Cardiac Output Calculator
Calculate cardiac output and cardiac index using the Fick equation method
Calculate Cardiac Output
Arterial Blood
Venous Blood
Cardiac Output Results
Fick Equation
CO = VO₂ / (Ca - Cv)
Where:
- • CO = Cardiac Output (L/min)
- • VO₂ = Oxygen Consumption (0 mL/min)
- • Ca = Arterial O₂ Concentration (0.00 mL/L)
- • Cv = Venous O₂ Concentration (0.00 mL/L)
Medical Disclaimer
This calculator is for educational purposes only and should not replace professional medical assessment. Cardiac output measurements require specialized equipment and medical supervision. Always consult healthcare professionals for accurate cardiac function evaluation and interpretation of results.
Example Calculation
Healthy Adult Example
Patient: 30-year-old healthy male
Height: 175 cm, Weight: 70 kg
BSA: √(175 × 70 / 3600) = 1.85 m²
Hemoglobin: 15.0 g/dL
Arterial: SaO₂ 98%, PaO₂ 95 mmHg
Venous: SvO₂ 75%, PvO₂ 35 mmHg
Calculation Steps
1. VO₂ = 1.85 × 125 = 231 mL/min
2. Ca = (1.34 × 15.0 × 0.98) + (0.031 × 95) = 19.7 + 2.9 = 22.6 mL/L
3. Cv = (1.34 × 15.0 × 0.75) + (0.031 × 35) = 15.1 + 1.1 = 16.2 mL/L
4. CO = 231 / (22.6 - 16.2) = 231 / 6.4 = 3.6 L/min
Result: CO = 3.6 L/min, CI = 1.9 L/(min·m²)
Normal Values
Cardiac Output
4-8 L/min (adults at rest)
Cardiac Index
2.5-4.0 L/(min·m²)
Hemoglobin
Men: 13.8-17.2 g/dL
Women: 12.1-15.1 g/dL
Arterial SaO₂
94-99%
Venous SvO₂
60-80%
Clinical Significance
Low CO/CI
Heart failure, cardiogenic shock, severe dehydration
Normal CO/CI
Adequate cardiac function and tissue perfusion
High CO/CI
Hyperdynamic state, sepsis, hyperthyroidism
About Fick Method
Gold standard for cardiac output measurement
Requires arterial and venous blood sampling
Most accurate when oxygen consumption is measured directly
Used in cardiac catheterization procedures
Understanding Cardiac Output
What is Cardiac Output?
Cardiac output is the volume of blood pumped by the heart per minute. It represents the heart's ability to meet the body's metabolic demands and is a critical measure of cardiovascular function.
Fick Principle
The Fick equation is based on the principle that the amount of oxygen consumed by the body equals the difference in oxygen content between arterial and venous blood multiplied by cardiac output.
Clinical Applications
- •Diagnosis of heart failure
- •Assessment of shock states
- •Monitoring during cardiac procedures
- •Evaluation of cardiac interventions
Fick Equation Components
Oxygen Consumption (VO₂)
Estimated as 125 mL/min/m² of body surface area. Can be measured directly using spirometry for more accurate results.
Oxygen Content
Calculated using hemoglobin level, oxygen saturation, and partial pressure of oxygen. The formula accounts for both hemoglobin-bound and dissolved oxygen.
Cardiac Index
Cardiac output normalized to body surface area, allowing comparison between patients of different sizes. More useful for clinical decision-making.