Diagnosis

Understanding End Tidal Carbon Dioxide Monitoring

Choose a preferred language


What is end tidal carbon dioxide monitoring?

End tidal carbon dioxide (ETCO2) monitoring is a painless way to assess your breathing (respiration). It’s used in many medical settings and situations. It’s also called capnometry or capnography.

ETCO2 monitoring checks the carbon dioxide (CO2) levels that you breathe out (exhale). Doctors use CO2 levels as a way to see how well the heart is pumping blood. They also use them to see how well blood is flowing (circulating) through the lungs.

ETCO2 monitors give continuous, real-time details about how a person is breathing. They analyze each breath you take. The devices can show if breathing becomes fast, slow, or shallow. They provide an early warning if you are starting to have trouble breathing. This lets doctors act quickly if any possible problems are found.


How is ETCO2 monitoring done?

There are two types of CO2 monitoring devices: mainstream and sidestream.

  • Mainstream devices. These are used only for people with breathing tubes.

  • Sidestream devices. These can be used for people with or without breathing tubes.

A sidestream ETCO2 monitoring device is made up of:

  • Plastic tubing. This is worn on your face and connected to a monitor.

  • An electronic monitor (capnography monitor). This records the information from your exhaled breath.

To use the device, a thin plastic tube with small plastic prongs is fitted under your nose then draped over your ears. The small plastic prongs go into your nostrils. A small, round plastic piece also sits in front of your mouth. Samples of your exhaled breath are taken from your nose and mouth.

The other end of the tube is attached to the monitor. Your exhaled breath samples are sent to the monitor. A sensor analyzes your CO2 levels breath-by-breath for any changes. The monitor will set off an alarm if your breathing becomes fast, slow, or shallow.


When is ETCO2 monitoring used?

ETCO2 monitoring can give an early alert that someone may be having trouble breathing. It can also assess a person’s responses to different treatments. It’s used in many situations such as:

  • For people with acute respiratory distress or other breathing problems.

  • For people in the intensive care unit (ICU).

  • When a breathing tube is inserted (intubation).

  • When taking someone by ambulance to the emergency room.

  • When someone has been given general anesthesia, sedation, or certain opioid pain medicines.

  • During cardiopulmonary resuscitation (CPR) for cardiac arrest.

  • Before, during, or after surgery.

This type of monitoring can also help when assessing people who:

  • Are having seizures.

  • Have sepsis.


When wearing an ETCO2 monitoring device

  • Don’t take off the tubing.

  • If the tubing falls off, put it back on. Or ask a health care provider to help you.

  • Your doctor will let you know when it's okay to eat and drink while you are wearing the tubing and being monitored.

  • Your doctor will tell you when you don’t need to wear the tubing anymore. They will remove it for you.

© 2000-2026 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.

Find the right providers for your needs.

CalOptima Health works with thousands of Orange County providers, including doctors, specialists, health networks, medical groups and more.

Find a Doctor

Get Care Now

Your health is everything to us. Please reach out for support if you need it.

Get Care Now
Related Articles
Read article
Lung Health
CT Scan of the Chest

A computed tomography (CT) scan is a type of imaging test. It uses X-rays and a computer to make images or slices of the body. A CT scan can make detailed pictures of any part of the body, including the bones, muscles, fat, organs, and blood vessels. They are more detailed than regular X-rays.

Read article
Lung Health
Lung Scan

A lung scan is an imaging test to look at your lungs and help diagnose certain lung problems. A lung scan may also be used to see how well treatment is working.

Read article
Lung Health
Diagnosing COPD

Your healthcare provider will use your past health history, a physical exam, and certain tests to diagnose COPD.

Read article
Lung Health
Mediastinoscopy

A mediastinoscopy is a procedure used to examine the mediastinum. This is the space behind the breastbone (sternum). Read on to learn more about the procedure, and what to expect.