FEV1 response to bronchodilation in an adult urban population

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.

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.

In the population sample, the average increase in FEV(1) 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 FEV(1) 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 FEV(1) was 8.5%, while it was 5.9% among healthy asymptomatic nonsmokers. The absolute change in FEV(1) correlated significantly with baseline FVC (p < 0.01). The FEV(1)/FVC ratio at baseline was the strongest influencing factor for the bronchodilation response.

The results indicate that a significant increase in FEV(1) from baseline in a bronchodilation test is around 9% in an urban population. The level of the significant absolute increase in FEV(1) seems to depend on FVC. Low baseline FEV(1)/FVC ratio, reflecting airflow limitation, is the strongest determinant for FEV(1) response to bronchodilation.