Preventing hypothermia:: Convective and intravenous fluid warming versus convective warming alone

Study Objective: To test the hypothesis that warming intravenous (IV) fluids in conjunction with convective warming results in less intraoperative hypothermic (core temperature <36.0 degrees C) than that seen with convective warming alone. Design: Prospective, randomized study. Setting: University affiliated tertiary care teaching hospital. Patients: 61 ASA physical status I, II, and III adults undergoing major surgery and general anesthesia with isoflurane. Interventions: All patients received convective warming. Group 1 patients received warmed fluids (setpoint 42 degrees C). Group 2 patients received room temperature fluids (similar to 21 degrees C). Measurements and Main Results: Lowest and final intraoperative distal esophageal temperatures were higher (p < 0.05) In Group 1 (mean +/- SEM: 35.8 +/- 0.1 degrees C and 36.6 +/- 0.1 degrees C) versus Group 2 (35.4 +/- 0.1 degrees C and 36.1 +/- 0.1 degrees C, respectively). Compared with Group 1, more Group 2 patients were hypothermic at the end of anesthesia (10 of 26 patients, or 38.5 % vs. 4 of 30 patients, or 13 %; p < 0.05). After 30 minutes In the recovery room, there were no differences in temperature between groups (36.7 +/- 0.1 degrees C and 36.5 +/- 0.1 degrees C in Groups 1 and 2, respectively). Intraoperative cessation of convective warming because of core temperature greater than 37 degrees C was required in 33 % of Group 1 patients (vs. 11.5% in Group 2; p = 0.052), Conclusions: The combination of convective and fluid warming was associated with a decreased likelihood of patients leaving the operating room hypothermic. However, average final temperatures were greater than 36 degrees C in both groups, and intergroup differences were small. Care must be taken to avoid overheating the patient when both warming modalities am employed together. (C) 1998 by Elsevier Science Inc.