How To Use A Peak Flow Meter

1. Place the indicator at the base of the numbered scale.

2. Stand up

3. Take a deep breath.

4. Put the meter in your mouth and close your lips around the mouthpiece. Do not put your tongue inside the hole.

5. Blow out as hard and fast as you can.

6. Write down the number you get.

7. Repeat steps one through six two more times.

8. Write down the highest of the three numbers achieved.

Find Your Personal Best Peak Flow Number

Your personal best peak flow number is the highest peak flow number you can achieve over a 2-week period when your asthma is under good control. Good control is when you feel good and do not have any asthma symptoms.

Each patient’s asthma is different, and your best peak flow may be higher or lower than the usual average number for someone of your height, weight, and sex. This means that it is important for you to find your personal best peak flow number. Your medicine plan needs to be based on your personal best peak flow number.

To find out your personal best peak flow number:

  • take peak flow readings every day for two weeks mornings and evenings (when you wake up and about 10-12 hours later).
  • Before and after taking inhaled beta2-agonist (if you take this medication).
  • As instructed by your doctor

The Peak Flow Zone System

Once you know your personal best peak flow number, your doctor will give you the numbers that tell you what to do. The peak flow numbers are put into zones that are set up like a traffic light. This will help you know what to do when your peak flow number changes. For example:

Green Zone (80 to 100 percent of your personal best number) signals all clear. No asthma symptoms are present, and you may take your medicines as usual.

Yellow Zone (60 to 80 percent of your personal best number) signals caution. You may be having an episode of asthma that requires an increase in your medicines. Alternatively, your overall asthma may not be under control, and the doctor may need to change your medication plan.

Red Zone (below 60 percent of your personal best number) signals a medical alert. You must take an inhaled beta2-agonist right away and call your doctor immediately if your peak flow number does not return to the Yellow or Green Zone and stay in that zone. You will need Prednisone at this stage.

Use A Diary To Keep Track Of Your Peak Flow

Write down your peak flow number in the diary every day, or as instructed by your doctor.

Discuss With Your Doctor What To Do When Peak Flow Numbers Change

The most important thing about peak flow is how much it changes from your personal best number and one reading to another.

Don’t Forget: A decrease in peak flow of 20-30 percent of your personal best means the start of an asthma episode. When this happens, follow your asthma control plan for treating an asthma episode.

Peak Flow Meter


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