Venous occlusion plethysmography using a load cell as the sensing element

An application of the load cell as a sensor in venous occlusion plethysmography, which is a well-established method for limb or digit blood-flow measurements is presented. In this method, the limb volume changes that follow venous occlusion are transferred into the volume change of a water pool. The hydrostatic pressure as well as the water surface level are measured and used for the calculation of the volume change. By using this method, the influence of water pressure on limb blood flow is avoided together with drift and leakage of the sensing element. The load cell has the advantage that it measures the weight of the displaced water volume, which simplifies the design principles of the plethysmography. The plethysmography is found to be sensitive, highly linear, and easy to handle. The results of using a manufactured water-displacement plethysmography to determine actual blood-flow measurements in forearms and fingers are presented