Cardiac Output Calculator
Calculate Cardiac Output (CO) and Cardiac Index (CI) for cardiovascular function and tissue perfusion assessment.
Important Medical Disclaimer
This calculator is an educational and clinical decision support tool. Results DO NOT replace professional medical evaluation, laboratory tests, or clinical judgment. Always consult a qualified healthcare professional for diagnosis, treatment, and clinical decisions. Calculations are based on scientifically validated formulas but may not be applicable to all patients.
Calculate Cardiac Output
What is Cardiac Output?
Cardiac Output (CO) is the volume of blood pumped by the heart per minute. It is calculated by multiplying heart rate (HR) by stroke volume (SV), which is the amount of blood ejected with each heartbeat. CO reflects the heart's ability to meet the metabolic needs of tissues. Cardiac Index (CI) is CO adjusted for body surface area, allowing comparisons between individuals of different body sizes.
Calculation Formulas
CO (L/min) = HR (bpm) × SV (mL) ÷ 1000
CI (L/min/m²) = CO (L/min) ÷ BSA (m²)
Conversion from mL to L is done by dividing by 1000. Cardiac Index normalizes CO by body surface area.
Normal Reference Values
Cardiac Output (CO)
4.0 - 8.0 L/min
Cardiac Index (CI)
2.5 - 4.0 L/min/m²
Clinical Significance
Cardiac output is a fundamental parameter in hemodynamic assessment of critical patients. Low CO may indicate heart failure, hypovolemia, cardiac tamponade, or cardiogenic shock. Elevated CO can occur in hyperdynamic states such as sepsis, hyperthyroidism, severe anemia, or pregnancy. CI is preferable to CO when comparing patients of different sizes, being especially useful in pediatrics and intensive care. CI values < 2.2 L/min/m² generally indicate cardiogenic shock, while values > 4.5 L/min/m² may suggest a hyperkinetic state.
Frequently Asked Questions about Cardiac Output
What's the difference between Cardiac Output and Cardiac Index?
Cardiac Output (CO) is the absolute volume of blood pumped per minute (L/min). Cardiac Index (CI) is CO normalized by body surface area (L/min/m²), allowing comparisons between patients of different sizes. CI is more clinically useful as it accounts for individual differences.
How is Stroke Volume measured in clinical practice?
Stroke volume can be measured by several methods: echocardiography (most common non-invasive method), cardiac catheterization (gold standard but invasive), thermodilution (Swan-Ganz catheter), pulse contour analysis, or thoracic bioimpedance. The choice of method depends on availability, patient condition, and need for continuous monitoring.
What causes low CO?
Low CO can result from: systolic heart failure (inadequate pumping), hypovolemia (reduced blood volume), cardiac tamponade (heart compression), massive pulmonary embolism, severe arrhythmias, extensive acute myocardial infarction, or cardiogenic shock. It requires urgent investigation and treatment.
What does high CO mean?
Elevated CO can occur physiologically during intense exercise or pregnancy. Pathologically, it may indicate: sepsis (systemic vasodilation), hyperthyroidism, severe anemia, arteriovenous fistulas, Paget's disease, beriberi, or severe aortic or mitral regurgitation. Clinical context is essential for interpretation.
When is CO monitoring indicated?
CO monitoring is indicated in: shock of any etiology, acute decompensated heart failure, post-cardiac or major surgery, severe sepsis or septic shock, acute respiratory distress syndrome (ARDS), severe pulmonary hypertension, and whenever there is hemodynamic instability not responding to initial treatment.
Scientific References
- 1. Guyton AC, Hall JE. Textbook of Medical Physiology. 13th ed. Philadelphia: Elsevier Saunders; 2015.
- 2. Vincent JL, Rhodes A, Perel A, et al. Clinical review: update on hemodynamic monitoring--a consensus of 16. Crit Care. 2011;15(4):229.
- 3. Hoeper MM, Maier R, Kaulen C, et al. Determination of cardiac output by the Fick method, thermodilution, and acetylene rebreathing in pulmonary hypertension. Am J Respir Crit Care Med. 1999;160(2):535-541.