DYE INJECTION METHOD FOR DETERMINATION OF CARDIAC OUTPUT.

The dye injection method for determination of cardiac output is based on analysis of the time-concentration curve of dye in the arterial blood during its first circulation after rapid intravenous injection. Technical difficulties included selection and preparation of dye for injection, the proper placement of arterial and venous needles, the collection of adequate samples at one second intervals, the prevention of clotting and hemolysis, and the colorimetric determination of dye concentration. Determinations of cardiac output in normal resting subjects at sea level gave values of approximately 5 liters per minute. Two determinations performed on resting subjects in the low pressure chamber at a simulated altitude of 20,000 feet gave values for cardiac output of 9.8 liters per minute and 16.8 liters per minute. This work constitutes preliminary use and evaluation of the injection method in our hands. Results are to be considered as only approximate. Further evaluation is in progress. Author