Impact of carbon dioxide insufflation and water exchange on postcolonoscopy outcomes in patients receiving on-demand sedation: a randomized controlled trial

Abstract

Background and aims: Water exchange (WE) is the least painful insertion method during colonoscopy. Its impact on postcolonoscopy discomfort has not been well-described. Carbon dioxide (CO₂) insufflation consistently reduced postcolonoscopy discomfort. We compared postcolonoscopy outcomes of various combinations of insertion and withdrawal techniques (insertion-withdrawal modality): WE-CO₂, WE-air insufflation (WE-AI), and CO₂-CO₂.

Methods: A total of 240 patients undergoing on-demand sedation diagnostic colonoscopy were randomized to WE-CO₂ (n = 79), WE-AI (n = 80), CO₂-CO₂ (n = 81), with postprocedural data collected up to 24 hours. The primary outcome was postcolonoscopy bloating. Other postcolonoscopy outcomes included pain scores, flatus and incontinence episodes, toilet use, interference with normal activities, patient satisfaction, and patient willingness to repeat the procedure.

Results: Demographic and procedural data were comparable. Compared with WE-AI, WE-CO₂ and CO₂-CO₂ resulted in significantly less bloating (all P < .0005) and lower pain scores (P values ranged from .008 to < .0005) up to 3 hours and fewer flatus episodes up to 6 hours (P values ranged from .003 to < .0005). WE-CO₂ resulted in less interference with same-day activities compared with WE-AI (P = .043). The differences in postprocedural outcomes were significant, but the magnitude was small. Patient satisfaction and willingness to repeat the procedure were high and comparable among groups. WE was the least painful insertion technique (P < .0005).

Conclusions: The combination WE-CO₂ appears to be the optimal choice to decrease pain during the examination and to reduce bloating and other undesired procedural outcomes afterward. If a CO₂ insufflator is already available, it seems advisable to adopt the combination WE-CO₂. In the absence of a CO₂ insufflator, the cost effectiveness of the addition of withdrawal CO₂ to WE in diagnostic and nondiagnostic settings needs to be critically assessed. (Clinical trial registration number: NCT02409979.).