A meta-analysis of carbon dioxide versus room air insufflation on patient comfort and key performance indicators at colonoscopy

Background Carbon dioxide (CO 2 ) has been used as an alternative to air insufflation at endoscopy with good results; however, uptake of the technique has been poor, possibly due to perceived lack of outcome equivalency. This meta-analysis evaluates the effectiveness of CO 2 versus air in reducing pain post-colonoscopy and furthermore examines other key performance indicators (KPIs) such as sedative use, procedure times and polyp detection rates. Methods This meta-analysis was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Pubmed, Pubmed Central, Embase and Cochrane Library were searched for randomized studies from 2004 to 2019, reporting outcomes for patients undergoing colonoscopy with air or CO 2 insufflation, who reported pain on a numerical or visual analogue scale (VAS). Results were reported as mean differences (MD) or pooled odds ratios (OR) with 95% confidence intervals (95% CI). Results Of 3586 citations, 23 studies comprising 3217 patients were analysed. Patients undergoing colonoscopy with air insufflation had 30% higher intraprocedural pain scores than those receiving CO 2 (VAS 3.4 versus 2.6, MD -0.7, 95% CI − 1.4–0.0, p = 0.05), with a sustained beneficial effect amongst those in the CO 2 group at 30 min, 1–2-h and 6-h post procedure (MD − 0.8, − 0.6 and − 0.2, respectively, p