title: Towards painless colonoscopy: a randomized controlled trial on carbon dioxide-insufflating colonoscopy.
abstract: BACKGROUND
  Carbon dioxide (CO2) insufflation during colonoscopy was reported to reduce pain, but data are limited. The objective of this randomized controlled trial was to assess the effect of CO2 insufflation on pain during and after colonoscopy.
  
  
  METHODS
  Patients were randomized into CO2 insufflation (CO2i) or air insufflation (AIRi) groups. Pain during and after the examination were recorded using a visual analogue scale. Other outcomes included the caecal intubation rate, time to reach the caecum and complication. With questionnaire, patients' satisfaction and acceptance of the procedure were assessed.
  
  
  RESULTS
  Over a 4-month period, 96 patients were recruited. The caecal intubation rate was 96 and 98% in the CO2i group and the AIRi group, respectively. No complication occurred in the CO2i group whereas one patient from the AIRi group developed late haemorrhage after polypectomy. Patients in the CO2i group had a lower pain score during (P < 0.01) and 30 min after (P = 0.02) the examination. Significantly more patients in the CO2i group reported the examination as painless (visual analogue scale 0) during the procedure (45 vs 14%, P < 0.01) and 30 min after (70 vs 51%, P = 0.04). In both groups, high satisfaction scores were recorded. Most patients (93% for the CO2i group and 98% for the AIRi group) would accept another colonoscopy if indicated.
  
  
  CONCLUSIONS
  Insufflation with CO2 during colonoscopy results in less pain during and after the examination. Because of better tolerance, colonoscopy with CO2 insufflation might gain wide acceptance in the community to be used as a screening tool.
authors.affiliation: Department of Surgery, Pamela Youde Nethersole Eastern Hospital, Hong Kong SAR, China. pyjameswong@yahoo.com
authors.forename: James C H
authors.initials: JC
authors.lastname: Wong
authors.forename: Kevin K
authors.initials: KK
authors.lastname: Yau
authors.forename: Hester Y S
authors.initials: HY
authors.lastname: Cheung
authors.forename: Denis C T
authors.initials: DC
authors.lastname: Wong
authors.forename: Cliff C
authors.initials: CC
authors.lastname: Chung
authors.forename: Michael K W
authors.initials: MK
authors.lastname: Li
mesh_terms: D000368:Aged; D000388:Air; D002245:Carbon Dioxide; D003113:Colonoscopy / Q000009:adverse effects*; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007327:Insufflation / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000209:etiology / Q000517:prevention & control*; D010147:Pain Measurement; D016037:Single-Blind Method
chemical_list: D002245:Carbon Dioxide