The diagnostic accuracy of lung ultrasound to determine PiCCO-derived extravascular lung water in invasively ventilated patients with COVID-19 ARDS

Background: Lung ultrasound (LUS) can detect pulmonary edema and it is under consideration to be added to updated acute respiratory distress syndrome (ARDS) criteria. However, it remains uncertain whether different LUS scores can be used to quantify pulmonary edema in patient with ARDS. Objectives: This study examined the diagnostic accuracy of four LUS scores with the extravascular lung water index (EVLWi) assessed by transpulmonary thermodilution in patients with moderate-to-severe COVID-19 ARDS. Methods: In this predefined secondary analysis of a multicenter randomized-controlled trial (InventCOVID), patients were enrolled within 48 hours after intubation and underwent LUS and EVLWi measurement on the first and fourth day after enrolment. EVLWi and ∆EVLWi were used as reference standards. Two 12-region scores (global LUS and LUS–ARDS), an 8-region anterior–lateral score and a 4-region B-line score were used as index tests. Pearson correlation was performed and the area under the receiver operating characteristics curve (AUROCC) for severe pulmonary edema (EVLWi > 15 mL/kg) was calculated. Results: 26 out of 30 patients (87%) had complete LUS and EVLWi measurements at time point 1 and 24 out of 29 patients (83%) at time point 2. The global LUS (r = 0.54), LUS–ARDS (r = 0.58) and anterior–lateral score (r = 0.54) correlated significantly with EVLWi, while the B-line score did not (r = 0.32). ∆global LUS (r = 0.49) and ∆anterior–lateral LUS (r = 0.52) correlated significantly with ∆EVLWi. AUROCC for EVLWi > 15 ml/kg was 0.73 for the global LUS, 0.79 for the anterior–lateral and 0.85 for the LUS–ARDS score. Conclusions: Overall, LUS demonstrated an acceptable diagnostic accuracy for detection of pulmonary edema in moderate–to–severe COVID-19 ARDS when compared with PICCO. For identifying patients at risk of severe pulmonary edema, an extended score considering pleural morphology may be of added value. Trial registration: ClinicalTrials.gov identifier NCT04794088, registered on 11 March 2021. European Clinical Trials Database number 2020–005447-23.