Neuroprotective effect of mild hypothermia in patients undergoing coronaryartery surgery with cardiopulmonary bypass - A randomized trial

Background-Neuropsychological deficits occur in 30% to 80% of patients unde rgoing heart surgery and are due in part to ischemic cerebral injury during cardiopulmonary bypass. We tested whether mild hypothermia.. the most effi cacious neuroprotective strategy found in laboratory studies, improved cogn itive outcome in patients undergoing coronary artery surgery. Methods and Results-Patients 60 years or older scheduled for coronary arter y surgery were enrolled. During cardiopulmonary bypass, patients were initi ally cooled to 32 degreesC then randomly assigned to rewarming to 37 degree sC (control) or 34 degreesC (hypothermic), with no further intraoperative w arming. Testing was scheduled preoperatively and 1 week and 3 months postop eratively. Eleven tests were combined into 3 cognitive domains: memory, att ention, and psychomotor speed and dexterity. A patient was classified as ha ving a cognitive deficit if a decrease of greater than or equal to0.50 SD w as realized in 1 or more domains. The incidence of cognitive deficits 1 wee k after surgery, which was the primary outcome. was 62% (62/100) in the con trol group and 48% (45/94) in the hypothermic group (relative risk 0.77, P= 0.048). In the hypothermic group. the magnitude of deterioration in attenti on and in speed and dexterity was reduced by 55.6% (P=0.038) and 41.3% (P=0 .042). respectively. At 3 months, the hypothermic group still performed bet ter on one test of speed and dexterity (grooved pegboard). There was no dif ference in morbidity or mortality. Conclusions-Our findings support a neuroprotective effect of mild hypotherm ia in patients undergoing coronary artery surgery and should encourage phys icians and perfusionists to pay careful attention to brain temperature duri ng cardiopulmonary bypass.