Registered Cardiovascular Invasive Specialist (RCIS) Practice Test

Which cardiac output measurement is considered most accurate in patients with tricuspid regurgitation?

1. Doppler ultrasound

2. Indicator dilution method

3. Thermodilution method

4. Fick method

The correct answer is: Fick method

The Fick method is considered the most accurate measurement of cardiac output in patients with tricuspid regurgitation due to its reliance on the principle of oxygen consumption and the measurement of arterial and venous oxygen content. This method calculates cardiac output based on the amount of oxygen consumed by the body and the difference in oxygen content between arterial and venous blood. It is particularly useful in patients with valvular heart diseases, such as tricuspid regurgitation, where other methods may give less reliable results. In patients with tricuspid regurgitation, there is a disturbance in the hemodynamic flow that can complicate interpretations of other methods. For instance, Doppler ultrasound relies on the accurate alignment and assessment of flow velocities across valves, which can be challenging with regurgitant flow. The indicator dilution method often requires the accurate placement of catheters that may be influenced by the abnormal physiology present in these patients. Similarly, the thermodilution method involves injecting a cold solution and measuring temperature changes, but inaccuracies can arise from turbulent blood flow due to regurgitation. Therefore, the Fick method's ability to directly measure the equilibrium of oxygen content provides a clearer and more accurate assessment of cardiac output in this particular context, making it