Controversies / Cutting Edge
Controversies / Cutting Edge
In the future, prehospital care providers may use pharmacologic agents to manage patients with presumed variceal bleeding. As the medical management of variceal upper GI bleeding has developed, the use of pharmacologic agents in the prehospital environment has begun to be considered and studied.131,132 A recent French study, for example, found that the prehospital use of terlipressin (a vasopressin analog) in cirrhotic patients with upper GI bleeding reduced the mortality rate from 46.5% in the placebo group to 27.5% in the treated group.131 Different models for prehospital care, including the use of physicians to provide care outside the hospital, may affect the interpretation of studies such as this.
Endoscopy and related technologies are continuing to evolve. The development of "push" enteroscopes and laparoscopically assisted enteroscopy has allowed for viewing of small bowel locations that were previously inaccessible by endoscopy.133 Injection of bleeding vessels with cyanoacrylate is a relatively new endoscopically based treatment for varices that has shown promise, though the technique awaits prospective validation.134
The discomfort of traditional endoscopy, the need for sedation, and its inability to visualize the small bowel have prompted research into "wireless capsule endoscopy." 135 Israeli and British researchers have developed a self-contained endoscope small enough to be swallowed. The device was approved by the FDA for use in humans in August 2001 and has been used on about 4000 patients to date. The capsule is propelled by peristalsis through the GI tract while images are transmitted using radiotelemetry to an array of receivers that record images and triangulate the position of the capsule in the body. In its current iteration, it is capable of about seven hours of continuous recording, during which time the patient can go about his or her daily routine (undergoing the GI equivalent of a Holter monitor). The wireless capsule endoscope has reportedly performed well when compared with push enteroscopy, imaging abnormalities never seen before with flexible endoscopes. It is anticipated that this wireless capsule endoscopy will be especially valuable in patients with GI bleeding when EGD and colonoscopy both fail to identify the site of bleeding. In development are the use of a color "sensing algorithm" to improve detection of blood in the lumen and a system of remote control via local electrical stimulation of peristalsis.135 This wireless technology has not been employed to evaluate acute bleeding yet, but it is conceivable that it may be in the future.
Another new technique that may one day have a role in the evaluation of acute GI bleeding is virtual endoscopy. The use of CT scanning in evaluating lower GI bleeding is being studied.136 Virtual endoscopy is a modified form of helical CT scanning that uses a technique of three-dimensional image reconstruction and virtual reality computing.137 Unlike "real" endoscopy, the scan is done without sedation, is well-tolerated, and can be done literally in the minute it takes to acquire the images. Bowel preparation, however, is still required. Virtual endoscopy has not yet been studied in the setting of acute GI bleeding.
John L. Westhoff; Kurtis R. Holt
March 1, 2004