What is a Peak Flow Meter?

A peak flow meter is a hand held device which measures the amount of air which someone can push through their bronchial tubes in a single rapid burst. These devices are commonly used in asthma management, although they can be utilized in the management of other lung conditions. The lower the peak flow reading, the more obstructed the patient's airways.

To use a peak flow meter, a patient stands up straight, takes a deep breath, and blows hard into the base of the meter, pushing as much air out of the lungs as possible. A slider on the meter moves up with the breath, indicating the volume of air exhaled. This process is repeated twice to arrive at an average, and the average is typically recorded in a peak flow chart.

Acceptable ranges on the peak flow meter vary, depending on the patient and his or her condition. Many doctors ask patients to find a personal best range by using the peak flow meter twice a day for two weeks, and picking the highest reading as the personal best. This reading can be used to establish green, yellow, and red zones on the peak flow meter which can be used in an asthma management plan.

When a reading falls in the green zone, it means that it is between 80 and 100 percent of the personal best, and that the patient's condition is under control and being well managed. Yellow readings between 50 and 80 percent indicate that a problem may be developing, and that the patient may need to adjust asthma medications, moderate an exercise program, or remain indoors to avoid air inversions and pollution. Red readings below 50 percent of normal lung function suggest that the patient needs medical attention immediately.

Patients use peak flow meters to get a picture of their overall health over time. The peak flow meter is often used in the morning and in the afternoon to get two examples of readings from different periods of the day. Asthma management plans may include specific measures to take in response to changes in peak flow readings, such as increasing the dosage or frequency of a medication if readings fall into the yellow zone.

Peak flow meters can provide useful early warnings to patients. Thanks to the fact that the device is portable, patients can also bring their peak flow meters to exercise and on other outings to monitor their lung function, and the device is unobtrusive, for patients who do not wish to attract attention.