In the accompanying article in this issue, we reported the survival of a 4 month old infant with severe necrotizing pneumonia due to respiratory syncytial virus (RSV) and methicillin-resistant Staphylococcus aureus (MRSA), resulting in cardiogenic shock and respiratory failure, who required a total of 233 days of extracorporeal membrane oxygenator (ECMO) support. In this article, we report the function of the ECMO membrane (oxygenator). To preserve oxygenator function, nitric oxide was added to the ECMO sweep gas (sNO). Despite prolonged ECMO support, a single membrane lung functioned effectively for 5 months. Structural analysis of the polymethylpentene (PMP) oxygenator postdecannulation revealed no thrombus or fibrin deposition. This is the first known structural evaluation of a PMP oxygenator after prolonged clinical use with sNO, suggesting that sNO may prolong oxygenator longevity and maintain functional performance.