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Should You Test Your Lung Function at Home?

Medically Reviewed by Jennifer Robinson, MD on August 28, 2020

If you have asthma, COPD, or other problems with your lungs, your doctor will likely check your breathing at every checkup. COPD, or chronic obstructive pulmonary disease, means you have one of three lung diseases that makes it harder to breathe and gets worse over time:

An office breathing test typically means you blow into a machine that measures how much air your lungs can take in and how quickly and forcefully you can blow it out. These numbers tell your doctor if the main airways in your lungs are healthy.

Some doctors suggest home monitoring as well, as it can help you keep better track of your health. A gadget called a peak flow meter lets you do that. You hold it in your hand and blow into it as hard as you can to get a measure of the greatest airflow rate you can produce.

About 600 liters per minute is normal for the average man, and 370 liters per minute for the average woman. But each case is different, so talk to your doctor about whether a home test is right for you and what your numbers should be.

What It Does

Both children and adults can use a peak flow meter. The meter can help you:

  • Track how well your condition is under control
  • Judge how much your treatment helps
  • Spot a flare-up before it happens so you can act to avoid it
  • Help you decide if you need to call your doctor or go to the emergency room

You may also need a home test if:

  • Your condition wakes you up at night.
  • Your symptoms get worse during the day.
  • You come down with a cold, the flu, or something else that interferes with your breathing.
  • You need to use your emergency inhaler.

How to Use It

You can buy the meter over the counter at a drugstore. There are several types, but they work in pretty much the same way: You blow into the mouthpiece as hard and as fast as you can, and the meter gives you a number that tells how well your lungs are working.

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Your doctor can help you choose the meter that’s right for you. Your doctor or your nurse also can make sure that you’ve got the hang of using the meter. When you do, you’ll start by figuring out your personal best reading. That’s the one you get when you feel fine and don’t have symptoms.

To check your best reading, test yourself with the meter every day for 2-3 weeks. Write down your highest number for each day. When you finish the whole series of tests, the highest reading of all is your personal best. This can be a kind of benchmark. You and your doctor will use it to make a plan to manage your condition with medication and other therapies. Many of these plans use a system that’s color-coded, like the traffic lights you see when you’re driving.

If you’re doing fine most of the time and your illness doesn’t cause much trouble, your doctor may say you don’t need to use the meter every day. Every few days may be enough. But if your condition worsens, you may need to test yourself several times a day.

WebMD Medical Reference

Sources

SOURCES:

Mayo Clinic: “Spirometry,” “Peak flow meter.”

Cleveland Clinic: “Peak flow meter.”

American Lung Association: “Measuring your peak flow rate.”

American Academy of Allergy, Asthma & Immunology: “Peak Flow Meter.”

University of Washington: “New health sensing tool measures lung function over a phone call, from anywhere in the world.”

Cleveland Clinic: “Emphysema.”

National Emphysema Foundation: “Assessment of the Patient -- Your Evaluation as a Possible COPD Patient.”

UpToDate: “Chronic obstructive pulmonary disease: Definition, clinical manifestations, diagnosis, and staging.

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