RESUMO
BACKGROUND AND STUDY AIMS: Compared with air insufflation, water exchange and carbon dioxide (CO2) insufflation have been shown to reduce colonoscopy discomfort; however, head-to-head studies of the two methods are lacking. We aimed to compare water exchange and CO2 insufflation directly with regard to pain during primary unsedated colonoscopy. METHODS: Patients willing to undergo unsedated colonoscopy at three centers in Norway and Poland were randomized 1:1 to water exchange or CO2 insufflation during colonoscope insertion. Patients were blinded to group allocation. The primary end point was the proportion of patients reporting moderate or severe procedural pain on a 4-point verbal rating scale (VRS-4) at discharge. Secondary outcomes included the proportion of patients reporting no pain on the VRS-4. RESULTS: A total of 473 patients were randomized. A discharge pain questionnaire was completed by 226 of 234 patients (97â%) in the water exchange group versus 226 of 239 patients (95â%) in the CO2 group (Pâ=â0.37). Moderate or severe pain was reported by 47 of 226 patients (21â%) in the water exchange group versus 60 of 226 patients (27â%) in the CO2 group (Pâ=â0.15). No pain was reported by 100 of 226 patients (44â%) and 69 of 226 patients (31â%) in the water exchange and CO2 groups, respectively (Pâ=â0.003). On-demand sedation was used in 15 patients (6â%) in each group (Pâ=â0.95). CONCLUSIONS: There was no significant reduction in moderate or severe pain in a comparison of water exchange with CO2 insufflation. The secondary outcome of no pain was significantly more frequent in the water exchange group.âClinical trials registry number: NCT01633333.