POSTOPERATIVE HEMODYNAMIC AND THERMOREGULATORY CONSEQUENCES OF INTRAOPERATIVE CORE HYPOTHERMIA

Study Objective: To evaluate the postoperative hemodynamic and thermor egulatory consequences of intraoperative core hypothermia. Design: Pro spective, randomized clinical trial. Setting: Operating room and posta nesthesia care unit of a university hospital.Patients: 74 healthy, ASA status I, II, and III patients (average age 58 yrs) undergoing electi ve colon surgery. Interventions: Patients were randomly assigned to be kept normothermic or approximate to 2.5 degrees C hypothermic during surgery. Anesthesia was maintained with isoflurane, nitrous oxide, and fentanyl. Postoperatively, surgical pain was treated with patient-con trolled analgesia (PCA) opioid. Measurements and Main Results: An obse rver blinded to group assignment and core temperatures evaluated shive ring thermal comfort, surgical pain, heart rates (HRs), and blood pres sures (BPs) during the first six postoperative hours. Morphometric cha racteristics, oxygen saturation, fluid balance, PCA-administered opioi d, and visual analog pain scores were comparable in the two groups. Hy pothermic patients felt uncomfortably cold during recovery, and their postoperative core temperatures remained significantly less than in th e normothermic patients for more than four hours. Peripheral vasoconst riction and shivering were common in the hypothermic patients but rare in those kept normothermic. HRs and BPs were comparable in the two gr oups. Conclusions: These data confirm that the effects of intraoperati ve hypothermia on postoperative HR and BP are modest in relatively you ng, generally healthy patients. In contrast, intraoperative hypothermi a caused substantial postoperative thermal discomfort, and full recove ry from hypothermia required many hours. Delayed return to core normot hermia apparently resulted largely from postoperative thermoregulatory impairment.