Clinical Measurement of Circulation Time. A Comparison of Magnesium Sulphate and Evans Blue Dye in Normal Subjects

¹ From the Cardiopulmonary Laboratory of the Department of Internal Medicine, University of Texas Southwestern Medical School, Dallas, Texas

Simultaneous injections of T-1824 dye and MgSO₄ were done 71 times in 39 normal subjects, the injection site being the antecubital vein. The MgSO₄ time (CT) and the appearance and peak times (AT and PT) of the dye curves were compared. AT was 14.7 ± 5.0 sec., CT 17.9 ± 5.5 sec. and PT 25.3 ± 8.2 sec., CT always occurring after AT and before PT. Variance analysis on repeated trials showed that all three time intervals are highly repeatable but that there is large interindividual variation. Much of the latter may be attributable to age and sex differences. The results suggest that the time intervals are shorter in women than in men and that they tend to be prolonged in both sexes with advancing age.