Lung transplantation is sometimes the final therapeutic step for patients with end-stage lung diseases such as pulmonary fibrosis, chronic obstructive pulmonary disease (COPD), and pulmonary hypertension. Traditionally, cardiopulmonary bypass (CPB) has been the preferred intraoperative support technique, providing complete hemodynamic support while maintaining oxygenation and decarboxylation during surgery. However, CPB use is associated with significant complications, including systemic inflammation, coagulopathy, and a higher risk of bleeding due to the need for heparinization.

With advancements in medical technology, extracorporeal membrane oxygenation (ECMO) has emerged as a viable alternative, offering many benefits of CPB with a reduced complication profile. ECMO uses a smaller, closed circuit and requires lower anticoagulation doses, reducing bleeding risks and coagulopathy-related complications. However, ECMO adoption has not been uniform, and debates continue regarding the optimal choice of intraoperative support.

This review was conducted through a comprehensive PubMed search for studies on the use of intraoperative mechanical circulatory support in lung transplantation. Both prospective and retrospective studies evaluating the clinical outcomes of patients undergoing lung transplantation with CPB or ECMO were selected. Inclusion and exclusion criteria were rigorous, prioritizing recent, relevant, and well-designed studies. Study characteristics, patient populations, interventions, and clinical outcomes were analyzed. Data were synthesized using descriptive and comparative statistical techniques to evaluate the findings of the included studies.

The main findings indicated that ECMO was associated with better clinical outcomes than CPB. Reviewed studies showed that ECMO was linked to lower in-hospital mortality, reduced need for blood and platelet transfusions, and fewer postoperative complications. Additionally, patients receiving ECMO support tended to experience a significant reduction in primary graft dysfunction and postoperative mechanical ventilation time. For example, the study by Lus et al. found that ECMO use during lung transplantation resulted in a 10% in-hospital mortality rate compared with 30% in patients receiving CPB. Another study by Bermúdez et al. reported that patients on ECMO had an average ventilation time of 48 hours, significantly shorter than the 72-hour average for CPB patients. Additionally, ECMO showed a lower incidence of complications such as excessive bleeding and acute renal failure.

In conclusion, the authors suggest that ECMO should be considered the standard intraoperative support for lung transplantation due to its demonstrated benefits in survival and complication reduction. The adoption of ECMO could significantly improve postoperative outcomes and patient quality of life, especially for those with high-risk preoperative factors.

COMMENTARY:

The critical analysis of this work reveals several significant strengths and weaknesses. First, the systematic review is well-structured and addresses a clinically relevant question. Understanding the outcomes of the CPB versus ECMO comparison is crucial to improving lung transplantation outcomes and reducing complications associated with intraoperative mechanical circulatory support. The evidence presented suggests that ECMO is superior to CPB in several important aspects, including in-hospital mortality and postoperative complications.

One of the main strengths of this work is the thoroughness of the literature search and inclusion of recent, relevant studies, providing a solid foundation for the authors’ conclusions and recommendations. Additionally, the detailed comparison of clinical outcomes between CPB and ECMO offers valuable insights into the benefits and drawbacks of each modality, which is of great value to medical teams performing lung transplants. However, some limitations should also be considered. The variability in the designs of the included studies and the differences in patient populations may affect the generalizability of the results. For example, some studies may have included patients with more severe preoperative conditions, which could influence observed outcomes. Indeed, since the evidence used is not based on randomized studies, the need for more effective circulatory support, as CPB is capable of providing, leads to patient selection in this group with poorer clinical conditions. Furthermore, most of the reviewed studies are retrospective, introducing potential selection and information biases, as older studies more frequently used CPB than recent studies.

Nevertheless, in clinical practice, the routine implementation of ECMO could transform the intraoperative management of lung transplantation. ECMO offers not only survival benefits but also enhances postoperative recovery by reducing the need for prolonged mechanical ventilation and ICU stays. This, in turn, may reduce the costs associated with postoperative care and improve patient quality of life. Moreover, this work raises new questions about optimizing ECMO protocols. For instance, what are the best criteria for selecting patients who would benefit most from ECMO? How can the risk of ECMO-associated complications be further minimized? These are important areas for future research that could help refine and enhance ECMO use in lung transplantation. Another area of interest for future research is the cost comparison between CPB and ECMO. Although ECMO may reduce postoperative complications and ICU stays, its initial implementation may be more costly due to technical requirements and staff training. Detailed economic evaluations could provide a better understanding of ECMO’s cost-effectiveness compared to CPB.

In summary, this systematic review provides robust evidence of the benefits of ECMO in lung transplantation, offering clear answers to a crucial clinical question and raising new questions about its application and optimization in daily practice. Adopting ECMO as the standard of care could significantly impact clinical outcomes for lung transplant patients, improving both postoperative survival and quality of life. The implementation of standardized protocols for ECMO use, along with additional research on its costs and long-term benefits, could solidify its position as the preferred support modality in lung transplantation.

REFERENCE:

Laskey D, Housman B, Dawodu G, Scheinin S. Intraoperative Extracorporeal Support during Lung Transplantation: Not Just for the High-Risk Patient. J Clin Med. 2023 Dec 29;13(1):192. doi: 10.3390/jcm13010192.