Reproducibility of Doppler blood flow velocity waveform measurements: study on variability within and between day and during haemodynamic intervention in normal subjects.

Reproducibility of Doppler blood velocity waveform measurements in external and internal carotid, middle cerebral, and brachial arteries and ascending aorta was determined in 8 normal male volunteers twice daily on three occasions each separated by two or more weeks. Measurements were made in supine and standing positions at rest and after taking glyceryl trinitrate and in the supine position after performing a standardized exercise test. The Doppler blood flow waveform indices showed a between days coefficient of variation of less than 15% both for baseline measurements and during haemodynamic change induced by exercise or glyceryl trinitrate. We conclude that Doppler blood velocity waveform measurement in different vascular beds is reproducible at baseline and when the cardiovascular system is interrupted pharmacologically or physiologically.