Effectiveness of an underbody forced warm-air blanket in preventing postoperative hypothermia after coronary artery bypass graft surgery with normothermic cardiopulmonary bypass

Introduction

Perioperative hypothermia in coronary artery bypass graft (CABG) is associated with adverse outcomes [1, 2]. An underbody forced-air warming blanket was developed for use in cardiac surgery. The primary aim of this investigation was to study whether this blanket could prevent postoperative hypothermia in routine CABG.

Methods

Sixty low-risk patients who underwent elective CABG were assigned into an intervention group that received the full underbody forced warm-air system (n = 30) and a control group that received standard thermal care (n = 30). Routine heat-conservation methods were applied in both groups including draping of the patient, fluid warming and normothermic cardiopulmonary bypass (CPB) at core temperature ~36.5°C. The forced warm-air system was set at 43°C at the end of perfusion until departure from the operating room (OR). Bladder temperature was measured at: T1 – end of perfusion, T2 – departure from the OR, T3 – arrival in the ICU, T4 – 1 hour after arrival in the ICU, and T5 – 3 hours after arrival in the ICU.

Results

The number of patients arriving in the ICU with a bladder temperature ≥ 36°C was significantly higher in the intervention group than in the control group, respectively 27 patients (90%) vs. 14 patients (46.7%) (P < 0.001). Initial temperatures (mean ± SD) at T1 were similar in both groups: 36.7°C ± 0.3°C vs. 36.5°C ± 0.2°C, respectively (P = 0.091). At time points T2, T3 and T4, the core temperature was significantly lower in the control group as compared with the intervention group, T2: 36.0°C ± 0.3°C vs. 36.5°C ± 0.3°C, respectively (P < 0.001); T3: 35.9°C ± 0.4°C vs. 36.2°C ± 0.3°C (P < 0.001); and T4: 36.0°C ± 0.6°C vs. 36.4°C ± 0.5°C (P = 0.026). At T5, 3 hours after arrival in the ICU, both groups had similar bladder temperatures (37.3°C ± 0.6°C vs. 37.2°C ± 0.7°C; P = 0.568). The temperature drop from the end of CPB to arrival in the ICU was significantly less in the intervention group compared with the control group (0.4°C ± 0.3°C vs. 0.6°C ± 0.4°C; P = 0.027).

Conclusion

The present study shows that additional warmth management with a full underbody forced warm-air system, applied in the OR to patients undergoing normothermic CABG, prevents hypothermia with its deleterious effects in the early postoperative phase.