Peak Flow Meter

A peak flow meter is a device that measures the air coming out of your lungs as you blow hard into the device.

This measurement is called your peak expiratory (ex-PIE-rah-tory) flow rate. It can tell you if your airways are getting narrow well ahead of an asthma attack.

Using a peak flow meter can also tell you:

• When to get emergency medical care
• How well your asthma treatment plan is working
• If your medications need adjustment, and
• What triggers your asthma attacks

Peak Flow Zones

Peak flow zones are like traffic lights: red means danger, yellow means caution, and green means safe. Peak flow zones can help you know when your asthma is getting out of control.

This is how peak flow zones work:

Green means your asthma is under control and you are between 80 and 100 percent of your personal best peak flow measurement.

Yellow means your asthma is getting worse and you may need to use quick-relief medications. You are between 50 and 79 percent of your personal best peak flow measurement. Follow your asthma action plan as directed by your health care provider.

Red means you may be in danger. Take your quick-relief medication and get medical help immediately. You are below 50 percent of your personal best peak flow measurement.

Using Your Peak Flow Meter

Use your peak flow meter to measure your lung function:

• Every morning, before taking your asthma medications
• When you are having asthma symptoms or an asthma attack
• After taking medication for an asthma attack, and
• Any other times your health care provider suggests

Use colored tape to mark your personal peak flow levels on your meter. And be sure to add the numbers to your written asthma action plan.

Bring your peak flow meter and your log of daily peak flow numbers with you when you visit your health care provider. Show your health care provider how you use your meter to be sure you are doing it right.

Follow these steps to take your peak flow reading:

Step 1

Move the marker on your meter to 0 or to the lowest number on the scale. Stand up. If you can't stand, sit up straight in a chair. Be sure you're in the same position each time you do this test.

Step 2

Take a deep breath. Fill your lungs all the way. While holding your breath, put the mouthpiece of the meter between your teeth. Close your lips tightly around it, making a tight seal around the mouthpiece. Be sure your tongue does not block the hole.

Blow into the mouthpiece once, as hard and fast as you can. Your peak flow meter will measure how fast you can blow air out.

Take the meter out of your mouth. Check where the marker has moved to on the numbered scale. Write this number down.

Step 3

Move the marker back to 0. Repeat those same steps 2 more times. Then, record the highest of the three numbers in a daily log. This is your peak flow number.

Each person has a personal best peak flow number. To establish your personal best, take your peak flow measurement at the same time in the middle of each day, for two to three weeks, when your asthma is under control.

Your personal best peak flow measurement may change over time. Ask your health care provider when you should test your peak flow measurement and find your new personal best.

Things to Remember

• A peak flow meter measures air coming out of your lungs as you blow hard into the device.
• Peak flow zones are like traffic lights: red means danger, yellow means caution, and green means safe.
• Your personal best peak flow measurement may change over time.

What We Have Learned

A peak flow meter can tell you how well your asthma treatment plan is working. True or False? The answer is true. It can also tell you how well your medication is working and what may be causing your attacks.

You don't need to use your peak flow meter during an asthma attack. True or false? The answer is false. Peak flow meters can tell you how well your short-term, quick-relief asthma medication is working.