Randomized non-inferiority trial of the vitalHEAT(TM) Temperature Management System vs the Bair Hugger^sup ®^ warmer during total knee arthroplasty

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(TM) 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(TM) system is non-inferior to the Bair Hugger^sup ®^ during unilateral total knee arthroplasty. Physical status I-III patients who were ≥18 yr-old were eligible to participate. The patients were randomly assigned to the vitalHEAT(TM) system (n = 30) or to Bair Hugger^sup ®^ (n = 25) warming. Intraoperative and first recovery room temperatures were recorded in both groups. 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(TM) 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(TM) system also underperformed compared with the Bair Hugger^sup ®^. The vitalHEAT(TM) 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^sup ®^, especially around and after the time of tourniquet release. Clinical trial registration number: NCT00711867.[PUBLICATION ABSTRACT]