Air and carbon dioxide volumes insufflated during colonoscopy

Background: During colonoscopy, air or carbon dioxide is insufflated to secure adequate visualization of the colon, and endoscopy trainees are reminded to use as little gas as possible to avoid patient discomfort. However, the volume of gas insufflated by endoscopists during colonoscopy is unknown. The aim of the present study was to measure volumes of carbon dioxide and air insufflated during colonoscopy. Methods: A total 249 consecutive patients participating in a colorectal cancer screening program were randomized to undergo colonoscopy with either carbon dioxide or air insufflation. Gas volumes insufflated during the procedure were measured with a mass-flowmeter. Four experienced endoscopists performed all of the examinations. Results: Gas volumes were successfully measured in 218 (87%) patients. A mean of 8.3 L of carbon dioxide (range 1.2-19.8 L) and 8.2 L of air (range 1.8-18 L) were insufflated (p = 0.9). Mean volumes insufflated per minute were estimated to be 0.26 L and 0.24 L, respectively, in the carbon dioxide and air groups (p = 0.5). Statistically significant differences in the volumes of gas insufflated per minute were observed among some of the endoscopists. Conclusions: The volumes of carbon dioxide and air used during colonoscopy can be estimated. Differences in volumes of gas used by experienced endoscopists were detected.