What Is Cardiac Output?

It’s how much blood your heart pumps in 1 minute. Your doctor uses the measurement to see if you might have heart problems or to check how well a treatment works.

Your blood carries oxygen and nutrients to your cells, and it takes away wastes like carbon dioxide. If your heart pumps too little or too much blood through your body, it could be a sign of heart failure or other medical problems.

Normal Output

It’s different for different people, depending on their size. Usually, an adult heart pumps about 3-4 liters of blood per minute at rest. But when you run or exercise, your heart may pump 3-4 times that much to make sure your body gets enough oxygen and fuel.

How It’s Measured

Your cardiac output is your heartbeats per minute multiplied by the amount of blood pumped with each beat.

Your doctor can measure it in lots of ways.

Pulmonary artery catheter. Your doctor inserts this device into the artery that sends blood to the lungs to pick up oxygen.

Echocardiogram. This uses sound waves to make an image of your heart and blood flow through your heart.

Arterial pulse waveform analysis. These calculate the cardiac output from shock waves created by blood flow.

Low Output

If your heart doesn’t pump enough blood to supply your body and tissues, it could signal heart failure. Low output also could happen after you’ve lost too much blood, had a severe infection called sepsis, or had severe heart damage.

High Output

Sometimes, sepsis, your body’s response to blood infections that can lead to a dangerous drop in blood pressure and organ failure, can cause high cardiac output.

High output also can happen when your body lacks enough oxygen-carrying red blood cells, a condition called anemia. That makes your heart pump more blood faster. Another common cause is hyperthyroidism, which is when your thyroid gland makes more thyroid hormones than needed.

WebMD Medical Reference Reviewed by Brunilda Nazario, MD on January 12, 2018



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