Simplified Diagnostic Criteria for Venous Insufficiency

These criteria may be applied to any plethysmograph. The only restriction is that the volume measurements be taken accurately. In order to simplify the diagnostic criteria for venous phlethysmographic studies we have focused on three parameters. The first is Venous Refilling Time (VRT). In patients with significant venous insufficiency, venous refilling develops secondary to venous reflux and clearly reduces the time necessary to complete the process. If VRT is >20 seconds, the limb is not demonstrating significant reflux. If VRT is <20 seconds, the diagnosis of venous reflux should be considered.17 This should be taken in light of the finding that subjects with VRT <10 seconds very often present with venous ulceration.18 The second parameter is Ejection Fraction (EF). In patients with deep or superficial venous insufficiency or deep venous thrombosis, EF is reduced. If EF is >60% the limb is presenting with normal venous hemodynamics. For superficial venous insufficiency the average EF is 50%. Average EF is reduced to 40% in subjects with deep venous insufficiency and 35% in deep venous obstruction. The third measurement is Residual Volume Fraction (RVF). If RVF is elevated, the limb is demonstrating venous ambulatory hypertension. A normal value for RVF is <35%. Subjects with RVF >35% should be evaluated further for venous disease.17

FIGURE 5.2 This figure illustrates parameter definitions and maneuvers used generically in plethysmography studies for venous insufficiency.
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