BACKGROUND: Small airways dysfunction (SAD) is not uncommon in asthma without fixed airflow obstruction (FAO). OBJECTIVE: We aimed to determine if SAD in non-FAO asthma is different from FAO-asthma and COPD. METHODS: Cases of obstructive airway diseases who underwent spirometry, plethysmography, and impulse oscillometry [resistance at 5 Hz (R5) and at 20 Hz (R20), peripheral resistance (R5-R20), and reactance area (AX)] were reviewed, and classified as; 1) COPD, 2) FAO-asthma, and 3) non-FAO asthma. FAO was defined as post-bronchodilator (post-BD) FEV1/ FVC < 0.7. SAD was considered if 1) RV/TLC ≥ 40%, or 2) post-BD R5-R20 ≥ 0.075 kPa.L-1s. RESULTS: A total of 73 patients (22 COPD, 24 FAO-asthma, and 27 non-FAO asthma) were analyzed. RV/TLC ratio was higher in FAO-asthma and COPD (45 ± 5% and 42 ± 8%) than in non-FAO asthma (32 ± 8%), p < 0.001. Post-BD values of R5-R20 and AX (median; range) were higher in FAO-asthma (0.17; 0.08, 0.47, 13.24; 6.52, 82.11) than in non-FAO asthma (0.11; 0.03, 0.23, 8.63; 2.40, 22.02), p = 0.007 and p = 0.017, respectively. The prevalence of SAD among diagnosis group by RV/TLC criterion was different (95%, 59%, and 15% in FAO-asthma, COPD, and non-FAO asthma, p < 0.001), but those were not observed by R5-R20 criterion (95%, 68%, and 77%, p = 0.052). CONCLUSIONS: SAD in non-FAO asthma was less prevalent than FAO-asthma and COPD.
BACKGROUND: Small airways dysfunction (SAD) is not uncommon in asthma without fixed airflow obstruction (FAO). OBJECTIVE: We aimed to determine if SAD in non-FAO asthma is different from FAO-asthma and COPD. METHODS: Cases of obstructive airway diseases who underwent spirometry, plethysmography, and impulse oscillometry [resistance at 5 Hz (R5) and at 20 Hz (R20), peripheral resistance (R5-R20), and reactance area (AX)] were reviewed, and classified as; 1) COPD, 2) FAO-asthma, and 3) non-FAO asthma. FAO was defined as post-bronchodilator (post-BD) FEV1/ FVC < 0.7. SAD was considered if 1) RV/TLC ≥ 40%, or 2) post-BD R5-R20 ≥ 0.075 kPa.L-1s. RESULTS: A total of 73 patients (22 COPD, 24 FAO-asthma, and 27 non-FAO asthma) were analyzed. RV/TLC ratio was higher in FAO-asthma and COPD (45 ± 5% and 42 ± 8%) than in non-FAO asthma (32 ± 8%), p < 0.001. Post-BD values of R5-R20 and AX (median; range) were higher in FAO-asthma (0.17; 0.08, 0.47, 13.24; 6.52, 82.11) than in non-FAO asthma (0.11; 0.03, 0.23, 8.63; 2.40, 22.02), p = 0.007 and p = 0.017, respectively. The prevalence of SAD among diagnosis group by RV/TLC criterion was different (95%, 59%, and 15% in FAO-asthma, COPD, and non-FAO asthma, p < 0.001), but those were not observed by R5-R20 criterion (95%, 68%, and 77%, p = 0.052). CONCLUSIONS: SAD in non-FAO asthma was less prevalent than FAO-asthma and COPD.
Authors: Alberto Papi; Dave Singh; J Christian Virchow; G Walter Canonica; Andrea Vele; George Georges Journal: Clin Transl Allergy Date: 2022-04-17 Impact factor: 5.657