Improvement in radiologic findings over time is associated with increased survival in patients with viral ARDS requiring extracorporeal membrane oxygenation.

Introduction: Acute respiratory distress syndrome (ARDS) requiring venovenous extracorporeal membrane oxygenation (VV ECMO) support is associated with chest radiograph changes commonly referred to as "drowning ECMO lung" ECMO lung presents as white-out of both lung fields, involving all lobes of the bilateral lungs. While the clinical significance of chest radiograph findings over time has been described in the general ARDS population, it has not been evaluated specifically in VV ECMO patients. This subpopulation suffers the most severe disease as well as the confounding effects of ECMO support.

Materials and methods: We identified 28 patients requiring VV ECMO cannulation for influenza-related ARDS between September 2009 and January 2018. Interpretation of chest X-ray images was divided into zones that correspond to anatomical lobes on computed tomography. Progression of radiologic injury was assessed by analysing the number of zones involved on the chest radiograph (X-ray) at days 1, 3, 7, 14, and 21 from cannulation and discharge. The primary endpoint was survival to hospital discharge.

Results: The majority of patients had complete opacification on days 1, 3, and 7 after VV ECMO cannulation. Patients with persistent complete opacification on chest X-ray infiltrate by day 14, following cannulation had an increased mortality. Survival to hospital discharge was increased in patients demonstrating improvement in radiological findings at day 19 compared to patients without significant radiologic improvement (100% vs 53%, log-rank P = 0.003).

Conclusion: The evolution and recovery of lung injury reflected by serial chest X-ray imaging studies after influenza-related ARDS requiring VV ECMO support is associated with improved survival in this single centre, retrospective cohort.