Bedside Electrical Impedance Tomography Unveils Respiratory "Chimera" in COVID-19

• Published in: American journal of respiratory and critical care medicine 2021-01, Vol.203 (1), p.120-121
• Main Authors: Morais, Caio C A, Safaee Fakhr, Bijan, De Santis Santiago, Roberta R, Di Fenza, Raffaele, Marutani, Eizo, Gianni, Stefano, Pinciroli, Riccardo, Kacmarek, Robert M, Berra, Lorenzo
• Format: Article
• Language: English
• Subjects: COVID-19; COVID-19 - diagnosis; COVID-19 - epidemiology; Electric Impedance; Humans; Images in Pulmonary, Critical Care, Sleep Medicine and the Sciences; Lung - physiopathology; Pandemics; Point-of-Care Systems; Respiratory diseases; Respiratory distress syndrome; Respiratory failure; SARS-CoV-2; Tomography; Tomography - methods
• ISSN: 1073-449X; 1535-4970
• DOI: 10.1164/rccm.202005-1801IM

In 1981, Dr. Reginald Greene and colleagues illustrated extensive pulmonary artery filling defects in patients with different severity of acute respiratory failure by bedside angiographic studies. More recently, perfusion distribution and regional lung ventilation can be assessed at bedside by noninvasive, radiation-free electrical impedance tomography (EIT). In this report, the authors present three patients intubated for acute hypoxic respiratory failure owing to coronavirus disease (COVID-19). The three patients had similar levels of oxygenation but different respiratory system compliance (Figure 1). EIT was used to determine regional ventilation and perfusion distribution. Cases 1, 2, and 3 were assessed after 2, 17, and 19 days of mechanical ventilation, respectively. All patients were assessed by computed tomography (CT) without contrast. Case 1 CT imaging shows peripheral and basilar ground-glass opacities, compatible with known COVID-19 pneumonia. Case 2 and case 3 CT images describe diffuse bilateral ground-glass opacities. Case 1 had threefold higher respiratory system compliance than case 3. In Case 1, EIT showed severe right-lung perfusion anomalies, homogenous ventilation, and a moderate decrease in respiratory compliance (40 ml/cm H2O). Clinical diagnosis of pulmonary embolism was suggested by a high D-dimer (∼5,000 ng/ml) and lower extremity dopplers showing deep venous thrombosis. Case 2 and case 3 showed a progressive decrease of respiratory compliance (as low as 11 ml/cm H2O in case 3), without major perfusion disturbances. This report shows that clinical information of the patient coupled with real-time noninvasive bedside EIT might be helpful to characterize the etiology of hypoxemia of patients with respiratory failure with COVID-19..