Evaluation of abdominal circumference and salivary amylase activities after unsedated colonoscopy using carbon dioxide and air insufflations.

To assess and compare abdominal distention and stress in unsedated colonoscopy using carbon dioxide (CO2 ) and air insufflations.Two hundred and five patients underwent colonoscopic examinations without sedation using either CO2 or air insufflation. Abdominal circumference and salivary amylase (sAMY) activities before and 0 and 15 min after colonoscopy were measured by a nurse who was blinded to the grouping of the patients.In all, 102 and 103 patients were randomly recruited in the CO2 and air insufflation groups, respectively. sAMY activities before and 0 and 15 min after colonoscopy were not significantly different between the two groups. Abdominal circumference measured immediately and 15 min after colonoscopy was significantly smaller in CO2 insufflation group than in the air insufflation group (81.2 cm vs 84.0 cm, and 79.7 cm vs 83.6 cm, respectively; P <0.05). The increasing ratio of abdominal circumference immediately after colonoscopy was not significantly different between the two groups; however, the ratio at 15 min after colonoscopy using CO2 insufflation was significantly lower than that in the air insufflation group (1.007 vs 1.028, P <0.001).sAMY activities after unsedated colonoscopy using CO2 insufflation were not improved; however, CO2 insufflation decreases abdominal circumference after colonoscopy compared with air insufflation.