RESUMO
PURPOSE: Peak expiratory flow rate (PEFR) monitoring plays an important role in the diagnosis of airway obstruction and management of patients with bronchial asthma. This study compared the PEFR taken by a Microplus pocket spirometer and mini-Wright peak flow meter by assessing the extent of agreement between the instruments and the repeatability of measurements with each instrument. METHODS: Eighty healthy children (age 11-12 years, 43 females, 37 males) performed three PEFR maneuvers on the Microplus pocket spirometer and on the mini-Wright peak flow meter in a random order. Agreement and reproducibility between the two instruments were assessed by the statistical methods proposed by Bland and Altman. RESULTS: Seventy six (95%) of the PEFR taken by the mini-Wright peak flow meter were higher than that of Microplus pocket spirometer. The 95% limits of agreements (mean difference+/-2SD) between each instrument were very wide (2.7 to 144.3 L/min). The repeatability coefficient for the mini-Wright peak flow meter was 27 L/min and for the Microplus pocket spirometer was 33.5 L/min. Analysis by sex and order of usage did not show any significant differences. CONCLUSION: The limit of agreement between the Microplus pocket spirometers and the mini-Wright peak flow meter was too wide to use interchangeably.