What is a peak flow meter?
A peak flow meter is a portable device for people with asthma that measures the force of the airflow leaving the lungs. Measuring peak flow with this device is an important part of controlling asthma symptoms and preventing asthma attacks; therefore, it should be part of your personal asthma action plan.
Why should I measure the force of my exhalation?
Peak flow is a measure of how fast you can expel air from your lungs when exhaling forcefully after a full inhalation. This measurement is known as "peak flow" or "peak expiratory flow" (PEF). Monitoring PEF is a way to determine whether your asthma is under control or worsening. By combining this information with your prescribed asthma treatment plan, you can take appropriate steps to manage your asthma.
Asthma monitoring
When your asthma is not flaring up, your airways are open and allow air to be expelled quickly from your lungs, resulting in a high peak flow reading. Conversely, if your asthma is uncontrolled, your airways narrow and you cannot exhale rapidly, leading to a lower peak flow reading.
How is it measured?
Peak flow is measured using a small, portable device called a peak flow meter. This value is measured in liters per minute (L/min). When you blow into the mouthpiece, the indicator moves according to the force of your breath, and the marker's final position indicates the peak flow. To obtain the best peak flow reading, it is recommended to record the best result from three attempts.
Your healthcare professional will mark the color zones based on the best personal peak expiratory flow measurement recorded by you or your child (the best possible result when asthma is under control). The peak flow measurement will fall into one of these three zones, as shown below.
