Thermodilution Stewart-Hamilton — FRCA Primary MCQ

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ModeratePhysiology - CardiovascularThermodilution Stewart-HamiltonFRCA Primary

The cardiac output can be measured by the thermodilution technique using a pulmonary artery catheter. This is based on which principle?

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Correct answer: D — Stewart-Hamilton equation (indicator dilution)

Thermodilution cardiac output uses the modified Stewart-Hamilton equation. A known volume of cold saline is injected into the right atrium and the temperature change is measured at the pulmonary artery thermistor. CO is inversely proportional to the area under the temperature-time curve. Fick principle uses oxygen consumption and arteriovenous O2 difference.

Reference: Power Kam 2018 Principles of Physiology for the Anaesthetist