The effect of humidified warmed CO2 during open colorectal surgery on body temperature and postoperative pain: a randomized controlled trial.

IntroductionOpen abdominal surgery exposes the intestine to negative ventilation (20°C, 0-5% RH), which along with the large surface area of peritoneum has the potential to cause loss of body heat. This study examined whether the warmed, humidified CO2 (WHCO2) can reduce heat loss and reduce postoperative pain.MethodsA randomized controlled trial was performed at a tertiary colorectal unit (Concord Repatriation General Hospital, The University of Sydney, Australia). The study group received WHCO2 at a rate of 10L/min. The control group did not receive any insufflation during the operation. Patients were over 18 years of age undergoing elective open colorectal operations. Core body temperature measurement was made every 15 minutely with a trans-oesophageal probe. Postoperative pain was assessed via: (1) duration of use of patient controlled analgesia (PCA), (2) total oral morphine equivalent daily dose (oral MEDD).Results39 Patients were recruited in the study, with 20 patients receiving WHCO2. There was no difference in the core body temperature between the WHCO2 and the Control group (36.1 vs. 35.9°C, p=0.35). There was no difference in the % of the operating time where core body temperature dropped below the lower limit of normal of 35.8°C (28.4% vs 35.8%, p=0.51), or to the level of hypothermia of 35°C (7.7% vs. 13.4%, p=0.50). No difference in postoperative PCA duration, as well as MEDD, were noted between the CO2 group and control group.ConclusionWHCO2 had no effect on core body temperature during open colorectal surgery and the postoperative pain experienced.