The Venous Reflux test is used to determine the competence of the superficial venous valves in the calves of the legs. This test is performed with a DC PPG sensor.
When performing Venous Reflux test, the patient is requested to sit upright with the legs not touching the ground. A Photo-plethysmograph (PPG) sensor is attached to the leg above the ankle in the region of the posterior tibial artery. When the DC signal reaches a steady state baseline, the patient is requested to perform multiple leg dorsiflexions which result in "pumping" of all of the venous blood. After the dorsiflexions the patient is requested to remain still, while the PPG DC signal returns back to the initial baseline. Optionally, the test can be repeated with a cuff wrapped around a segment on the leg (thigh, above/below knee) acting as a tourniquet.
The duration from the end of the dorsiflexions (maximal signal change) until the signal return to baseline (VRT, Venous Recovery Time) indicates the status of the valves. A slow recovery time indicates competent valves, while a fast VRT would indicate a suspicion of valvular incompetency.
Above is an example of a Venous Reflux specialty test performed
on a patient with Viasonix FALCON/Pro. The Venous Recovery Time (VRT)
is an index of venous valve patency. A fast recovery time such as
in this example, indicates a suspicion of valvular incompetency.