Fick Principle Cardiac Output Calculator

How to use

Input the measured oxygen consumption (VO2) and the arterial/venous oxygen contents (CaO2 and CvO2) using consistent units. Hit Calculate or rely on the instant recalculation to derive the cardiac output in liters per minute.

Methodology

This calculator implements the Fick principle: cardiac output equals oxygen consumption divided by the arteriovenous oxygen content difference. It assumes steady-state measurements and yields a single, steady-volume output for the provided inputs.

• Ensure VO2 is in mL/min and oxygen contents are in mL O2/L for consistency.
• The denominator is CaO2 − CvO2; a positive difference is required for a meaningful result.
• Values are rounded to two decimals for clarity.

Full original guide (expanded)

This tool is designed for healthcare professionals needing a quick cardiac output estimate. When the measurement inputs are precise, the result helps confirm or question hemodynamic assumptions.

The calculator mirrors the classic formula:

Cardiac Output = VO2 / (CaO2 − CvO2)

For example, VO2 = 250 mL/min, CaO2 = 200 mL/L, CvO2 = 150 mL/L yields 5 L/min. Repeat the calculation with updated measurements as needed.

FAQ

What is the Fick principle?

It equates the oxygen uptake rate to the blood flow multiplied by the oxygen content difference across the pulmonary circulation.

Why is cardiac output important?

It reflects heart pump performance and guides critical care decisions.

How can I improve accuracy?

Use calibrated devices for VO2 and consistent lab values for CaO2/CvO2.

Can this be used in pediatrics?

Yes, ensure pediatric norms for the inputs.