Abstract
Of noninvasive venous function tests two are well known: photoplethysmography (PPG) and strain-gauge plethysmography (SGP). Their effectiveness in assessment of insufficiency in candidates for venous reconstructive surgery however, is debated. The two methods were studied in these patients, and compared to invasive measurements. Nineteen limbs of patients with deep venous disease, and seven limbs of healthly volunteers were evaluated. Measurements were taken in standing, as well as in the more patient-compliant sitting position. Venous reflux time (RT) proved to be significantly different in patients vs. controls. Differences between expelled volume of controls and patients were only significant for invasive measurements in any position (p < 0.01), but not with one of the noninvasive methods.
RT invasively and non-invasively measured were well correlated in both positions with PPG (R = 0.83 – 0.86), and with SGP (R = 0.85 — 0.92). The percentage residual pressure however, showed in both methods a poor correlation of < 0.50.
The studied noninvasive techniques offer no alternative to invasive measurements in the evaluation of patients with deep venous disease, considered for venous reconstructive surgery.
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