Carbon dioxide insufflation during colonoscopy in deeply sedated patients

AIM： TO compare the impact of carbon dioxide （CO2） and air insufflation on patient tolerance/safety in deeply sedated patients undergoing colonoscopy. METHODS： Patients referred for colonoscopy were randomized to receive either CO2 or air insufflation dur- ing the procedure. Both the colonoscopist and patient were blinded to the type of gas used. During the proce- dure, insertion and withdrawal times, caecal intubationrates, total sedation given and capnography readings were recorded. The level of sedation and magnitude of patient discomfort during the procedure was assessed by a nurse using a visual analogue scale （VAS） （0-3）. Patients then graded their level of discomfort and ab- dominal bloating using a similar VAS. Complications during and after the procedure were recorded. RESULTS： A total of 142 patients were randomized with 72 in the air arm and 70 in the CO2 arm. Mean age between the two study groups were similar. Inser- tion time to the caecum was quicker in the CO2 group at 7.3 min vs 9.9 min with air （P = 0.0083）. The aver- age withdrawal times were not significantly different between the two groups. Caecal intubation rates were 94.4% and 100% in the air and CO2 groups respective- ly （P = 0.012）. The level of discomfort assessed by the nurse was 0.69 （air） and 0.39 （CO2） （P = 0.0155） and by the patient 0.82 （air） and 0.46 （CO2） （P = 0.0228）. The level of abdominal bloating was 0.97 （air） and 0.36 （CO2） （P = 0.001）. Capnography readings trended to be higher in the CO2 group at the commencement, caecal intubation, and conclusion of the procedure, even though this was not significantly different when compared to readings obtained during air insufflation. There were no complications in both arms. CONCLUSION： CO2 insufflation during colonoscopy is more efficacious than air, allowing quicker and better cecal intubation rates. Abdominal discomfort and bloat- ing were significantly less with CO2 insufflation.