Semi-quantitative photoplethysmography in the diagnosis of lower extremity venous insufficiency

A new standardization device has permitted calibration of the Photopulse Adaptor, thus, making venous photoplethysmography (PPG) a more accurate, semiquantitative technique. Using this device, we studied 10 normal volunteers and 151 extremities in 69 symptomatic patients We also developed a formula for calculating the slope of the venous recovery curve which took into consideration the degree of venous emptying as well as the duration of venous recovery. The PPG was "abnormal" if there was no measurable venous emptying despite effective calf contraction or if the calculated venous recovery rate (VRR) exceeded 2.0 mm/sec. VRR clearly separated normal extremities (1.28 mm/sec) from those in which venous reflux was present (3.34 mm/sec). If we had relied on measurement of venous recovery time (VRT) alone, 30% of hour normal volunteers and 52% of our symptomatic patients would have been misdiagnosed. We feel that these modifications have made PPG a more accurate technique less subject to the vagaries of arterial inflow, and thereby more valuable to the vascular surgeon in elucidating venous pathophysiology and following the results of his therapy.