**5. Conclusions**

*Advances in Extracorporeal Membrane Oxygenation - Volume 3*

survival was over 85% [56].

**4.3 Routine ECMO prolongation**

these trends toward better outcomes after primary graft dysfunction appear to be improving due to ECMO support; in a large database study of the highest-risk transplant patients, patients demonstrate improving outcomes, particularly at high-volume centers [55]. In a review of the UNOS database, the use of postoperative ECMO support for primary graft dysfunction was still associated with a 6-month survival of over 60%, and while the subset of ECMO recipients also requiring dialysis had a only a 25% 6-month survival, if dialysis was not needed

Unfortunately, while early postoperative ECMO in the setting of primary graft

With increasing comfort with ECMO as postoperative support, the indications for extending its use have continued to expand. In some institutions, for example, intraoperative extracorporeal membrane oxygenation has been adopted for all unstable lung transplantations. Protocols have been proposed in which ECMO is prophylactically extended into the postoperative period based on graft quality and the preoperative presence of pulmonary hypertension. A recent single-institution analysis of this prophylactic protocol identified patients receiving ECMO as having improved survival compared to non-ECMO patients despite higher levels of medical complexity. Prophylactic ECMO prolongation is being increasingly recognized as a safe option for the routine postoperative support of patients with either marginal

In the same vein, research has been conducted to identify those patients at increased risk of ECMO weaning failure after lung transplantation, in order to identify those patients who might benefit from continued extracorporeal support. Identified risk factors including older donors, longer periods of donor mechanical ventilation, donor PaO2 prior to organ procurement and longer operative time [58]. In these patients, prophylactic ECMO support postoperatively may be

Ex vivo lung perfusion is another exciting breakthrough for the reconditioning of poor quality grafts as high risk of postoperative primary graft dysfunction. In this setup, retrieved donor lungs are perfused in an ex vivo circuit. This provides an opportunity for transplant surgeons to reassess graft function before transplantation, providing a more accurate window into the likelihood of success in transplantation with high-risk donor lungs. The use of an ex vivo circuit allows time for toxic waste products and inflammatory cytokines to be filtered out, for more optimal recruitment of collapsed lung areas, and for the fluid-overloaded lung tissue to be dehydrated by the perfusate high oncotic pressure [59]. In a 2015 study, lung transplant recipients who received lungs reconditioned in an ex vivo manner demonstrated significantly shorter hospital stay and trends toward shorter length

dysfunction is associated with reasonable outcomes, the late implementation of ECMO postoperatively (after 7 days) does not appear to have the same good outcomes. In a 2011 study of late ECMO support in lung transplant patients with infection or graft failure, none of the individuals who received late ECMO support survived to hospital discharge, due to the propagation of uncontrolled infection or organ failure that preempted ECMO support. This suggests that while ECMO can provide early support while awaiting graft recovery, it does not represent a means of

reversing complications existing prior to initiation of ECMO [57].

graft function or underlying pulmonary hypertension [12].

**4.4 Ex-vivo lung perfusion using ECMO**

of mechanical ventilation [48, 49].

**118**

recommended.

Ultimately, recent advances in ECMO have led it to become a critical tool in the armamentarium of the transplant surgeon, in both the preoperative period as a bridging strategy, as a tool for cardiopulmonary support during the operation, and for the rescue of potentially dysfunctional grafts postoperatively. The use of ECMO in lung transplantation has been need-driven in an incredibly complex and medically challenging complication; innovative thinking by basic scientists and transplant surgeons has led to remarkable improvements in patient outcomes. Continued advances in ECMO technologies, deeper experience with the implementation of ECMO in complicated clinical situations, and further high-quality research will help determine the areas where ECMO can help provide a benefit to lung transplant recipients.
