated ULA, especially with a low ambient temperature. Actively warming may help prevent the harmful effects of PIH.