Plethysmographic Measurement of Venous Flow Resistance and Venous Capacity in Humans with Deep Venous Thrombosis

Abstract

Venous flow resistance ( Rv) and venous capacity ( C10) 2 was studied in humans with deep vein thrombosis (DVT) using strain-gauge plethysmography. Rv was found to be significantly higher than normal while C10 was significantly lower, notably in measurements at the calf-level. In a follow-up study it was demonstrated that Rv usually decreased sharply within the first few months after the acute event while C10 increased. Rv usually returned to (high-level) non-thrombotic values, while C10 returned to (low-level) normal values. The sensitivity of Rv when used as a diagnostic criterion for recent proximal DVT was assessed retrospectively. For proximal DVT, the sensitivity of Rv-prox (measured with strain-gauges around the calf) was 95% (95% confidence limits 83–99%) and for distal DVT, the sensitivity of Rv-dist (measured with strain-gauges around the foot) was 36% (95% confidence limits 13–65%). The specificity for Rv was 100% (95% confidence limits Rv-prox: 90–100%; Rv-dist: 59–100%). Influencing factors for sensitivity and specifity are discussed.