However, this invasive technique is not without its hazards. The technique also has limitations. Most patients undergoing evaluation for suspected ischemia as a contributor to poor wound healing are first evaluated by noninvasive techniques. In the 1960s, plethysmographic techniques for arterial assessment became available. Pulse volume recordings are based on air plethysmography using standard blood pressure cuffs at the thigh, calf, and ankle.
Sensitive transducers detect small increases in pressure within the cuffs.
These increases are caused by a slight increase in the volume of the extremity during systole. The resulting recording closely resembles arterial pressure wave tracings. Diagnosis of occlusive disease is based on the qualitative interpretation of the pulse volume waveform. As with the arterial pressure wave, a normal pulse volume tracing has a brisk upstroke and a dicrotic notch. With occlusive disease, the pulse volume waveform takes on a rounded and flattened appearance.