peak flow monitoring

A peak flow meter is a cheap, handheld tube you blow into as hard and fast as you can; it reads the top speed of your exhaled air. Tracking that number day to day is like a weather gauge for the airways — a small drop can warn of a storm before you feel much wrong.

Peak flow monitoring is the home measurement of peak expiratory flow (PEF) to detect worsening asthma early. Because narrowed airways slow the fastest part of a forced exhalation, a falling PEF often signals trouble before symptoms become obvious. Readings are compared against the person's own 'personal best' rather than population averages, and trends matter more than a single value.

It is especially useful for those who do not sense airway narrowing well or who have had severe attacks, and it underpins written asthma action plans that use zones (often green, yellow, red) to tell people when to step up treatment or seek help. It does not replace spirometry for diagnosis, and good technique plus a consistent meter are essential for reliable readings.