Effectiveness of humidifying CO2 gas on hypothermia during laparoscopic surgery

Intra-operative hypothermia caused by a pneumoperitoneum is common in patients during laparoscopic surgery. Hypothermia is known to cause many adverse complications. The purpose of this study was to evaluate the factors influencing hypothermia. Core temperatures during surgery were recorded in patients undergoing laparoscopic surgery (n=158). Forty-seven and 51 patients were insufflated with heated CO2 gas and humidified gas, respectively. The room temperature was kept at 25°C, and warming blankets were placed under the patients. Bottles of infusate and saline (for irrigation) were kept at 37°C. The parameters for multiple regression analysis included: age, BMI, duration of surgery, initial body temperature, and the mean decrease in temperature (maximal decrease and the decrease at the end of surgery) in 3 groups (control [n= 60], warmed gas [n= 47], humidified gas [n= 51]) ; were analyzed to evaluate the effectiveness of warm and humidified gas; there was no significant difference in those parameters influencing body temperature. Multiple regression analysis showed that the factors had a significant correlation with the decrease in BMI, duration of surgery, initial body temperature, and humidified gas. The mean maximal decrease in temperature in the control, warmed gas, and humidified gas groups was 1.03 °C, 0.90 °C, and 0.75°C, respectively; here was no statistical significance between the groups. The mean decrease in temperature at the end of surgery in the control, warmed gas, and humidified gas groups was 0.93 °C, 0.84 °C, and 0.49°C, respectively; there was statistical significance between the humidified gas group and the other groups.