title: Prospective randomized clinical trial comparing nitrous oxide and carbon dioxide pneumoperitoneum for laparoscopic surgery.
abstract: 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.
  
  
  METHODS
  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 postoperatively (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.
authors.affiliation: Department of Surgery, Oregon Health and Science University, Portland 97201-3098, USA.
authors.forename: Zurab
authors.initials: Z
authors.lastname: Tsereteli
authors.forename: Maria L
authors.initials: ML
authors.lastname: Terry
authors.forename: Steven P
authors.initials: SP
authors.lastname: Bowers
authors.forename: Hadar
authors.initials: H
authors.lastname: Spivak
authors.forename: Steven B
authors.initials: SB
authors.lastname: Archer
authors.forename: Kathy D
authors.initials: KD
authors.lastname: Galloway
authors.forename: John G
authors.initials: JG
authors.lastname: Hunter
mesh_terms: D000328:Adult; D000368:Aged; D002245:Carbon Dioxide / Q000627:therapeutic use*; D004311:Double-Blind Method; D005260:Female; D018662:Fundoplication; D006439:Hemodynamics; D006801:Humans; D010535:Laparoscopy; D008297:Male; D008875:Middle Aged; D009609:Nitrous Oxide / Q000627:therapeutic use*; D010147:Pain Measurement; D011028:Pneumoperitoneum, Artificial / Q000379:methods*; D011446:Prospective Studies; D012086:Reoperation
chemical_list: D002245:Carbon Dioxide; D009609:Nitrous Oxide