Single-source PPG-based local pulse wave velocity measurement: a potential cuffless blood pressure estimation technique.

OBJECTIVE

A novel photoplethysmograph probe employing dual photodiodes excited using a single infrared light source was developed for local pulse wave velocity (PWV) measurement. The potential use of the proposed system in cuffless blood pressure (BP) techniques was demonstrated.

APPROACH

Initial validation measurements were performed on a phantom using a reference method. Further, an in vivo study was carried out in 35 volunteers (age  =  28  ±  4.5 years). The carotid local PWV, carotid to finger pulse transit time (PTT) and pulse arrival time at the carotid artery (PAT) were simultaneously measured. Beat-by-beat variation of the local PWV due to BP changes was studied during post-exercise relaxation. The cuffless BP estimation accuracy of local PWV, PAT, and PTT was investigated based on inter- and intra-subject models with best-case calibration.

MAIN RESULTS

The accuracy of the proposed system, hardware inter-channel delay (<0.1 ms), repeatability (beat-to-beat variation  =  4.15%-11.38%) and reproducibility of measurement (r  =  0.96) were examined. For the phantom experiment, the measured PWV values did not differ by more than 0.74 m s compared to the reference PWV. Better correlation was observed between brachial BP parameters versus local PWV (r  =  0.74-0.78) compared to PTT (|r|  =  0.62-0.67) and PAT (|r|  =  0.52-0.68). Cuffless BP estimation using local PWV was better than PTT and PAT with population-specific models. More accurate estimates of arterial BP levels were achieved using local PWV via subject-specific models (root-mean-square error  ⩽2.61 mmHg).

SIGNIFICANCE

A reliable system for cuffless BP measurement and local estimation of arterial wall properties.