Variation and variability in carotid-femoral pulse wave velocity

Abstract

Background: There are very limited data on the day-to-day variability and virtually no data on within-subject measurement variation of carotid-femoral pulse wave velocity (c-fPWV). Therefore, we conducted this study in healthy volunteers to measure both day-to-day variability and day-to-day within-subject measurement variation. Methods: C-fPWV values were measured in ten adult volunteers resting in supine position for at least 10 min using the SphygmoCor system {AtCor Medical Pty Ltd, West Ryde (Sydney), Australia} on two consecutive days. The data were captured for ten seconds from the right carotid and then right femoral arteries. Results: The average c-fPWV readings and the between-subject standard deviations (SD) was 7.43 ± 1.9 m/sec for day 1 and 6.93 ± 1.36 m/sec for day 2, which are statistically insignificant with a paired t-test (p = 0.197). However, the Pearson’s correlation showed a coefficient of 0.8 (p value = 0.005). There was a statistically significant difference (p = 0.01) in the within-subject c-fPWV measurement variation, calculated as the mean of the SD comparing day 1 (0.74 ± 0.09 m/sec) and day 2 (0.53 ± 0.07 m/sec). The average MAP was 93.9 ± 2.3 mmHg for day 1 and 90.5 ± 1.7 mmHg for day 2, which were not statistically different (p = 0.1). Conclusions: The c-fPWV readings were highly reproducible between the two days and the measurement variation in the within-subject c-fPWV is significantly lower on the second day. Our study highlights that day-to-day variability and within-subject measurement variation of c-fPWV, although present is not significant enough to influence the assessment of outcome measures of interventions that alter the arterial stiffness.

Keywords

• Pulse wave velocity
• Variability
• Variation