What is Cardiac Index (CI)?

Cardiac Index (CI) is a hemodynamic parameter that relates the cardiac output (CO) from the left ventricle in one minute to body surface area (BSA). This measurement allows for a direct comparison of cardiac function among individuals of different sizes. While Cardiac Output tells us how much blood the heart pumps, the Cardiac Index tells us if that amount is sufficient for that specific person's body size.

How to Use This Calculator

To use the Cardiac Index Calculator, you need three primary pieces of data. First, input the Cardiac Output in Liters per minute (L/min). Next, provide the patient's height and weight. Our tool uses the Mosteller formula to calculate the Body Surface Area (BSA) and then divides the Cardiac Output by the BSA to find the CI. You can toggle between metric (cm/kg) and imperial (in/lb) units for convenience.

Clinical Significance and Normal Ranges

The normal range for Cardiac Index in a healthy adult is typically between 2.5 to 4.0 L/min/m². If the CI falls below 2.0 L/min/m², the patient may be in cardiogenic shock. Clinicians use this metric to diagnose heart failure, monitor patients in intensive care units, and determine the effectiveness of medications like inotropes or vasodilators.

Frequently Asked Questions

Q: Why is CI better than CO?
A: Cardiac Output doesn't account for body size. An output of 4 L/min might be normal for a small individual but insufficient for a large athlete. CI normalizes this value.

Q: What formula is used for BSA?
A: This calculator utilizes the Mosteller formula: BSA (m²) = √([Height(cm) x Weight(kg)] / 3600), which is widely accepted in clinical practice.