Effect of CO2 gas warming on pain after laparoscopic surgery - A randomized double-blind controlled trial

Background: Previous studies have suggested that gas temperature has an inf luence on postlaparoscopy pain. This trial therefore was conducted to study the effect of gas warming on pain after upper abdominal laparoscopic surge ry. Methods: Patients who underwent laparoscopic cholecystectomy, fundoplicatio n, or Heller's myotomy were included and randomly allocated to receive eith er 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 ot her postoperative events. Criteria of pain assessment were the visual analo g 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 signi ficantly more intense after gas warming (p < 0.05). The three assessment cr iteria showed the same differences. No difference was observed concerning t rocar wound and visceral pains and the ether secondary end points. Subdiaph ragmatic temperature was not significantly different (34.4 degrees with war ming vs. 34 degrees without warming). Conclusions. Gas warming does not reduce, and probably increases, postopera tive shoulder tip and subcostal pains.