Interpretation of Venous Occlusion Plethysmography Using a Nonlinear Model

F. A. Anderson, Jr., University of Massachusetts Medical School Worcester
William W. Durgin, Worcester Polytechnic Institute
H. Brownell Wheeler, University of Massachusetts Medical School Worcester

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http://dx.doi.org/10.1007/BF02442692.

NOTE: At the time of publication, the author William W. Durgin was associated with Worcester Polytechnic Institute. Currently, September 2008, he is Provost and Vice President of Academic Affairs at California Polytechnic State University - San Luis Obispo.

Abstract

Venous occlusion plethysmography (VOP) is a noninvasive technique widely employed for the detection of deep-vein thrombosis. Previous reports that VOP outflow curves are closely fit by a first-order exponential suggest that venous compliance and resistance are nearly constant. Typically, however, the venous compliance function has a sigmoid shape; in addition, the resistance in a collapsing tube must increase. This paradox was resolved by the surprising finding that for realistic nonlinear compliance and resistance these nonlinearities cancel, producing a quasilinear venous outflow that approximates a simple exponential.