Comparison of Cr51 RBC, I131-tagged albumin, I131-tagged rose bengal and I131-tagged Diodrast for cardiac output

Tagged rose bengal and tagged Diodrast were each compared with tagged red blood cells as indicators of central flow rate and central volume in the dog. Tagged rose bengal was unsuitable because it stained the plastic tubing used to convey the blood sample through the well crystal. The average cardiac output by tagged Diodrast was 0.8 ± 5.5% greater than that by tagged red cells. The average volume of dilution by tagged Diodrast was 4.9 ± 6.4% greater than by tagged cells. The slightly larger volume of dilution obtained by the plasma phase could be explained by the greater mean circulation time for plasma as compared with that of associated red cells in small blood vessels. RISA and tagged Diodrast were compared by 10-minute spaced injections in 11 patients at cardiac catheterization. The average cardiac output by tagged Diodrast was 0.3 ± 5.2% greater than that by RISA. The average volume of dilution by tagged Diodrast was 0.8 ± 8.9% lower than that by RISA.