Autonomic nervous responses in colorectal polypectomy: Randomized controlled trial comparing air and carbon dioxide insufflation.

Background and Aim Carbon dioxide (CO₂) insufflation devices are commonly used for endoscopic examination and treatment. In this prospective randomized controlled trial (RCT), we compared patient acceptance, cardiovascular tolerance, and autonomic nervous responses between patients receiving air insufflation and CO₂ insufflation. Methods We initially enrolled 170 patients and, of these, 158 patients in total were analyzed (air group, 83; CO₂ group, 75). Autonomic nervous responses were evaluated by analysis of heart rate variability (HRV). Primary end point was superiority in the effects of CO₂ insufflation on the autonomic nervous system by HRV analysis. Results Visual analog scale disclosed significantly less abdominal pain and abdominal fullness with CO₂. Percentage heart rate change rate at 1 h and 4 h after the procedure was also significantly lower in the CO₂ group than in the air group (1 h after: P < 0.01, 4 h after: P < 0.05). Comparison based on age showed that % heart rate change was significantly lower in the younger CO₂ patients (just after colonoscopy and 1 h after: P < 0.01, 4 h after: P < 0.05), but this difference was not apparent in an older group of patients. Conclusions This is the first RCT showing that colorectal polypectomy using CO₂ insufflation significantly decreases abdominal pain and abdominal fullness common in such patients with lowered stress to the autonomous nervous system. The effects using CO₂ insufflation on the sympathetic nervous system also seemed to be more prominent among younger patients. [ABSTRACT FROM AUTHOR]