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FDA Approves New Endoscopic Tool
Alan L. Buchman, MD, MSPH, Northwestern University, Chicago, IL
Even in the best circumstances, undergoing an endoscopy is something most people would rather avoid. The following article describes a new tool for this procedure, which offers a less painful and intrusive alternative to the conventional scope. Three of the major drawbacks currently, are its limited: availability, use in the colon, and use in patients who have undergone major bowel surgery.
A revolutionary new endoscopic tool was approved by the Food and Drug Administration in August, 2001. The Given M2A™ capsule video endoscope allows the gastroenterologist to see much of the small intestine as never before visualized. The capsule is like a cruise balloon that is propelled through the intestinal tract by peristalsis, or contractions of the intestines. While the scenery is not like that of an exotic jungle cruise, the Given video capsule endoscope does take the gastroenterologist on a fantastic voyage in a far away land that has previously not been well explored.
The capsule spends its first 30 to 60 minutes in the stomach before passing through the pylorus into the duodenum, or first part of the small intestine. With its 240° viewing area, the capsule can allow relatively complete viewing of the small intestine. It also magnifies the actual intestine (about eight times) so that villi can be seen. Along the way, the wireless capsule snaps photographs at a rate of two per second. These 50,000 to 60,000 images are transmitted via high frequency radio waves to a data recorder worn on a belt. The images are then downloaded to a computer after the capsule’s amazing two to six hour voyage through the small intestine, and are viewed by the gastroenterologist as a video. Currently, we are unable to take biopsies with the capsule, but it is anticipated that next generation devices may permit this function within a few years.
How it Compares to Conventional Tools
Visualizing the small intestine to diagnose Crohn’s disease, rare tumors and sources of bleeding when endoscopy and colonoscopy were unrevealing, has always been a challenge for gastroenterologists. We are studying how well the capsule endoscope compares to the traditional small bowel study, using barium, for diagnosing Crohn’s disease, finding the origin of bleeding, and determining whether a patient’s body has rejected a transplanted small intestine. Using the “camera-in-a-capsule,” we have diagnosed patients with Crohn’s disease who had virtually no symptoms of the disease, only microscopic amounts of blood in their stool.
Conventional endoscopy into the small intestine, when possible, can visualize only about 20% of the intestine at most. In the 1980’s the Sonde endoscope was developed. This procedure required a long tube to be inserted into the intestinal tract over 6 to 8 hours. The patient lay on a table until x-rays showed the end of the tube to have passed through the small intestine; sometimes it never did. The gastroenterologist could then slowly pull the tube back, observing the intestine during withdrawal. Unfortunately, even under the most optimal conditions, only 50-80% of the intestine could be seen.
Barium x-ray studies of the small intestine do not show pictures of the intestine, but offer an outline of the intestine. Thus they are often successful in identifying an ulcer because an ulcer is similar to an incomplete hole in the mucosa, or lining of the digestive tract, and barium fills in the hole. However, flat lesions, (like vascular ectasias that may cause bleeding,) ulcers from Crohn’s disease, some strictures or blockages of the intestine, and tumors, might be missed.
Although the capsule often passes into the colon while the videotaping continues, its battery runs out before the journey through the colon is complete. Passage through the colon is generally much slower than through the intestine because the contractions in the colon are slower. Therefore, the capsule does not replace traditional colonoscopy for colon cancer screening or other purposes.
How it Works
It takes about 20 minutes for a patient to be wired up for the procedure. Several wires are attached to the abdomen like ECG leads. These wires pick up the radio signal from the capsule as it travels through the intestine. The wires are connected to a lightweight data recorder worn on a belt about the size a loading dock worker might wear. The capsule itself measures only 0.4 x 1.0 inches. Inside this miniature ‘Voyager’ are a color camera, four light sources, a radio transmitter and batteries. The capsule is swallowed along with a small amount of simethicone, which helps prevent air bubbles in the small intestine and makes viewing of the video easier for the gastroenterologist.
We have found that patients tolerate the capsule better than traditional scoping methods, and they can return to work, home or shopping while undergoing the endoscopy. Strenuous exercise is discouraged to avoid pulling off one of the wires. No eating or drinking is permitted for the first two hours of the study, after which liquids can be consumed. A small meal is permitted after four hours. The patient returns to the gastroenterologist after eight hours to have the belt and wires removed. The capsule is excreted naturally in a couple of days and is disposable; most patients never notice it.
Unlike conventional endoscopy, there is no air insufflation during the video capsule procedure, so the patient is less distended and not uncomfortable. The lack of air insufflation does not affect the viewing of the video, but does make it appear a little different to the gastoenterologist than what he/she may be used to during conventional endoscopy. Unlike conventional endoscopy, the capsule can flip over and the view can be much like CircleVision™ at Disney World.
It takes about 2-1/2 hours to load the video onto a computer, so the video is generally not seen by the gastroenterologist until the following day. Special software to help the gastroenterologist pinpoint the location of the intestine that is abnormal will soon be available, most likely in early 2002. Currently, it may be difficult for the gastroenterologist to determine the exact location of an abnormality.
There is a small risk the capsule could become lodged in the intestine. Although the capsule is quite small, it should be used with caution in patients who have had major abdominal surgery. The capsule should not be used in patients with symptoms of a bowel obstruction, including nausea, vomiting and abdominal distention, unless the patient clearly understands the capsule could cause a complete bowel obstruction that may require hospitalization, and possibly surgery.
Physicians at Northwestern University have used the video capsule procedure on two patients with significant small bowel strictures without a problem, although the capsule did take more time to pass. There have been a couple of cases, at institutions other than Northwestern, in which patients were found to have asymptomatic strictures. These patients required hospitalization for bowel obstruction and were treated with NG tube suction. To the best of my knowledge, no patient has required surgery to remove the unplanned obstruction by a capsule, but it is always a concern.
If you think you may benefit from undergoing testing with the video capsule endoscope, you should first speak with your doctor to determine if this test would be helpful for you and potentially change the way you are treated. For more information on studies with the capsule endoscope in patients with Crohn’s disease visit Northwestern’s website at www.ibdcenter.net.
Reprinted with permission from the author, Alan L. Buchman, MD, MSPH