Combined liver and lung transplantation with extended normothermic lung preservation in a patient with end-stage emphysema complicated by drug-induced acute liver failure

How do we expand the lung donor pool?

PURPOSE OF REVIEW

Lung transplantation activity continues to be limited by the availability of timely quality donor lungs. It is apparent though that progress has been made. The steady evolution of clinical practice, combined with painstaking scientific discovery and innovation are described.

RECENT FINDINGS

There have been successful studies reporting innovations in the wider use and broader consideration of donation after circulatory death donor lungs, including an increasing number of transplants from each of the controlled, uncontrolled and medically assisted dying donor descriptive categories. Donors beyond age 70 years are providing better than expected long-term outcomes. Hepatitis C PCR positive donor lungs can be safely used if treated postoperatively with appropriate antivirals. Donor lung perfusion at a constant 10 degrees appears capable of significantly improving donor logistics and ex-vivo lung perfusion offers the potential of an ever-increasing number of novel donor management roles. Bioartificial and xenografts remain distant possibilities only at present.

SUMMARY

Donor lungs have proved to be surprisingly robust and combined with clinical, scientific and engineering innovations, the realizable lung donor pool is proving to be larger than previously thought.

Advances in lung transplantation: 60 years on

Lung transplantation is a well-established treatment for advanced lung disease, improving survival and quality of life. Over the last 60 years all aspects of lung transplantation have evolved significantly and exponential growth in transplant volume. This has been particularly evident over the last decade with a substantial increase in lung transplant numbers as a result of innovations in donor utilization procurement, including the use donation after circulatory death and ex-vivo lung perfusion organs. Donor lungs have proved to be surprisingly robust, and therefore the donor pool is actually larger than previously thought. Parallel to this, lung transplant outcomes have continued to improve with improved acute management as well as microbiological and immunological insights and innovations. The management of lung transplant recipients continues to be complex and heavily dependent on a tertiary care multidisciplinary paradigm. Whilst long term outcomes continue to be limited by chronic lung allograft dysfunction improvements in diagnostics, mechanistic understanding and evolutions in treatment paradigms have all contributed to a median survival that in some centres approaches 10 years. As ongoing studies build on developing novel approaches to diagnosis and treatment of transplant complications and improvements in donor utilization more individuals will have the opportunity to benefit from lung transplantation. As has always been the case, early referral for transplant consideration is important to achieve best results.

Controlled Hypothermic Storage for Lung Preservation: Leaving the Ice Age Behind

Controlled hypothermic storage (CHS) is a recent advance in lung transplantation (LTx) allowing preservation at temperatures higher than those achieved with traditional ice storage. The mechanisms explaining the benefits of CHS compared to conventional static ice storage (SIS) remain unclear and clinical data on safety and feasibility of lung CHS are limited. Therefore, we aimed to provide a focus review on animal experiments, molecular mechanisms, CHS devices, current clinical experience, and potential future benefits of CHS. Rabbit, canine and porcine experiments showed superior lung physiology after prolonged storage at 10°C vs. ≤4°C. In recent molecular analyses of lung CHS, better protection of mitochondrial health and higher levels of antioxidative metabolites were observed. The acquired insights into the underlying mechanisms and development of CHS devices allowed clinical application and research using CHS for lung preservation. The initial findings are promising; however, further data collection and analysis are required to draw more robust conclusions. Extended lung preservation with CHS may provide benefits to both recipients and healthcare personnel. Reduced time pressure between procurement and transplantation introduces flexibility allowing better decision-making and overnight bridging by delaying transplantation to daytime without compromising outcome.

Normothermic Machine Perfusion Systems: Where Do We Go From Here?

Normothermic machine perfusion (NMP) aims to preserve organs ex vivo by simulating physiological conditions such as body temperature. Recent advancements in NMP system design have prompted the development of clinically effective devices for liver, heart, lung, and kidney transplantation that preserve organs for several hours/up to 1 d. In preclinical studies, adjustments to circuit structure, perfusate composition, and automatic supervision have extended perfusion times up to 1 wk of preservation. Emerging NMP platforms for ex vivo preservation of the pancreas, intestine, uterus, ovary, and vascularized composite allografts represent exciting prospects. Thus, NMP may become a valuable tool in transplantation and provide significant advantages to biomedical research. This review recaps recent NMP research, including discussions of devices in clinical trials, innovative preclinical systems for extended preservation, and platforms developed for other organs. We will also discuss NMP strategies using a global approach while focusing on technical specifications and preservation times.

First in Poland Simultaneous Liver-Lung Transplantation With Liver-First Approach for Recipient Due to Cystic Fibrosis: A Case Report

Cystic fibrosis is an autosomal progressive disease affecting the lung, pancreas, and liver. Some patients develop end-stage respiratory and liver failure. For such patients, combined lung-liver transplantation remains the only therapeutic option. In this article we present the first simultaneous lung-liver transplantation in Poland, as well as in Central and Eastern Europe, with detailed clinical history, surgical aspects, and postoperative course.

Machine Perfusion of Donation After Circulatory Death Liver and Lungs Before Combined Liver-lung Transplantation

Shortage of deceased donor organs for transplantation has led to the increased use of organs from donation after circulatory death (DCD) donors. There are currently no reports describing outcomes after multiorgan transplantation with DCD livers. The use of DCD organs for multiorgan transplantation can be enhanced if the detrimental effects of prolonged cold ischemia and subsequent ischemia-reperfusion injury are overcome. We present a case in which the liver and lungs of a DCD donor were preserved using ex situ machine perfusion for combined liver-lung transplantation. The recipient was a 19-year-old male patient requiring bilateral lung transplantation for severe progressive pleural parenchymal fibroelastosis and portal hypertension with portal vein thrombosis. The donor liver was preserved with dual hypothermic oxygenated machine perfusion, whereas the lungs were perfused using ex vivo lung perfusion. With ex vivo lung perfusion, total preservation time of right and left lung reached 17 and 21 h, respectively. Now, 2 y after transplantation, liver function is normal and lung function is improving. To conclude, we suggest that combined transplantation of DCD liver and lungs is feasible when cold ischemia is reduced with ex situ machine perfusion preservation.

A review of liver dysfunction in the lung transplant patient

Liver dysfunction is an increasingly common finding in patients evaluated for lung transplantation. New or worsening dysfunction in the perioperative period, defined by presence of clinical ascites/encephalopathy, high model for end-stage liver disease (MELD) score, and/or independent diagnostic criteria, is associated with high short- and long-term mortality. Therefore, a thorough liver function assessment is necessary prior to listing for lung transplant. Unfortunately, identification and intraoperative monitoring remain the only options for prevention of disease progression with isolated lung transplantation. Combined lung and liver transplantation may provide an option for definitive long-term management in selecting patients with known liver disease at high risk for postoperative progression. However, experience with the combined operation is extremely limited and indications for combined lung and liver transplant remain unclear. Herein, we present a comprehensive literature review of patients with liver dysfunction undergoing lung transplantation with and without concurrent liver transplant in an effort to illuminate the risks, benefits, and clinical judgement surrounding decision to pursue combined lung-liver transplantation (CLLT). We also argue description of liver function is currently a weakness of the current lung allocation scoring system. Additional algorithms incorporating liver function may aid in risk stratification and decision to pursue combined transplantation.

Prolonged (≥24 Hours) Normothermic (≥32 °C) Ex Vivo Organ Perfusion: Lessons From the Literature

For 2 centuries, researchers have studied ex vivo perfusion intending to preserve the physiologic function of isolated organs. If it were indeed possible to maintain ex vivo organ viability for days, transplantation could become an elective operation with clinicians methodically surveilling and reconditioning allografts before surgery. To this day, experimental reports of successfully prolonged (≥24 hours) organ perfusion are rare and have not translated into clinical practice. To identify the crucial factors necessary for successful perfusion, this review summarizes the history of prolonged normothermic ex vivo organ perfusion. By examining successful techniques and protocols used, this review outlines the essential elements of successful perfusion, limitations of current perfusion systems, and areas where further research in preservation science is required.

Survival following simultaneous liver-lung versus liver alone transplantation: Results of the US National experience

BACKGROUND

There are little data to compare the post-transplant survival between lung-liver transplant (LLT) and liver-alone recipients. This study was undertaken to compare survival between LLT and liver-alone transplant.

METHODS

UNOS data for patients undergoing LLT from 2002 to 2017 was analyzed. LLT recipients (n = 81) were matched 1:4 to liver-alone recipients (n = 324) by propensity score and patient survival was compared in the matched cohorts.

RESULTS

Unadjusted 1, 3, and 5-year patient survival in the matched cohort was significantly worse in the LLT (82.5%, 72.2%, and 62.2%) versus liver-alone (92.2%, 82.8%, and 80.9%; p = 0.005). This difference persisted after adjusting for covariates with residual imbalance (HR 2.05, 95% CI 1.37-3.08; p = 0.001).

CONCLUSION

LLT has significantly worse survival than liver-alone transplant. With an increasing organ shortage, medical necessity criteria such as those developed for simultaneous liver-kidney transplantation should be developed for simultaneous lung-liver transplants to assure liver allografts are only allocated when truly needed.

A Propensity-matched Survival Analysis: Do Simultaneous Liver-lung Transplant Recipients Need a Liver?

BACKGROUND

There is debate whether simultaneous lung-liver transplant (LLT) long-term outcomes warrant allocation of 2 organs to a single recipient. We hypothesized that LLT recipients would have improved posttransplant survival compared with matched single-organ lung recipients with an equivalent degree of liver dysfunction.

METHODS

The Organ Procurement and Transplant Network/United Network for Organ Sharing STAR file was queried for adult candidates for LLT and isolated lung transplantation from 2006 to 2016. Waitlist mortality and transplant odds were calculated for all candidates. Donor and recipient demographic characteristics were compiled and compared. The LLT recipients were matched 1:2 with a nearest neighbor method to single-organ lung recipients. Kaplan-Meier methods with log-rank test compared long-term survival between groups. Univariate regression was used to calculate the association of LLT and mortality within 6 months of transplant. A proportional hazards model was used to calculate risk-adjusted mortality after 6 months posttransplantation.

RESULTS

Thirty-eight LLT patients were matched to 75 single-organ lung recipients. After matching, no differences in baseline demographics or liver function were observed between cohorts. Length of stay was significantly longer in LLT recipients compared to isolated lung recipients (45.89 days vs 22.44 days, P < 0.001). There was no significant difference in survival probability between LLT and isolated lung transplant (1 y, 89.5% vs 86.7%; 5 y, 67.0% vs 64.6%; P = 0.20).

CONCLUSIONS

After matching for patient characteristics and level of liver dysfunction, survival in simultaneous LLT was comparable to isolated lung transplantation. Although this population is unique, the clinical picture prompting liver transplant is not clear. National guidelines to better elucidate patient selection are needed.

Perfusate adsorption during ex vivo lung perfusion improves early post-transplant lung function

OBJECTIVE

Improvement in ex vivo lung perfusion protocols could increase the number of donors available for transplantation and protect the lungs from primary graft dysfunction. We hypothesize that perfusate adsorption during ex vivo lung perfusion reconditions the allograft to ischemia-reperfusion injury after lung transplantation.

METHODS

Donor pig lungs were preserved for 24 hours at 4°C, followed by 6 hours of ex vivo lung perfusion according to the Toronto protocol. The perfusate was additionally adsorbed through a CytoSorb adsorber (CytoSorbents, Berlin, Germany) in the treatment group, whereas control lungs were perfused according to the standard protocol (n = 5, each). Ex vivo lung perfusion physiology and biochemistry were monitored. Upon completion of ex vivo lung perfusion, a left single lung transplantation was performed. Oxygenation function and lung mechanics were assessed during a 4-hour reperfusion period. The inflammatory response was determined during ex vivo lung perfusion and reperfusion.

RESULTS

The cytokine concentrations in the perfusate were markedly lower with the adsorber, resulting in improved ex vivo lung perfusion physiology and biochemistry during the 6-hour perfusion period. Post-transplant dynamic lung compliance was markedly better during the 4-hour reperfusion period in the treatment group. Isolated allograft oxygenation function and dynamic compliance continued to be superior in the adsorber group at the end of reperfusion, accompanied by a markedly decreased local inflammatory response.

CONCLUSIONS

Implementation of an additional cytokine adsorber has refined the standard ex vivo lung perfusion protocol. Furthermore, cytokine removal during ex vivo lung perfusion improved immediate post-transplant graft function together with a less intense inflammatory response to reperfusion in pigs. Further studies are warranted to understand the beneficial effects of perfusate adsorption during ex vivo lung perfusion in the clinical setting.

Lung Transplantation and Precision Medicine

Lung transplantation is an accepted therapeutic option for end-stage lung diseases. Its history starts in the 1940s, initially hampered by early deaths due to perioperative problems and acute rejection. Improvement of surgical techniques and the introduction of immunosuppressive drugs resulted in longer survival. Chronic lung allograft dysfunction (CLAD), a new complication appeared and remains the most serious complication today. CLAD, the main reason why survival after lung transplantation is impaired compared to other solid-organ transplantations is characterized by a gradually increasing shortness of breath, reflected in a deterioration of pulmonary function status, respiratory insufficiency and possibly death.

Normothermic Ex-vivo Liver Perfusion and the Clinical Implications for Liver Transplantation

Despite significant improvements in outcomes after liver transplantation, many patients continue to die on the waiting list, while awaiting an available organ for transplantation. Organ shortage is not only due to an inadequate number of available organs, but also the inability to adequately assess and evaluate these organs prior to transplantation. Over the last few decades, ex-vivo perfusion of the liver has emerged as a useful technique for both improved organ preservation and assessment of organs prior to transplantation. Large animal studies have shown the superiority of ex-vivo perfusion over cold static storage. However, these studies have not, necessarily, been translatable to human livers. Small animal studies have been essential in understanding and improving this technology. Similarly, these results have yet to be translated into clinical use. A few Phase 1 clinical trials have shown promise and confirmed the viability of this technology. However, more robust studies are needed before ex-vivo liver perfusion can be widely accepted as the new clinical standard of organ preservation. Here, we aimed to review all relevant large and small animal research, as well as human liver studies on normothermic ex-vivo perfusion, and to identify areas of deficiency and opportunities for future research endeavors.

Single-Center Long-Term Analysis of Combined Liver-Lung Transplant Outcomes

Background

Combined lung-liver transplantation (LLT) applies 2 technically challenging transplants in 1 patient with severe 2-organ failure.

Methods

Institutional medical records and United Network for Organ Sharing database were queried for patients at our institution that underwent LLT from 2000 to 2016.

Results

Twelve LLTs were performed from 2000 to 2016 including 9 male and 3 female recipients with a median age of 28.36 years. Indications for lung transplantation were cystic fibrosis (8), idiopathic pulmonary fibrosis (3), and pulmonary fibrosis secondary to hepatopulmonary syndrome (1). Indications for liver transplantation were cystic fibrosis (8), alcoholic cirrhosis (1), idiopathic cirrhosis (2), and alpha-1 antitrypsin deficiency (1). Median forced expiratory volume in 1 second at transplant was 27.8% (±20.38%), and mean Model for End-Stage Liver Disease was 10.5 (±4.68). Median hospital stay was 44.5 days. Seventy-five percent of recipients had 1+ new infection during their transplant hospitalization. Patients experienced 0.68 incidences of acute rejection per year with a 41.7% (95% confidence interval, 21.3%-81.4%) probability of freedom from rejection in the first-year. Patient survival was 100% at 30 days, 91.6% at 1 year, and 71.3% at 3 years. At the time of analysis, 7 of 12 patients were alive, of whom 3 survived over 8 years post-LLT. Causes of death were primary liver graft failure (1), bronchiolitis obliterans syndrome (2), and solid tumor malignancies (2).

Conclusions

Our results indicate that LLT is associated with comparable survival to other LLT series and provides a granular assessment of infectious and rejection rates in this rare population.

Prolonged EVLP Using OCS Lung: Cellular and Acellular Perfusates

BACKGROUND

We report the ability to extend lung preservation up to 24 hours (24H) by using autologous whole donor blood circulating within an ex vivo lung perfusion (EVLP) system. This approach facilitates donor lung reconditioning in a model of extended normothermic EVLP. We analyzed comparative responses to cellular and acellular perfusates to identify these benefits.

METHODS

Twelve pairs of swine lungs were retrieved after cardiac arrest and studied for 24H on the Organ Care System (OCS) Lung EVLP platform. Three groups (n = 4 each) were differentiated by perfusate: (1) isolated red blood cells (RBCs) (current clinical standard for OCS); (2) whole blood (WB); and (3) acellular buffered dextran-albumin solution (analogous to STEEN solution).

RESULTS

Only the RBC and WB groups met clinical standards for transplantation at 8 hours; our primary analysis at 24H focused on perfusion with WB versus RBC. The WB perfusate was superior (vs RBC) for maintaining stability of all monitored parameters, including the following mean 24H measures: pulmonary artery pressure (6.8 vs 9.0 mm Hg), reservoir volume replacement (85 vs 1607 mL), and PaO2:FiO2 ratio (541 vs 223). Acellular perfusion was limited to 6 hours on the OCS system due to prohibitively high vascular resistance, edema, and worsening compliance.

CONCLUSIONS

The use of an autologous whole donor blood perfusate allowed 24H of preservation without functional deterioration and was superior to both RBC and buffered dextran-albumin solution for extended lung preservation in a swine model using OCS Lung. This finding represents a potentially significant advance in donor lung preservation and reconditioning.

Recipient selection process and listing for lung transplantation

Lung transplantation remains the ultimate treatment option for selected patients with end-stage (cardio) pulmonary disease. Given the current organ shortage, it is without any doubt that careful selection of potential transplant candidates is essential as this may greatly influence survival after the procedure. In this paper, we will review the current guidelines for referral and listing of lung transplant candidates in general, and in more depth for the specific underlying diseases. Needless to state that these are not absolute guidelines, and that decisions depend upon center's activity, waiting list, etc. Therefore, every patient should be discussed with the transplant center before any definite decision is made to accept or decline a patient for lung transplantation.

Cytokine filtration modulates pulmonary metabolism and edema formation during ex vivo lung perfusion

BACKGROUND

Ex vivo lung perfusion (EVLP) has improved the process of donor lung management. Cytokine accumulation during EVLP has been shown to correlate with worse outcome after lung transplantation. Our objective in this study was to test the safety and efficacy of cytokine filtration during EVLP in a large animal model.

METHODS

Pig donor lungs were preserved for 24 hours at 4°C, followed by 12 hours of EVLP, according to the Toronto protocol. The perfusate was continuously run through an absorbent device (CytoSorb) via a veno-venous shunt from the reservoir in the filter group. EVLP was performed according to the standard protocol in the control group (n = 5 each). EVLP physiology, lung X-ray, perfusate biochemistry, inflammatory response and microscopic injury were assessed.

RESULTS

Cytokine filtration significantly improved airway pressure and dynamic compliance during the 12-hour perfusion period. Lung X-rays acquired at the end of perfusion showed increased consolidation in the control group. Electrolyte imbalance, determined by increased hydrogen, potassium and calcium ion concentrations in the perfusate, was markedly worsened in the control group. Glucose consumption and lactate production were markedly reduced, along with the lactate/pyruvate ratio in the filter group. Cytokine expression profile, tissue myeloperoxidase activity and microscopic lung injury were significantly reduced in the filter group.

CONCLUSIONS

Continuous perfusate filtration through sorbent beads is effective and safe during prolonged EVLP. Cytokine removal decreased the development of pulmonary edema and electrolyte imbalance through the suppression of anaerobic glycolysis and neutrophil activation in this setting. Further studies are needed to test the beneficial effect of cytokine filtration on post-transplant lung function.

Ex vivo lung perfusion

Lung transplantation is an established life-saving therapy for patients with end-stage lung disease. Unfortunately, greater success in lung transplantation is hindered by a shortage of lung donors and the relatively poor early-, mid-, and long-term outcomes associated with severe primary graft dysfunction. Ex vivo lung perfusion has emerged as a modern preservation technique that allows for a more accurate lung assessment and improvement in lung quality. This review outlines the: (i) rationale behind the method; (ii) techniques and protocols; (iii) Toronto ex vivo lung perfusion method; (iv) devices available; and (v) clinical experience worldwide. We also highlight the potential of ex vivo lung perfusion in leading a new era of lung preservation.

Combined or Serial Liver and Lung Transplantation for Epithelioid Hemangioendothelioma: A Case Series

Epithelioid hemangioendothelioma (EHE) is a rare vascular tumor with variable biological and clinical behavior. There is increasing experience with liver transplantation (LiTx) for hepatic EHE, even in cases of extrahepatic disease localization. Until now, no cases of lung transplantation (LuTx) had been reported for pulmonary EHE. This report describes three cases of EHE with multifocal disease in patients who underwent either serial or combined LiTx and LuTx.

Evaluating acellular versus cellular perfusate composition during prolonged ex vivo lung perfusion after initial cold ischaemia for 24 hours

Normothermic ex vivo lung perfusion (EVLP) has developed as a powerful technique to evaluate particularly marginal donor lungs prior to transplantation. In this study, acellular and cellular perfusate compositions were compared in an identical experimental setting as no consensus has been reached on a preferred technique yet. Porcine lungs underwent EVLP for 12 h on the basis of an acellular or a cellular perfusate composition after 24 h of cold ischaemia as defined organ stress. During perfusion, haemodynamic and respiratory parameters were monitored. After EVLP, the lung condition was assessed by light and transmission electron microscopy. Aerodynamic parameters did not show significant differences between groups and remained within the in vivo range during EVLP. Mean oxygenation indices were 491 ± 39 in the acellular group and 513 ± 53 in the cellular group. Groups only differed significantly in terms of higher pulmonary artery pressure and vascular resistance in the cellular group. Lung histology and ultrastructure were largely well preserved after prolonged EVLP and showed only minor structural alterations which were similarly present in both groups. Prolonged acellular and cellular EVLP for 12 h are both feasible with lungs prechallenged by ischaemic organ stress. Physiological and ultrastructural analysis showed no superiority of either acellular or cellular perfusate composition.

Organ preservation review: history of organ preservation

PURPOSE OF REVIEW

To summarize the history of organ preservation and place into this context the current trends in preservation.

RECENT FINDINGS

Multiple large retrospective studies have analyzed cold preservation solutions in an attempt to determine superiority with largely negative results. Experimental and some clinical studies have examined machine perfusion of procured grafts, in both hypothermic and normothermic contexts with variable, but promising, results. Lastly, there are experimental efforts to evaluate mesenchymal stem cell therapy on rehabilitation of marginal donor organs.

SUMMARY

New trends in organ preservation may soon translate into more efficient use of the limited donor pool.