Advanced Chronic Venous Insufficiency is Associated with Increased Calf Muscle Deoxygenation

Schematic diagram of the instrument.

NIRS examination. Calf venous blood filling index (FI-HHb) was calculated by dividing 90% of the venous blood volume (HHbV90) by the time taken to fill 90% of the venous volume (HHbFT90). The patient was then asked to perform one tiptoe movement with weight-bearing on both legs, which produced an ejected volume (HHbEV), and then to return to the initial position, the changes in HHb being observed. The calf venous ejection index (EI-HHb) was calculated as HHbEI = HHbEV/HHbV. After a new plateau had been reached, the patient was asked to perform 10 tiptoe movements, allowing venous expulsion (HHbE) and subsequent retention (HHbR). The venous retention index (RI-HHb) was determined as HHbRI = HHbR/HHbE. a, Rest: b, Standing: c, One tiptoe: d, Ten tiptoes: e, Rest.

Correlation between ultrasound-derived parameters and NIRS-derived parameters. A, PRV in POPV had the strongest correlation with NIRS-derived retention index (RI−HHb) (r = 0.78, P < 0.0001). B, PRV in SFJ had a relative good correlation with NIRS-derived retention index (RI−HHb) (r = 0.42, P = 0.002). C, PRV in GV had a relatively good correlation with NIRS-derived ejection index (EI−HHb) (r = 0.72, P = 0.029).

Ability of NIRS-derived HHb to discriminate clinical severity. A, An optimal cut-off point of 0.2 for filling index (FI+HHb) had the highest power to discriminate between early and advanced CVI with a sensitivity of 79.6% and a specificity of 81.9% (area under the ROC curve 0.84, 95% CI 0.78–0.89, P = 0.0001). B, Clinical discrimination performance was decreased using a single cut-off point of 2.9 for retention index (RI−HHb) as compared to that of filling index (FI+HHb) (area under the ROC curve 0.71, 95% CI 0.64–0.78, P = 0.0001).