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Cardiac Output

Dye Dilution Method

The dye dilution method is done by rapidly injecting a dye, indocyanine green, into the right atrium of the heart. The dye flows with the blood into the aorta. A probe is inserted into the aorta to measure the concentration of the dye leaving the heart at equal time intervals [0, T] until the dye has cleared. Let c(t) be the concentration of the dye at time t. By dividing the time intervals from [0, T] into subintervals Δt, the amount of dye that flows past the measuring point during the subinterval from to is:

where is the rate of flow that is being calculated. The total amount of dye is:

and, letting , the amount of dye is:

Thus, the cardiac output is given by:

where the amount of dye is known, and the integral can be determined using the concentration readings. [3]

The dye dilution method is one of the most accurate methods of determining cardiac output during exercise. The error of a single calculation of cardiac output values at rest and during exercise is less than 5%. This method does not allow measurement of 'beat to beat' changes, and requires a cardiac output that is stable for approximately 10 s during exercise and 30 s at rest.[4]

Notes

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  1. ^ Be bold guideline. Wikipedia, The Free Encyclopedia. Retrieved October 26, 2016.
  2. ^ Broughton, John (2008). Wikipedia : the missing manual (1st ed. ed.). Beijing: O'Reilly. ISBN 0-596-51516-2. {{cite book}}: |edition= has extra text (help)
  3. ^ Stewart, James (2010). Calculus: Early Transcententals. Cengage Learning. pp. 565–566. ISBN 9780538497909.
  4. ^ pubmeddev. "Error - PubMed - NCBI". Retrieved 2016-12-08.