Perfusion Abnormalities Shown On Subtraction CT Angiography In Apparently Normal Lungs And Their Impact On Patient Outcome. A Prospective Cohort Study: What Could We Be Missing?

Abstract Background: COVID-19 pneumonia seems to affect the regulation of pulmonary perfusion. In this study, through iodine distribution maps obtained with subtraction CT angiography, we quantified and analyzed perfusion abnormalities in patients with COVID-19 pneumonia and correlated them with clinical outcomes.Methods: 205 patients were included in this cohort, from two different tertiary-care hospitals in Chile. All patients had RT-PCR confirmed SARS-CoV-2 infection. CT scans were performed within 24 h of admission, in supine position. Airspace compromise was assessed with CT severity score, and the extension of hypoperfusion in apparently healthy lung parenchyma with perfusion score. CT severity and perfusion scores were then correlated with clinical outcomes. Multivariable analyses using Cox Proportional Hazards regression were used to control for clinical confounders.Results: Fourteen patients were excluded due to uninterpretable images. This left 191 patients, 112 males and 79 females. The mean age was 60.8±16.0 years. The median SOFA score on admission was 2 and average PaFi ratio was 250±118. Patients with severe perfusion abnormalities showed significantly higher SOFA scores and lower Pa/Fi ratios when compared to individuals with mild or moderate anomalies. Severe perfusion abnormalities were associated with an increased risk of intensive care unit (ICU) admission and the requirement of invasive mechanical ventilation (IMV).Conclusion: Patients with severe perfusion anomalies have a higher risk of admission to the ICU and IMV. Perfusion alterations could be considered as an independent risk factor in patients with COVID-19 pneumonia.Summary Statement: Lung perfusion abnormalities in patients with COVID-19 pneumonia were associated with admission to Intensive Care Unit and requirement of invasive mechanical ventilation. Perfusion abnormalities could be considered as an independent risk factor in patients with COVID-19 pneumonia.