Cardiac Output: Definition, Calculation, and Clinical Significance

Cardiac output (CO) represents the volume of blood the heart pumps per minute. It is the product of two fundamental variables:

• Stroke volume (SV): The amount of blood ejected by the left ventricle per beat (typically ~70 mL in a healthy adult).
• Heart rate (HR): The number of beats per minute (typically 60–100 bpm at rest).

Formula: CO = SV × HR

At rest, a typical adult cardiac output is approximately 5 L/min. During exercise, it can increase four- to five-fold to meet heightened metabolic demands. Cardiac output is a vital hemodynamic parameter used to assess cardiovascular function in critical care, cardiology, and exercise physiology.