Pulse volume and changes in perfusion flow pertaining to a segment such as the arm or leg may easily be followed by radiofrequency impedance plethysmography. Volume varies directly with electrical conductance and inversely as the resistive electrical impedance of the conductor.
The method is sketched briefly in Figure 1 and defined in its legend. Thus, we propose by this type of study (1) to measure pulse volume and blood flow on the basis of electrical properties of tissue and blood; (2) to calculate pulse volume and blood flow from such electrical data, and (3) to apply the electrical impedance method to physiological and clinical flow problems.
Electrical impedance to radiofrequency current through tissues is capacitative as well as resistive in nature. The former is less than three per cent of the latter in value and may be regarded as insignificant when volume pulses are derived from the limbs. A
NYBOER J. Regional Pulse Volume and Perfusion Flow Measurement: Electrical Impedance Plethysmography. AMA Arch Intern Med. 1960;105(2):264–276. doi:10.1001/archinte.1960.00270140086010
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