VasTrack: Anchoring Nocturnal Drift for Physics-Informed Blood Pressure Monitoring

摘要

Nocturnal blood pressure (BP) is a stronger predictor of cardiovascular risk than daytime measurements, yet its unobtrusive monitoring remains a formidable challenge. For practical convenience, existing cuffless methods typically rely on daytime calibration. However, through a retrospective analysis of a 1,328-patient ICU dataset, we reveal a pronounced day-night domain gap: vascular states undergo highly personalized, non-stationary drifts during sleep. Consequently, conventional daytime calibrations fail to capture nocturnal hemodynamic shifts, leading to substantial measurement errors. To address this, we propose VasTrack, a mmWave wearable system that bridges the day-night gap via a novel “Anchor-and-Track” architecture. Specifically, to establish a vascular anchor, we design a full-spectrum pressure scan method to extract the user's intrinsic vascular compliance during a standard cuff measurement, serving as a personalized biomechanical prior for nocturnal BP tracking. To track nocturnal vascular dynamics, our multi-granular tracking network transforms temporal signals into 2D phase-aligned physiological manifolds. It then employs biomechanical-based rhythmic gating to dynamically compensate for vascular tone variations using cardiopulmonary rhythms as proxies. Evaluation on 43 participants spanning healthy individuals and clinical patients over 340 hours shows that VasTrack achieves a mean error and standard deviation of 0.24±7.31 mmHg for systolic blood pressure and 0.10±4.87 mmHg for diastolic blood pressure. It also captures acute BP fluctuations exceeding 30 mmHg and a preliminary six-month evaluation suggests feasibility for extended monitoring periods, offering a potential pathway toward long-term cardiovascular health management.