Beat-to-Beat Blood Pressure Monitoring During Sleep

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Project Summary The project aims to advance a prototype device for continuous non-invasive blood pressure (BP) monitoring into a versatile platform technology for beat-to-beat BP monitoring during sleep. Nocturnal BP has been shown to be a stronger predictor of cardiovascular events than daytime BP. However, the traditional method for monitoring BP during sleep is with ambulatory BP monitoring (ABPM), which is uncomfortable to wear, disturbs sleep, and only provides intermittent measurements. A platform technology that accurately and comfortably monitors beat-to-beat BP and BP variability during sleep is needed to better characterize the complex relationship between sleep disorders and cardiovascular health. For example, BP surges associated with apneic and hypopneic events in obstructive sleep apnea occur over a period of seconds and go undetected by ABPM monitors. Quantification of the effects that sleep disorders have on hemodynamic function can potentially lead to new biomarkers, improved diagnostics, and personalized treatment and management. Prior attempts at cuffless non-invasive technologies fall into several categories (finger volume clamp, pulse transit time, pulse decomposition analysis, tonometry, and combinations thereof), but all have experienced distinct limitations in accuracy, usability, or cost, thereby preventing widespread clinical adoption. Our technology overcomes these limitations. First, our technology achieves high accuracy due to the soft elastomeric properties that allow conformal contact of our sensors to the skin’s surface, detecting high resolution signals and dynamic fluctuations in the arterial waveform. Second, our devices are low-cost and can be fabricated using roll-to-roll processes that do not require photolithography or clean rooms, and have low power consumption that can be supported with common electrical components. Finally, our technology ensures usability through a low-profile system that is comfortable to wear over long periods, such as during sleep. In this project, we will develop and validate the beat-to-beat BP monitor to be used during sleep. We will develop the hardware, firmware, and algorithms necessary to maintain the accuracy of the monitored blood pressure throughout the sleep cycle while correcting for motion and holding the calibration. We will validate our prototype through clinical testing and correlate detected BP events to sleep study parameters. This will be the first of its kind technology that not only will improve how nocturnal BP is monitored, diagnosed, and managed to improve cardiovascular health, but also serve as a platform to enable new directions in clinical research and understanding of cardiovascular function in sleep.