Lung transplantation via cardiopulmonary bypass: excellent survival outcomes from extended criteria donors

Which strategy is better for lung transplantation: Cardiopulmonary bypass or extracorporeal membrane oxygenation?

Background: In lung transplantation surgery, extracorporeal life support (ECLS) is essential for safety. Various support methods, including cardiopulmonary bypass (CPB) and off-pump techniques, are used, with extracorporeal membrane oxygenation (ECMO) gaining prominence. However, consensus on the best support strategy is lacking.Purpose: This article reviews risks, benefits, and outcomes of different support strategies in lung transplantation. By consolidating knowledge, it aims to clarify selecting the most appropriate ECLS modality.Research Design: A comprehensive literature review examined CPB, off-pump techniques, and ECMO outcomes in lung transplantation, including surgical results and complications.Study Sample: Studies, including clinical trials and observational research, focused on ECLS in lung transplantation, both retrospective and prospective, providing a broad evidence base.Data Collection and/or Analysis: Selected studies were analyzed for surgical outcomes, complications, and survival rates associated with CPB, off-pump techniques, and ECMO to assess safety and effectiveness.Results: Off-pump techniques are preferred, with ECMO increasingly vital as a bridge to transplant, overshadowing CPB. However, ECMO entails hidden risks and higher costs. While safer than CPB, optimizing ECMO postoperative use and monitoring is crucial for success.Conclusions: Off-pump techniques are standard, but ECMO's role is expanding. Despite advantages, careful ECMO management is crucial due to hidden risks and costs. Future research should focus on refining ECMO use and monitoring to improve outcomes, emphasizing individualized approaches for LT recipients.

Initial experience and outcomes with a hybrid extracorporeal membrane oxygenation and cardiopulmonary bypass circuit for lung transplantation

Background

The utilization of extracorporeal life support (ECLS) for intraoperative support during lung transplantation has increased over the past decade. Although veno-arterial extracorporeal membrane oxygenation (VA-ECMO) has recently emerged as the preferred modality over cardiopulmonary bypass (CPB), many centers continue to use both forms of ECLS during lung transplantation. Our novel hybrid VA-ECMO/CPB circuit allows for seamless transition from VA-ECMO to CPB at a significant cost savings compared to a standalone VA-ECMO circuit. This study describes our initial experience and outcomes in the first 100 bilateral lung transplantations using this novel hybrid VA-ECMO/CPB circuit.

Methods

Medical records from September 2017 to May 2021 of the first 100 consecutive patients undergoing bilateral lung transplantation with intraoperative hybrid VA-ECMO support were examined retrospectively. We excluded patients with single lung transplants, retransplantations, preoperative ECLS bridging, and veno-venous (VV) ECMO and those supported with CPB only. Perioperative recipient, anesthetic, perfusion variables, and outcomes were assessed.

Results

Of the 100 patients supported with VA-ECMO, 19 were converted intraoperatively to CPB. Right ventricular dysfunction was seen in 37% of patients, and the median mean pulmonary artery pressure was 28 mm Hg. No oxygenator clotting was observed with a median heparin dose of 13,000 units in the VA-ECMO group. Primary graft dysfunction grade 3 at 72 hours was observed in 10.1% of all patients and observed 1-year mortality was 4%.

Conclusions

The use of a hybrid VA-ECMO/CPB circuit in our institution allows for rapid conversion to CPB with acceptable outcomes across a diverse recipient group at a significantly reduced cost compared to standalone VA-ECMO circuits.

Taking a Deep Breath: an Examination of Current Controversies in Surgical Procedures in Lung Transplantation

Purpose of Review

This article reviews controversial questions within the field of lung transplantation, with a focus on data generated within the last 3 years. We aim to summarize differing opinions on a selection of topics, including bridge-to-transplantation, intraoperative machine circulatory support, bronchial anastomosis, size mismatch, delayed chest closure, and ex vivo lung perfusion.

Recent Findings

With the growing rate of lung transplantations worldwide and increasing numbers of patients placed on waiting lists, the importance of determining best practices has only increased in recent years. Factors which promote successful outcomes have been identified across all the topics, with certain approaches promoted, such as ambulation in bridge-to-transplant and widespread intraoperative ECMO as machine support.

Summary

While great strides have been made in the operative procedures involved in lung transplantation, there are still key questions to be answered. The consensus which can be reached will be instrumental in further improving outcomes in recipients.

Intraoperative support during lung transplantation

The role of intraoperative mechanical support during lung transplantation (LTx) is essential to provide a safe hemodynamic and ventilatory status during critical intraoperative events. This hemodynamic and ventilatory stability is vital to minimize the odds of suboptimal outcomes, especially considering that, due to the scarcity of donors and the fact that more and more patients with significant comorbidities are being considered for this therapy, a more aggressive approach is often needed by the transplant centers. Hence, the attenuation of any potential injury that can happen during this complex event is paramount. While a thorough assessment of the donor and optimization of postoperative care is pursued, certainly protective intraoperative management would also contribute to better outcomes. Understanding each patient’s underlying anatomy and cardiopulmonary physiology, associated with awareness of critical events during a complicated procedure like LTx, is essential for a precise indication and safe use of support. Cardiopulmonary bypass (CPB) and veno-arterial extracorporeal membrane oxygenation (VA ECMO) have been the most common approaches used, with the latter gaining popularity more recently and we have used VA ECMO exclusively for the last decade. New technologies certainly contributed to more liberal use of VA ECMO intraoperatively, enabling a protecting and physiologic environment for the newly implanted grafts. In this setting, potential prophylactic use for lung protection during a critical period is also considered.

Meticulous closure of collateral vessels in the perihilar mediastinal pleura to control intraoperative bleeding during lung transplantation for pulmonary hypertension

Background

Massive blood transfusion compensating hemorrhage during lung transplantation (LT) results in primary graft dysfunction (PGD) and worse outcomes after LT. Collateral vessels in the perihilar mediastinal pleura could be the source of hemorrhage during LT in patients with pulmonary hypertension (PH). The purpose of this study was to examine the effect of closure with hemoclips of the vessels in the perihilar mediastinal pleura on the risk of intraoperative hemorrhage and outcomes after LT in patients with PH.

Methods

We retrospectively reviewed 80 patients who underwent LT, including 13 patients with primary PH, 29 patients with secondary PH, and 38 patients with non-PH.

Results

The median number of hemoclips was significantly higher in the primary PH group than in the non-PH group (P=0.0045) or secondary PH group (P=0.0060). The intraoperative blood loss, transfusion volume, maximum PGD grade, and the 30-day and 90-day mortality rates in the primary PH group were equivalent to those in the other two groups.

Conclusions

Meticulous closure of collateral vessels in the perihilar mediastinal pleura during LT in patients with primary PH allowed intraoperative hemorrhage to be controlled and might be associated with acceptable mortality rate in these patients similar to that of LT in patients with other diseases.

Extracorporeal life support during lung transplantation

Lung transplantation surgeries are performed without extracorporeal life support (ECLS) by using an off-pump technique; however, in cases of hypoxemia or hemodynamic instability, intraoperative ECLS may be required. Cardiopulmonary bypass (CPB) has traditionally been the standard practice for ECLS but has been associated with an increased risk of bleeding in the perioperative period, increased transfusion requirements, prolonged postoperative intubation, and possibly primary graft dysfunction. More recently, because of the flexibility of using extracorporeal membrane oxygenation (ECMO) in bridging to transplantation and during postoperative recovery, its use has increased. CPB and ECMO each has advantages and disadvantages; however, because comparisons of CPB and ECMO have been limited to small retrospective observational and single-institution studies, more research is required to determine the superiority of one modality. In this review, we critically examine the pros and cons of performing lung transplantation surgery off-pump or by using the ECLS modalities of ECMO and CPB support during lung transplantation surgery.

Comparison of mechanical cardiopulmonary support strategies during lung transplantation

INTRODUCTION

Lung transplantation outcomes are influenced by the intraoperative mechanical cardiopulmonary support strategy used. This surgery was historically done either on cardiopulmonary bypass (CPB) or off pump. Recently, there has been increased interest in intraoperative support with veno-arterial (VA) or veno-venous (VV) extracorporeal membrane oxygenation (ECMO). However, there is a lack of consensus on the relative risks, benefits and indications for each intraoperative support strategy.

AREAS COVERED

This review includes information from cohort studies, case-control studies, and case series that compare morbidity and/or mortality of two or more intraoperative cardiopulmonary support strategies during lung transplantation.

EXPERT OPINION

The optimal strategy for intraoperative cardiopulmonary support during lung transplantation remains an area of debate. Current data suggest that off pump is associated with better outcomes and could be considered whenever feasible. ECMO is generally associated with preferable outcomes to CPB, but the data supporting this association is not robust. Interestingly, whether CPB is unplanned or prolonged might influence outcomes more than the use of CPB itself. These observations can help guide surgical teams in their approach for intraoperative mechanical support strategy during lung transplantation and should serve as the basis for further investigations.

Acute Kidney Injury in Patients Undergoing Cardiopulmonary Bypass for Lung Transplantation

BACKGROUND

Cardiopulmonary bypass (CPB) is often used to support patients undergoing lung transplantation who are intolerant of anatomic manipulation or single lung ventilation during the procedure. However, CPB may be associated with adverse outcomes. We evaluated the hypothesis that CPB is associated with increased acute kidney injury (AKI) and postoperative mortality after lung transplantation.

MATERIALS AND METHODS

This was a retrospective review of our institutional lung transplant database at the University of Texas Southwestern Medical Center from 2012 to 2018. Patients were grouped based on their need for CPB. The primary outcome was AKI within 48 h of transplantation, which was defined as Kidney Disease Improving Global Outcomes stage 1 or greater. Secondary outcomes included all-cause mortality.

RESULTS

A total of 426 patients underwent lung transplantation with 39.0% (n = 166) requiring CPB. There were no differences in demographics and comorbidities, including baseline renal function, between CPB and no CPB. CPB use was higher in recipients with interstitial lung diseases and primary pulmonary hypertension. Median lung allocation score was higher in those needing CPB (47 [interquartile range, 40-59] versus 39 [interquartile range, 35-47]). Patients requiring CPB were significantly more likely to experience AKI (61.44% versus 36.5.3%, P < 0.01) and postoperative hemodialysis (6.6% versus 0.4%, P < 0.01). On multivariable analysis, CPB was significantly associated with postoperative AKI (odds ratio, 1.66; 95% CI, 1.01-2.75; P = 0.04). Thirty-day mortality was higher in patients undergoing CPB (4.2% versus 0.8%, P = 0.03).

CONCLUSIONS

CPB for lung transplantation is associated with a higher incidence of AKI, renal failure requiring hemodialysis, and 30-d mortality. CPB should be used selectively for lung transplantation.