Aside from bowel prep, one of the most frequent complaints that patient have with lower GI endoscopy (colonoscopy and flexible sigmoidoscopy) is the discomfort they experience from trapped air in the colon as a result of insufflation of air during the examination procedure. Room air is used to distend the colon for optimal visualization of the large intestine. Given its low cost, ample supply and effectiveness, it has always been medium of choice for GI endoscopy. However room air can be problematic during prolonged colonoscopies, in patients with advanced diverticulosis and small bowel endoscopic examinations which can take over an hour to complete. Also in non-sedated patients undergoing flexible sigmoidoscopy room air distention can cause significant intestinal spasm and pain. I have noticed this to be especially true in patients undergoing endoscopic rubber band ligation and diagnostic sigmodoscopy.
In the past decade their has been interest in substituting carbon dioxide (CO2) for room air during GI endoscopy. Carbon dioxide absorption is 150 times faster than room air absorption and results in much less post-procedure distention and pain complaints. It is routinely being used in CT (virtual) colonoscopy. It may also be useful in ERCP, enteroscopy, intra-operative endoscopy and laporascopy. Clinical studies have shown that CO-2 based systems are safe and effective during routine GI endoscopy including colonoscopy.
Although CO-2 gas tanks are inexpensive to purchase, endoscopic carbon dioxide insufflation require an extra CO2 regulation unit costing $4,500 (Olympus). This compact unit fits on the endoscope cart and can provide adjustable flow rates of CO2 through the air channel of the GI endoscope. Unfortunately, the extra expense of the unit and the CO2 gas are not reimbursed by insurance and contribute to the overhead in the GI unit. The only local use of the CO2 regulation unit is restricted to enteroscopy at the University of North Carolina Hospital at Chapel Hill. Also CO2 insufflation may be contraindicated in patients with emphysema / COPD undergoing deep sedation during colonoscopy.
Yamano, H, Yoshikawa Y, et. al. Carbon dioxide insufflation for colonoscopy; evaluation of gas volume, abdominal pain, examination time and transcutaenous partial CO2 pressure. J of Gastroenterology. DOI 10.1007/s00535-010-0286-5
Sumanac K, Zealley I, et. al. Minimizing postcolonoscopy abdominal pain by using C)2 insufllation; a prosepective randomized, doluble blind controlled trial evaluation a new commercially available CO2 delivery. Gastriintest Endosc. 2002:56(2):190-194.