This study presents a custom-designed device employing two photoplethysmography (PPG) sensors to measure Pulse Transit Time (PTT) and Velocity of Pulse (VoP) at different anatomical sites on the hand. Sensor placements included the fingertip, proximal phalanx, and wrist, with inter-sensor distances as short as 53 mm. The investigation involved three setups with the hand positioned at heart level, raised, returned to rest, and lowered to induce hydrostatic pressure changes. Signal processing included identification of five characteristic fiducial points on each PPG waveform: systolic peak, diastolic minimum, maximum first derivative, maximum second derivative, and derivative-intercept point (intersection between diastolic baseline and systolic upslope tangent). Results for one subject demonstrated stable beat-by-beat PTT (3 ± 2 ms) and VoP (15 ± 3 m/s) with expected physiological changes during the hand maneuvers for PTT (range: 2–10 ms) and VoP (range: 6–16 m/s). The derivative-intercept method provided the most consistent PTT measurements, especially for the shortest distance where resolution was critical. The findings confirm the feasibility of measuring dynamic arterial properties non-invasively with wearable PPG sensors with minimal inter-sensor distance and highlight the importance of signal processing methods.

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Device for Measuring Pulse Transit Time and Velocity of Pulse Using PPG at Multiple Hand Sites: Proof of Concept

  • Leonardo Casal,
  • Leandro Nicolás Camigliano

摘要

This study presents a custom-designed device employing two photoplethysmography (PPG) sensors to measure Pulse Transit Time (PTT) and Velocity of Pulse (VoP) at different anatomical sites on the hand. Sensor placements included the fingertip, proximal phalanx, and wrist, with inter-sensor distances as short as 53 mm. The investigation involved three setups with the hand positioned at heart level, raised, returned to rest, and lowered to induce hydrostatic pressure changes. Signal processing included identification of five characteristic fiducial points on each PPG waveform: systolic peak, diastolic minimum, maximum first derivative, maximum second derivative, and derivative-intercept point (intersection between diastolic baseline and systolic upslope tangent). Results for one subject demonstrated stable beat-by-beat PTT (3 ± 2 ms) and VoP (15 ± 3 m/s) with expected physiological changes during the hand maneuvers for PTT (range: 2–10 ms) and VoP (range: 6–16 m/s). The derivative-intercept method provided the most consistent PTT measurements, especially for the shortest distance where resolution was critical. The findings confirm the feasibility of measuring dynamic arterial properties non-invasively with wearable PPG sensors with minimal inter-sensor distance and highlight the importance of signal processing methods.