Extracorporeal Life Support as a Bridge to Lung Transplantation in Patients With Acute Respiratory Failure

Pushing the Survival Bar Higher: Two Decades of Innovation in Lung Transplantation

Survival after lung transplantation has significantly improved during the last two decades. The refinement of the already existing extracorporeal life support (ECLS) systems, such as extracorporeal membrane oxygenation (ECMO), and the introduction of new techniques for donor lung optimization, such as ex vivo lung perfusion (EVLP), have allowed the extension of transplant indication to patients with end-stage lung failure after acute respiratory distress syndrome (ARDS) and the expansion of the donor organ pool, due to the better evaluation and optimization of extended-criteria donor (ECD) lungs and of donors after circulatory death (DCD). The close monitoring of anti-HLA donor-specific antibodies (DSAs) has allowed the early recognition of pulmonary antibody-mediated rejection (AMR), which requires a completely different treatment and has a worse prognosis than acute cellular rejection (ACR). As such, the standardization of patient selection and post-transplant management has significantly contributed to this positive trend, especially at high-volume centers. This review focuses on lung transplantation after ARDS, on the role of EVLP in lung donor expansion, on ECMO as a principal cardiopulmonary support system in lung transplantation, and on the diagnosis and therapy of pulmonary AMR.

Percutaneous OxyRVAD in a Patient with Severe Respiratory Failure and Right Heart Failure: A Case Report

Venovenous extracorporeal membrane oxygenation (VV ECMO) is often used in cases of severe respiratory failure, especially in patients considered for lung transplantation. However, because many lung diseases can ultimately result in right heart failure, the treatment of secondary right heart failure can present a challenge when the patient is already under VV ECMO support. In such cases, an oxygenated-right ventricular assist device (OxyRVAD) can be used. OxyRVAD is designed to maintain anterograde blood flow and prevent right ventricular distension. Moreover, the pulmonary arterial cannula can be inserted percutaneously. We report a case in which percutaneous OxyRVAD was successfully implemented to manage right heart failure in a patient with respiratory failure who was on VV ECMO.

A case of severe respiratory failure due to interstitial pneumonia successfully bridged to lung transplantation from a brain-dead donor using 109-day veno-arterial extracorporeal membrane oxygenation

In Japan, successful cases of a bridge to lung transplantation (BTT) by extracorporeal membrane oxygenation (ECMO) are rare. We present the case of a man in his thirties, diagnosed with interstitial pneumonia 6 years prior and registered for lung transplant 1 year prior due to disease progression despite treatment. Due to the patient's worsening respiratory failure, he was transferred to our hospital for BTT by ECMO. Since long-term management was expected and pulmonary hypertension was present, veno-arterial (V-A) ECMO was conducted using the right atrial blood outflow via the right internal jugular vein and right axillary artery inflow via a vascular graft. After tracheostomy, he was managed as "Awake ECMO". In addition, interprofessional collaboration such as physiotherapist rehabilitation, nurses, and liaison teams prevented muscle weakness and supported the mental aspect. We were able to minimize complications such as severe infections and bleeding. A compatible brain-dead donor was found on day 108 after introducing ECMO, and the patient was transferred to a transplant facility on day 109. The peripheral upper V-A ECMO is one of the configurations suitable for long-term BTT management.

Fundamentals of weaning veno-arterial and veno-venous extracorporeal membrane oxygenation

Recent advances in veno-arterial (VA) and veno-venous (VV) extracorporeal membrane oxygenation (ECMO) technology and management have enabled us to support patients with cardiac and/or pulmonary failure, who may have previously been considered untreatable. VA ECMO and VV ECMO are by definition transient therapies and serve as a bridge to recovery, bridge to decision, bridge to transplant, or bridge to no recovery. Weaning ECMO should be considered for all patients once native cardiac and pulmonary function show signs of recovery. Currently, there are no universally accepted protocols for weaning VA and VV ECMO, and consequently, each individual center follows their own weaning protocols. The aim of this review article is to describe different approaches to safely wean from VA and VV ECMO.

Veno-venous extracorporeal membrane oxygenation for the treatment of respiratory compromise

Extracorporeal membrane oxygenation for the purpose of intervening upon profound cardiovascular or pulmonary compromise has proven to be a worthy intervention. Technological advancements have allowed this mode of therapy to become more effective and widespread. Veno-venous extracorporeal membrane oxygenation (VV-ECMO) is a commonly used strategy to help manage patients with pulmonary dysfunction refractory to traditional management methods. This review intends to focus upon common indications and the clinical considerations for the institution of VV-ECMO as well as some of its known complications.

Lung Transplantation for Patients with COVID-19 Acute Respiratory Distress Syndrome

Patients with severe coronavirus disease 2019 (COVID-19) acute respiratory distress syndrome (ARDS) may exhibit pulmonary fibrosis after the viral illness resolves. Some of these patients may experience severe functional lung impairment, and thus require transplants to prevent death or maintain a tolerable quality of life. Considering the reversibility of COVID-19 ARDS, lung transplant candidates are observed for 1–2 months and must be selected very carefully before transplantation. As the short-term outcomes of such patients are comparable to those of patients with other indications for transplantation, lung transplantation should be actively considered.

Inpatient Management of the Acutely Decompensating Lung Transplant Candidate

Lung allocation in the US changed nearly 15 years ago from time accrued on the waiting list to disease severity and likelihood of posttransplant survival, represented by the lung allocation score (LAS). Notably, the risk of death within a year plays a stronger role on the score calculation than posttransplant survival. While this change was associated with the intended decrease in waitlist mortality (most recently reported at 14.6%), it was predictable that transplant teams would have to care for increasingly older and complex candidates and recipients. This urgency-based allocation also led centers to routinely consider transplanting patients with higher acuity, often hospitalized and, not infrequently, in the intensive care unit (ICU). According to the Scientific Registry for Transplant Recipients, from 2009 to 2019, the proportion of lung recipients hospitalized and those admitted to the ICU at the time of transplant increased from 18.9% to 26.8% and from 9.2% to 16.5%, respectively..

Ambulatory extracorporeal membrane oxygenation (ECMO) as a bridge to lung transplantation

Ambulatory extracorporeal membrane oxygenation (ECMO) has shown promise as a bridge to lung transplantation. The primary goal of ambulatory ECMO is to provide enough gas exchange to allow patients to participate in preoperative physical therapy. Various strategies of ambulatory ECMO are utilized depending upon patients’ need. A wide spectrum of ECMO configurations is available to tackle this situation. We discuss those configurations in this article.

Extracorporeal membrane oxygenation in lung transplantation: Indications, techniques and results

The use of extracorporeal membrane oxygenation (ECMO) in the field of lung transplantation has rapidly expanded over the past 30 years. It has become an important tool in an increasing number of specialized centers as a bridge to transplantation and in the intra-operative and/or post-operative setting. ECMO is an extremely versatile tool in the field of lung transplantation as it can be used and adapted in different configurations with several potential cannulation sites according to the specific need of the recipient. For example, patients who need to be bridged to lung transplantation often have hypercapnic respiratory failure that may preferably benefit from veno-venous (VV) ECMO or peripheral veno-arterial (VA) ECMO in the case of hemodynamic instability. Moreover, in an intra-operative setting, VV ECMO can be maintained or switched to a VA ECMO. The routine use of intra-operative ECMO and its eventual prolongation in the post-operative period has been widely investigated in recent years by several important lung transplantation centers in order to assess the graft function and its potential protective role on primary graft dysfunction and on ischemia-reperfusion injury. This review will assess the current evidence on the role of ECMO in the different phases of lung transplantation, while analyzing different studies on pre, intra- and post-operative utilization of this extracorporeal support.

Perioperative, protective use of extracorporeal membrane oxygenation in complex thoracic surgery

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is increasingly used in patients undergoing complex thoracic surgical procedures. However, studies reporting the clinical outcomes of these patients are limited to case reports, without real consensus. Our aim was to evaluate the perioperative use of ECMO as respiratory and/or circulatory support in thoracic surgery: indications, benefits, and perioperative management.

METHODS

Between May 2013 and December 2018, we reviewed the clinical data of 15 patients (11 males and 4 females; mean age: 47 years old; range, 25-73 years) undergoing ECMO-assisted thoracic surgery in our hospital.

RESULTS

Of the 15 patients, 10 cases received peripheral veno-arterial (VA) ECMO and five cases received veno-venous (VV) ECMO. Indications for ECMO were pulmonary transplantation with hard-to-maintain oxygenation (n = 5), traumatic main bronchial rupture (n = 2), traumatic lung injury (n = 1), airway tumor leading to severe airway stenosis (n = 2), huge thoracic mass infiltrated vena cava (n = 5). The ECMO duration was 1-51 hours. All patients were successfully extubated and weaned from ECMO postoperatively. The main complications were hemorrhage (26.7%), infection (33.3%), acute hepatic dysfunction (33.3%), and venous thrombosis (26.7%). There was only one hospital death and postoperative one-year survival rate was 86%.

CONCLUSION

Our experience indicates that ECMO is a feasible method for complex trachea-bronchial surgery, huge thoracic mass excision and lung transplantation, and the ECMO-related risks may be justified. With further accumulation of experience with ECMO, a more sophisticated protocol for management of critical airway or heart failure problems in thoracic surgeries can be derived.

Artificial lungs--Where are we going with the lung replacement therapy?

Lung transplantation may be a final destination therapy in lung failure, but limited donor organ availability creates a need for alternative management, including artificial lung technology. This invited review discusses ongoing developments and future research pathways for respiratory assist devices and tissue engineering to treat advanced and refractory lung disease. An overview is also given on the aftermath of the coronavirus disease 2019 pandemic and lessons learned as the world comes out of this situation. The first order of business in the future of lung support is solving the problems with existing mechanical devices. Interestingly, challenges identified during the early days of development persist today. These challenges include device-related infection, bleeding, thrombosis, cost, and patient quality of life. The main approaches of the future directions are to repair, restore, replace, or regenerate the lungs. Engineering improvements to hollow fiber membrane gas exchangers are enabling longer term wearable systems and can be used to bridge lung failure patients to transplantation. Progress in the development of microchannel-based devices has provided the concept of biomimetic devices that may even enable intracorporeal implantation. Tissue engineering and cell-based technologies have provided the concept of bioartificial lungs with properties similar to the native organ. Recent progress in artificial lung technologies includes continued advances in both engineering and biology. The final goal is to achieve a truly implantable and durable artificial lung that is applicable to destination therapy.

Clinical Result and Feasibility of Transport ECMO in Thoracic Transplantation

INTRODUCTION

There is an increasing need for transport extracorporeal membrane oxygenation (ECMO) in thoracic transplantation. This study was performed to evaluate the safety and feasibility of transport ECMO in thoracic transplantation.

PATIENTS AND METHODS

A total of 24 patients referred from outside hospitals for ECMO treatment used our interhospital ECMO transport system from December 2011 to October 2018. We retrospectively analyzed the clinical data to evaluate the feasibility and safety of transport ECMO for thoracic transplantations.

RESULTS

The median transport distance was 34 km (interquartile range [IQR]: 29-45) and the median transport time was 38 minutes (IQR: 26-45). There were no adverse events during transit in any patient. ECMO weaning was possible in 19 patients (79%) and 13 patients (54%) were weaned from mechanical ventilation. Of these patients, only 14 (58%) underwent transplantation, of whom 8 received lung transplants (53%) and 6 received heart transplants (67%). Among the patients receiving transplants, intensive care unit discharge was possible in 9 patients (64%), and 8 patients (57%) were discharged home.

CONCLUSIONS

Transport ECMO to the transplantation center is a useful strategy to rescue patients with cardiorespiratory failure who may require transplantation, providing an additional means of improving the chance of survival.

Extracorporeal support, during and after lung transplantation: the history of an idea

During recent years, continuous technological innovation has provoked an increase of extracorporeal life support (ECLS) use for perioperative cardiopulmonary support in lung transplantation. Initial results were disappointing, due to ECLS-specific complications and high surgical risk of the supported patients. However, the combination of improved patient management, multidisciplinary team work and standardization of ECLS protocols has recently yielded excellent results in several case series from high-volume transplant centres. Therein, it was demonstrated that, although the prevalence of complications remains higher in supported patients, there may be no difference in long-term graft function between supported and non-supported patients. These results are important, because most of the patients who require ECLS support in lung transplantation are young and have no other chance to survive, but to be transplanted. Moreover, there is no device for "bridging to destination" therapy in lung transplantation. Of note, the evidence in favour of ECLS support in lung transplantation was never validated by randomized controlled trials, but by everyday experience at the patient bed-side. Here, we review the state-of-the-art ECLS evidence for intraoperative and postoperative cardiopulmonary support in lung transplantation.

Current Status and Future of Lung Donation in Korea

Lung transplantation is the only effective treatment option for patients with end-stage lung disease. However, donor organ shortage makes timely transplant not possible for all patients, especially in Korea. We investigated the number and utilization of donor lungs by retrospectively reviewing all donor organs registered in the Korea Network for Organ Sharing database from March 2012 to March 2016. The donors were stratified into 4 groups by donor acceptability criteria. A total of 1,304 donors were included. Of those, 295 brain-dead donors (22.6%) consented to lung donation. Among these consented donors, 168 donors (12.9%) were retrieved for lung transplant. Retrieval rate was very low compared with that of the kidney (93.9%), liver (86.3%), and heart (27.3%). The characteristics of utilized donor lungs were: mean age, 40.5 years (range: 18 to 63 years); mean partial pressure of oxygen, 356.5 mmHg; mean smoking history, 5.9 pack-years; and mean body mass index, 22.6 kg/m². The proportion of donors with acceptable condition of the transplanted lungs was only 39.3% (ideal 19, standard 47, marginal 70, unusable 32). Among brain-dead patients who denied to donate lungs (n = 1,009), 82 were potentially acceptable donors (ideal 19, standard 63), which was equal to half of actually transplanted lung donations. Many potential donor lungs, which are currently excluded, may be successfully used in lung transplantation in Korea. The available lung donors must be actively selected and managed to maximize the utilization of this precious resource.