Carbon dioxide insufflation vs conventional air insufflation for colonoscopy: a systematic review and meta‐analysis of published randomized controlled trials

AIM: Conventional air insufflation (AI) may cause prolonged abdominal bloating, excessive abdominal pain and discomfort during colonoscopy. Carbon dioxide may be an acceptable alternative to avoid these complications. The object of this study was to evaluate systematically the effectiveness of carbon dioxide insufflation (CI) for colonoscopy compared with AI. METHOD: Randomized controlled trials (RCTs) comparing the effectiveness of CI with that of AI during colonoscopy were retrieved from medical electronic databases and combined analysis was performed using the RevMan statistical package. The combined outcome of dichotomous and continuous variables was expressed as an odds ratio (OR) and standardized mean difference (SMD). RESULTS: Twenty-one RCTs comprising 3607 patients were included in the study. There was statistically significant heterogeneity among included studies. CI showed a significant trend towards reduced procedural pain [SMD -1.34; 95% confidence interval (95% CI) -2.23 to -0.45; z = 2.96; P < 0.003] and also postprocedural pain at 1 h (SMD -1.11; 95% CI -1.83 to -0.38; z = 2.97; P < 0.003), 6 and 24 h (OR 0.44; 95% CI 0.23-0.85; z = 2.44; P < 0.01). CI was associated with faster caecal intubation (SMD -0.20; 95% CI -0.37 to -0.02; z = 2.23; P < 0.03) but the caecal intubation rate was similar (P = 0.59) in both colonic insufflation techniques . CONCLUSION: CI seems to have clinical advantages over AI for colonoscopy with regard to pain during and after the procedure.