Randomized, controlled trial of carbon dioxide insufflation during colonoscopy

Insufflation of air is a cause of discomfort during and after colonoscopy. Although this can be minimized by good technique, the use of carbon dioxide insufflation may provide further benefits. Carbon dioxide is rapidly absorbed and excreted through the lungs. We hypothesized that carbon dioxide would alleviate post-colonoscopy discomfort.

After they had provided informed consent, patients presenting for colonoscopy were randomized into two groups: those in whom air was used for colonoscopy and those in whom carbon dioxide was used. Pain during and ten minutes after colonoscopy was measured on a ten-point analog scale. Data are mean and 95 percent confidence limits.

There were 124 patients in the air group and 123 in the carbon dioxide group. Age, body mass index, indication, diagnosis, and number of procedures were similar for the two groups. There were no differences between the groups in the amounts of sedation or analgesia used, the percentage of examinations that were complete (air, 98.4 percent; carbon dioxide, 95.2 percent), or patient satisfaction (on a scale of 1 to 10: air, 9.4; carbon dioxide, 9.5). Although there were more females in the carbon dioxide group (69 vs. 51), hysterectomy rates were the same. Pain scores (mean +/- 95 percent confidence interval; scale of 1 to 10) immediately after the examination were 4.3 +/- 0.3 for air and 3.6 +/- 0.3 for carbon dioxide (no significant difference). Pain scores 10 minutes later were 2.1 +/- 0.2 for air and 0.9 +/- 0.2 for carbon dioxide (P < 0.05, Student's t-test).

Because there was significantly less abdominal pain ten minutes after colonoscopy in the group in whom carbon dioxide was used, carbon dioxide should be considered as an insufflating gas for colonoscopy.