Use of warm carbon dioxide insufflators does not affect intra-colonic gas temperature and has no effect on polyp detection rate during colonoscopy – a randomized controlled trial

BACKGROUND AND STUDY AIMS  Methods to improve polyp detection during colonoscopy have been investigated, with conflicting results for warm water irrigation. Carbon Dioxide (CO 2) warmed to 37 °C may have similar or more pronounced effects on bowel motility. This study aimed to assess whether warmed CO 2 would improve polyp detection compared to room temperature air insufflation. PATIENTS AND METHODS  This was a double-blind, randomized controlled trial that enrolled 204 patients undergoing screening or surveillance outpatient colonoscopy. The primary outcome was polyp per patient detection rate. Secondary outcomes included adenoma per patient detection rates, bowel spasm, and patient comfort. RESULTS  The trial was terminated after an interim analysis determined futility. Between the warmed CO 2 and room air groups, no significant differences were found in the per-colonoscopy polyp detection rate ( P  = 0.57); overall polyp detection rate ( P  = 0.69); or adenoma detection rates ( P  = 0.74). More patients in the room temperature group had lower spasm scores (p = 0.02); however, there was a trend towards greater patient comfort in the warmed CO 2 group ( P  = 0.054). An ex-vivo study showed a significant difference between exiting CO 2 temperature at the insufflator end vs. delivered CO 2 temperature at the colonoscope tip end. The temperature of insufflation at the tip of the colonoscope was not different when using warmed vs. unwarmed insufflation ( P  = 0.62). CONCLUSION  When compared with room air insufflation, warmed CO 2 insufflation did not affect polyp detection rates.