A new statistical phase offset technique for the calculation of in vivo pulse wave velocity

Abstract

Pulmonary blood pressure measurements were collected from 5 clinically healthy horses. Pulse wave velocity (PWV) values were calculated using five techniques, four existing (minimum foot-to-foot, F2F; maximum 1st derivative, M1D; maximum 2nd derivative, M2D; and cross correlation, CC) and the new statistical phase offset technique (SPO). The SPO technique was also applied to systolic (SPO-S), diastolic (SPO-D) and full wave (SPO-FW) data. The reliability of each analysis technique was determined using the consistency of calculated PWV values. Using the original data sets, of variable length (2 ≤ n ≤ 5) due to the effects of respiration, the SPO technique gave the most consistent results (SPO-D, 2.31 ± 0.31 m/s; SPO-S, 2.18 ± 0.30 m/s; and SPO-FW, 2.45 ± 0.35 m/s). The CC technique, was complex to implement but also gave considerable consistency (CC, 2.64 ± 0.36 m/s). The family of techniques utilizing only a single point of comparison all provided less consistent results (M1D, 2.82 ± 0.56 m/s; M2D, 2.90 ± 1.09 m/s; and F2F, 3.42 ± 1.67 m/s). Consistent length data sets were then created (n = 5) and analyzed. Results were: SPO-S, 2.74 ± 0.34 m/s; SPO-D, 2.67 ± 0.40 m/s; SPO-FW, 2.78 ± 0.36 m/s; F2F, 2.53 ± 0.52 m/s; M1D, 3.39 ± 1.28 m/s; M2D, 3.20 ± 1.90 m/s; and CC, 3.23 ± 0.40 m/s. Comparison of the results indicate that of the techniques included in this study, the new SPO technique provided the greatest reliability for determining PWV values. It was also intuitive to implement.

Keywords

• Pulmonary artery
• Pulse wave velocity
• In vivo
• Analysis techniques
• Equine
• Arterial stiffness