Absolute flow measurements using pulsed Doppler US. Work in progress.

Quantitative flow measurements were assessed in both laboratory and canine models using pulsed Doppler ultrasonography (US). A hydrodynamic model consisting of a Harvard pulsatile pump, a water bath, tubing, and a variable resistance reservoir was used to obtain absolute volumetric flow measurements. Parameters including angle of incidence, size of tubing, stroke volume, stroke rate, sample volume, and transducer frequency were changed independently. The effect of varying these parameters on the determination of absolute flow was analyzed. Absolute flow measurements using duplex US were performed in the canine aorta and femoral artery with reference to the electromagnetic flow probe. These data are presented, along with methods to reduce error in flow measurements that can be directly applied to quantitative estimates of blood flow in humans.