Following injection of a dye into the bloodstream, its concentration rises briefly, then falls exponentially until recirculation occurs, whereupon it rises again slightly. Measurement of the dye directly or indirectly correlates with the cardiac output.


(1) indicator dose in mg

(2) mean blood concentration of indicator in mg/L

(3) duration of curve in seconds


cardiac output in liters per minute =

= ((amount of indicator injected in mg) * 60) / ((mean concentration of indicator in the blood in mg/L) * (time of total curve duration in seconds))



• 60 represents the number of seconds per minute

• The area under the curve can help determine the mean concentration of the indicator.

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