The following article is written Brian Fanning, product manager for ScopeGuide and colonoscopes, and Nadine Clark, product manager for GI and OR accessories, at Olympus America.
Despite the routine nature of many colonoscopies, two things frequently occur that can lead to increased patient discomfort during and after the procedure: intestinal looping and air retention in the intestines. The use of magnetic endoscopic imaging (MEI) and carbon dioxide insufflation are two solutions that can help. Here's how:
1. MEI — A primary source of patient discomfort during colonoscopy is caused by mesenteric stretching from looping of the scope's insertion tube. As the endoscope's insertion tube presses into the wall of the intestine, it can stop the scope's progression forward, requiring the physician to apply more pressure. This, in turn, can cause loops to form along the length of the endoscope, putting painful pressure against the intestinal wall. A 2002 study by Shaw et al. found that 90 percent of procedural-related pain was associated with either looping (79 percent) or straightening of the scope (11 percent). The study concluded that MEI may improve pain management by enabling the physician to more readily straighten loops in the sigmoid colon, and better target patient analgesia.1
MEI for assisted colonoscopy
Since the view through an endoscope only shows what is directly in front of the scope's tip, it is difficult to detect when intestinal loops are beginning to form, making the physician rely solely on feel to correct the problem. MEI allows real-time visualization of the colonoscope while it is inside the body. By seeing the shape of the scope as it moves through the colon, MEI can assist with earlier identification and reduction of loops, making even difficult colonoscopies easier to navigate. The physician can evaluate the extent of looping and gain a better sense of which rotational maneuvers will be required to straighten out various loop formations as they occur. A 2007 study by Hoff et al. of colonoscopy without the routine use of sedation and/or analgesics found that MEI significantly improved cecum intubation rates and reduced procedural pain.2
How it works
3-D visualization, such as the technology found in ScopeGuide from Olympus, is made possible through the device's built-in electromagnetic coils, which generate a pulsed, low-frequency magnetic field. These magnetic pulses are transmitted to an external receiver dish which sends them to the processor to generate a 3D image of the scope alongside the endoscopic image. This imaging provides the physician with the precise positioning and orientation of the scope during the procedure. An externally applied hand coil can also help map the scope location in relationship to the patient's abdomen to determine the optimal point to apply external pressure to assist in loop management.
2. CO2 insufflation — All colonoscopies require some form of bowel dilation, usually in the form of air insufflation, in order to perform an examination. The problem is that when room air is insufflated into the intestine, it can sit inside the lumen for hours. This can extend patient time in the recovery bay and cause pain and bloating long after the procedure.3 It can also limit the options for intraoperative endoscopy using other minimally invasive therapies such as laparoscopy because the space inside the abdominal cavity is taken up by the distended bowel.4
CO2 as an emerging standard
Over the past decade, studies indicate that CO2 insufflation is safe and less painful than air insufflation for the patient during and after routine endoscopy procedures.4 CO2 is 25 times more soluble than room air by blood and tissue. It is thus absorbed by the body 150 times faster than nitrogen in room air and is easily and quickly excreted through the lungs.3 In 2008, Dellon et al. conducted studies on various endoscopic procedures, including colonoscopy, that indicated less post-procedural pain at both one-hour and six-hour post-procedure time increments in the CO2 insufflation group compared with the air group.5 Because of its benefits and efficacy, CO2 is being recommended by some as the new standard of care in screening exams.3
As early as the 1970s, some gastroenterologists experimented with CO2 before FDA-approved devices existed.3 But today several devices, including the Olympus UCR Intraluminal Insufflation Unit, provide clinicians with access to CO2 insufflation technology, often in a compact, easy-to-use design.
When it doesn't work
For patients free of pulmonary disease, current findings indicate that CO2 insufflation is safe for endoscopy procedures. However, patients with respiratory disorders, sleep apnea or morbid obesity, or with known CO2 retention, may be at risk with CO2 insufflation.5 Prior to CO2 insufflation, careful clinical review should be undertaken by trained medical personnel.
From a patient perspective, CO2 insufflation and MEI-enabled devices may ease at least some of the discomforts associated with colonoscopy, and that's good news for both patients and providers.
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References
1 Shah, SG et al. Patient Pain during Colonoscopy: An Analysis Using Real-Time Magnetic Endoscope Imaging. Endoscopy. 2002; 34(6): 435-440. Accessed 6-17-11. http://www.ncbi.nlm.nih.gov/pubmed/12048623
2 Hoff, G et al. Improvement in Caecal Intubation Rate and Pain Reduction by using 3-dimensional Magnetic Imaging for Unsedated Colonoscopy: A Randomized Trial of Patients Referred for Colonoscopy. Scandinavian Journal of Gastroenterology. 2007; 42(7): 885-889. Accessed 6-17-11. http://www.ncbi.nlm.nih.gov/pubmed/17558914
3 Milsom, JW et al. Advancing the Future of Minimally Invasive Surgery. General Surgery News, Special Report (2009). McMahon Publishing. Accessed 6-17-11. http://www.generalsurgerynews.com/download/0854_Olympus_WM.pdf
4 Medco Forum. UCR-CO2 Intra-Luminal Insufflation Unit: A New Intra-Operative Platform for Advanced Laparoscopy. June 2008: V15:N30. Accessed 6-17-11. http://www.olympusamerica.com/presspass/press_pass_cut/documents/Medco_Forum_Article_UCR.pdf
5 Dellon, ES et al.; Carbon Dioxide Insufflation during GI Endoscopy. Gastrointestinal Endoscopy 69.4 (2009): 843-49. Accessed 6-17-11. http://www.tcgroup.it/attachFileMail/EmailAigo/AllegatiArticoli/1673-1657.pdf