Using a Peak Flow Meter

A peak flow meter measures how much air is passing through your airways. By testing regularly, you can often find out that you are having a flare-up before you can feel it.

Peak flow meters are very easy to use: Take a deep breath and breathe hard into the meter. Your doctor or nurse will show you how to use it the right way and what it is measuring.

Track your numbers
Every time you use the peak flow meter, write down the "peak flow number" in a log book. That way, you know for certain whether your symptoms are improving, staying the same or getting worse. Without the numbers, you are just guessing.  

Track your asthma "zones"
The numbers you get from the peak flow meter fall into what are called green, yellow and red "zones."

    Green Zone:  You're good to go
                o 80 to 100% of your personal best as measured by the peak flow
                   meter.
                o You are hitting your goals. Your daily medication is working. Asthma
                   is not stopping you from enjoying activities.
    Yellow Zone:  Warning
                o 50 to 80% of your personal best as measured by the peak flow
                   meter.
                o You are having some difficulty breathing, coughing, wheezing or
                   feeling short of breath.  
                o Take more medication as directed by your doctor.
    Red Zone:  Act now
                o Less than 50% of your personal best as measured by the peak flow
                   meter.
                o Your symptoms are constant. You may be waking up due to
                   wheezing or coughing.
                o Take quick-relief medication such as an inhaler as you and your
                   doctor have planned. If you don't improve, contact your doctor.