What is primarily affected by stroke volume?

Stroke volume refers to the amount of blood ejected by the heart with each beat. It is a critical component in determining cardiac output, which is the total amount of blood pumped by the heart per minute. Cardiac output is calculated using the formula: cardiac output equals stroke volume multiplied by heart rate. Therefore, changes in stroke volume will directly influence cardiac output, making it a primary factor.

When stroke volume increases, cardiac output increases as long as heart rate remains constant, and conversely, a decrease in stroke volume will lead to a decrease in cardiac output. This relationship illustrates why stroke volume is fundamentally linked to, and primarily affects, cardiac output. Understanding this connection is essential for EMTs and healthcare providers when assessing a patient's cardiovascular status or responding to emergency situations involving circulatory issues.