Abstract
Background: Previous reports suggest that small airway dysfunction (SAD) is associated with poor asthma control.
Objective: To determine the usefulness of the study of the SAD in assessing asthma control.
Methods: A cross-sectional study was performed in children aged between 6-15 years old diagnosed with moderate asthma and FEV1 >80% at the time of inclusion.A forced spirometry,a determination of R5-R20 by impulse oscillometry, a plethysmography and a bronchodilator test were performed.Exhaled nitric oxide (NO) at multiple flow rates was measured and alveolar NO concentration (CANO) was calculated.Asthma Control Questionnaire Test (ACT) and Asthma Quality of Life Questionnaire were completed by patients (PAQLQS) and caregivers (PACQLQ).The prevalence of the SAD was defined by the presence of one or more of the following criteria:CANO ≥4.5ppb,RV/TLC≥33%,R5-R20 ≥0.147kPa/L/s and FEF25-75 < 2 z-score.The association and correlation among CANO,R5-R20, RV/TLC, FEF25-75,PAQLQS/PACQLQ and ACT was studied using Spearman's rho and Pearson's chi-squared test (χ2).
Results: 100 subjects were studied distributed into group 1 (poor control, n=29) and 2 (good control, n=71). At least 1 criteria of SAD was found in 59% and 2 criteria in 27%.R5-R20 was increased in 49%, RV/TLC in 20%, CANO in 7% and FEF25-75 was decreased in19%.FEF25-75 and PAQLQS/PACQLQ scores were significantly lower in group 1.Moderate correlation was found between FEF25-75 and R5-R20. No association was found to establish the degree of asthma control among the rest of the variables studied.
Conclusion: In our sample, SAD was found in more than half of asthmatic children, but only FEF25-75 provides additional information to assess asthma control.
- Copyright ©the authors 2016
