A new thermoregulation system for maintaining perioperative normothermia and attenuating myocardial injury in off-pump coronary artery bypass surgery.

BACKGROUND

Most patients undergoing coronary artery bypass surgery demonstrate perioperative mild-to-moderate hypothermia (<36 degrees C). Patients undergoing off-pump coronary artery bypass (OPCAB) grafting may become even more severely hypothermic for want of cardiopulmonary bypass rewarming. One consequence is increased circulating catecholamine 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 normothermia and its impact on hemodynamics and myocardial function 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 degrees C +/- 0.5 degrees C at induction of anesthesia to 37 degrees C +/- 0.5 degrees C during surgery) than in the RTC group (from 35.8 degrees C +/- 0.4 degrees C to 35.2 degrees C +/- 0.8 degrees 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 g/L versus 31.9 +/- 47.4 g/L; P =.03). These findings indicate the possibility for less ischemic damage sustained intraoperatively in the AT group.

CONCLUSIONS

Maintenance of perioperative normothermia (36.5 degrees C-37.5 degrees C) during OPCAB procedures can be efficiently 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).