A client develops an increase in cardiac output. Which finding would be observed?

• A. Decrease in blood pressure
• B. Increase in respiratory rate
• C. Increase in stroke volume
• D. Decrease in heart rate

Answer: (C)

An increase in cardiac output means more blood is being pumped each minute. The key relationship is CO = heart rate × stroke volume. To raise CO, the heart can either beat faster or eject more blood with each beat, or both. The option that best fits a higher CO is an increase in stroke volume because it shows more blood being ejected with every beat, which directly increases the total output. This can happen with greater preload (more venous return), stronger contractility, or lower afterload allowing the ventricle to push out more blood per beat. The other options don’t directly indicate a higher amount of blood being pumped per minute: a higher respiratory rate is a ventilatory change, not a direct measure of CO; a decreased heart rate would generally lower CO unless compensated by a much larger stroke volume; and blood pressure can vary due to factors beyond CO, such as vascular resistance.