title: Warming and humidification of insufflation carbon dioxide in laparoscopic colonic surgery: a double-blinded randomized controlled trial.
abstract: OBJECTIVE
  We aimed to test the hypothesis that warming and humidification of insufflation CO2 would lead to reduced postoperative pain and improved recovery by reducing peritoneal inflammation in laparoscopic colonic surgery.
  
  
  BACKGROUND
  Warming and humidification of insufflation gas is thought be beneficial in laparoscopic surgery, but evidence in prolonged laparoscopic procedures is lacking.
  
  
  METHODS
  We used a multicenter, double-blinded, randomized controlled design. The Study Group received warmed (37 degrees C), humidified (98% RH) insufflation carbon dioxide, and the Control Group received standard gas (19 degrees C, 0% RH). Anesthesia and analgesia were standardized. Intraoperative oesophageal temperature was measured at 15 minutes intervals. At the conclusion of surgery, the primary surgeon was asked to rate camera fogging on a Likert scale. Postoperative opiate usage was determined using Morphine Equivalent Daily Dose (MEDD), and pain was measured using visual analogue scores. Peritoneal and plasma cytokine concentrations were measured at 20 hours postoperatively. Postoperative recovery was measured using defined discharge and complication criteria, and the Surgical Recovery Score.
  
  
  RESULTS
  Eighty-two patients were randomized, with 41 in each arm. Groups were well matched at baseline. Intraoperative core temperature was similar in both groups. Median camera fogging score was significantly worse in the Study group (4 vs. 2, P = 0.040). There were marginal differences in pain scores, but no significant differences were detected in MEDD usage, cytokine concentrations, or any recovery parameters measured.
  
  
  CONCLUSIONS
  Warming and humidification of insufflation CO2 does not attenuate the early inflammatory cytokine response, and confers no clinically significant benefit in laparoscopic colonic surgery.
authors.affiliation: Department of Surgery, South Auckland Clinical School, University of Auckland, Middlemore Hospital, Otahuhu, Auckland, New Zealand. tsammour@middlemore.co.nz
authors.forename: Tarik
authors.initials: T
authors.lastname: Sammour
authors.forename: Arman
authors.initials: A
authors.lastname: Kahokehr
authors.forename: Julian
authors.initials: J
authors.lastname: Hayes
authors.forename: Mike
authors.initials: M
authors.lastname: Hulme-Moir
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Hill
mesh_terms: D000368:Aged; D001202:Ascitic Fluid / Q000378:metabolism; D001831:Body Temperature; D002245:Carbon Dioxide / Q000008:administration & dosage*; D003106:Colon / Q000601:surgery*; D016207:Cytokines / Q000032:analysis; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006813:Humidity; D007327:Insufflation; D010535:Laparoscopy; D008297:Male; D010147:Pain Measurement; D010149:Postoperative Pain / Q000517:prevention & control; D011028:Pneumoperitoneum, Artificial; D013696:Temperature
chemical_list: D016207:Cytokines; D002245:Carbon Dioxide