Randomized non-inferiority trial of the vitalHEAT™ temperature management system vs the bair hugger® warmer during total knee arthroplasty

Abstract

Purpose: Intraoperative and postoperative hypothermia occur commonly; mild hypothermia (34-36°C) is associated with adverse events. The use of perioperative warming devices has become routine, but currently available active warming devices may be limited in certain circumstances. The vitalHEAT™ Temperature Management System provides conductive warming (circulating warm water) around a single extremity together with a vacuum that is applied to the limb. In this randomized trial, we tested the hypothesis that the vitalHEAT™ system is non-inferior to the Bair Hugger® during unilateral total knee arthroplasty. Methods: Physical status I-III patients who were ≥18 yr-old were eligible to participate. The patients were randomly assigned to the vitalHEAT™ system (n = 30) or to Bair Hugger ® (n = 25) warming. Intraoperative and first recovery room temperatures were recorded in both groups. Results: The baseline characteristics of the groups were similar. In terms of the primary outcome measure, i.e., sublingual temperature measured within 10 min of recovery room arrival, the vitalHEAT™ system did not meet the criterion for non-inferiority. Specifically, the confidence interval for the difference between means included the non-inferiority margin (-0.5°C). In terms of the secondary measures, i.e., intraoperative esophageal temperatures, the vitalHEAT™ system also underperformed compared with the Bair Hugger®. Conclusions: The vitalHEAT™ system may have advantages over convective warming systems because it requires a much smaller body surface area; however, in this study of warming during total knee arthroplasty, it underperformed when compared with the Bair Hugger®, especially around and after the time of tourniquet release. Clinical trial registration number: NCT00711867. © 2009 Canadian Anesthesiologists' Society.