Cardiac index

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Cardiac index (CI) is a haemodynamic parameter that relates the cardiac output (CO) to body surface area (BSA),[1] thus relating heart performance to the size of the individual. The unit of measurement is litres per minute per square metre (L/min/m2).

Calculation[edit]

The index is usually calculated using the following formula:

CI = \frac{CO}{BSA} = \frac{SV*HR}{BSA}

where

CI=Cardiac index
BSA=Body surface area
SV=Stroke volume
HR=Heart rate
CO=Cardiac output

Clinical significance[edit]

The normal range of cardiac index in rest is 2.6 - 4.2 L/min/m2.

It is frequently measured and used in intensive care medicine, and cardiac intensive care. It is a useful marker of how well the heart is functioning as a pump by directly correlating the volume of blood pumped by the heart with an individual's body surface area.

If the CI falls below 1.8 L/min/m2, the patient may be in cardiogenic shock.

References[edit]