Determination of the values of specific physiologic tests has not been well studied in long-term asthma management in preschool children. We sought to determine the utility of impulse oscillometry in a long-term management in preschool children after asthma exacerbation.
40 outpatients, aged 3 to 5 years old, with mild-to-moderate asthma exacerbation from Shengjing Hospital of China Medical University were enrolled. The impulse oscillometry was performed immediately after enrollment (T0). And then during 24 weeks of therapy with inhaled corticosteroid, which were adjusted according to GINA report, impulse oscillometry was performed at 4 (T1), 12 (T2) and 24 (T3) weeks separately for every children. The differences of resistance at 5Hz (R5), resistance at 20Hz (R20), R5-R20, resonant frequency (Fres) and low frequency integrated reactance from 5Hz to Fres (AX), among four visits were measured by repeated-measures analysis.
For the 40 children, 26 were boys, the average age was 3.68±0.58 years old, the weight was 17.74±3.17 kg and the height was 103.95±6.49 cm. R5 was 1.27±0.33, 1.12±0.26, 1.01±0.26 and 0.89±0.24 kPa/L/s at T0, T1, T2 and T3 separately and the differences were significant when compared in pairs. R20 was 0.77±0.19, 0.67±0.16, 0.66±0.16 and 0.59±0.15 kPa/L/s separately, and the differences were significant except between T1 and T2. R5-R20 was 0.50±0.24, 0.45±0.18, 0.35±0.19 and 0.30±0.20 kPa/L/s separately, and the differences were significant except between T0 and T1. The Fres was 25.38±6.91, 22.70±3.19, 21.41±2.40 and 20.13±2.69 Hz separately, and the differences were significant. The AX was 4.29±1.91, 3.23±1.33, 2.48±1.28 and 1.81±0.90 kPa/L separately, and the differences were significant.
In preschool children, with the management of asthma after exacerbation, lung function assessed by impulse oscillometry improved in different degrees. R5, Fres and AX may reflect the ongoing improvements. Assessment of respiratory mechanics over time with oscillometry might offer useful insights into the response of asthmatic preschool children to therapy. Further studies should focus on longer term of management and the relationship between impulse oscillometry and airway inflammations.