EVALUATION of the peripheral circulation can be accomplished with the use of radioactive isotopes.1 Determination of a circulatory index depends on the rate of deposition of radioactive phosphorus (P32 as a phosphate ion, in either phosphoric acid [H3PO4] or sodium phosphate [Na2HPO4]) in the tissues of an extremity; the index is then derived from a semilogarithmic plotting of the minute by minute increase in radioactivity in a selected site in the extremity (usually the sole of the foot). For statistical purposes, the reciprocal of the rate of deposition is used to calculate this index, according to the equations
where C20 is the theoretic number of counts at the end of twenty minutes and C2 is the theoretic number of counts at the end of two minutes.
In a series of normal persons, the mean rate of deposition of radioactive phosphorus in the tissues was actually less than in
SCHAFFNER F, FRIEDELL MT, PICKETT WJ, HUMMON IF. RADIOACTIVE ISOTOPES IN THE STUDY OF PERIPHERAL VASCULAR DISEASE: II. Method of Evaluation of Various Forms of Treatment. Arch Intern Med (Chic). 1949;83(6):620–631. doi:10.1001/archinte.1949.00220350030003
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