cardiac index
Cardiac output normalized to body surface area, expressed in liters per minute per square meter (L/min/m²).
Full Definition
Cardiac index (CI) is a hemodynamic parameter that adjusts cardiac output for body surface area, providing a more accurate assessment of cardiac performance relative to patient size. Normal cardiac index ranges from 2.5-4.0 L/min/m², with values below 2.2 L/min/m² generally indicating reduced cardiac performance. CI is calculated by dividing stroke volume by body surface area and multiplying by heart rate, or alternatively by dividing cardiac output by BSA. The measurement is particularly important in critically ill patients, during cardiac catheterization, and in assessing response to interventions. Low cardiac index may indicate heart failure, cardiogenic shock, or other conditions affecting cardiac performance, while elevated values may suggest high-output states such as sepsis, hyperthyroidism, or arteriovenous fistulas.
Usage
Usage note: Always include units (L/min/m²) and specify measurement method; distinguish from absolute cardiac output.
In Context
- "The cardiac index was reduced at 1.8 L/min/m², consistent with cardiogenic shock." — Hemodynamic assessment
- "Following inotropic support, the cardiac index improved to 2.6 L/min/m²." — Critical care note