Impaired pulmonary ventilation beyond pneumonia in COVID-19: A preliminary observation

Abstract

Background Coronavirus disease 2019 (COVID-19) may severely impair pulmonary function and cause hypoxia. However, the association of COVID-19 pneumonia on CT with impaired ventilation remains unexplained. This pilot study aims to demonstrate the relationship between the radiological findings on COVID-19 CT images and ventilation abnormalities simulated in a computational model linked to the patients’ symptoms. Methods Twenty-five patients with COVID-19 and four test-negative healthy controls who underwent a baseline non-enhanced CT scan: 7 dyspneic patients, 9 symptomatic patients without dyspnea, and 9 asymptomatic patients were included. A 2D U-Net-based CT segmentation software was used to quantify radiological futures of COVID-19 pneumonia. The CT image-based full-scale airway network (FAN) flow model was employed to assess regional lung ventilation. Functional and radiological features were compared across groups and correlated with the clinical symptoms. Heterogeneity in ventilation distribution and ventilation defects associated with the pneumonia and the patients’ symptoms were assessed. Results Median percentage ventilation defects were 0.2% for healthy controls, 0.7% for asymptomatic patients, 1.2% for symptomatic patients without dyspnea, and 11.3% for dyspneic patients. The median of percentage pneumonia was 13.2% for dyspneic patients and 0% for the other groups. Ventilation defects preferentially affected the posterior lung and worsened with increasing pneumonia linearly (y = 0.91x + 0.99, R2 = 0.73) except for one of the nine dyspneic patients who had disproportionally large ventilation defects (7.8% of the entire lung) despite mild pneumonia (1.2%). The symptomatic and dyspneic patients showed significantly right-skewed ventilation distributions (symptomatic without dyspnea: 0.86 ± 0.61, dyspnea 0.91 ± 0.79) compared to the patients without symptom (0.45 ± 0.35). The ventilation defect analysis with the FAN model provided a comparable diagnostic accuracy to the percentage pneumonia in identifying dyspneic patients (area under the receiver operating characteristic curve, 0.94 versus 0.96). Conclusions COVID-19 pneumonia segmentations from CT scans are accompanied by impaired pulmonary ventilation preferentially in dyspneic patients. Ventilation analysis with CT image-based computational modelling shows it is able to assess functional impairment in COVID-19 and potentially identify one of the aetiologies of hypoxia in patients with COVID-19 pneumonia.

129Xe MRI ventilation defects in ever-hospitalised and never-hospitalised people with post-acute COVID-19 syndrome

“…This evidence was also supported by the significant associations between CT findings including total airway count (reflecting airway narrowing or obliteration/occlusion), airway lumen area (narrowing or occlusion) and airway wall thickness with spirometry measurements of airflow obstruction. Recent studies have provided evidence of small airways disease in post-COVID-19 patients using the full-scale airway network flow model 50 or CT air-trapping functional small airways disease. 51 We did not acquire inspiratory-expiratory CT and thus could not quantify CT air-trapping, although the ratio of residual volume to total lung capacity (RV/TLC) was measured in 38 of our 76 participants and of these, 14 (37%) reported RV/TLC > upper limit of normal.…”

Postacute COVID-19 Syndrome: 129Xe MRI Ventilation Defects and Respiratory Outcomes 1 Year Later

“…In a pilot demonstration in four asymptomatic patients with COVID-19, 129 Xe MRI ventilation defects improved 12-months post-infection ( 20 ). In another investigation, full-scale airway network modelling of ventilation abnormalities differentiated dyspneic patients after COVID-19 infection ( 21 ).…”

COVID-19-Associated Pulmonary Embolism: Facts and Fallacies

“…The same happens in "lack of clinical improvement in ventilated patients" or in the patient with covid-19 pneumonia who develops right heart failure [51]. Another clinical scenario that suggests pulmonary thromboembolism in a patient with Covid-19 is a rapid deterioration in lung function, heart function, neurological function, and loss of perfusion (blood supply) to an extremity [52].…”