[Blood flow measurement with impedance plethysmography--experimental and clinical application in orthopaedic surgery]

Impedance plethysmography has been used clinically to measure the cardiac output. We have improved the apparatus of impedance plethysmography and applied it in the orthopaedic field. It is now possible to measure the blood flow in human fingers and in the extremities of rabbits. Experimentally, we measured the blood flow through the rabbit extremities with the measured values reflecting the ischemic condition. Clinically, we measured the blood flow through the fingers with arteriosclerosis obliterans with the measured values consistent with the angiographic findings. The measurement of blood flow in vascular injuries and attachment of fingers reflected the ischemic condition. By using the impedance plethysmography, we cannot obtain an absolute value because the measured value is affected by the type of electrode and the position of the electrode. We can nevertheless seek a relative value by comparing with the values at normal site. We can also identify any differences before and at the after change in blood flow. When the advantages and disadvantages of this method are better understood, this method will be of wide clinical use.