Peak flow meter

Peak flow is the maximum exhalation speed after maximum inhalation. The measurement is carried out by means of a simple hand-held device, the Peak Flow Meter. The measurement can be performed by a well-trained patient himself. The patient compares the current value with his personal best value. The results, which can be kept in an "asthma diary", allow an orienting check of the lung function.

A drop in the peak flow values can herald an asthma attack. A so-called peak flow variability of >20% between morning and evening measurements is also a diagnostic criterion for bronchial asthma.