Cardiac Output Formula

For those moments when the equation eludes you, our Cardiac Output Formula worksheet will ensure your calculations are accurate every time.

By Alex King on Apr 08, 2024.

Fact Checked by RJ Gumban.

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What is a Cardiac Output Formula?

Cardiac output, often called CO, is a crucial measure of heart function. It represents the blood pumped by the left ventricle into the aorta per minute (Martini et al., 2017, 680-681). This is typically measured in liters of blood per minute. Another way to think of it is the volume of blood circulating through the body's systemic circuit in a minute.

While there are analytical methods like Fick’s principle to measure cardiac output, a simple way to express it is by considering its two main components: stroke volume and heart rate.

As a reminder, stroke volume is the amount of blood pumped with each heartbeat, and heart rate is the number of beats per minute. If we multiply these two parameters, we get the blood pumped per minute—cardiac output!

So, we can express cardiac output as the product of heart rate and stroke volume:

Cardiac Output = Heart Rate x Stroke Volume.

You might also see it written as:

CO = HR x SV.

It may seem straightforward, but there's a bit more to it. Thankfully, our cardiac output formula template can help you understand all the factors affecting heart rate, stroke volume, and cardiac output.

Printable Cardiac Output Formula

Download this Cardiac Output Formula, which measures heart function.

How Does it Work?

Our Cardiac Output Formula can be completed digitally, printed, and filled in by hand. Let's walk through the steps to ensure you calculate cardiac output accurately each time.

Step 1: Input End-Diastolic Volume (EDV)

If you already have the stroke volume value, feel free to skip ahead to Step 3. Otherwise, enter the end-diastolic volume (in milliliters) into the designated EDV box.

Step 2: Provide End-Systolic Volume (ESV)

Next, input the end-systolic volume (in milliliters) into the ESV box.

Step 3: Calculate Stroke Volume

If you already know the exact value for stroke volume, just put it in the SV box in Equation 2. If not, subtract ESV from EDV in Equation 1, resulting in your stroke volume in milliliters. Enter this value, changed into liters, into the SV box.

Step 4: Insert Heart Rate

Enter the heart rate in beats per minute (bpm) into the HR box.

Step 5: Compute Cardiac Output

In this final step, multiply the stroke volume and heart rate values (or those in the SV and HR boxes). This will give you the cardiac output in liters per minute.

That's it! You're all set to calculate cardiac output accurately.

Cardiac Output Formula Example (Sample)

In a real-life scenario, let's explore how to calculate cardiac output using the end-systolic volume (ESV), end-diastolic volume (EDV), and heart rate. Take Marie, for instance, with an end-systolic volume of 45mL, end-diastolic volume of 120mL, and a heart rate of 80 bpm.

We've prepared a downloadable PDF of the cardiac output formula template to guide you through this calculation. Feel free to download it here and work through the example to enhance your understanding.

Download this Cardiac Output Formula Example:

Cardiac Output Formula Example (Sample)

When Would You Use This Cardiac Output Formula?

When to apply this formula? Cardiac output estimation can be approached through various methods like echocardiography, thermodilution techniques, Fick techniques, or angiography.

This Cardiac Output Formula is versatile and can be employed with any technique that enables quantitative measurement of left ventricular volume at different phases of the cardiac cycle. Whether you're utilizing cardiac MRI, echocardiography, or angiography, this formula will prove helpful.

While Fick techniques are known for their precision and are considered the gold standard, imaging-based techniques offer an efficient estimate. This is particularly valuable for monitoring changes in relative cardiac output over time (Maleki et al., 2017, 183-184).

Practitioners who might benefit from having this Cardiac Output Formula on hand include:

  • Medical or nursing students
  • Trainee cardiologists, physiologists, or medical research scientists
  • Imaging scientists or radiologists.

What do the Results Mean?

Remembering that a single number can't capture all the factors affecting a patient's cardiac health is crucial. Cardiac output is exceptionally variable and can be influenced by factors like exercise, hormones, or body temperature. Consequently, each patient will have a unique baseline for their heart function, and normal values for cardiac output can vary widely.

For a healthy adult, stroke volume is often cited around 70mL, and when combined with a typical resting heart rate of 60-80 bpm, a specific cardiac output is usually given as 5 L/min.

Suppose a patient's cardiac output falls below the expected value for a healthy individual. In that case, it might indicate a heart condition like congestive heart failure, cardiomyopathy, or another underlying issue leading to heart failure.

Conversely, a higher-than-expected cardiac output can result from hyperthyroidism, stress, or vigorous exercise. This underscores the importance of interpreting a single cardiac output value in context to determine whether it indicates an underlying pathology. Understanding the broader picture is critical in assessing cardiac health.

Why Use Carepatron as Your Cardiac Output Formula App?

Cardiovascular diseases represent a considerable proportion of the global disease burden, creating a substantial workload for healthcare professionals who deal with test orders, image interpretations, result sharing, and treatment decisions. Fortunately, the advent of automation and electronic health records has significantly reduced the burden of these routine tasks. If you're seeking a solution to streamline your medical billing, scheduling, and electronic patient records processes, look no further than Carepatron.

Carepatron is a comprehensive software suite designed to enhance efficiency in medical and healthcare practices. With smart practice management solutions, you can provide patients with their patient portal software for booking appointments, accessing results, or engaging in telehealth appointments.

Use our AI-powered smart dictation software and a library of useful templates, including the cardiac output formula, to optimize your workflow and save valuable time. Carepatron is your ally in delivering efficient and patient-centric healthcare services.

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Maleki, M., Alizadehasl, A., & Haghjoo, M. (Eds.). (2017). Practical Cardiology. Elsevier.

Martini, F., Ober, W., Nath, J., Bartholomew, E., & Petti, K. (2017). Visual Anatomy and Physiology. Pearson.

Young, D. B. (2010). Control of Cardiac Output. Morgan & Claypool Life Sciences.

What are ESV and EDV?
What are ESV and EDV?

Commonly asked questions

What are ESV and EDV?

ESV and EDV, or end-systolic and end-diastolic volumes, play pivotal roles in understanding cardiac function. The end-diastolic volume (EDV) signifies the blood amount in the ventricle at the end of ventricular diastole or filling. In contrast, the end-systolic volume (ESV) represents the blood remaining in the ventricle after ventricular systole or ejection. The stroke volume, obtained by subtracting ESV from EDV, is a crucial parameter for calculating cardiac output (Martini et al., 2017, 686).

Is this the only formula for cardiac output?

Various cardiac output formulae exist, ranging in complexity. The formula discussed here is among the simplest, applicable when stroke volume, or EDV and ESV, are known. Different formulae cater to specific techniques like thermodilution or Fick cardiac output calculation, each requiring a distinct set of parameters.

How long does this equation take?

In terms of efficiency, this particular cardiac output formula stands out as one of the quickest and simplest methods for estimating cardiac output. If you have the stroke volume, measuring the patient's heart rate and plugging the numbers into the formula involves just a couple of straightforward calculations, providing you with the cardiac output efficiently.

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