The Asthma Center

Peak flow meters

Monitoring asthmatic symptoms and periodically measuring breathing function (with pulmonary function tests) are important parts of the asthma treatment program. A peak flow meter is a simple device that may be used to monitor pulmonary function outside your physician's office by documenting the Peak Expiratory Flow Rate (PEFR). The peak flow meter is an inexpensive hand-held device that objectively indicates the degree of airflow obstruction and can be used easily at home or at work with proper training and effort. Your asthma specialists may request that you obtain a peak flow meter and record the test results while at home. The information gathered from measuring your peak flows in many cases will assist both you and your asthma specialists in better controlling your asthmatic symptoms. Peak flow rate monitoring may also offer you an early warning of an impending severe asthmatic attack.

PEFRs are not as sensitive or accurate as the spirometry tests performed in your doctors' office. Nevertheless, they are a valuable tool to self monitor asthma activity. Decreasing PEFRs below your best values indicate deteriorating asthma control. Also increasing differences between the morning PEFR (which is usually lower than evening rates) and the evening PEFR also indicate worsening asthma and is referred to as Peak Expiratory Flow Rate (PEFR) variability. Both PEFR variability and decreasing PEFRs indicate that your asthma is getting worse, even if you feel fine, and that you may need to increase your medications and/or speak to your doctor.

Peak Flow Meter Technique
PEFR Zones