CONVECTION VERSUS CONDUCTION COOLING FOR INDUCTION OF MILD HYPOTHERMIA DURING NEUROVASCULAR PROCEDURES IN ADULTS

Hypothermia for cerebral protection is usually achieved by administrat ion of intravenous fluids at room temperature, cooling ambient air, ic e packs, and a temperature-adjustable circulating water mattress. We c ompared cooling by conduction by using a water mattress to cool by con vection by using a forced-air cooling device, Twenty patients were pro spectively randomized to two groups: 10 patients cooled by convection (CC) and 10 patients cooled by traditional methods (TC). Two patients in the CC group were withdrawn from the study and excluded from the an alysis; one patient for failure to cool despite the use of both techni ques, and the other for the abrupt onset of arrhythmias and myocardial depression during hypothermia. Temperature was measured at the tympan ic membrane, pulmonary artery, and esophageal probe sites and recorded even 15 min, The time required to reach the target temperature range of 33-34 degrees C was recorded. We found no differences in the temper atures measured at the three sites during cooling and rewarming. Basel ine temperatures recorded from the pulmonary artery catheter before be ginning ''active cooling'' were similar in both groups (TC, 35.0 +/- 0 .2 degrees C vs. CC, 35.3 +/- 0.1 degrees C). Frit: found no differenc e in the time to target temperature between TC and CC (TC, 178 +/- 25 min vs. CC, 142 +/- 21 min). One patient had some arrhythmias on cooli ng in the convective group, but her preoperative condition may have be en responsible, In conclusion, cooling by convection appears to be a s afe alternative to conduction cooling.