What is the formula for cardiac output (CO)?

Cardiac output (CO) is defined as the volume of blood that the heart pumps per minute. The correct way to calculate cardiac output is by multiplying heart rate (HR), which is the number of beats per minute, by stroke volume (SV), the amount of blood pumped by the heart with each beat. This relationship illustrates that cardiac output increases with either an increase in the heart rate or an increase in stroke volume.

In terms of the physiological concepts, understanding that CO is a product of HR and SV helps in assessing a patient's hemodynamic status. If either heart rate or stroke volume is compromised, it directly affects cardiac output, which is critical for tissue perfusion and overall body function. Hence, the formula HR x SV succinctly encapsulates this relationship, making it essential for clinical practice and critical care assessments.