[Impedance plethysmography. Comparison of sensibility and specificity in recent deep venous thromboses of the lower limbs (author's transl)].J Mal Vasc. 1982; 7(1):81-4.JM
Although phlebocavography remains the ideal technique of diagnosis and reference, impedance plethysmography is a simple non-invasive technique which records variations in impedance of a limb segment through which a H.F. current is injected and with distal venous occlusion. Variations in impedance go hand in hand with variations in volume. It is thereby possible to demonstrate any obstacle to venous flow, either of an obstructive type if there is thrombosis of the major proximal collecting vessels, or of a restrictive type if there is thrombosis in the leg. The technical conditions of the examination and measurement are here fundamental and hence the value of a specially designed apparatus and multi-input abacuses in order to determine indices of emptying, filling and filling rate with simultaneous examination of both limbs. The method is selective for the diagnosis of recent deep venous thrombosis: 83% correlation between impedance and phlebography, 16% false positive and 1% false negative, reliability at the level of the thigh in 98% of cases, lesser reliability in the calf though the score can be improved and touch 94% by comparison of the two legs (Franco). Wuydin has reported a specificity of 85% and a sensitivity of 96%. This reliable, specific, objective, atraumatic, inexpensive and easily repeatable method may be used to give an overall quantification of a proximal obstructive thrombosis and define the existence of a thrombosis in the calf.