What is a Peak Flow Meter?

What is a peak flow meter?

A peak flow meter is a small device that you blow forcefully into after having taken a deep breath. It records the rate at which you've blown into it in liters exhaled per minute (L/min). This is called the peak expiratory flow rate (PEF or PEFR). The meter comprises a cylinder with a mouthpiece at one end, and a place for the air to escape at the other end, with a calibrated meter on the side. When air is blown into it, your PEF (peak expiratory flow) is measured.

Many asthmatics find that their maximum peak flow provides a good objective measure of how their asthma is doing, therefore peak flow meters are used extensively for self-monitoring of asthma, and also for monitoring the effectiveness of asthma medications.