Cardiac Index
Enter cardiac output and patient size to obtain cardiac index. By default, body surface area is calculated using the Mosteller equation, but a measured BSA may also be entered directly.
How to Use This Calculator
Measure cardiac output
Use thermodilution, Fick method, or echocardiographic stroke volume × heart rate to determine CO in L/min.
Provide patient size
Input height and weight for Mosteller BSA or supply a manually measured BSA (e.g., from Du Bois or Haycock formulas).
Review cardiac index and clinical context
Compare the cardiac index with normal ranges (2.5–4.0 L/min/m²) and correlate with hemodynamic status, lactate, urine output, and perfusion markers.
Formula
Body surface area (Mosteller) = √[(Height(cm) × Weight(kg)) ÷ 3600]
Cardiac index (CI) = Cardiac output ÷ BSA
Normal CI ≈ 2.5 – 4.0 L/min/m².
Full Description
Cardiac index normalizes cardiac output to body size, providing a more individualized assessment of perfusion adequacy. Low CI suggests cardiogenic shock, heart failure, or hypovolemia, while elevated CI may be seen in distributive shock, anemia, or pregnancy. Clinicians interpret CI alongside systemic vascular resistance, pulmonary pressures, and organ perfusion.
BSA estimation affects CI accuracy; Mosteller is widely used due to simplicity. In critically ill patients, direct BSA measurement or other formulas may be employed. Continuous or repeated CO monitoring aids titration of inotropes, vasopressors, fluids, and mechanical circulatory support.
Frequently Asked Questions
Can I use other BSA formulas?
Yes. Mosteller is provided for convenience, but Du Bois, Haycock, or Gehan-Georg formulas may be preferred in certain populations. Enter a manual BSA if using alternative formulas.
Is thermodilution necessary?
Any reliable cardiac output measurement can be used: thermodilution (PAC), Fick, echocardiography (LVOT area × VTI × HR), or pulse contour analysis. Ensure consistent technique for trending.
What CI threshold suggests cardiogenic shock?
CI < 2.2 L/min/m² with elevated filling pressures typically indicates cardiogenic shock. Intervention includes inotropes, vasopressors, or mechanical support depending on etiology.
Does CI alone guide therapy?
CI is one component. Combine with systemic vascular resistance, mean arterial pressure, lactate, urine output, and tissue perfusion to guide comprehensive hemodynamic management.