Monitoring of peak expiratory flow rates in subjects with mild airway hyperexcitability.

Twenty-seven subjects with mild symptoms of bronchial hyperexcitability (cough, dyspnea, wheezing) and low to moderate degree of airway response to histamine monitored their peak expiratory flow rates (PEFR) for a mean +/- SD of 14.4 +/- 4.0 days. This assessment was performed without the use of any medication in 15 subjects, and before and after inhalation of salbutamol in 12 others. 100% and 52% of individuals, respectively, showed baseline FEV1 and maximum mid-expiratory flow rates greater than 80% of predicted. The improvement in FEV1 after salbutamol was less than 20% in every subject and from 10 to 20% in 15%. The mean daily percentage changes in PEFR were greater than the ones observed in normal individuals in only 21% and 50% of the subjects on no medication and on salbutamol, respectively. Diurnal changes in PEFR were significantly negatively correlated with the response to histamine (r = -0.51; p less than 0.01) and baseline FEV1 (r = -0.49; p less than 0.02). We conclude that there are minor fluctuations of PEFR in subjects with mild symptoms and low degree of airway excitability.