A device for quantifying the severity of lower extremity edema

Venous stasis disease (VSD), characterized by edema, occurs when there is an obstruction and/or incompetence of the venous valves or veins in the arms and legs. Edema, an atypical accumulation of fluid in the interstitial space, is caused by fluid leaking out of the vasculature into the surrounding tissue subsequent to the buildup of pressure in the venous walls. While uncomfortable for the patient and capable of leading to other serious complications, edema may also be a valuable indicator of the extent of VSD. The ability to quantifiably assess the magnitude of edema, and thus the efficacy of treatments for VSD, would greatly benefit clinicians treating patients with this ailment. Currently, there is no device which is capable of measuring the severity of edema in a feasible, economical and quantifiable way. The most widely used clinical method for assessing the amount of edema is digital manipulation. This assessment is accomplished by pressing into the patient's leg and qualitatively evaluating the degree of pitting. Pitting is the indentation in the swollen tissue that remains following removal of pressure from the edemas area. Due to the altered tissue composition resulting from edema, there is a putty-like consistency to the tissue, and the tissue remains in the indented position for seconds to minutes before returning to its original form. The doctor performing the test assesses the depth of the indention, how much force is required to reach the tibia, how long the tissue takes to return to the original state, and skin quality. The level of edema is described using a ranking system of one to four (slight to severe). Despite the qualitative nature of this technique, it is still considered the state of the art for edema assessment. The goal of this project is to create a device that will provide a reliable, accurate and quantifiable measure of a patient's edema. The device will improve on the current method of digital manipulation by evaluating the pitting phenomena in a user-independent manner. The output of the device will allow doctors to categorize edema into at least ten different severities, improving on digital manipulation's subjective one to four scale.