Initial study on pulse wave velocity acquired from one hand using two synchronized wireless reflectance pulse...

Area of Science:

• Biomedical Engineering
• Cardiovascular Physiology
• Medical Instrumentation

Background:

• Pulse wave velocity (PWV) is a key indicator of arterial elasticity and cardiovascular health.
• Accurate PWV measurement is crucial for non-invasive assessment of vascular function.
• Existing methods for PWV assessment can be complex or require specialized equipment.

Purpose of the Study:

• To present a novel, accessible method for measuring PWV using readily available wireless pulse oximeters.
• To evaluate the feasibility of calculating PWV from photoplethysmograms (PPGs) acquired from the wrist and fingertip.
• To compare PWV measurements derived from different waveform features (foot, inflection point, peak).

Main Methods:

• Two synchronized wireless pulse oximeters were placed on the wrist and fingertip of the same hand.
• A custom MATLAB interface was developed to acquire and time-align the photoplethysmogram (PPG) signals.
• PWV was calculated by measuring the time difference between PPG features (foot, inflection point, peak) at the two measurement sites.

Main Results:

• PWV values calculated at the inflection point were consistently higher than those calculated at the waveform foot.
• This finding aligns with the physiological understanding that PWV increases with intra-arterial pressure.
• PWV calculations using PPG peaks were complicated by the influence of pulse wave reflections, introducing variable time delays.

Conclusions:

• Synchronized wireless pulse oximeters offer a practical approach for PWV estimation.
• PWV measurement at the inflection point provides a potentially more sensitive indicator of arterial stiffness compared to the foot.
• Care must be taken when interpreting PWV derived from PPG peaks due to the confounding effects of wave reflections.