Lung Function and Lung Mechanics in Post-COVID-19 Patients: What we can Learn?

This study investigated the possible effects of different severities of COVID-19 on lung function and mechanics. Four patients’ groups were studied: Non-COVID-19 patients (n=21), Mild Post-COVID-19 patients (n=75), Moderate Post-COVID-19 patients (n=33), Severe Post-COVID-19 patients (n=20). Post-COVID-19 were evaluated between 3-15 days after hospital discharge. Lung function was evaluated by spirometry and lung mechanics by impulse oscillometry using MasterScreen (Jaeger, Germany), pre and post 400mcg of salbutamol sulfate. We observed that none post-COVID-19 patients presented impaired lung function (FVC, FEV1, FEV1/FVC, PEF, MEF25%, MEF50%, MEF75%) compared with non-post-COVID-19 patients. Severe post-COVID-19 patients presented increased resistance of the whole respiratory system (R5Hz) compared to non-post-COVID-19 patients (p<0.01), which has not been observed for Mild and Moderate Post-COVID-19. Severe post-COVID-19 presented increased resistance of the whole respiratory system (R5Hz) compared with Mild (p<0.01) and Moderate (p<0.01) post-COVID-19. Severe post-COVID-19 displayed increased resistance of the proximal airways (R20Hz) compared to non-post-COVID-19 (p<0.01), which has not been observed for Mild and Moderate Post-COVID-19. Severe post-COVID-19 presented increased proximal airway resistance (R20Hz) compared with Mild (p<0.01) and Moderate (p<0.01) post-COVID-19. No differences were found for the resistance of small/distal airways (R5Hz-R20Hz). No response was found for bronchodilator for spirometric and impulse oscillometry parameters. Impulse oscillometry is a more sensible method to detect pulmonary alterations in post-COVID-19 patients, without response to bronchodilator.