Peak expiratory flow rate (PEFR) is the volume of air forcefully exhaled at maximum speed. This can be measured using a peak flow meter or a spirometry device. Peak flow meters are portable, inexpensive and widely available. The technique is non-invasive, carries no risk to the person, can be taught and learned quickly, and can easily be mastered by the patient. Published evidence for the use of peak expiratory flow rate (PEFR) and peak flow monitoring in asthma is limited, despite the use of the peak flow meter being documented in national and international guidelines for many years. National and international guidelines recommend the use of easily calibrated spirometers, which can provide accurate results
with good technique, along with fractional exhaled nitrous oxide (FeNO) testing, which requires a greater analysis and interpretation of the results. Is the use therefore of the peak flow meter redundant? This article discusses the indications for use of peak flow meters, technique and clinical context.