Effect of preoperative warming on intraoperative hypothermia: a randomized-controlled trial

Can J Anaesth. 2018 Sep;65(9):1029-1040. doi: 10.1007/s12630-018-1161-8. Epub 2018 Jun 5.

Abstract

Purpose: The purpose of this study was to evaluate the effects of preoperative forced-air warming on intraoperative hypothermia.

Methods: In this randomized-controlled trial, adult patients scheduled for elective, non-cardiac surgery under general anesthesia were stratified by scheduled surgical duration (< 2.5 hr or ≥ 2.5 hr) and then randomized to a pre-warming group using a BairPaws™ forced-air warming system for at least 30 min preoperatively or to a control group with warmed blankets on request. All patients were warmed intraoperatively via convective forced-air warming blankets. Perioperative temperature was measured using the SpotOn™ temperature system consisting of a single-use disposable sensor applied to the participant's forehead. The primary outcome was the magnitude of intraoperative hypothermia calculated as the area under the time-temperature curve for core temperatures < 36°C between induction of general anesthesia and leaving the operating room. Secondary outcomes included surgical site infections, packed red blood cell requirements, and 24 hr postoperative opioid consumption.

Results: Two hundred participants were analyzed (101 control; 99 pre-warmed). Pre-warmed participants had a lower median [interquartile range] magnitude of hypothermia than controls (0.00 [0.00-0.12] °C·hr-1 vs 0.05 [0.00-0.36] °C·hr-1, respectively; median difference, -0.01°C·hr-1; 95% confidence interval, -0.04 to 0.00°C·hr-1; P = 0.005). There were no between-group differences in the secondary outcomes.

Conclusion: A minimum of 30 min of preoperative forced-air convective warming decreased the overall intraoperative hypothermic exposure. While redistribution hypothermia still occurs despite pre- and intraoperative forced-air warming, their combined application results in greater preservation of intraoperative normothermia compared with intraoperative forced-air warming alone.

Trial registration: www.clinicaltrials.gov (NCT02177903). Registered 25 June 2014.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Aged
  • Female
  • Hot Temperature
  • Humans
  • Hypothermia / prevention & control*
  • Intraoperative Complications / prevention & control*
  • Male
  • Middle Aged
  • Outcome Assessment, Health Care
  • Preoperative Care

Associated data

  • ClinicalTrials.gov/NCT02177903