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May 6, 2020 / in Scientific Article

Abstract

BACKGROUND AND OBJECTIVE

Fixed airflow obstruction (FAO) in asthma occurs despite optimal inhaled treatment and no smoking history, and remains a significant problem, particularly with increasing age and duration of asthma. Increased lung compliance and loss of lung elastic recoil has been observed in older people with asthma, but their link to FAO has not been established. We determined the relationship between abnormal lung elasticity and airflow obstruction in asthma.

METHODS

Non‐smoking asthmatic subjects aged >40 years, treated with 2 months of high‐dose inhaled corticosteroid/long‐acting beta‐agonist (ICS/LABA), had FAO measured by spirometry, and respiratory system resistance at 5 Hz (Rrs5) and respiratory system reactance at 5 Hz (Xrs5) measured by forced oscillation technique. Lung compliance (K) and elastic recoil (B/A) were calculated from pressure–volume curves measured by an oesophageal balloon. Linear correlations between K and B/A, and forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC), Rrs5 and Xrs5 were assessed.

RESULTS

Eighteen subjects (11 males; mean ± SD age: 64 ± 8 years, asthma duration: 39 ± 22 years) had moderate FAO measured by spirometry ((mean ± SD z‐score) post‐bronchodilator FEV1: −2.2 ± 0.5, FVC: −0.7 ± 1.0, FEV1/FVC: −2.6 ± 0.7) and by increased Rrs5 (median (IQR) z‐score) 2.7 (1.9 to 3.2) and decreased Xrs5: −4.1(−2.4 to −7.3). Lung compliance (K) was increased in 9 of 18 subjects and lung elastic recoil (B/A) reduced in 5 of 18 subjects. FEV1/FVC correlated negatively with K (rs = −0.60, P = 0.008) and Rrs5 correlated negatively with B/A (rs = −0.52, P = 0.026), independent of age. Xrs5 did not correlate with lung elasticity indices.

CONCLUSIONS

Increased lung compliance and loss of elastic recoil relate to airflow obstruction in older non‐smoking asthmatic subjects, independent of ageing. Thus, structural lung tissue changes may contribute to persistent, steroid‐resistant airflow obstruction."

The articles include uses of tremoflo products or describes research devices that may not have been cleared by FDA
Source

Tonga KO, Chapman DG, Farah CS, Oliver BG, Zimmermann SC, Milne S, et al. Reduced lung elastic recoil and fixed airflow obstruction in asthma. Respirology. 2019:1–7.

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Longitudinal monitoring of asthma in the clinic using respiratory oscillometry
Asthma guidelines emphasize the importance of assessing lung function and symptoms. The forced oscillation technique (FOT) and its longitudinal relationship with spirometry and symptoms are unresolved. We examined concordance between longitudinal spirometry, FOT and symptom control, and determined FOT limits of agreement in stable asthma.
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We read with interest the article in the June 2020 issue of CHEST from Cottee et al,1 examining 52 patients with asthma, which concluded that bronchodilator response to albuterol 400 mg using forced oscillation technique (airway oscillometry [AO]) with Thorasys Tremoflo was more sensitive than spirometry at identifying poor disease control with the asthma control test.1 This pattern was observed for reactance area (AX) and reactance at 5Hz but not for resistance at 5Hz (R5).
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In an issue of CHEST (September 2020), Karakioulaki et al1 reinforced mounting evidence for the presence of regionally heterogeneous airway abnormalities in patients with asthma by showing histopathologic airway differences across lung lobes on endobronchial biopsy. At the lobar level, airway smooth muscle cell mass and the distance between the basement membrane and airway smooth muscle were significantly different across lobes. Airway smooth muscle cell mass was greater in lower lobes compared with upper lobes, and, although specific interlobar differences were not measured, the right upper lobe notably exhibited the least amount of airway smooth muscle mass.
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