Effect of CO 2 gas warming on pain after laparoscopic surgery

Background: Previous studies have suggested that gas temperature has an influence on postlaparoscopy pain. This trial therefore was conducted to study the effect of gas warming on pain after upper abdominal laparoscopic surgery. Methods: Patients who underwent laparoscopic cholecystectomy, fundoplication, or Heller's myotomy were included and randomly allocated to receive either warm or cold gas. Primary end point was shoulder tip pain, and secondary end points were subcostal, trocar wound, and visceral pains, as well as other postoperative events. Criteria of pain assessment were the visual analog scale, verbal rating scale, and amount of analgesics. Results: A total of 100 patients were suitable for postoperative evaluation. The groups were well matched. Shoulder tip and subcostal pains were significantly more intense after gas warming ( p < 0.05). The three assessment criteria showed the same differences. No difference was observed concerning trocar wound and visceral pains and the other secondary end points. Subdiaphragmatic temperature was not significantly different (34.4° with warming vs. 34° without warming). Conclusions: Gas warming does not reduce, and probably increases, postoperative shoulder tip and subcostal pains.