Prospective randomized clinical trial comparing nitrous oxide and carbon dioxide pneumoperitoneum for laparoscopic surgery

BACKGROUND: Recent publications demonstrating the safety and advantages of N₂O for pneumoperitoneum (PP) prompted us to reconsider N₂O as an agent for PP in general surgical laparoscopy. The purpose of this prospective, double-blind, randomized clinical trial was to determine whether N₂O PP has any benefits over CO₂ PP. STUDY DESIGN: One hundred three patients received N₂O (group I, n = 52) or CO₂ (group II, n = 51) PP for elective laparoscopic surgery. Heart rate, mean arterial blood pressure, end-tidal CO₂, minute ventilation, and O₂ saturation were recorded before PP, during PP, and in the recovery room. Postoperative pain medication use was recorded. Pain was assessed by means of visual analog scale (VAS) at postoperative hours 2 and 4, and on day 1. RESULTS: There were no differences between groups I and II in patient age, gender, weight, anesthesia risk (American Society of Anesthesiologists Score > 2), operative time, duration of PP, or length of hospital stay. Mean end-tidal CO₂ increase under anesthesia was greater in group II than group I (3.0 versus 0.5 mmHg, p < 0.001) despite a greater mean intraoperative increase in minute ventilation in group II than group I (0.7 versus - 0.2 L/min p < 0.001). The patients who had N₂O PP had less pain 2 hours postoperatively (VAS: 4.9 versus 5.7, p < 0.05), 4 hours post-operatively (VAS: 3.3 versus 5.1, p < 0.01), and 1 day postoperatively (VAS: 1.7 versus 3.5, p < 0.01) than patients who had CO₂ PP. Postoperative narcotic or ketorolac use was not statistically different between groups. There were no adverse events related to either N₂O or CO₂ pneumoperitoneum. CONCLUSIONS: These results suggest that the use of N₂O PP has sufficient advantages over CO₂ that it should be considered as the standard agent for therapeutic PP.