A comparison of intracardiac and intravenous injections for the measurement of cardiac output by the dilution technic.

Using HsPO4 and the dye T-1824 as labels, simultaneous injections were made into the right ventricle and into a peripheral vein, and cardiac output was calculated from the individual flowdilution curves. When a discrepancy beyond the range expected from the use of the two labels occurred, the output from the central injection was always the larger (approximately one-third of the observations, in a small series). This may be attributable to progressive blood loss from sampling, since delayed intraventricular injections under comparable conditions, measure a similarly reduced cardiac output.