Abstract
Introduction Venous thromboembolism (VTE) is common after lung transplantation, yet inferior vena cava (IVC) thrombosis is a rare and easily overlooked cause of postoperative hypoxemia. Failure to recognize central venous obstruction can lead to unnecessary escalation of ventilatory or extracorporeal support. This case highlights IVC thrombosis above a pre-existing filter as a reversible cause of severe hypoxemia following lung transplantation. Case Description A 65-year-old man underwent bilateral lung transplantation for post-COVID pulmonary fibrosis. The early postoperative period was complicated by primary graft dysfunction requiring prolonged ventilation and, in postoperative week two, venovenous extracorporeal membrane oxygenation (VV-ECMO) rescue. ECMO cannulation was complicated by right femoral venous injury requiring repair and subsequent groin re-explorations. Anticoagulation was maintained with bivalirudin at a conservative activated partial thromboplastin time target due to thrombocytopenia and hemolysis. In week eight, worsening hypoxemia occurred despite stable ECMO flows and appropriate ventilator settings. Abdominal CT venography and catheter venography demonstrated thrombus within and extending above a previously placed IVC filter. Bilateral lower extremity duplex scans were repeatedly negative. Anticoagulation was intensified, and vascular surgery was consulted regarding thrombectomy, thrombolysis, and potential stenting. Careful coordination among transplant, critical care, and vascular teams led to stabilization and improved oxygenation without further intervention. Discussion This case underscores that persistent or unexplained hypoxemia after lung transplantation warrants imaging beyond the chest to evaluate for central venous obstruction. IVC thrombosis can occur despite negative duplex findings and may critically impair venous return during ECMO support. Awareness of this entity prevents misattribution of hypoxemia to graft dysfunction alone. Management requires a multidisciplinary approach balancing anticoagulation, bleeding risk, and potential endovascular options. Bivalirudin offers a titratable, non-heparin alternative in patients with bleeding concerns or heparin exposure. Early recognition of IVC obstruction allows targeted therapy and may restore gas exchange without unnecessary escalation of respiratory support. This abstract is funded by: None