Man Ther. 2000 Feb; 5(1): 21-9.

Measurement of blood flow in the vertebral artery using colour duplex Doppler ultrasound: establishment of the reliability of selected parameters.

Johnson C, Grant R, Dansie B, Taylor J, Spyropolous P.

Division of Health Sciences, University of South Australia, Australia.

This study was designed to determine the reliability of the ultrasound testing procedure for evaluating vertebral artery blood flow, and to determine a robust testing protocol for future studies. Blood flow parameters were tested in ten asymptomatic subjects (mean age 33 years, standard deviation 6 years 8 months) using colour duplex Doppler imaging. Volume flow rate data at C5-6 demonstrated good reliability from a single measurement (Intraclass correlation coefficient [ICC]=0.81). Peak velocity sampled at C1-2 showed poor reliability if a single measurement was used (ICC=0.26) improving to fair levels with three measurements (ICC=0.77). Reliability for this parameter was good if five measurements were taken (ICC=0.83-0.84). Systolic/diastolic ratio measured at C5-6 showed poor reliability (ICC=0.57) if a single measurement was taken in the manner of Thiel et al. (1994). This improved to fair reliability (ICC=0.75) if the mean of three measurements was used. There was no further improvement if five measures were sampled. Sampling at C2-3 in the manner of Refshauge (1994) was found to be technically difficult and it was not possible to detect a Doppler shift in three of the ten subjects at this level. Reliability of peak velocity at C2-3 was found to be poor, regardless of whether single or multiple averaged measurements were taken (ICC=0.37-0.63). Mean (time averaged) velocity measurements at C2-3 showed poor reliability if a single measurement was taken (ICC=0.39), fair reliability if the first three measurements were averaged (ICC=0.73) and good to high reliability levels if five measurements were sampled (ICC=0.88-0.91). A review of the literature suggests that sampling volume flow rate at C5-6 and peak velocity at C1-2 represents a clinically meaningful combination of parameters to detect narrowing in the VA. The results of this current study indicate the desirability of taking a single measurement of volume flow rate at C5-6 and the mean of three measurements of peak velocity at C1-2, with the additional calculation of the standard error of measurement, if reliable results are to be achieved.Copyright 2000 Harcourt Publishers Ltd.