“…Dellon et al [10] reviewed 9 randomized controlled studies (6 studies of colonoscopy [1,2,11,12,13,14] and 1 study each of flexible sigmoidoscopy [15], ERCP [3], and double-balloon enteroscopy [16]) and 6 non-randomized studies [4,17,18,19,20,21] related to the safety of administering CO 2 during gastrointestinal endoscopy. Adverse respiratory complications or episodes of suppressed ventilation were not reported, although most studies excluded patients with severe respiratory compromise or COPD with known CO 2 retention.…”