Question

The Fick principle enables

A. Blood flow through an organ to be calculated if organ uptake (U), arterial concentration (A) and venous concentration (V) are known for a given substance.

B. Cardiac output to be calculated by injecting an indicator into the pulmonary artery and monitoring its concentration downstream in a systemic artery.

C. Renal plasma flow to be calculated using PAH as the substance measured.

D. Cardiac output to be estimated using the lungs as the organ and carbon dioxide as the substance measured.

E. Cerebral blood flow to be measured using nitrous oxide as the substance taken up by the brain.

Answer 1

A. True From the principle, U = F (AV), so F = U/(AV).

B. False This method is related to the indicator dilution rather than the Fick principle.

C. True Uptake = volume x concentration, V = zero; the formula is then the same as for PAH clearance.

D. True Either oxygen or carbon dioxide can be the substance measured.

E. True The Kety method to measure cerebral blood flow uses the Fick principle.