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

## TL;DR

This study compares two methods for measuring pulse wave arrival time and finds that bioimpedance can be promising for vascular health assessment.

## Contribution

The study introduces a novel comparison of bioimpedance and Doppler ultrasound for measuring pulse wave arrival time at multiple arterial sites.

## Key findings

- Bioimpedance shows lowest average error when estimating the midpoint of systolic flow.
- Significant discrepancies exist when comparing bioimpedance with Doppler ultrasound at flow start and peak.
- Agreement between methods varies depending on the arterial site measured.

## Abstract

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.