The peak expiratory flow rate (PEFR) is used to assess the severity of wheezing in those who have asthma or COPD. PEFR measures how quickly a person can exhale air from the lungs. A peak flow meter measures the airflow to determine the PEFR.

Those who monitor the PEFR must learn the proper technique for using the peak flow meter. Most children over 5 years of age can learn how to use the peak flow meter correctly.

Examples:

• Peak flow device
• Using a peak flow meter
• How to use a peak flow meter

The personal best PEFR represents a person's highest peak flow measurement: it is measured during a time when symptoms of lung disease are absent. The personal best PEFR is then used as a reference point for comparison. When wheezing or shortness of breath worsens, the PEFR is measured, and this value is compared to the personal best PEFR. This comparison is represented as a percentage, which is further classified into a PEFR zone.

PEFR zones:

• Green Zone: a PEFR that is 80-100% of personal best represents good control
• Yellow Zone: a PEFR that is 50-80% of personal best represents a moderate attack
• Red Zone: a PEFR that is less than 50% of personal best represents a severe attack and may identify the need for treatment in an emergency department

The PEFR zones help identify the best treatment for an acute attack of asthma.

Example:

• Treatment recommendations by peak flow zone