title: A randomized controlled trial comparing water exchange and air insufflation during colonoscopy without sedation.
abstract: OBJECTIVE
  Previous studies have shown that water exchange is superior to air insufflation in attenuating insertion pain during colonoscopy. We conducted a randomized controlled trial with head-to-head comparison of these methods to assess their effectiveness in colonoscopy without sedation.
  
  
  METHODS
  A total of 447 outpatients were randomized to either water exchange (WE) or the standard air (CO2) insufflation (AI). The primary outcome was the improvement of patient intraprocedural pain (pain score), evaluated using a questionnaire (scores 1 to 5).
  
  
  RESULTS
  After exclusion of 44 patients from further analysis, 403 patients were analyzed. There was no difference in clinical background between the WE and AI groups. Patients in the WE group reported less intraprocedural pain than those in the AI group (2.17 ± 1.06 vs. 2.42 ± 1.03; unpaired t test, p = 0.021). We divided the cases into two groups, more or less painful colonoscopy, based on age, body mass index, use of anti-peristaltic drugs or not, and physician's experience. In less painful colonoscopy, the WE method could reduce pain effectively but its effect was limited in the more painful group.
  
  
  CONCLUSIONS
  WE is superior to AI for attenuating insertion pain during colonoscopy without sedation, but its efficacy is limited in more painful endoscopy.
authors.affiliation: Department of Gastroenterology and Nephrology (K1), Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chiba, 260-8670, Japan. araim-cib@umin.ac.jp.
authors.forename: Makoto
authors.initials: M
authors.lastname: Arai
authors.affiliation: Department of Gastroenterology and Nephrology (K1), Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chiba, 260-8670, Japan.
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Okimoto
authors.affiliation: Department of Gastroenterology and Nephrology (K1), Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chiba, 260-8670, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Ishigami
authors.affiliation: Department of Gastroenterology and Nephrology (K1), Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chiba, 260-8670, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Taida
authors.affiliation: Department of Gastroenterology and Nephrology (K1), Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chiba, 260-8670, Japan.
authors.forename: Arata
authors.initials: A
authors.lastname: Oyamada
authors.affiliation: Department of Gastroenterology and Nephrology (K1), Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chiba, 260-8670, Japan.
authors.forename: Shoko
authors.initials: S
authors.lastname: Minemura
authors.affiliation: Department of Gastroenterology and Nephrology (K1), Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chiba, 260-8670, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Saito
authors.affiliation: Department of Gastroenterology and Nephrology (K1), Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chiba, 260-8670, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Tsuboi
authors.affiliation: Department of Gastroenterology and Nephrology (K1), Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chiba, 260-8670, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Maruoka
authors.affiliation: Department of Gastroenterology and Nephrology (K1), Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chiba, 260-8670, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Matsumura
authors.affiliation: Department of Gastroenterology and Nephrology (K1), Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chiba, 260-8670, Japan.
authors.forename: Tomoo
authors.initials: T
authors.lastname: Nakagawa
authors.affiliation: Department of Gastroenterology and Nephrology (K1), Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chiba, 260-8670, Japan.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Katsuno
authors.affiliation: Chiba Foundation for Health Promotion and Disease Prevention, Chiba, Japan.
authors.forename: Kanae
authors.initials: K
authors.lastname: Mitsuhashi
authors.affiliation: Chiba Foundation for Health Promotion and Disease Prevention, Chiba, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Nakagawa
authors.affiliation: Chiba Foundation for Health Promotion and Disease Prevention, Chiba, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Yamaguchi
authors.affiliation: Department of Gastroenterology and Nephrology (K1), Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chiba, 260-8670, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Yokosuka
mesh_terms: D000368:Aged; D000388:Air; D000758:Anesthesia; D003113:Colonoscopy; D023381:Endpoint Determination; D005260:Female; D006801:Humans; D007327:Insufflation / Q000379:methods*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D016896:Treatment Outcome; D014867:Water
chemical_list: D014867:Water
keywords: Air insufflation; Colonoscopy; Randomized control trial; Sedation; Water exchange