From the Research
The normal cardiac index ranges from 1.9 to 4.3 L/min/m², as established by a recent study published in 2021 1. This measurement represents cardiac output adjusted for body surface area, making it a more standardized assessment of heart function across different body sizes. Cardiac index is calculated by dividing cardiac output (the amount of blood pumped by the heart per minute) by body surface area. A value below 1.9 L/min/m² may indicate decreased cardiac function or cardiogenic shock, while values above 4.3 L/min/m² can occur during exercise, pregnancy, or hyperdynamic states like sepsis. Some key points to consider when evaluating cardiac index include:
- The cardiac index is a stable parameter that is not influenced by age, gender, and body size 1
- A low cardiac index is an independent predictor of long-term cardiac outcomes in patients with heart failure 2
- The normal range of cardiac index may be lower in older patients, with a yearly decline in cardiac index reported in some studies 3
- Clinicians use cardiac index to guide treatment decisions in critically ill patients, particularly those with heart failure, shock, or after cardiac surgery. Measurement typically requires invasive monitoring such as pulmonary artery catheterization or less invasive methods like transpulmonary thermodilution. Understanding a patient's cardiac index helps clinicians assess the adequacy of tissue perfusion and oxygen delivery, which are essential for maintaining organ function. It is worth noting that other studies have reported slightly different ranges for normal cardiac index, such as 2.1 to 3.2 L/min/m² in healthy volunteers over 60 years of age 3, and 2.5 to 4.0 L/min/m² in a general population 4, 5. However, the most recent and highest quality study 1 provides the most accurate and reliable range for normal cardiac index.