Cardiac Output (Fick Method)
This calculator estimates cardiac output in liters per minute using the Fick method. It is especially useful for clinicians to assess the pumping efficiency of the heart based on oxygen consumption, hemoglobin concentration, and oxygen saturation. By inputting the patient’s body surface area (BSA), hemoglobin (Hgb), arterial (SaO₂) and venous (SvO₂) oxygen saturation, you can get a non-invasive approximation of cardiac output.
Cardiac Output
Fick Method Cardiac Output Formula
Where:
- $$BSA$$ = Body Surface Area (m²)
- $$Hgb$$ = Hemoglobin concentration (g/dL)
- $$SaO₂$$ = Arterial oxygen saturation (fraction or %)
- $$SvO₂$$ = Venous oxygen saturation (fraction or %)
The constant 135 is an assumed oxygen consumption value per square meter (ml O₂/min/m²), and 13 is derived from the oxygen carrying capacity of hemoglobin.
The Fick method is a classical approach to measure cardiac output without catheterization. It assumes a steady state of oxygen consumption and is particularly useful when oxygen saturation values are available. This calculation is useful for assessing patients with heart failure, pulmonary hypertension, or during critical care evaluation. The formula can be adjusted if actual VO₂ (oxygen consumption) is measured instead of using 135 ml/min/m².