Nitrous Oxide and Laparoscopic Bariatric Surgery

Background: Nitrous oxide (N₂O) is frequently used to supplement more potent anesthetic agents. One side-effect of N₂O is its ability to expand an air-containing space. We investigated if N₂O adversely affected operating conditions by distending normal bowel during laparoscopic bariatric procedures. Methods: 50 morbidly obese patients were divided into 2 study groups. Group 1 patients were ventilated with a halogenated anesthetic/oxygen/air mixture, while Group 2 received a halogenated anesthetic/oxygen/N₂O mixture. At 30, 60, and 90 min intervals during the operation, the surgeon was asked if N₂O was being used. Results: The surgeons responded correctly only 42% (30 min), 50% (60 min), and 48% (90 min) of the time. In Group 2 (N₂O) patients, they incorrectly answered that N₂O was not being used 88% (30 min), 68% (60 min), and 68% (90 min); and in Group 1 (air) patients, they incorrectly answered that N₂O was being used 28% (30 min), 32% (60 min), and 36% (90 min) of the time. Conclusion: We found that using N₂O did not cause noticeable bowel distention during laparoscopic bariatric procedures of relatively short duration.