Chest dual energy CT to assess the effects of steroids on lung function in severe COVID-19 patients

Background: Steroids have been shown to reduce inflammation, hypoxic pulmonary vasoconstriction (HPV) and lung oedema. Based on evidences from clinical trials, steroids are widely used in severe COVID-19. However, the effect on lung aeration and perfusion in this group of patients are unexplored. Objective: Profiting by dual energy computed tomography (DECT), we investigated whether steroids affect HPV in severe COVID-19 and whether they reduce lung oedema and improve gas distribution. Methods: . Severe COVID-19 patients included in a single-center prospective observational study at the intensive care unit at Uppsala University Hospital who had undergone DECT were enrolled in the current study. Patients’ cohort was divided in two groups depending on the administration of steroids. From each patient’s DECT, 20 inflation maps and 20 perfusion maps, evenly distributed along the cranial-caudal axis, were analyzed. To estimate HPV, perfusion distribution was analyzed in both the whole lung and the hypoinflated areas. Total lung weight, index of lung oedema, was estimated. Results: . Sixty patients were analyzed, whereof 43 received steroids. Patients exposed to steroids showed a better (non-perfused area 10% vs 15%, p < 0.01) and more homogeneous (kurtosis: 2.51 vs 1.85, p < 0.01) perfusion of hypoinflated areas, indicating reduced HPV. Moreover, they showed a significantly lower lung weight (853gr vs 1005gr, p = 0.01). Conclusions: . The use of steroids was associated with impaired HPV and reduced lung oedema in severe COVID-19. This is consistent with previous findings in other diseases. Moreover, reduced lung weight and a more homogeneous distribution of gas within the lung were shown in patients treated with steroids.Trial registration: Clinical Trials ID: NCT04316884, Registered March 13, 2020