Cardiac Output During Exercise: Thermodilution Versus Direct Fick.

Area of Science:

• Cardiology
• Pulmonary Medicine
• Medical Devices

Background:

• Accurate cardiac output (CO) measurement is crucial for diagnosing exercise pulmonary hypertension (PH).
• Comparing thermodilution CO to direct Fick CO (dfCO) is essential for clinical accuracy.
• Exercise PH diagnosis requires reliable CO assessment at rest and during exertion.

Purpose of the Study:

• To compare the performance of thermodilution CO against the gold-standard dfCO.
• To evaluate CO measurements at rest and during exercise.
• To assess the impact of CO measurement differences on PH classification.

Main Methods:

• Prospective cohort study of 302 patients undergoing invasive cardiopulmonary exercise testing.
• Generalized additive modeling used to predict CO at various exercise stages.
• Bland-Altman analysis performed to assess agreement between thermodilution and dfCO.

Main Results:

• Thermodilution CO showed significant differences from dfCO, underestimating at rest and overestimating at maximal exercise.
• Wide limits of agreement were observed between the two CO measurement methods, especially at peak exercise.
• Despite differences, the classification of exercise PH, precapillary PH, and postcapillary PH was not significantly altered.

Conclusions:

• Significant differences and wide limits of agreement exist between thermodilution and dfCO.
• Sequential thermodilution measurements during exercise may mitigate clinical impact on PH diagnosis.
• Clinical implications of CO measurement discrepancies require careful consideration in exercise PH assessment.