Are we recording peak flows properly in young children?

Abstract

Peak flow rate is used in young children to assess bronchodilator response and monitor asthma status at home. Frequently the best of only three peak flow manoeuvres is reported. The aim of this study was to assess if this was sufficient to give the maximum peak flow rate and to determine the reproducibillty of the measurement. Thirty nine children aged between three and ten years were recruited. Peak expiratory flow rate (PEFR) was measured six times in each child at two minute intervals. Less than half (13 of 39) of the children made their maximum blow in the first three manoeuvres. The maximum peak flow from the second set of three blows was a median of 7% greater than that from the first three blows. The coefficient of variation of the measurement was 8.8% suggesting a change in PEFR greater than 17.6% is necessary to demonstrate a response to bronchodilator. We conclude three peak flow manoeuvres are insufficient in the majority of young children to demonstrate the maximum peak flow.