Assessment of variable obstruction by forced expiratory volume in 1 second, forced oscillometry, and interrupter technique.

The aim of this study was to evaluate the presence and the degree of reversible airflow obstruction as detected by forced expiratory volume in 1 second (FEV1), forced oscillometry (FOT), and interrupter technique (resistance measured by the interrupter technique [Rint]) in mild asthmatic children compared with controls. FOT, Rint, and FEV1 were evaluated before and after albuterol (200 microg) administered by metered-dose inhaler and spacer in 28 asthmatic children (mean age +/-SD, 9.1 +/- 1.9 years) and in 20 healthy children (mean age +/-SD, 8.5 +/- 2.1 years). No correlation was found between FEV1, FOT, and Rint values either before or after albuterol. FOT and Rint values were highly correlated pre- and postbronchodilatation. An improvement in FEV1 > or =12\% after albuterol was observed in 11 (39\%) asthmatic subjects. As suggested using the cutoff value at R6 > or =29\%, significant bronchodilatation was observed in 20 (71\%) children with FOT and using a reduction > or = 0.20 kPa or 2 cm of H2O, 22 (78\%) subjects showed significant bronchodilatation with Rint. No significant changes were observed after albuterol in controls. FOT and Rint techniques showed a greater sensitivity in detecting reversibility of bronchoconstriction in mild asthmatic patients. Prospective studies are needed to clarify the possible advantages of these findings in mild-moderate asthmatic children.