Medicine:Cardiac index
Cardiac index (CI) is a haemodynamic parameter that relates the cardiac output (CO) from left ventricle in one minute 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
The index is usually calculated using the following formula:[citation needed]
- [math]\displaystyle{ \text{CI} = \frac{\text{CO}}{\text{BSA}} = \frac{\text{SV}\times\text{HR}}{\text{BSA}} }[/math]
where
- CI
- Cardiac index
- BSA
- Body surface area
- SV
- Stroke volume
- HR
- Heart rate
- CO
- Cardiac output
Clinical significance
The normal range of cardiac index at rest is 2.6–4.2 L/min/m2.
The cardiac index is frequently measured and used in both intensive care medicine and cardiac intensive care. The CI 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.[citation needed]
If the CI falls acutely below 2.2 L/min/m2, the patient may be in cardiogenic shock.[citation needed]
References
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