Technology for Continuously Monitoring the Effectiveness of Compression Therapy for Improving Patient Outcome.

HEGARTY, MEGHAN SARAH. Technology for Continuously Monitoring the Effectiveness of Compression Therapy for Improving Patient Outcome. (Under the direction of Edward Grant.) Compression therapy has traditionally been considered the cornerstone of the treatment and management process for chronic venous disease and other conditions affecting the peripheral vascular system. It is delivered in the form of bandages, multi-layer wraps, or stockings/socks, although pneumatic systems may be used. In order for compression therapy to be effective, adequate levels of pressure must be maintained. The pressure profile of medical compression hosiery is determined by the tension in the fabric and the radius of the limb, and can be calculated using Laplace’s Law. The tension in the fabric also relates to the radius of the limb insofar as determining the amount that it is stretched from its original length. Therefore, information related to the size of the limb and the material properties of the fabric are needed to ensure that the desired pressure is being delivered so that compression therapy is clinically effective. Unfortunately, the current tools and tests that are in place are confined to the hospital, clinic, or laboratory environment. Furthermore, many are subjective and/or do not provide comprehensive information. Because swelling and other symptoms associated with vascular conditions often change throughout the day, this introduces bias both from the discontinuous nature of the information, as well as differences between the health professionals evaluating the patients. In response to this need, a wearable bioimpedance analysis system was created in order to continuously quantify tissue impedance. This information can be used to indicate changes in volume and edema, and different properties can be studied depending upon the interrogation frequency. The system was tested both in a controlled environment, as well as in a realistic wear test, and found to be able to measure small changes in impedance in both instances. In order to be able to predict how to best modify the amount of pressure being delivered, more information about the material properties of compression hosiery was also needed. Currently, there is no international standard for measuring the pressure profile of medical compression hosiery, and many of the existing methods rely on taking pressure measurements at select points only. An independent method of correlation that verified the point pressure measurements from traditional testing devices with continuous data was proposed and tested. This information was used to predict the pressures that would be recorded on the limb using Laplace’s Law. Future work for this research involves studying the body’s response to fully characterized compression garments and pneumatic systems. Different pressures and fabric stiffness will be tested on both healthy individuals and those suffering from various venous and lymphatic diseases. This information will be used to improve the effectiveness of compression therapy by intelligently selecting the best properties to treat a given condition. © Copyright 2013 by Meghan Sarah Hegarty