1 Esophageal Stricture Compliance Device William Stanford- Team Leader Karissa Thoma – Communicator Dan Frost – BWIG Allie Finney – BSAC Advisor: Dr. Tompkins Client: Dr. Reichelderfer May 12, 20082 Table of Contents Abstract…………………………………………………………………………...………3 Background/Motivation……………………………………………………….…..………3 Problem Statement…………………………………………………………….…..………5 Design Requirements and Restraints……………………………………………..……….5 Previous Work…………………………………………………………………………….7 A/D Converters ………………….……………………………………………………….8 Option 1…………………………………………………………………………..8 Option 2……………………………………………………………………..……9 Option 3………………………………………………………………...………..10 Design Matrix…………………………………………………………………....11 Sealants…………………………………………………………………………………..12 Option 1…………….……………………………………………………………12 Option 2……………………………………………………………………….....12 Option 3………………………………………………………………………….13 Design Matrix……………………………………………………………………13 Device Setup……………………………………………………………………………..14 Testing…………………………………………………………………………………...16 Future Work……………………………………………………………………………..21 References……………………………………………………………………………….23 Appendix……………………………………………………………………………..24-253 Abstract Esophageal strictures are the narrowing of the esophagus due to the build-up of scar tissue. Dilation is used to treat the stricture by increasing the diameter of the esophagus. Currently, there is very little known about the compliance of esophageal strictures. Our objective is to create a device that can measure the compliance of esophageal strictures. Currently, a linear potentiometer and pressure sensor record the volume and pressure of saline in the balloon and record the data in real time on a graph via a LabVIEW VI. Several latex esophagi were used to generate compliance curves. From these, it was determined that as the thickness of a stricture increases and the diameter decreases, the slope of the compliance curve increases, indicating a decrease in overall compliance. Future work of the project should focus on obtaining curves from human subjects and an A/D converter that can work with LabVIEW so the device can be made compact and ready for hospital use. Background/Motivation Esophageal strictures are the narrowing of the esophagus due to the build-up of scar tissue following healing from previous injury. The injury of the esophagus is known to be caused by one of 3 general categories: (1) intrinsic diseases that narrows the esophageal lumen through inflammation, fibrosis, or neoplasia, (2) extrinsic diseases that alter the lumen via intrusion leading to lymph node enlargement, (3) or diseases that disrupt the control and innervation of the smooth esophageal muscles and the lower esophageal sphincter [1]. The most common cause of esophageal strictures is the side effect of untreated gastrointestinal reflux disorder (GERD). GERD left untreated causes continual damage to the esophagus from the regurgitation of stomach acid entering the lumen of the esophagus [2]. The epithelium lining the esophagus is not designed to be in contact with acid from the stomach and is injured. Repetitive injury causes build-up of scar tissue from previous healings which gradually narrow the luminal diameter of the esophagus.4 Esophageal strictures are associated with dysphagia or difficulty with eating, since the esophagus is narrowing from about 25 mm to 10-22 mm [3]. Esophageal strictures are treated using balloon dilation, in which the strictures are slowly stretched through a radially inflated balloon, in an attempt to restore normal luminal diameters. Dilation is typically performed multiple times during a patient’s lifetime to best alleviate symptoms [4]. While dilation improves dysphagia, it can be dangerous if perforations are incurred during the procedure leading to costly hospital expenses, infection, death and malpractice law suits. Recently, eosinophilic esophagitis has been found to be increasingly important in the formation of esophageal strictures. This is a growing concern since eosinophilic esophagitis is associated with a higher rate of mucosal tearings and perforations during balloon dilation. The rate of perforations and mucosal tearing is based on the equipment used and the skill of the clinician. Dilation is performed either with mechanical dilators or balloon dilation. Dilation with balloon dilators reduces the shear stress on the esophageal lumens through radial dilation, thus reducing the risk of perforations [3]. Our client a specialist in balloon Figure 1: Eosinophilic esophagitis.5 dilation admitted that even in his department at the UW hospital 1or 2 patients are perforated each year during this procedure. Although perforations rarely occur at the UW clinic, the expertise and the experience in smaller areas is thought to increase the rate of perforations. A long-term goal is to implement a real-time pressure volume compliance curve with the current equipment, to alert the clinician to a potential mucosal tears or perforation. Problem Statement Currently, there is very little known about the compliance of esophageal strictures. With more research and work on this subject, particularly in understanding compliance trends with different size strictures, clinicians would be able to categorize them and this would lead to more and better treatment options. There are currently no devices on the market that measure esophageal
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