Physiology, Cardiac Index

The human heart is one of the most studied and vital organs to life. There are many ways to describe the status of the heart’s function and health. One measure of heart function is the cardiac index. The cardiac index relies on another important parameter, cardiac output, and turns cardiac output into a normalized value that accounts for the body size of the patient. For example, the cardiac output of a person who weighs 120 (54 kg) pounds might be expectedly different from a person who weighs 220 pounds (100 kg). For this reason, a simple cardiac output alone cannot be a reliable indicator of cardiac performance. Calculating a cardiac index helps solve this problem. The equation for the cardiac index is below with units of (Liters/minute)/(meter^2). Cardiac Index = Cardiac Output / Body Surface Area = (Heart Rate * Stroke Volume) / Body Surface Area