Because there is doubt over the usefulness of the peak expiratory flow meter in assessing the course of chronic asthma, 55 children aged 6 to 18 years were studied over a period of 12 months. All children, who were receiving cromolyn sodium prophylaxis, were tested at monthly intervals with the peak expiratory flow rate (PEFR) meter and at three-month intervals by conventional spirometry.
The patients were separated into three groups according to their monthly PEFR results: (1) values always within normal limits; (2) values fluctuating between normal and abnormal ranges; and (3) values consistently subnormal. A "drop-off" of at least 15% in PEFR was observed with 25 of the 55 children when five successive expirations were measured.
The PEFR, the forced expiratory volume in the first second, and the maximum voluntary ventilation correlated well (P =.001) in all cases. Pulmonary function values in 16 patients (29%) failed to show the expected return to normal during the one-year period.
Isenberg PD, Hyde JS, Stine RH. Peak Expiratory Flow Rates in Chronic Asthma: A Gauge of Progression and Improvement. Am J Dis Child. 1973;125(3):341–345. doi:10.1001/archpedi.1973.04160030021004
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