Cardiac output is defined as which of the following?

Cardiac output is defined as which of the following?

• A. Heart rate multiplied by stroke volume
• B. Heart rate divided by stroke volume
• C. Stroke volume only
• D. Blood pressure multiplied by heart rate

Answer: (A)

Cardiac output is the volume of blood the heart pumps each minute. It’s found by multiplying heart rate (beats per minute) by stroke volume (milliliters per beat): CO = HR × SV. For example, with a heart rate of 75 beats per minute and a stroke volume of 70 mL per beat, the cardiac output is about 75 × 70 = 5250 mL per minute (roughly 5.25 L/min). Dividing heart rate by stroke volume doesn’t represent blood flow per minute; it would give a nonsensical unit for this context. Stroke volume alone is only the amount ejected per beat, not per minute. Blood pressure multiplied by heart rate mixes a pressure measure with rate, producing a value that isn’t a volume per minute, so it doesn’t define cardiac output.

Cardiac output is the volume of blood the heart pumps each minute. It’s found by multiplying heart rate (beats per minute) by stroke volume (milliliters per beat): CO = HR × SV. For example, with a heart rate of 75 beats per minute and a stroke volume of 70 mL per beat, the cardiac output is about 75 × 70 = 5250 mL per minute (roughly 5.25 L/min).

Dividing heart rate by stroke volume doesn’t represent blood flow per minute; it would give a nonsensical unit for this context. Stroke volume alone is only the amount ejected per beat, not per minute. Blood pressure multiplied by heart rate mixes a pressure measure with rate, producing a value that isn’t a volume per minute, so it doesn’t define cardiac output.