Extracorporeal membrane oxygenation (ECMO) has continued to evolve since the 1950s when the pioneers of cardiac surgery, Gibbon and Lillehei, developed cardiopulmonary bypass. While the cardiopulmonary bypass circuit is used for hours during cardiac surgery, the ECMO circuit can last for days to weeks. For lung transplantation, ECMO is used pre-transplantation for acute deterioration (severe respiratory failure with hypoxia or hypercarbia), bridge to organ availability, intraoperatively for poor lung function immediately post-transplantation, and post-operatively for acute rejection, infection, and bridge to re-transplantation. An analysis of United Network of Organ Sharing (UNOS) data found that pre-transplantation mechanical ventilation was associated with a twofold higher risk of death in the first 6 months after transplant (hazard ratio [HR], 1.92; 95% confidence interval [CI], 1.3–2.8; p < 0.0005), particularly in patients with cystic fibrosis, idiopathic pulmonary fibrosis, and restrictive lung disease.1
ECMO technique has evolved into four distinct categories: veno-venous (VV), veno-arterial (VA), veno-arterial-venous (VAV), and arterio-venous (AV). The approach utilized depends on the nature of the cardiopulmonary failure, such as acute respiratory (hypercarpnic or hypoxic), acute cardiac, or mixed. Importantly, many ECMO centers take the support system a step further by placing cannulas in configurations that allow ambulation.2,3 Therefore, patients are able to extubate and exercise to optimize physical conditioning in preparation for or recovery from lung transplantation. Use of ECMO in the setting of lung transplantation continues to grow rapidly as more centers address preoperative optimization of the donor and/or recipient, postoperative support for ischemia/reperfusion injury, and rescue during acute infection/rejection, all to improve overall outcomes.
The original ECMO circuit was veno-arterial (VA) as popularized by Robert Bartlett in the early 1980s for neonatal respiratory failure.4 Although Bartlett’s group began using ECMO for rescue following lung transplantation in the late 1980s, the first successful use of ECMO as a bridge to lung transplantation was described by Jurmann et al. in 1991.5 Two patients with severe primary graft dysfunction (PGD) after lung transplantation were placed on VA ECMO and underwent a successful retransplant procedure. One year later, the same group reported successful use of VV ECMO (femoral vein to internal jugular vein) as a bridge to primary lung transplantation in a patient who developed posttraumatic respiratory distress syndrome.6
ECMO equipment and applications have rapidly evolved in the last 10–15 years. Significant advances in commercially available oxygenator membranes have resulted in improved durability for all ECMO applications, including lung transplantation. Currently, most ECMO systems have replaced polypropylene with polymethylpentene (PMP) fiber gas exchange devices. PMP membrane oxygenators are smaller, provide efficient gas exchange without plasma leak, and allow faster priming (saving blood and valuable time and making CO2 flushing unnecessary). In addition, the PMP oxygenators have less circuit resistance, are less prone to malfunctioning secondary to blood trauma or blood clots, ...