A peak flow meter is a portable, easy-to-use device that measures how well your lungs are able to expel air. By blowing hard through a mouthpiece on one end, the peak flow meter can measure the force of air in liters per minute and give you a reading on a built-in numbered scale. If you have asthma, your doctor may recommend that you use a peak flow meter to help track your asthma control.
Regular use of a peak flow meter can help keep tabs on your asthma by detecting airway narrowing even before you feel any symptoms, giving you time to adjust your medication or take other steps before your symptoms get worse. A peak flow meter can be useful for adults and children as young as 5.
A peak flow meter allows you to measure day-to-day changes in your breathing. Using a peak flow meter can help you:
Work with your doctor to make sure you get the right type of peak flow meter. Peak flow meters are available over-the-counter and can be purchased at a pharmacy. There are several types of peak flow meters available, and all of them work basically the same way: You blow a fast, hard breath into a mouthpiece and record the resulting score.
For the most accurate reading, be sure your peak flow meter is clean and, if applicable, fully charged.
Here's the correct way to use a peak flow meter:
To get accurate readings, make sure you know how to use your peak flow meter properly. Ask your doctor or other health care provider to watch you use it. It's also important to keep your peak flow meter clean. Follow the manufacturer's instructions — most peak flow meters require weekly cleaning with warm water and a mild detergent.
To start, your doctor will want to get an idea of your peak flow measurements when you feel good and have no asthma symptoms.
You'll record your daily peak flow rate over a two- to three-week period. Your highest peak flow rate over this period is known as your "personal best." Your personal best serves as a benchmark in your daily asthma management plan.
If your asthma is under control most of the time, your doctor may say it's OK to check your peak flow every few days instead of every day. If your asthma isn't very well-controlled, you may need to take peak flow readings more than once a day.
In addition to regular peak flow monitoring, you may need to check your peak flow in these situations:
Record your peak flow rate in an asthma diary. Some people record their peak flow meter readings by hand.
If you have an electronic personal health record, you may choose to enter your information into the record using a computer or mobile device. This gives you the option of sharing your data with your health care providers and family members. Some peak flow meters upload this data automatically.
Once you and your doctor have established your peak flow zones, you'll use a color-coded system based on your symptoms and your peak flow. This system tells you what to do when you are in each zone.
Your doctor will use your personal best to set your peak flow zones. Each zone is determined by your peak flow rate and symptoms. The color code for each zone reflects progressively more-severe symptoms:
Using a peak flow meter can be an effective tool for managing your asthma — but there are other things you need to do: