A New Thermoregulation System for Maintaining Perioperative Normothermia and Attenuating Myocardial Injury in Off-Pump Coronary Artery Bypass Surgery

Abstract

Background: Most patients undergoing coronary artery bypass surgery demonstrate perioperative mild-to-moderate hypothermia (<36°C). Patients undergoing off-pump coro-nary artery bypass (OPCAB) grafting may become even more severely hypothermic for want of cardiopulmonary bypass rewarming. One consequence is increased circulating cate-cholamine levels that induce an elevated systemic vascular resistance (SVR), which causes a subsequent deterioration in cardiac output.
Materials and Methods: We assessed the ability of the Allon thermoregulatory (AT) system to maintain normother-mia and its impact on hemodynamics and myocardial func-tion in patients undergoing OPCAB surgery. In this study, the first 60 of 120 suitable patients were assigned to AT (n = 40) or routine thermal care (RTC) (n = 20). Core body temperature, cardiac index (CI), SVR, and cardiac-specific troponin I (cTnI) were analyzed perioperatively for patients in both groups.
Results: Core body temperature was significantly higher in the AT group (from 36.1°C ± 0.5°C at induction of anes-thesia to 37°C ± 0.5°C during surgery) than in the RTC group (from 35.8°C ± 0.4°C to 35.2°C ± 0.8°C , respectively; P < .01). SVR was significantly lower, and CI was greater (at comparable time points), whereas cTnI levels in the AT group were lower than in the RTC group from the end of surgery until 24 hours postoperatively (7.4 ± 17.7 μg/L ver-sus 31.9 ± 47.4 μg/L; P = .03). These findings indicate the possibility for less ischemic damage sustained intraoperatively in the AT group.

Conclusions: Maintenance of perioperative normother-mia (36.5°C-37.5°C) during OPCAB procedures can be effi-ciently achieved with the Allon thermoregulation system. The system was found to be superior to other routinely used methods of temperature maintenance. Benefits may include lowering afterload (as expressed by reduced SVR), an improved CI, and attenuation of myocardial injury (as assessed by cTnI levels).