[Peak flow monitoring of asthmatic patients. 1. Basis for measurement procedures and normal values]

Abstract

Peak flow monitoring (PEFM) consists of repeated measurements of the peak expiratory flow rate (PEF) frequently measured by means of small transportable peak flow metres which have proved sufficiently accurate for registration of alterations in PEF. In the majority of persons, not only asthmatics but also healthy individuals, characteristic diurnal variations in PEF are found. The variation amplitude is greatest in asthmatics. The scientific basis for the proposed norms and standards is incomplete but suggests that normal daily variations in PEF are less than 15-20%, calculated as the difference between the highest and lowest daily values as a percentage of the highest. At least 2-4 daily measurements should be made to obtain a reliable picture of the pattern of variation.