Non-Invasive Monitoring of Peripheral Artery Behavior via Wearable Sensors

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

The goal of this project is to monitor vascular tone and peripheral vascular resistance of human arteries using non-invasive, wearable sensors. Vascular tone refers to the relative dilation or constriction of arteries, while peripheral vascular resistance refers to the resistance felt by the heart as it attempts to pump blood through the arterial system outside the body's core. At present, there are no effective means of monitoring these effects outside of the hospital or other critical care settings. Nonetheless, changes in vascular tone and peripheral vascular resistance are known to be key indicators of the progression of various forms of shock, dangerous blood pressure changes during dialysis, and post-surgical complications, among other potentially life-critical medical conditions. This research will provide a means to quickly detect changes in the condition of the peripheral arteries, allowing for more timely intervention and more accurate assessment of treatment effectiveness. The project also includes outreach at the secondary education level on topics such as electronic circuits and fluid behavior. This research will include the creation of a dynamic model capturing the most significant contributions of sensor, tissue, and local arterial fluid dynamics to the response of an externally worn compliant piezoelectric pressure sensor and associated pulse plethysmograph. Advanced parameter identification techniques and viscoelastic hysteresis inversion methods will be used to estimate properties of the underlying artery, and correlate trends in sensor response with changes in arterial diameter. The final objective will be to track changes in relative peripheral artery radius without reliance on wearable sensor calibration to invasive cardiovascular measurements. Results will be validated by comparing non-invasive to invasive vascular resistance estimates in experiments with swine, and comparing peripheral blood pressure and arterial radius estimates from the created sensors to measurements from larger clinical systems such as blood pressure finger cuffs and ultrasound. The intellectual significance of the work is expected to include insight into key model features describing dynamic arterial behavior at the far periphery of the arterial system, novel techniques for identifying parameters in nonlinear, polynomial based models, and information on variability in peripheral vascular response across individuals undergoing cardiovascular stresses.