Evaluation of core temperature during laparoscopic and open gastric bypass

Background: Intraoperative hypothermia is a common event during open and laparoscopic abdominal surgery. The aim of this study was to compare changes in core temperature between laparoscopic and open gastric bypass (GBP). Methods: 101 patients with a body mass index (BMI) of 40-60 kg/m² were randomly assigned to open (n=50) or laparoscopic (n=51) GBP. Anesthetic technique was similar for both groups. An external warming blanket and passive airway humidification were used intraoperatively. Core temperature was recorded at preanesthesia, at baseline (after induction) and at 30-min intervals; intra-abdominal temperature was additionally measured at 30-min intervals in a subset of 30 laparoscopic GBP patients. The number of patients who developed intraoperative and postoperative hypothermia (<36°C) was recorded. Length of operation for both groups and the amount of CO₂ gas delivered during laparoscopic operations were also recorded. Results: There was no significant difference between groups with respect to age, gender, mean BMI, and amount of intravenous fluid administered. After induction of anesthesia, core temperature significantly decreased in both groups; 36% of patients in the open group and 37% of patients in the laparoscopic group developed hypothermia. This percentage increased to 46% in the open group and 41% in the laparoscopic group during the operation, and then decreased to 6% in the open group and 8% in the laparoscopic group in the recovery-room, Core temperature increased during the operative procedure to reach 36.5 ± 0.6°C in the open group and 36.3 ± 0.5°C in the laparoscopic group at 2.5 hours after surgical incision. Intra-abdominal temperature during laparoscopic GBP was significantly lower than core temperature at all measurement points (p<0.05). Operative time was longer in the laparoscopic group than in the open group (232 ± 43 vs 201 ± 38 min, p<0.01). Mean volume of gas delivered during laparoscopic GBP was 650 ± 220 liters. Conclusion: Perioperative hypothermia was a common event during both laparoscopic and open GBP. Despite a longer operative time, laparoscopic GBP did not increase the rate of intraoperative hypothermia when efforts were made to minimize intraoperative heat loss.