Noninvasive Monitor of Vascular Volume Fluid Shifts

Accurate intravascular volume assessment improves the detection of hemorrhage and hypovolemia and facilitates decision-making relative to resuscitation, surgery and selection of higher level of medical care. Non-invasive assessment techniques are particularly important in the field. Current approaches and devices do not have broad utility and availability. The phonocardiogram, acquired and interpreted from inexpensive worn transducers, provides insight into the systolic component of the cardiac cycle and, thereby, trends in intravascular volume. The team proposes to evaluate a phonocardiographic systolic index against accepted measurements of intravascular volume in healthy volunteers exposed to lower body negative pressure and patients undergoing hemodialysis. Measurements of various analytes (phonocardiographic index, bioimpedance, continuous hematocrit, vital signs, etc..) taken during testing provide both validation of the approach and a controlled data set to build software algorithms to identify blood volume changes. Algorithm development using linear discriminant analysis or neural networks will use the acquired data separated into training and validation data for algorithm evaluation. Hardware development will focus on robust and reliable transducer design and a wearable system. During the effort, the team will validate the approach and demonstrate a breadboard prototype. A follow-on effort will continue system design and testing and plan for regulatory clearance.