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Peak Flow Meter



A peak flow meter is a small device that measures how fast you can blow air out of your lungs after taking a deep breath. It can help to predict an asthma episode, let you know how well your medications are working, and tell you if your lungs are improving after an asthma attack. Children as young as 4 to 5 years old can use a peak flow meter to manage their asthma.

To measure your peak flow, first remove any food or gum from your mouth. Hold the peak flow meter, making sure that your fingers don’t block the opening. Stand or sit up straight and take a deep breath, completely filling your lungs with air. Put the mouthpiece in your mouth, making a seal with your lips, and blow out as hard and as fast as you can. The highest number recorded by the device is your peak flow. Repeat this process two more times.

Write down the date, time and highest of the three measurements in your asthma diary. The highest number blown regularly is your personal best. This number will be helpful to you and your doctor when determining your asthma management plan. These numbers will help you decide what to do when you have changes in your asthma.

Generally, peak flow zones are given the colors of green, yellow and red. If you peak flow falls into the GREEN zone, your asthma and its symptoms are under control and it’s advisable to continue with your current therapy. If your peak flow falls into the YELLOW zone, it’s normally a sign that your airways are narrowing. Call you physician to see if changes in your medications are needed to prevent an asthma attack. A measurement less than 50 percent of your normal peak flow will put you into the RED zone. You should take your rescue medication right away because severe narrowing of the airways may be occurring. Call your doctor right away.

Use your peak flow meter daily when you’re feeling good. This will tell you how well-controlled your asthma is and give you the earliest signs of an asthma flare-up. You should check your peak flow more often if you begin to wake up at night with asthma symptoms, have a respiratory infection, or have more daytime symptoms than usual. Sometimes your peak flow numbers will decrease a few hours or a day or two before other asthma symptoms appear.

When you monitor your peak flow on a regular basis, you can identify the trend, take your medication as directed by your physician and head off an asthma episode!

Click here for more information on peak flow meters, as well as illustrations.