Peripheral vascular Doppler measurements are normally performed using CW (Continuous Wave) Doppler probes.
Different Probe frequencies are used depending on the target vessels: 4 or 8 MHz are used for larger and deeper vessels such as the Carotid, Femoral or Popliteal arteries, and higher 8 or 10 MHz are used for the smaller and shallower vessels such as the Dorsalis Pedis or Tibial arteries.
The main objective is to qualitatively examine the waveform shapes: a normal peripheral artery (not in the carotids) will show 3 phases during a cardiac cycle, a prominent early systolic forward flow, a late systolic reverse flow, followed by a small component of forward flow again. This signifies a healthy elastic artery. As the vessel becomes less elastic (for example due to diabetes), the third and/or second phase will disappear.
In addition, significantly high velocities may indicate the presence of a stenosis or some other obstruction to the blood flow.
Below is an example of a CW Doppler waveform measured using Viasonix FALCON/Pro.