Background Understanding asthmatic airway structural changes and the bronchodilator responses may help unravel targets for intervention. However, structural abnormalities of asthmatic airways with different disease severity and the major anatomical site of bronchodilator responses have not been well elucidated. We aim to evaluate the airway remodeling characteristics and the bronchodilator responses in medium-sized and small airways of asthma. Methods We recruited 104 asthmatic patients and 31 non-smoking control subjects to compare the airway inner area (Ai) and airway wall area percentage (Aw%) with endobronchial optical coherence tomography. We also enrolled 32 patients with moderate-to-severe asthma to dynamically assess the airway morphological changes after salbutamol inhalation. Results More prominent airway structural abnormalities correlated with greater asthma severity, evidenced by the decreased Ai and greater Aw% in medium-sized and small airways. Patients with mild asthma yielded comparable Ai but greater Aw% than control subjects. Salbutamol inhalation led to a rapid dilatation of both medium-sized and small airways, the lung function improvement correlated significantly with the increase in Ai of the medium-sized, but not small, airways at 15 min. Conclusion Luminal narrowing and airway wall thickening of the medium-sized and small airways are present in mild asthma and reflect asthma severity, lending support to the use of anti-imflammatory intervention in mild asthma. The medium-sized airways are the crucial site of the bronchodilator responses, providing the scientific rationale for future development of more effective delivery of inhaled medications for asthma.

Objectives: We determined the clinical and imaging features of patients with severe COVID-19 that were associated with survival. Methods: Sixty-seven patients hospitalised with severe laboratory-confirmed COVID-19, were consecutively enrolled. Clinical data, blood measurements and chest computed tomographic (CT) scans were analyzed. Results: We compared the findings between 39 survivors and 28 non-survivors. At admission, although there were no differences in white blood cell (WBC) and platelet (PLT) counts, there was an increase of WBC, neutrophil, platelet distribution width and mean platelet volume with a marked decrease of lymphocyte, monocyte, eosinophil and PLT in non-survivor group on their last day compared to survivors (P < 0.05). Non-survivors had higher ratios of peak creatinine(P<0.05) and peak lactate dehydrogenase (LDH) (P<0.05). Compared to survivors, the incremental rate of total lesion area, ground-glass opacity (GGO) area and consolidation area on CT scans was increased in non-survivors (P<0.05).The deceleration rate of total lung volume was greater in non-survivors than survivors(P<0.05). Using the univariate survival analysis, the following were predictive of non-survival: time from admission to peak of D-dimer (D2D)<16 days , initial pro-BNP>319.0 pg/ml, peak procalcitonin (PCT) ≥0.19 ng/ml, peak creatinine>96.5 μmol/l ,peak alkaline phosphatase (ALP)>81.5 u/l, median time from admission to peak ALP<18 days, the acceleration rate of total lesional area> -11.5 cm3 /day, incremental rate of GGO area> 2.4 cm3 /day and the acceleration of consolidation area> 2.3 cm3 /day. Conclusion: Hematological counts, serum analytes and radiological indicators, the latter assessed by artificial intelligence, are robust predictors of survival outcome in COVID-19.