The cardiac index (CI) is a hemodynamic measure that represents the cardiac output (CO) of an individual divided by their body surface area (BSA), expressed in liters per minute per square meter (L/min/m²). This parameter provides a more accurate assessment of heart function relative to the size of the individual, as opposed to absolute cardiac output alone. Cardiac index is crucial in assessing patients with heart failure and other cardiovascular conditions, providing insight into the adequacy of cardiac function in relation to the individual's metabolic needs.[1]