Nonresistive Vessels - high diastolic component for organs that need constant perfusion, internal carotid, hepatic and renal arteries.
Resistive Vessels - litttle to reversed flow in diastole for organs that do not need constant perfusion, external carotid, iliac and brachial arteries.
Resistive Index - compares peak systole to minimum diastole (see diagram).
Hepatic artery stenosis - parvus trades waveform or velocity > 200 cm/s
Portal vein stenosis - narrowing < 2.5 cm or velocity > 150 cm/s at anastomoses
Hepatic vein stenosis - flattening of the normal triphasic waveform