# Forced-Air Warming Temperature Settings for Treating Postoperative Hypothermia in the Postanesthesia Care Unit: Randomized Controlled Trial

## TL;DR

This study tested different temperature settings for forced-air warming to treat post-surgery hypothermia and found that a two-step approach minimized temperature drops after recovery.

## Contribution

A novel two-step forced-air warming protocol is proposed to reduce post-normothermia temperature drops in postoperative patients.

## Key findings

- The F2 group had the shortest mean rewarming time of 33.3 minutes.
- F2 had the lowest incidence of temperature drops after normothermia (2.27%).
- Group C had the highest incidence of rewarming exceeding 1 hour (22.73%).

## Abstract

Hypothermia, defined as a core body temperature below 36 °C, is a common postoperative complication associated with adverse outcomes, including delayed wound healing, infections, and increased bleeding.

This randomized controlled trial evaluated the efficacy of different forced-air warming system temperature settings in treating postoperative hypothermia in the postanesthesia care unit.

A total of 132 patients undergoing elective surgery at Ramathibodi Hospital between April 2023 and May 2024 were randomized into 3 groups (n=44 per group): group C (warming set to 38 °C), group F1 (warming set to 42 °C), and group F2 (warming set to 42 °C, reduced to 38 °C after achieving 36 °C). Tympanic temperature was recorded at 5-minute intervals during rewarming and every 10 minutes after normothermia (≥36 °C) was achieved. The primary outcome was rewarming time. Secondary outcomes included the incidence of temperature drops, hemodynamic parameters, adverse events, and patient comfort scores.

Baseline characteristics and clinical variables, including vital signs, were comparable among groups (P>.05). Group F2 achieved the shortest mean rewarming time of 33.3 (SD 13.81) min; however, differences between groups were not statistically significant (P=.460). Group F2 had the lowest incidence of temperature drops below 36 °C after normothermia (1/44, 2.27%; P=.009). Group C had the highest incidence of rewarming exceeding 1 hour (10/44, 22.73%; P=.017).

While rewarming times were similar across groups, the protocol using an initial setting of 42 °C followed by a reduction to 38 °C (group F2) effectively minimized temperature drops after normothermia, suggesting its superiority for managing postoperative hypothermia in the postanesthesia care unit.