MICROWAVE VOLUMETRY OF EXTREMITIES - AN A LTERNATIVE MEASURING TECHNIQUE FOR THE REACTION-FREE VEIN OCCLUSION TEST

Venous occlusion plethysmography is a well-established noninvasive pro cedure for the investigation of venous outflow disorders. Various diff erent sensor systems are available for the purpose, e.g. photoplethysm ography, strain-gauge plethysmography and impedance plethysmography. T he technique of microwave volumetry described in this paper is based o n the interaction of the electromagnetic fields within the loss medium , tissue, and uses an air-filled resonant cavity as a sensor. As in th e case of a microwave oven, this is excited by a high-frequency genera tor, but involves the use of far less power, As the volume of the meas ured objects (foot, arm) increases, the losses in the resonator also i ncrease and can be analysed in a computer. The results can be represen ted in the form of a classical venous occlusion curve.