Comparison of Pulse Wave Arrival Times Measured by Bioimpedance Method and Doppler Ultrasound

Pulse wave velocity is a key indicator of vascular health. This study compared pulse wave arrival time (PWAT) measurements obtained by non-invasive bioimpedance with Doppler ultrasound, the gold standard, at multiple arterial sites. Simultaneous PWAT measurements were performed using bioimpedance (-dZMAX) and Doppler ultrasound (t1 – the beginning of the blood flow, t2 – the peak of the blood flow, t3 – the end of blood flow, t1-2 – the midpoint of the blood flow/center between t1 and t2) in healthy volunteers. The agreement between R-dZMAX and the Doppler-derived time points was assessed at various locations. The lowest average error (2.46 %) was observed between R-dZMAX and t1-2, the increase at the midpoint of the systolic flow. However, significant discrepancies were found when comparing R-dZMAX with t1, t2, and t3. The level of agreement also varied according to the arterial site. Bioimpedance shows promise for PWAT estimation, particularly when R-dZMAX is used to estimate t1-2 derived from Doppler ultrasound, representing the phase of maximal systolic flow acceleration. This suggests that the maximum rate of impedance change during rapid arterial filling provides a more accurate PWAT measurement. More research is warranted to refine bioimpedance techniques for a reliable vascular assessment under various conditions.