Noninvasive determination of venomuscular efficiency

The purpose of this study was to express quantitatively and noninvasively the efficiency of the venomuscular pump by using photoplethysmography (PPG). METHODS AND PATIENTS PPG was used to record volume changes induced by dorsiflexion resulting in exercise displacement volume (EDV) and subsequently by passive limb elevation resulting in tilt displacement volume (TDV). Dividing EDV by TDV yields efficiency of the venomuscular pump. Twenty-four control subjects, 21 patients with venous valvular insufficiency (VVI), and 10 additional patients with both VVI and deep venous thrombosis (DVT) were studied. Data for one leg in each subject are reported. Though calculation of efficiency does not require calibrated or quantitative PPG, in this case because we used calibrated PPG we recorded the respective values for EDV after dorsiflexion and TDV after passive leg elevation.

EDV decreased from a normal value of 3.15% optical reflectance (% OR) to 1.68% OR in patients with VVI and 1.09% OR in patients with VVI plus DVT. TDV response was quite opposite, increasing from 6.55% OR in the control group to 10.30% OR in the VVI group and 16.66% OR in the VVI plus DVT group. Finally, efficiency decreased from the average normal value of 50.5% to 24.4% in the VVI group and 8.8% in the VVI plus DVT group.

Dividing EDV by TDV, venomuscular efficiency can be determined and may be considered a useful index of venous hemodynamics.