This test measures the effect of the venous obstruction following Deep Venous Thrombosis (DVT)
Two blood pressure cuffs are placed on the lower leg as shown in the picture. The one at the ankle is connected to the machine as a sensor cuff. The one in the calf is the occluder cuff.
The distal cuff is primed and the veins emptied by inflating the cuff to 40mm of Hg. Pressure is reduced to 15mm of Hg and the sensor cuff is connected to the machine.
The proximal occluder cuff is inflated to 60mm of Hg and kept in place for 90 secs. The pressure is released at 91 secs and the drop in pressure in the sensor cuff due to blood draining out of the leg is recorded by the machine.
This measures the maximum venous outflow from the leg veins and can be used to estimate the performance of the leg veins after they are blocked by DVT.