THE MANAGEMENT OF TEMPERATURE DURING HYPOTHERMIC CARDIOPULMONARY BYPASS .1. CANADIAN SURVEY

During hypothermic cardiopulmonary bypass (CPB) patients are cooled, u sually to between 30-32 degrees C, and, after myocardial bloodflow is restored they are rewarmed with blood healed in the pump-oxygenator. W e audited our local practice by recording tympanic and nasopharyngeal temperatures in 11 patients undergoing hypothermic CPB. We found that, during rewarming, nasopharyngeal and tympanic temperatures commonly e xceeded 38 degrees C although temperature measured in the bladder was <37 degrees C. A survey of cardiac surgery centres in Canada suggested that most centres induce hyperthermia in highly perfused tissues duri ng rewarming, sometimes inadvertently. This may be of some importance because it has become widely appreciated by neuroscientists that mild degrees of brain cooling (2-5 degrees C) are capable of conferring dra matic protection from ischaemic brain injury and, conversely, mild tem perature elevation may be markedly deleterious. If control of brain te mperature is considered desirable then we would suggest that nasophary ngeal temperature be monitored during rewarming on CPB.