Background: Most studies evaluating bronchodilation in flow-volume spirometry have been conducted in patients with obstructive airways diseases, but less is known about bronchodilation responses in the general population or in healthy subjects.
Methods: We evaluated an urban population sample of 628 adults (260 men, 368 women) aged 25 to 74 years with flow-volume spirometry using inhalation of 0.4 mg of a salbutamol aerosol with a spacer device for bronchodilation. On the basis of a structured interview, a subgroup of 219 healthy, asymptomatic nonsmokers was selected.
Results: In the population sample, the average increase in FEV1 from baseline after salbutamol inhalation was 77.2 mL (SD, 109.7 mL) or 2.5% (SD, 3.9%). In healthy asymptomatic nonsmokers, the mean change in FEV1 was 62.0 mL (SD, 89.7 mL) or 1.8% (SD, 2.6%). In the whole population, the 95th percentile limit of the increase in FEV1 was 8.5%, while it was 5.9% among healthy asymptomatic nonsmokers. The absolute change in FEV1 correlated significantly with baseline FVC (p < 0.01). The FEV1/FVC ratio at baseline was the strongest influencing factor for the bronchodilation response.
Conclusions: The results indicate that a significant increase in FEV1 from baseline in a bronchodilation test is around 9% in an urban population. The level of the significant absolute increase in FEV1 seems to depend on FVC. Low baseline FEV1/FVC ratio, reflecting airflow limitation, is the strongest determinant for FEV1 response to bronchodilation.