Doppler blood velocity waveforms and the relation to peripheral resistance in the brachial artery

The relationship between peripheral resistance and the Doppler blood velocity indices--pulsatility index (PI), A/B ratio, resistance index (RI), and the minimum velocity (Vmin)--was evaluated in the brachial arteries of five young women. All the indices showed a very good correlation with resistance (r greater than 94%); the regression line for both PI and A/B were linear, whereas the relationships between resistance and RI, and resistance and Vmin, were best described by a logarithmic and by power function, respectively. Although the women were carefully selected to be as alike as possible, there were significant differences in the individual slopes of the regression lines.