Peak Flow Meters


Peak Flow Meter Monitoring


What is a Peak Flow Meter?

A peak flow meter is a simple, hand-held device that measures how fast a person can blow out air after a maximum inhalation. It helps measure how well your lungs are working.


Why Use a Peak Flow Meter? 

When your asthma is under control, your airways are open and you can blow more air into the peak flow meter. However, people with asthma cannot always feel the early changes taking place in their airways because these changes often occur gradually.  By the time you do start to feel like your asthma is a problem, you could be experiencing a 25 percent or greater decrease in lung function. A daily record of peak flow numbers can provide you with a valuable early warning sign that your asthma is getting worse. Peak flow numbers may decrease hours, or even a day or two before you feel asthma symptoms. By recognizing this drop in numbers, you can take steps to prevent an asthma attack.


Your doctor may recommend using a peak flow meter at least once a day-typically before taking your asthma medications in the morning. Record your daily readings in an asthma diary and bring this with you to your follow-up visits. This diary will help you and your doctor make decisions about the following:


  • Effectiveness of asthma medications
  • Adding or stopping medications
  • Determining the severity of your asthma
  • Recognize an asthma attack before signs or symptoms appear
  • When to seek emergency care


How to Use Your Peak Flow Meter? 

Peak flow meters are available for sale at this clinic or over the counter.  They are very easy to use and even young children, often by age 4 or 5, can learn how to use them accurately.  The frequency that you or your child record peak flow numbers depends upon the severity of your asthma, the season, and the pattern of symptoms. People with severe or unstable asthma may need to record peak flow values twice a day. People with mild or stable asthma may only need to use their peak flow two to three times a week.  However, remember to use it at least daily if you or your child are exposed to asthma triggers (such as allergens or smoke), for respiratory infections, or when there has been a change in your asthma medications. If you find yourself using Albuterol (rescue medication) more than two times a day, try checking your peak flow numbers before using Albuterol and 15 minutes after you have used Albuterol. If your numbers rise by more than 10-20% after using the Albuterol, you will know that your symptoms are likely related to an asthma flare. If they do not rise by more than 10-20%, you may be unnecessarily using Albuterol and you should speak with your doctor about other reasons that may be causing your symptoms of shortness of breath, cough, chest tightness or wheezing.


These are the steps to take when using your peak flow meter:


  1. Place the marker at the bottom of the numbered scale.
  2. Stand up.
  3. Take a deep breath in.
  4. Place your lips tightly around the mouthpiece and do not put your tongue in the hole.
  5. Blow as hard and fast as you can without bending over.
  6. Write down the number that you get. This is your peak flow rate.
  7. Repeat steps 1 through 6 two more times.
  8. Write down the highest of the three numbers that you get in your asthma diary.

It is important to keep your peak flow meter clean so that you continue to get accurate results. Follow the manufacturer’s instructions.


How to Determine Your Personal Best 

The highest number that you or your child can blow on a regular basis is your “personal best”.  You can determine this number by recording values twice daily for two to three weeks when your asthma is under good control.  Talk with your health care provider about your or your child’s “personal best”. A child’s “personal best” number will change as they grow.


How to Determine Your Zones 

Your healthcare provider will use your “personal best” number to establish peak flow zones: green (stable), yellow (caution) and red (alert).  They will then provide you with an “asthma action plan” that will explain your zones and what to do for each zone. If your peak flow readings fall into the yellow or red zone, you will need to take action to prevent or minimize an asthma attack.


  • Green Zone (80%-100% of “personal best”). If your numbers fall in this zone, your asthma is under good control. You probably have no asthma symptoms.  Continue to take your controller (preventative) medications.  There is a chance that your healthcare provider will reduce these medications if you continue to stay in your green zone over time.
  • Yellow Zone (50%-80% of “personal best”). If your numbers fall in this zone, you must exercise caution.  You or your child may have symptoms of asthma such as coughing, wheezing, difficulty breathing or chest tightness. You or your child may need more aggressive medical management for asthma. This may include a temporary increase in quick-relief (rescue) medicine and inhaled steroid medicine or an oral steroid burst.
  • Red Zone (50% or less of “personal best”). If your numbers fall in this zone, this could be a medical emergency. You may have severe coughing, wheezing and shortness of breath. You or your child need to immediately use a quick-relief medicine (i.e. Albuterol or Xopenex). Contact your doctor or seek emergency care if your numbers do not immediately return and stay in the yellow or green zones.


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Colorado Springs, Colorado 80906

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