title: Carbon dioxide insufflation does not reduce pain scores during colonoscope insertion in unsedated patients: a randomized, controlled trial.
abstract: BACKGROUND
  CO(2) is rapidly absorbed from the colon and eliminated via the lung. Insufflation of CO(2) instead of air during colonoscopy can reduce distention-induced pain.
  
  
  OBJECTIVE
  This study aimed to evaluate the effects of CO(2) insufflation on pain during intubation and extubation and to identify predictors of pain and discomfort during colonoscope insertion.
  
  
  METHODS
  Prospective, randomized, controlled trial.
  
  
  METHODS
  Single tertiary medical center in Taiwan.
  
  
  METHODS
  A total of 193 patients enrolled from September 2010 through June 2011.
  
  
  METHODS
  Colonoscope insertion with either air or CO(2) insufflation. CO(2) was used for extubation in both groups.
  
  
  METHODS
  The main outcome measurement was pain, recorded on a 10-point visual analog scale (VAS) for left-sided colonoscope insertion and right-sided colonoscope insertion and at 1, 3, 6, and 24 hours post-procedure. Colonoscope cecal intubation time and extubation time, completeness of intubation, and loop formation were also assessed.
  
  
  RESULTS
  CO(2) insufflation during colonoscope intubation was used in 98 patients and air in 97 patients. The mean pain scores during intubation were low (2-3) for patients undergoing air insufflation and were not reduced further in patients receiving CO(2). A mean pain score of 0 was reported by both groups for all postprocedure time points. Multivariate analysis identified sex, loop formation of the sigmoid colon, time to reach the transverse colon, and requested sedation as factors that significantly affect VAS pain scores.
  
  
  CONCLUSIONS
  This study was limited in scope to a single medical center with experienced endoscopists.
  
  
  CONCLUSIONS
  We detected no significant benefit to the use of CO(2) insufflation compared with air insufflation during intubation for colonoscopy performed by experienced colonoscopists. The absence of postprocedure pain in both groups supports previous observations that CO(2) insufflation during extubation is effective in reducing postprocedure pain. Female sex and loop formation were identified as key factors influencing pain scores on colonoscope insertion. (
  
  
  BACKGROUND
  TSGHIRB-099-05-081.).
authors.affiliation: Division of Gastroenterology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Peng-Jen
authors.initials: PJ
authors.lastname: Chen
authors.forename: Chung-Hsien
authors.initials: CH
authors.lastname: Li
authors.forename: Tien-Yu
authors.initials: TY
authors.lastname: Huang
authors.forename: Yu-Lueng
authors.initials: YL
authors.lastname: Shih
authors.forename: Heng-Cheng
authors.initials: HC
authors.lastname: Chu
authors.forename: Wei-Kuo
authors.initials: WK
authors.lastname: Chang
authors.forename: Tsai-Yuan
authors.initials: TY
authors.lastname: Hsieh
mesh_terms: D000388:Air; D015992:Body Mass Index; D002245:Carbon Dioxide; D003113:Colonoscopy / Q000009:adverse effects* / Q000379:methods*; D016292:Procedural Sedation; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007327:Insufflation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000175:diagnosis* / Q000517:prevention & control; D010147:Pain Measurement; D011446:Prospective Studies; D012737:Sex Factors
chemical_list: D002245:Carbon Dioxide