Fig. 1
Flowchart of small airway function at 3–6 months follow-up in 20 adult patients hospitalised due to COVID-19. AX area of reactance, R5-20 differential change in airway resistance between 5 and 20 Hz, FVC forced vital capacity, FEV1/FVC forced expiratory ratio, MEF50 maximal flow at 50% of FVC, MMEF maximal mid-expiratory flow, FEV1 forced expiratory volume in 1 s, FENO fractional concentration of nitric oxide with flow 50 ml/s, NOalv alveolar nitric oxide concentration