Abnormal pulmonary function and imaging studies in critical COVID-19 survivors at 100 days after the onset of symptoms

Abstract

Background: The long-term repercussions of critical COVID-19 on pulmonary function and imaging studies remains unexplored. In this study, we investigated the pulmonary function and computed tomography (CT) findings of critical COVID-19 patients approximately 100 days after symptom onset.

Methods: We retrospectively extracted data on critical COVID-19 patients who received invasive mechanical ventilation during hospitalization from April to December 2020 and evaluated their pulmonary function, residual respiratory symptoms and radiographic abnormalities on CT.

Results: We extracted 17 patients whose median age was 63 (interquartile range [IQR], 59-67) years. The median lengths of hospitalization and mechanical ventilation were 23 (IQR, 18-38) and 9 (IQR, 6-13) days, respectively. At 100 days after symptom onset, the following pulmonary function abnormalities were noted in 8 (47%) patients: a diffusion capacity of the lung for carbon monoxide (%DL_CO) of <80% for 6 patients (35%); a percent vital capacity (%VC) of <80% for 4 patients (24%); and a forced expiratory volume in one second/forced vital capacity (FEV₁%) of <70% for 1 patient (6%) who also presented with %DL_CO and %VC abnormalities. Twelve (71%) patients reported residual respiratory symptoms and 16 (94%) showed abnormalities on CT.

Conclusions: Over 90% of the critical COVID-19 patients who underwent invasive mechanical ventilation continued presenting with abnormal imaging studies and 47% of the patients presented with abnormal pulmonary function 100 days after symptom onset. The extent of the residual CT findings might be associated with the degree of abnormal pulmonary function in critical COVID-19 survivors.

Keywords: COVID-19; Computed tomography; Diffusion capacity of the lung for carbon monoxide; Long-term; Pulmonary function; Residual symptoms.