Anaesthesia for colonoscopy. An examination of the anaesthesia as an element of risk at colonoscopy

The importance of anaesthesia as an element of risk at colonoscopy has been examined retrospectively over a 10-year period from 1975 to 1984. The colonoscopic examinations were made by surgical gastroenterologists and anaesthesiologists working in cooperation. In 1242 cases the patients received diazepam/fentanyl anaesthesia during the colonoscopy (Group I) and in 126 cases they received general anaesthesia (Group II). The incidence of perforations of the large bowel in Group I was 0.8% (95% confidence limits: 0.4-1.5%) and in Group II 0.0% (95% confidence limits: 0.0-2.9%). Statistically the difference is not significant (P = 0.38). The groups were comparable with a view to the patients' age, weight, the duration of the colonoscopy and the number of times that polypectomy had been performed. All anaesthesia was administered by staff qualified by training and experience to administer anaesthesia, and did not cause any complications. However, four patients had vasovagal reflexes due to manipulation of the colonoscope. The dosing in the patients in Group I averaged: diazepam as premedication 9.2 mg, intravenous diazepam 12.4 mg, intravenous fentanyl 0.14 mg, and the duration of the colonoscopy was 36.5 min. The medication and the duration of the colonoscopy did not vary significantly in the patients with perforation of the large bowel. Our conclusion is that diazepam/fentanyl anaesthesia, administered by experienced staff, is harmless, and that general anaesthesia for colonoscopy did not involve an increased risk of perforation of the large bowel.