[The peak flow meter: limited role in the diagnosis and follow-up of children with asthma].

The peak flow meter is commonly used to diagnose and follow up asthma in children and adults. This practice, however, is not supported by evidence from the literature. The amount of overlap in peak flow level and variation between healthy and asthmatic subjects precludes the use of peak flow diaries as a reliable tool in diagnosing asthma. It has also become clear that the correlation between peak flow variation and other indices of asthma severity is inconsistent. Moreover, children and adults have been shown to be unreliable in keeping peak flow diaries: 20-40% of all recorded values in a peak flow diary are invented, and another 25% are recorded inaccurately. Finally, self-management programmes for asthma have been shown to be effective, whether they incorporate peak flow monitoring or not. Therefore, peak flow registration cannot be recommended for the routine diagnosis and follow-up of asthma. In isolated cases however, such as patients who poorly perceive a deterioration of their asthma, or when it is unclear what triggers asthmatic symptoms, the peak flow meter can be useful.