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Plethysmographs, Lower Limb, Impedance

Definition : Plethysmographs designed for non-invasive measuring and recording of data and graphics (i.e., a plethysmogram) of the volume and variations in the volume of the lower limbs due to the presence and flow of blood in the peripheral vascular system of the legs. This is based on the measurement of the changes of the values of the impedance (i.e., impedance plethysmography also known as impedance phlebography). These devices typically consist of a unit that includes an impedance meter, controls, and a recorder of the changes of electrical impedance. Two or four electrodes are typically attached to the main unit with electrodes at the distal tips that are placed on the calf. Pressure cuffs placed around the thighs are inflated at a pressure enough to cut off venous flow but not arterial flow. The venous blood pressure rises until it equals the pressure under the cuff; when the cuff is released there is a rapid venous runoff and a prompt return to the resting blood volume. The impedance changes follow a characteristic pattern when a venous obstruction is present that is displayed and/or printed as a graphic. Lower-limb impedance plethysmographs are used to assess peripheral circulation and to assist in diagnosing diseases/disorders related to venous blood flow (e.g., peripheral vascular disease, thrombosis) in the extremities, including deep venous thrombosis as a cause of pulmonary thrombosis.

Entry Terms : "Impedance Plethysmographs" , "Plethysmographs, Impedance" , "Plethysmographs, Impedance, Lower Limb"

UMDC code : 34579

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