Office of Technology Transfer – University of Michigan

Method of Monitoring Edema

Technology #5107

UM File # 5107

Background
In 2006, 26% of deaths in the U.S were caused by heart disease, 112,000 people had liver disease, and 12% of the population had some form of kidney disease. The common trait among these prevalent diseases and many others is one main symptom – edema. Edema is the retention of fluid in biological tissue. By monitoring the stress and strain on tissue and the level of fluid buildup, physicians can determine the status of patient’s health as it relates to a specific disease. For example, excessive fluid buildup over a certain time period can be indicative of poor kidney function and suggest to a physician that dialysis is the appropriate treatment response. However there is no real-time diagnostic tool to monitor and quantify the characteristics of a patient’s tissue. The current method involves squeezing the area of interest and qualitatively describing the amount of fluid in the tissue and stress on that tissue. A quantitative diagnostic tool to monitor edema in patients with varying diseases would improve the quality of care provided and quality of life of a large population of patients.
Technology Description
Researchers at the University of Michigan have developed a device to monitor real-time changes of fluid levels in biological tissue. The technology is based on custom ultrasound techniques and bioimpedance measurements of tissue. The technology has been validated with human tissue and has demonstrated accurate results as compared to the current method of physician evaluations. The device can measure bioimpedance over a wide range of frequencies, 100Hz to 1MHz, and has the capability to measure conductivities over a strain range of 0-80%. Through unique algorithms applied to the ultrasound signals from the device, high spatial resolution is achievable to detect the elastic properties of subsurface structures. By combining signals from both the ultrasound and bioimpedance components, the researchers have achieved a unique solution for real-time quantitative monitoring of a symptom common across multiple diseases.
Applications • Fluid characterization of soft tissue • Edema monitor • Tissue stress and strain characteristics due to various diseases
Advantages • Technology quantifies a subjective test • Diagnosis can be conducted and understood by all types of medical staff • Diagnostic tool for a symptom common across multiple diseases • Real-time monitoring of patient symptoms, preventive tool to avoid serious complications from edema