Self monitoring of peak expiratory flow rate in asthma

Peak Expiratory Flow Rate (PEF) is a simple and reproducible indicator of ventilatory function.1 It is the maximal airflow sustained for at least 10 msec during a forced expiration after deep inspiration. PEF is easy to measure with the Wright Peak Flow Minimeter. Results from this simple lightweight instrument correlate well with those from the older, bigger model.2 Predicted values vary with age, sex and height in adults;3,4 in children they are related to height alone.4,5 It is usual to record the best of three readings.