title: Comparison of carbon dioxide and air insufflation during consecutive EGD and colonoscopy in moderate-sedation patients: a prospective, double-blind, randomized controlled trial.
abstract: OBJECTIVE
  Endoscopy is performed with air insufflation and is usually associated with abdominal pain. It is well recognized that carbon dioxide (CO2) is absorbed more quickly into the body than air; however, to date, few studies have investigated the use of CO2insufflation during consecutive EGD and colonoscopy (CEC). Thus, this study evaluated the efficacy of CO2insufflation compared with air insufflation in CEC.
  
  
  METHODS
  From March 2014 to April 2016, a total of 215 consecutive patients were randomly assigned to receive CO2insufflation (CO2group, n = 108) or air insufflation (air group, n = 107). Abdominal pain after CEC was recorded on a visual analogue scale (VAS). The amount of sedatives administered, use of analgesics, polyp detection rate (PDR), adenoma detection rate (ADR), abdominal circumference, and adverse events were also analyzed.
  
  
  RESULTS
  Baseline patient characteristics were not significantly different between the groups. Abdominal pain on the VAS in the CO2group and air group 1 hour after CEC was, respectively, 13.8 and 20.1 (P = .010), 3 hours after CEC was 8.3 and 12.5 (P = .056), 6 hours after CEC was 3.5 and 5.3 (P = .246), and 1 day after CEC was 1.8 and 3.4 (P = .192). The dose of sedative administered, analgesic usage, PDR, ADR, and adverse events were not statistically different between the groups. However, the increase in abdominal circumference was significantly higher in the air group than in the CO2group.
  
  
  CONCLUSIONS
  CO2insufflation was superior to air insufflation with regard to the pain score on the VAS in the hour after CEC. (Clinical trial registration number: KCT0001491.).
authors.affiliation: Divison of Gastroenterology, Department of Internal Medicine, Gachon University, Gil Medical Center, Incheon, South Korea.
authors.forename: Su Young
authors.initials: SY
authors.lastname: Kim
authors.affiliation: Divison of Gastroenterology, Department of Internal Medicine, Gachon University, Gil Medical Center, Incheon, South Korea.
authors.forename: Jun-Won
authors.initials: JW
authors.lastname: Chung
authors.affiliation: Divison of Gastroenterology, Department of Internal Medicine, Gachon University, Gil Medical Center, Incheon, South Korea.
authors.forename: Dong Kyun
authors.initials: DK
authors.lastname: Park
authors.affiliation: Divison of Gastroenterology, Department of Internal Medicine, Gachon University, Gil Medical Center, Incheon, South Korea.
authors.forename: Kwang An
authors.initials: KA
authors.lastname: Kwon
authors.affiliation: Divison of Gastroenterology, Department of Internal Medicine, Gachon University, Gil Medical Center, Incheon, South Korea.
authors.forename: Kyoung Oh
authors.initials: KO
authors.lastname: Kim
authors.affiliation: Divison of Gastroenterology, Department of Internal Medicine, Gachon University, Gil Medical Center, Incheon, South Korea.
authors.forename: Yoon Jae
authors.initials: YJ
authors.lastname: Kim
authors.affiliation: Divison of Gastroenterology, Department of Internal Medicine, Gachon University, Gil Medical Center, Incheon, South Korea.
authors.forename: Jung Ho
authors.initials: JH
authors.lastname: Kim
mesh_terms: D015746:Abdominal Pain / Q000188:drug therapy*; D000236:Adenoma / Q000175:diagnosis*; D000328:Adult; D000368:Aged; D000388:Air; D002245:Carbon Dioxide; D003113:Colonoscopy / Q000379:methods*; D015179:Colorectal Neoplasms / Q000188:drug therapy*; D016292:Procedural Sedation; D004311:Double-Blind Method; D016145:Endoscopy, Digestive System / Q000379:methods; D005260:Female; D006801:Humans; D007327:Insufflation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D010149:Postoperative Pain / Q000188:drug therapy*
chemical_list: D002245:Carbon Dioxide