A Novel Sensor to Track Transient Blood Pressure Changes During Sleep

Abstract Introduction Sleep disordered breathing is associated with poor cardiovascular outcomes. However, measurements like blood pressure (BP) using ambulatory BP monitoring (ABPM) are not commonly utilized in sleep assessments because of its difficulty, discomfort, and interference with sleep. ABPM is intermittent and lacks the temporal resolution to identify rapid BP changes. A novel, wearable sensor that captures beat-by-beat BP changes, has been validated against the arterial line. We sought to adapt this device to measure BP changes continuously during sleep. Methods We developed a technique that measures transient BP changes during sleep using the novel sensor. The calibration-free technique measures BP changes based on evaluating the sympathetic and vascular tones during steady state breathing and comparing those with that of respiratory events like apneas, hypopneas, and arousals. We developed a machine learning classifier to automatically detect steady state breathing and validated this approach of measuring transient BP changes within twenty-seven patients’ arterial line. For each patient, we compared a total of 50 points that were 30 seconds apart exhibiting at least 15 mmHg systolic or 10 mmHg diastolic change for each point. Results In twenty-seven patients undergoing surgery, the 50th percentile and 85th percentile of error rate between the arterial line and our approach for estimating BP change was 23.8 and 42, respectively, meeting ISO 81060-3 (< 25% and < 50% error for the 50th and 85th percentiles, respectively). Using our calibration-free technique, we measured transient BP changes induced by sleep events in twenty-eight patients undergoing polysomnography. We observed BP surges in response to events such as EEG arousals (up to 72 mmHg) and obstructive hypopnea events (up to 84.6 mmHg). Conclusion This method leveraging a novel, flexible, and sleep-compatible beat-to-beat BP monitoring device accurately and non-invasively tracks transient BP changes during sleep. Applications of this hemodynamic monitoring include the ability to provide stratification of severity of sleep disordered breathing (SDB) events. Additionally, this device can be worn comfortably throughout the night, enabling real-time monitoring of cardiovascular disorders during sleep. Lastly, this device could allow for titration of SDB therapies using real time BP information and objective evaluation of treatment efficacy. Support (if any)