DRT4-PRM2 has an in-built pump to automatically inflate a pressure cuff to the target supra-systolic pressure. Automatic control enables linear cuff deflation at the user-selected rate. During deflation, laser Doppler monitoring is used to detect the onset of reperfusion distal to the cuff. This point is used to find the systolic pressure of a limb or digit.

A similar technique is applied as for limb pressure assessment. A low profile probe is used between the cuff and the skin to assess cuff pressure at which blood flow returns to
the skin.

DRT4-PRM2 is used to inflate the cuff to a target pressure below diastolic - this target pressure is typically 50mmHg. The oscillatory pressure fluctuations within the cuff are monitored at this pressure. These fluctuations carry pulse waveform information including the amplitude, frequency and shape.

The PORH test is used to assess microvascular status in patients with lower limb disease. Laser Doppler is used to follow the microvascular hyperaemic response after release of occlusion. The important parameters derived (by PC) are time to first recovery, time to maximum hyperaemia, maximum hyperaemia and the area under the response curve.