A three-parameter model for the venous pressure volume relation of the lower leg

Abstract

Objectives: To derive a three-parameter model for the curvilinear venous pressure volume relation of the lower leg, and to test its consistency. Methods: A model with venous pressure at rest (P0, mmHg), the venous compliance at P0 (C0, %/mmHg) and the venous stiffness constant ( k, 1/%) was derived. With strain gauge plethysmography the venous pressure volume relations of both legs at the mid-calf and at the ankle region were measured and fitted in 120 consecutive patients in the supine position. Results: No difference was observed between the mid-calf P0 (right 8.1 ± 2.2, left 8.4 ± 2.1) nor between ankle P0 (right 10.1 ± 2.3, left 10.0 ± 2.1). A significant pressure difference of -1.8 mmHg was found between mid-calf and ankle. Leg side differences were not observed for either C0 at the ankle (right 0.36 ± 0.29, left 0.49 ± 0.85) or in the mid-calf region (right 0.54 ± 1.1, left 0.46 ± 1.0). Differences for the leg region but not for the leg side were found for k (mid-calf right 0.54 ± 0.38, left 0.64 ± 0.52, ankle right 1.32 ± 0.66 and left 1.33 ± 0.65). Conclusion: The model demonstrated provided a proper description of the curvilinear venous pressure volume relation.