Pulmonary Congestion (White Lungs) on VA ECMO

Abstract

Background Veno-arterial extracorporeal membrane oxygenation therapy (VA ECMO) is used for short-term circulatory support in the setting of cardiogenic shock or cardiac arrest. While VA-ECMO improves hemodynamics and gas exchange, it may result in left ventricular distention and pulmonary congestion. Methods The records of all patients supported with VA ECMO for at least three consecutive days at our institution from 2012-2014 were retrospectively analyzed. All chest radiographs taken during VA ECMO support were graded on a scale of 1 to 4. A score of 1 was used when no pulmonary congestion was present. A score of 2 was used for congestion occupying less than half of both lungs. A score of 3 was used for diffuse congestion occupying over half of both lung fields. A score of 4 was used when complete opacification of both lungs was present. Grades 3 and 4 were considered “white lungs”. The presence of white lungs was examined as a categorical variable. The grade of congestion was examined as a continuous variable. Ordinal logistic regression was used for the analysis. Results The sample size analyzed included 46 events of VA ECMO support in 44 individual patients. In 34 (73.9%) patients the lungs became opacified and reached a score of 3 or 4 (the white lungs group), while in 12 (%) patients there were no white lungs. Overall, the percentage of patients that survived to weaning off VA ECMO was 60.9%. The percentage of patients that survived to hospital discharge was 37.0%. In patients who did not have white lungs the percentages of survival to weaning off VA ECMO and survival to hospital discharge were 91.7% and 66.7%, respectively. In those with white lungs, the percentages of survival to weaning off VA ECMO and survival to hospital discharge were 50.0% and 26.5%, respectively (p=0.019 for discharged alive). The duration of VA ECMO support, ECMO flow, daily fluid balance, sum net fluid balance for the length of stay, and use of hemodialysis predicted a higher degree of pulmonary congestion. Conclusion Severe pulmonary congestion, or white lungs, is common in patients on VA ECMO and is associated with very poor prognosis. Longer duration of support, greater positive fluid balance, higher ECMO flow, and use of hemodialysis are linked to development of white lungs.