Related Experiment Video
Updated: May 12, 2026

Employing the Forced Oscillation Technique for the Assessment of Respiratory Mechanics in Adults
Published on: February 9, 2022
Persisting airway obstruction in asymptomatic children with asthma with normal peak expiratory flow rates
1Department of Paediatrics, University of British Columbia, Vancouver, Canada.
Abstract:
Twice-daily symptom scores and peak expiratory flow readings were compared with spirometric values (FEV1 and forced expiratory flow rate between 25% and 75% of FVC [FEF 25-75]) measured at 2-week intervals in assessing airway obstruction in 20 children with asthma studied during 16 weeks. Of 56 2-week periods during which symptoms were absent, peak flow was decreased in 30 (54%), FEV1 in 20 (36%), and FEF 25-75 in 37 periods (66%). Peak flow readings were normal in 13 of 70 periods (16%) in which FEV1 was decreased, and in 33 of 113 periods (29%), in which FEF 25-75 was decreased. Of 25 periods in which symptoms were absent and peak flow was normal, 19 (76%) were associated with decreased FEF 25-75. The results confirm previous studies that indicate peak flow readings are a useful addition to symptom diaries. More importantly, they demonstrate that airway obstruction may be present in a large proportion of asymptomatic children with asthma who have normal peak flow rates and suggest that frequent assessment of FEF 25-75 is required, as well as daily monitoring of symptoms and peak flow both in trials of drug therapy and for more optimal assessment of the effectiveness of therapy in clinical practice.
Related Concept Videos
Respiratory Volumes and Capacities I
Assessment of Airway, Skin Color, and Use of Accessory Muscles
Introduction
The initial evaluation of a patient's respiratory system...
Asthma-III: Symptoms and Complications
Classification of Asthma
Asthma III: Clinical Manifestations
Chronic Obstructive Pulmonary Disease III: Chronic Bronchitis Features
Chronic Obstructive Pulmonary Disease IV: Clinical Manifestations

