What is a Peak Flow meter?

A Peak Flow Meter is a small, easy-to-use instrument that measures how fast you can blow air out of your lungs after taking in the deepest breath you can. This number is called your peak expiratory flow. It reveals how well your lungs or your child’s lungs are working.

Sometimes Peak Flow numbers will decrease hours, or even a day or two, before other asthma symptoms become evident. It is important to monitor your Peak Flow numbers regularly as any decrease in these numbers could indicate the impending onset of an asthma episode. The Peak Flow numbers, along with watching for asthma symptoms, can be used to make decisions about your asthma treatment.

How do I establish my Personal Best?

The highest number regularly blown into your Peak Flow Meter is considered your Personal Best. This is done by recording Peak Flow values for two weeks first thing in the morning before taking any medications and in the late afternoon but only when your asthma is under control.

Once you know your or your child’s Personal Best, it may be helpful for you and your Allergist to use these Peak Flow Numbers to determine what to do if your Peak Flow reading is in a different “zone” than your Personal Best. The zone system can be compared to the colors of a traffic light. The following table shows an example of how these zones work and what to do if your Peak Flow reading falls below your Personal Best.

Green: 80-100% of your Personal Best:

Yellow: Caution 60-79% of your Personal Best

Red: Danger Below 60% of your Personal Best:

How do I use my Peak Flow meter?

How often should I check my Peak Flow?

If you are in a stable period with your asthma and your numbers do not appear to change much, you should check your Peak Flow once a day. The best time to do this would ideally be in the morning when you first wake up. We suggest you check your Peak Flow number at least twice a day, once in the morning and again in the evening, or more often if necessary when you or your child:

When should I report my Peak Flow number to my doctor?

Take your Peak Flow Meter as well as your Asthma Health Diary with you each time you visit with your Allergist. If you have an Asthma Action Plan from your Allergist, follow the Plan for each Peak Flow zone. Compare your Peak Flow numbers to your Personal Best. Here’s what we suggest based upon the relationship between your daily Peak Flow number and your Personal Best Peak Flow Number:

Do not rely on your Peak Flow numbers alone when deciding whether to take your rescue medicine or call your Allergist. Your symptoms also need to be considered.

How do I keep track of my Peak Flow numbers?

Write your Peak Flow numbers on your Peak Flow sheet or Asthma Health Diary. You can make your own if you do not have one. Be sure to write down any Peak Flows that are different from your usual daily readings.

Record the date, time and Peak Flow numbers. Also note any changes in how you feel or changes in your medicines. List anything you think may be making your asthma or your child’s asthma worse. Make sure to share this information with your Allergist when you are seen for an appointment.

If you have questions about how to use your Peak Flow Meter, feel free to contact our offices. One of our staff would be happy to answer your questions and discuss different treatment options offered at Allergy & Asthma Clinics of Ohio.
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