Early institution of extracorporeal membrane oxygenation for primary graft dysfunction after lung transplantation improves outcome

Postreperfusion Pulmonary Artery Pressure Indicates Primary Graft Dysfunction After Lung Transplant

BACKGROUND

Primary graft dysfunction is a risk factor of early mortality after lung transplant. Models identifying patients at high risk for primary graft dysfunction are limited. We hypothesize high postreperfusion systolic pulmonary artery pressure is a clinical marker for primary graft dysfunction.

METHODS

This is a retrospective review of 158 consecutive lung transplants performed at a single academic center from January 2020 through July 2022. Only bilateral lung transplants were included and patients with pretransplant extracorporeal life support were excluded.

RESULTS

Primary graft dysfunction occurred in 42.3% (n = 30). Patients with primary graft dysfunction had higher postreperfusion systolic pulmonary artery pressure (41 ± 9.1 mm Hg) than those without (31.5 ± 8.8 mm Hg) (P < .001). Logistic regression showed postreperfusion systolic pulmonary artery pressure is a predictor for primary graft dysfunction (odds ratio 1.14, 95% CI 1.06-1.24, P < .001). Postreperfusion systolic pulmonary artery pressure of 37 mm Hg was optimal for predicting primary graft dysfunction by Youden index. The receiver operating characteristic curve of postreperfusion systolic pulmonary artery pressure at 37 mm Hg (sensitivity 0.77, specificity 0.78, area under the curve 0.81), was superior to the prereperfusion pressure curve at 36 mm Hg (sensitivity 0.77, specificity 0.39, area under the curve 0.57) (P < .01).

CONCLUSIONS

Elevated postreperfusion systolic pulmonary artery pressure after lung transplant is predictive of primary graft dysfunction. Postreperfusion systolic pulmonary artery pressure is more indicative of primary graft dysfunction than prereperfusion systolic pulmonary artery pressure. Using postreperfusion systolic pulmonary artery pressure as a positive signal of primary graft dysfunction allows earlier intervention, which could improve outcomes.

Primary graft dysfunction grade 3 following pediatric lung transplantation is associated with chronic lung allograft dysfunction

BACKGROUND

Severe primary graft dysfunction (PGD) is associated with the development of bronchiolitis obliterans syndrome (BOS), the most common form of chronic lung allograft dysfunction (CLAD), in adults. However, PGD associations with long-term outcomes following pediatric lung transplantation are unknown. We hypothesized that PGD grade 3 (PGD 3) at 48- or 72-hours would be associated with shorter CLAD-free survival following pediatric lung transplantation.

METHODS

This was a single center retrospective cohort study of patients ≤ 21 years of age who underwent bilateral lung transplantation between 2005 and 2019 with ≥ 1 year of follow-up. PGD and CLAD were defined by published criteria. We evaluated the association of PGD 3 at 48- or 72-hours with CLAD-free survival by using time-to-event analyses.

RESULTS

Fifty-one patients were included (median age 12.7 years; 51% female). The most common transplant indications were cystic fibrosis (29%) and pulmonary hypertension (20%). Seventeen patients (33%) had PGD 3 at either 48- or 72-hours. In unadjusted analysis, PGD 3 was associated with an increased risk of CLAD or mortality (HR 2.10, 95% CI 1.01-4.37, p=0.047). This association remained when adjusting individually for multiple potential confounders. There was evidence of effect modification by sex (interaction p = 0.055) with the association of PGD 3 and shorter CLAD-free survival driven predominantly by males (HR 4.73, 95% CI 1.44-15.6) rather than females (HR 1.23, 95% CI 0.47-3.20).

CONCLUSIONS

PGD 3 at 48- or 72-hours following pediatric lung transplantation was associated with shorter CLAD-free survival. Sex may be a modifier of this association.

Primary graft dysfunction following lung transplantation: From pathogenesis to future frontiers

Lung transplantation is the treatment of choice for patients with end-stage lung disease. Currently, just under 5000 lung transplants are performed worldwide annually. However, a major scourge leading to 90-d and 1-year mortality remains primary graft dysfunction. It is a spectrum of lung injury ranging from mild to severe depending on the level of hypoxaemia and lung injury post-transplant. This review aims to provide an in-depth analysis of the epidemiology, pathophysiology, risk factors, outcomes, and future frontiers involved in mitigating primary graft dysfunction. The current diagnostic criteria are examined alongside changes from the previous definition. We also highlight the issues surrounding chronic lung allograft dysfunction and identify the novel therapies available for ex-vivo lung perfusion. Although primary graft dysfunction remains a significant contributor to 90-d and 1-year mortality, ongoing research and development abreast with current technological advancements have shed some light on the issue in pursuit of future diagnostic and therapeutic tools.

Critical Care Management of the Lung Transplant Recipient

Lung transplantation is often the only treatment option for patients with severe irreversible lung disease. Improvements in donor and recipient selection, organ allocation, surgical techniques, and immunosuppression have all contributed to better survival outcomes after lung transplantation. Nonetheless, lung transplant recipients still experience frequent complications, often necessitating treatment in an intensive care setting. In addition, the use of extracorporeal life support as a means of bridging critically ill patients to lung transplantation has become more widespread. This review focuses on the critical care aspects of lung transplantation, both before and after surgery.

The American Association for Thoracic Surgery (AATS) 2022 Expert Consensus Document: The use of mechanical circulatory support in lung transplantation

OBJECTIVE

The use of mechanical circulatory support (MCS) in lung transplantation has been steadily increasing over the prior decade, with evolving strategies for incorporating support in the preoperative, intraoperative, and postoperative settings. There is significant practice variability in the use of these techniques, however, and relatively limited data to help establish institutional protocols. The objective of the AATS Clinical Practice Standards Committee (CPSC) expert panel was to review the existing literature and establish recommendations about the use of MCS before, during, and after lung transplantation.

METHODS

The AATS CPSC assembled an expert panel of 16 lung transplantation physicians who developed a consensus document of recommendations. The panel was broken into subgroups focused on preoperative, intraoperative, and postoperative support, and each subgroup performed a focused literature review. These subgroups formulated recommendation statements for each subtopic, which were evaluated by the entire group. The statements were then developed via discussion among the panel and refined until consensus was achieved on each statement.

RESULTS

The expert panel achieved consensus on 36 recommendations for how and when to use MCS in lung transplantation. These recommendations included the use of veno-venous extracorporeal membrane oxygenation (ECMO) as a bridging strategy in the preoperative setting, a preference for central veno-arterial ECMO over traditional cardiopulmonary bypass during the transplantation procedure, and the benefit of supporting selected patients with MCS postoperatively.

CONCLUSIONS

Achieving optimal results in lung transplantation requires the use of a wide range of strategies. MCS provides an important mechanism for helping these critically ill patients through the peritransplantation period. Despite the complex nature of the decision making process in the treatment of these patients, the expert panel was able to achieve consensus on 36 recommendations. These recommendations should provide guidance for professionals involved in the care of end-stage lung disease patients considered for transplantation.

Contemporary trends in PGD incidence, outcomes, and therapies

BACKGROUND

We sought to describe trends in extracorporeal membrane oxygenation (ECMO) use, and define the impact on PGD incidence and early mortality in lung transplantation.

METHODS

Patients were enrolled from August 2011 to June 2018 at 10 transplant centers in the multi-center Lung Transplant Outcomes Group prospective cohort study. PGD was defined as Grade 3 at 48 or 72 hours, based on the 2016 PGD ISHLT guidelines. Logistic regression and survival models were used to contrast between group effects for event (i.e., PGD and Death) and time-to-event (i.e., death, extubation, discharge) outcomes respectively. Both modeling frameworks accommodate the inclusion of potential confounders.

RESULTS

A total of 1,528 subjects were enrolled with a 25.7% incidence of PGD. Annual PGD incidence (14.3%-38.2%, p = .0002), median LAS (38.0-47.7 p = .009) and the use of ECMO salvage for PGD (5.7%-20.9%, p = .007) increased over the course of the study. PGD was associated with increased 1 year mortality (OR 1.7 [95% C.I. 1.2, 2.3], p = .0001). Bridging strategies were not associated with increased mortality compared to non-bridged patients (p = .66); however, salvage ECMO for PGD was significantly associated with increased mortality (OR 1.9 [1.3, 2.7], p = .0007). Restricted mean survival time comparison at 1-year demonstrated 84.1 days lost in venoarterial salvaged recipients with PGD when compared to those without PGD (ratio 1.3 [1.1, 1.5]) and 27.2 days for venovenous with PGD (ratio 1.1 [1.0, 1.4]).

CONCLUSIONS

PGD incidence continues to rise in modern transplant practice paralleled by significant increases in recipient severity of illness. Bridging strategies have increased but did not affect PGD incidence or mortality. PGD remains highly associated with mortality and is increasingly treated with salvage ECMO.

Exploring predisposing factors and pathogenesis contributing to injuries of donor lungs

INTRODUCTION

Lung transplantation (LTx) remains the only therapeutic strategy for patients with incurable lung diseases. However, its use has been severely limited by the narrow donor pool and potential concerns of inferior quality of donor lungs, which are more susceptible to external influence than other transplant organs. Multiple insults, including various causes of death and a series of perimortem events, may act together on donor lungs and eventually culminate in primary graft dysfunction (PGD) after transplantation as well as other poor short-term outcomes.

AREAS COVERED

This review focuses on the predisposing factors contributing to injuries to the donor lungs, specifically focusing on the pathogenesis of these injuries and their impact on post-transplant outcomes. Additionally, various maneuvers to mitigate donor lung injuries have been proposed.

EXPERT OPINION

The selection criteria for eligible donors vary and may be poor discriminators of lung injury. Not all transplanted lungs are in ideal condition. With the rapidly increasing waiting list for LTx, the trend of using marginal donors has become more apparent, underscoring the need to gain a deeper understanding of donor lung injuries and discover more donor resources.

Critical Care of the Lung Transplant Patient

Lung transplantation is a therapeutic option for end-stage lung disease that improves survival and quality of life. Prelung transplant admission to the intensive care unit (ICU) for bridge to transplant with mechanical ventilation and extracorporeal membrane oxygenation (ECMO) is common. Primary graft dysfunction is an important immediate complication of lung transplantation with short- and long-term morbidity and mortality. Later transplant-related causes of respiratory failure necessitating ICU admission include acute cellular rejection, atypical infections, and chronic lung allograft dysfunction. Lung transplantation for COVID-19-related ARDS is increasingly common..

Critical Care Management Following Lung Transplantation

Postoperative critical care management for lung transplant recipients in the intensive care unit (ICU) has expanded in recent years due to its complexity and impact on clinical outcomes. The practical aspects of post-transplant critical care management, especially regarding ventilation and hemodynamic management during the early postoperative period in the ICU, are discussed in this brief review. Monitoring in the ICU provides information on the patient’s clinical status, diagnostic assessment of complications, and future management plans since lung transplantation involves unique pathophysiological conditions and risk factors for complications. After lung transplantation, the grafts should be appropriately ventilated with lung protective strategies to prevent ventilator-induced lung injury, as well as to promote graft function and maintain adequate gas exchange. Hypotension and varying degrees of pulmonary edema are common in the immediate postoperative lung transplantation setting. Ventricular dysfunction in lung transplant recipients should also be considered. Therefore, adequate volume and hemodynamic management with vasoactive agents based on their physiological effects and patient response are critical in the early postoperative lung transplantation period. Integrated management provided by a professional multidisciplinary team is essential for the critical care management of lung transplant recipients in the ICU.

Early Postoperative Management of Lung Transplant Recipients

The early postoperative period after lung transplantation is a critical time. Prompt recognition and treatment of primary graft dysfunction can alter long-term allograft function. Cardiovascular, gastrointestinal, renal, and hematologic derangements are common and require close management to limit their negative sequelae.

Postoperative Management of Lung Transplant Recipients in the Intensive Care Unit

The number of lung transplantations is progressively increasing worldwide, providing new challenges to interprofessional teams and the intensive care units. The outcome of lung transplantation recipients is critically affected by a complex interplay of particular pathophysiologic conditions and risk factors, knowledge of which is fundamental to appropriately manage these patients during the early postoperative course. As high-grade evidence-based guidelines are not available, the authors aimed to provide an updated review of the postoperative management of lung transplantation recipients in the intensive care unit, which addresses six main areas: (1) management of mechanical ventilation, (2) fluid and hemodynamic management, (3) immunosuppressive therapies, (4) prevention and management of neurologic complications, (5) antimicrobial therapy, and (6) management of nutritional support and abdominal complications. The integrated care provided by a dedicated multidisciplinary team is key to optimize the complex postoperative management of lung transplantation recipients in the intensive care unit.

Primary graft dysfunction: what we know

Many advances in lung transplant have occurred over the last few decades in the understanding of primary graft dysfunction (PGD) though effective prevention and treatment remain elusive. This review will cover prior understanding of PGD, recent findings, and directions for future research. A consensus statement updating the definition of PGD in 2016 highlights the growing complexity of lung transplant perioperative care taking into account the increasing use of high flow oxygen delivery and pulmonary vasodilators in the current era. PGD, particularly more severe grades, is associated with worse short- and long-term outcomes after transplant such as chronic lung allograft dysfunction. Growing experience have helped identify recipient, donor, and intraoperative risk factors for PGD. Understanding the pathophysiology of PGD has advanced with increasing knowledge of the role of innate immune response, humoral cell immunity, and epithelial cell injury. Supportive care post-transplant with technological advances in extracorporeal membranous oxygenation (ECMO) remain the mainstay of treatment for severe PGD. Future directions include the evolving utility of ex vivo lung perfusion (EVLP) both in PGD research and potential pre-transplant treatment applications. PGD remains an important outcome in lung transplant and the future holds a lot of potential for improvement in understanding its pathophysiology as well as development of preventative therapies and treatment.

Primary graft dysfunction

PURPOSE OF REVIEW

Primary graft dysfunction (PGD) is a devastating complication in the acute postoperative lung transplant period, associated with high short-term mortality and chronic rejection. We review its definition, pathophysiology, risk factors, prevention, treatment strategies, and future research directions.

RECENT FINDINGS

New analyses suggest donation after circulatory death and donation after brain death donors have similar PGD rates, whereas donors >55 years are not associated with increased PGD risk. Recipient pretransplant diastolic dysfunction and overweight or obese recipients with predominant abdominal subcutaneous adipose tissue have increased PGD risk. Newly identified recipient biomarkers and donor and recipient genes increase PGD risk, but their clinical utility remains unclear. Mixed data still exists regarding cold ischemic time and PGD risk, and increased PGD risk with cardiopulmonary bypass remains confounded by transfusions. Portable ex vivo lung perfusion (EVLP) may prevent PGD, but its use is limited to a handful of centers. Although updates to current PGD treatment are lacking, future therapies are promising with targeted therapy and the use of EVLP to pharmacologically recondition donor lungs.

SUMMARY

There is significant progress in defining PGD and identifying its several risk factors, but effective prevention and treatment strategies are needed.

Primary Graft Dysfunction

Primary graft dysfunction (PGD) is a form of acute lung injury after transplantation characterized by hypoxemia and the development of alveolar infiltrates on chest radiograph that occurs within 72 hours of reperfusion. PGD is among the most common early complications following lung transplantation and significantly contributes to increased short-term morbidity and mortality. In addition, severe PGD has been associated with higher 90-day and 1-year mortality rates compared with absent or less severe PGD and is a significant risk factor for the subsequent development of chronic lung allograft dysfunction. The International Society for Heart and Lung Transplantation released updated consensus guidelines in 2017, defining grade 3 PGD, the most severe form, by the presence of alveolar infiltrates and a ratio of PaO₂:FiO₂ less than 200. Multiple donor-related, recipient-related, and perioperative risk factors for PGD have been identified, many of which are potentially modifiable. Consistently identified risk factors include donor tobacco and alcohol use; increased recipient body mass index; recipient history of pulmonary hypertension, sarcoidosis, or pulmonary fibrosis; single lung transplantation; and use of cardiopulmonary bypass, among others. Several cellular pathways have been implicated in the pathogenesis of PGD, thus presenting several possible therapeutic targets for preventing and treating PGD. Notably, use of ex vivo lung perfusion (EVLP) has become more widespread and offers a potential platform to safely investigate novel PGD treatments while expanding the lung donor pool. Even in the presence of significantly prolonged ischemic times, EVLP has not been associated with an increased risk for PGD.

Extracorporeal Membrane Oxygenation for Primary Graft Dysfunction After Lung Transplantation

Extracorporeal membrane oxygenation (ECMO) is used as the last resort for primary graft dysfunction (PGD). The aim of this study is to explore the predictors and outcomes for early mortality in postlung transplant patients who required ECMO for PGD. Between January 2006 and December 2015, 1,049 cases of lung transplantation were performed at our center. Ninety-six patients required ECMO support after lung transplantation, 52 patients (54%) had PGD. Seven patients (13.5%) required venoarterial ECMO due to concomitant hemodynamical instability, and the others required venovenous ECMO. The patients were on ECMO for 5.00 ± 10.6 days. Forty-four patients (84.6%) were successfully decannulated. The 90 day, 1 year, and 5 year survival of patients who required ECMO for PGD after lung transplantation were 67.3%, 50.0%, and 31.5%, respectively. Cox regression indicated that when the patient was placed on ECMO later than 48 hours after transplantation, the patient could have higher in-house mortality (hazard ratio, 2.79; 95% CI, 1.21-6.43) and also higher 3 year mortality (hazard ratio, 2.30; 95% CI, 1.13-4.68) regardless of the patients' preoperative conditions or complexity of lung transplantation. Earlier recognition of PGD and initiation of ECMO may be beneficial in this population.

Ischemia-reperfusion Injury in the Transplanted Lung: A Literature Review

Lung ischemia-reperfusion injury (LIRI) and primary graft dysfunction are leading causes of morbidity and mortality among lung transplant recipients. Although extensive research endeavors have been undertaken, few preventative and therapeutic treatments have emerged for clinical use. Novel strategies are still needed to improve outcomes after lung transplantation. In this review, we discuss the underlying mechanisms of transplanted LIRI, potential modifiable targets, current practices, and areas of ongoing investigation to reduce LIRI and primary graft dysfunction in lung transplant recipients.

Extracorporeal Membrane Oxygenation in the Perioperative Care of the Lung Transplant Patient

Lung transplantation (LT) is definitive therapy for end-stage lung disease. Donor allocation based on medical urgency has led to an increased trend in the transplantation of sicker and older patients. Mechanical ventilation (MV) formerly was the only method of bridging high-acuity patients to LT. When the physiological demands of ventilatory support exceeds the capability of MV, extracorporeal membrane oxygenation (ECMO) may become necessary. Recent improvements in ECMO technology and component design have led to a resurgence of interest in its use before, during, and after LT. Survival with ECMO as a bridge to LT has improved over time, now with many centers reporting little or no difference in outcomes, and some even reporting better outcomes, as compared with MV. Extracorporeal life support may also be used intraoperatively. In many studies to date, ECMO or cardiopulmonary bypass (CPB) has been reserved for patients who became hemodynamically unstable during the procedure or patients who could not tolerate single-lung ventilation. Both methods of support are fraught with potential complications. However, multiple studies comparing ECMO with CPB have shown that intraoperative use of ECMO resulted in improved outcomes and overall survival as well as lower rates of bleeding complications. In order to further reduce complications associated with ECMO, planned intraoperative ECMO use is occasionally reserved for high-risk patients who might otherwise require CPB. Future studies will need to improve patient selection to fully take advantage of the use of ECMO in LT while minimizing its costs.

Critical Care after Lung Transplantation

Since the first successful lung transplantation in 1983, there have been many advances in the field. Nevertheless, the latest data from the International Society for Heart and Lung Transplantation revealed that the risk of death from transplantation is 9%. Various aspects of postoperative management, including mechanical ventilation, could affect intensive care unit stay, hospital stay, and immediate postoperative morbidity and mortality. Complications such as reperfusion injury, graft rejection, infection, and dehiscence of anastomosis increase fatal adverse side effects immediately after surgery. In this article, we review the possible immediate complications after lung transplantation and summarize current knowledge on prevention and treatment.

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

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is being used more often as a bridge to transplantation (BTT) in patients with acutely decompensated end-stage lung disease in Korea. ECMO as a BTT may be the only rescue strategy for severe acute respiratory failure, but many centers still consider it to be a relative contraindication to lung transplantation because of its poor outcome. Because there are not enough lung donors, it is important to determine their optimal use. We reviewed and analyzed our experiences with the use of ECMO as a BTT in patients with acute respiratory failure.

METHODS

This was a retrospective analysis of all patients with acutely decompensated end-stage lung disease treated with ECMO as a bridge to lung transplantation between March 2012 and February 2016.

RESULTS

Of the 194 patients who underwent respiratory ECMO over a 4-year period, a BTT strategy was used for 19 patients (median age, 58 years) on our institution's lung transplantation waiting list (15 veno-venous, 3 veno-veno-arterial, 1 veno-arterial). Fourteen patients (73.7%) were successfully bridged to transplantation; however, 3 died while on the waiting list and 2 returned to their baseline functions without transplantation. The overall in-hospital survival rate was 57.9% (11 of 19), including the 9 (64.3%) patients who underwent transplantation.

CONCLUSIONS

Our findings support the view that well-selected candidates with acutely decompensated end-stage lung disease may be safely bridged until a suitable donor is identified. ECMO is not able to reverse the course of patients; however, it could be a life-saving option for patients with acute respiratory failure requiring lung transplantation.

Prone positioning as a bridge to recovery from refractory hypoxaemia following lung transplantation

OBJECTIVES

Refractory hypoxaemia is the leading cause of mortality in the postoperative period after lung transplantation. The role of prone positioning as a rescue therapy in this setting has not been assessed. We evaluated its effects in lung transplant recipients presenting refractory hypoxaemia following the surgery.

METHODS

Prospectively collected data from 131 consecutive adult patients undergoing lung transplantation between January 2013 and December 2014 were evaluated. Twenty-two patients received prone position therapy. Indications, associated complications, time to initiation and duration of the manoeuvre were analysed and the effects of prone position on gas exchange were evaluated. Finally, outcomes in this cohort were compared against the rest of lung transplant recipients.

RESULTS

Prone positioning was more frequently implemented within the first 72 h (68.2%) and its main indication was primary graft dysfunction. The manoeuvre was maintained during a median of 21 h. After prone position, the pressure of arterial oxygen/fraction of inspired oxygen ratio significantly increased from 81.0 mmHg [interquartile range (IQR) 71.5-104.0] to 220.0 (IQR 160.0-288.0) (P < 0.001). No complications related with the technique were reported. Patients who underwent the manoeuvre had longer hospital stay [50.0 days (IQR 36.0-67.0) vs 30.0 (IQR 23.0-56.0), P = 0.006] than the rest of the population. No differences were found comparing either 1-year mortality (9.1% vs 15.6%; P = 0.740) or 1-year graft function [forced expiratory volume in 1 second of 70.0 (IQR 53.0-83.0) vs 68.0 (IQR 53.5-80.5), P = 0.469].

CONCLUSIONS

Prone positioning is safe and significantly improves gas exchange in patients with refractory hypoxaemia after lung transplantation. It should be considered as a possible treatment in these patients.

Intraoperative extracorporeal membrane oxygenation and the possibility of postoperative prolongation improve survival in bilateral lung transplantation

OBJECTIVES

The value of intraoperative extracorporeal membrane oxygenation (ECMO) in lung transplantation remains controversial. In our department, ECMO has been used routinely for intraoperatively unstable patients for more than 15 years. Recently, we have extended its indication to a preemptive application in almost all cases. In addition, we prolong ECMO into the early postoperative period whenever graft function does not meet certain quality criteria or in patients with primary pulmonary hypertension. The objective of this study was to review the results of this strategy.

METHODS

All standard bilateral lung transplantations performed between January 2010 and June 2016 were included in this single-center, retrospective analysis. Patients were divided into 3 groups: group I-no ECMO (n = 116), group II-intraoperative ECMO (n = 343), and group III-intraoperative and prolonged postoperative ECMO (n = 123). The impact of different ECMO strategies on primary graft function, short-term outcomes, and patient survival were analyzed.

RESULTS

The use of intraoperative ECMO was associated with improved 1-, 3-, and 5-year survival compared with non-ECMO patients (91% vs 82%, 85% vs 76%, and 80% vs 74%; log-rank P = .041). This effect was still evident after propensity score matching of both cohorts. Despite the high number of complex patients in group III, outcome was excellent with higher survival rates than in the non-ECMO group at all time points.

CONCLUSIONS

Intraoperative ECMO results in superior survival when compared with transplantation without any extracorporeal support. The concept of prophylactic postoperative ECMO prolongation is associated with excellent outcomes in recipients with pulmonary hypertension and in patients with questionable graft function at the end of implantation.

Primary Graft Dysfunction After Lung Transplantation

Primary graft dysfunction is a form of acute injury after lung transplantation that is associated with significant short- and long-term morbidity and mortality. Multiple mechanisms contribute to the pathogenesis of primary graft dysfunction, including ischemia reperfusion injury, epithelial cell death, endothelial cell dysfunction, innate immune activation, oxidative stress, and release of inflammatory cytokines and chemokines. This article reviews the epidemiology, pathogenesis, risk factors, prevention, and treatment of primary graft dysfunction.

Outcomes of perioperative extracorporeal membrane oxygenation use in patients undergoing lung transplantation

Background

The aim of this single-center study is to review the transplant outcomes of patients receiving lung transplantation (LTx) using intraoperative extracorporeal membrane oxygenation (ECMO) according to the perioperative use of ECMO.

Methods

We retrospectively reviewed the transplant outcomes of 107 consecutive patients who underwent LTx using intraoperative ECMO between March 2013 and August 2016 at Severance Hospital of Yonsei University (Seoul, Korea).

Results

Patients were divided into the following three groups according to the use of perioperative ECMO: only intraoperative ECMO (n=47) or extended post-operative ECMO but no bridging and no postoperative ECMO re-implantation (secondary ECMO; n=28) as Group A (n=75); bridging ECMO without secondary ECMO (n=14) as Group B; and secondary ECMO with (n=7) or without (n=11) bridging as Group C. Baseline demographics were comparable among the three groups. The mean duration of preoperative ECMO bridging was 16.4±15.6 (n=21). After a median of 17.7 months (range, 3.1-40.9 months) for survivors, the one year overall survival (OS) rates after LTx for the three groups were 76.3%±5.2% for Group A, 59.9%±14.3% for Group B, and 14.0%±9.0% for Group C (P<0.0001). The secondary ECMO (Group C) was established a mean of 7.9±5.3 days after LTx. The main cause of secondary ECMO was acute respiratory failure from pneumonia, and the main cause of death was infection-related events.

Conclusions

Our data suggests that the use of perioperative ECMO, including its extended postoperative use during LTx, is feasible and has favorable outcomes. However, as shown by the poor survival outcome after secondary ECMO, the development of solid strategy to reduce the need for secondary ECMO implantation after LTx seems important.

Extracorporeal membrane oxygenation in adult patients with acute fulminant myocarditis : Clinical outcomes and risk factor analysis

BACKGROUND

Our study aimed to summarize the clinical outcomes of extracorporeal membrane oxygenation (ECMO) in adult patients with acute fulminant myocarditis and to investigate the risk factors associated with its application.

PATIENTS AND METHODS

We retrospectively examined patients with cardiogenic shock and acute fulminant myocarditis. The following data were collected: patients' preoperative general condition, related clinical factors during ECMO, complications, and outcomes of ECMO. The patients were divided into a survivor group and a nonsurvivor group.

RESULTS

From a total of 33 patients, seven died in hospital. The survival rate was 78.7%. The following complications were observed during ECMO: 16 cases of acute renal failure (48.4%), seven cases of sepsis (21.2%), six cases of pulmonary infection (18.1%), six cases of multiple organ failure (MOF; 18.1%), three cases of cerebral hemorrhage (9%), and four cases of limb ischemia (12.1%). Pre-ECMO cardiopulmonary resuscitation, high levels of lactic acid, high amounts of blood transfusion during ECMO, renal failure, encephalorrhagia, gastrointestinal complications, lower-limb ischemia, high bilirubin levels, and MOF during ECMO were associated with unfavorable patient outcomes.

CONCLUSION

ECMO is an effective auxiliary tool for treating acute fulminant myocarditis. Acute renal failure is the most common complication during ECMO. Improving tissue perfusion, reducing blood transfusions, and preventing acute kidney failure may improve patient outcomes.

Increased Extravascular Lung Water and Plasma Biomarkers of Acute Lung Injury Precede Oxygenation Impairment in Primary Graft Dysfunction After Lung Transplantation

BACKGROUND

After lung transplantation (LT), early prediction of grade 3 pulmonary graft dysfunction (PGD) remains a research gap for clinicians. We hypothesized that it could be improved using extravascular lung water (EVLWi) and plasma biomarkers of acute lung injury.

METHODS

After institutional review board approval and informed consent, consecutive LT recipients were included. Transpulmonary thermodilution-based EVLWi, plasma concentrations of epithelial (soluble receptor for advanced glycation endproducts [sRAGE]) and endothelial biomarkers (soluble intercellular adhesion molecule-1 and endocan [full-length and cleaved p14 fragment]) were obtained before and after LT (0 [H0], 6, 12, 24, 48 and 72 hours after pulmonary artery unclamping). Grade 3 PGD was defined according to the International Society for Lung and Heart Transplantation definition, combining arterial oxygen partial pressure (PaO2)/inspired fraction of oxygen (FiO2) ratio and chest X-rays. Association of clinical risk factors, EVLWi and biomarkers with grade 3 PGD was analyzed under the Bayesian paradigm, using logistic model and areas under the receiver operating characteristic curves (AUCs).

RESULTS

In 47 LT recipients, 10 developed grade 3 PGD, which was obvious at H6 in 8 cases. Clinical risk factors, soluble intercellular adhesion molecule-1 and endocan (both forms) were not associated with grade 3 PGD. Significant predictors of grade 3 PGD included (1) EVLWi (optimal cutoff, 13.7 mL/kg; AUC, 0.74; 95% confidence interval [CI], 0.48-0.99), (2) PaO2/FiO2 ratio (optimal cutoff, 236; AUC, 0.68; 95% CI, 0.52-0.84), and (3) sRAGE (optimal cutoff, 11 760 pg/mL; AUC, 0.66; 95% CI, 0.41-0.91) measured at H0.

CONCLUSIONS

Immediate postreperfusion increases in EVLWi and sRAGE along with impaired PaO2/FiO2 ratios were early predictors of grade 3 PGD at or beyond 6 hours and may trigger early therapeutic interventions.

Implementation and results of a new ECMO program for lung transplantation and acute respiratory distress

Objective

The development of the extracorporeal membrane oxygenation in Latin America represents a challenge in this specialty field. The objective of this article was to describe the results of a new extracorporeal membrane oxygenation program in an intensive care unit.

Methods

This retrospective cohort study included 22 patients who required extracorporeal membrane oxygenation and were treated from January 2011 to June 2014. The baseline characteristics, indications, duration of the condition, days on mechanical ventilation, days in the intensive care unit, complications, and hospital mortality were evaluated.

Results

Fifteen patients required extracorporeal membrane oxygenation after lung transplantation, and seven patients required oxygenation due to acute respiratory distress. All transplanted patients were weaned from extracorporeal membrane oxygenation with a median duration of 3 days (Interquartile range - IQR: 2 - 5), were on mechanical ventilation for a median of 15.5 days (IQR: 3 - 25), and had an intensive care unit stay of 31.5 days (IQR: 19 - 53) and a median hospital stay of 60 days (IQR: 36 - 89) with 20% mortality. Patients with acute respiratory distress had a median oxygenation membrane duration of 9 days (IQR: 3 - 14), median mechanical ventilation time of 25 days (IQR: 13 - 37), a 31 day stay in therapy (IQR: 11 - 38), a 32 day stay in the hospital (IQR: 11 - 41), and 57% mortality. The main complications were infections (80%), acute kidney failure (43%), bleeding at the surgical site and at the site of cannula placement (22%), plateletopenia (60%), and coagulopathy (30%).

Conclusion

In spite of the steep learning curve, we considered this experience to be satisfactory, with results and complications comparable to those reported in the literature.

Extracorporeal membrane oxygenation treatment of a H7N9-caused respiratory failure patient with mechanical valves replacement history: A case report

BACKGROUND

Patients with respiratory failure caused by H7N9 may benefit from veno-venous, veno-arterial, and veno-veno-arterial extracorporeal membrane oxygenation (ECMO) support.

CASE SUMMARY

A 55-year-old male patient was suffering from H7N9-caused acute respiratory distress syndrome (ARDS). He had a mechanical mitral and aortic valve replacement surgery and was using warfarin for anticoagulation. After prolonged mechanical ventilation, oxygen saturation was not improved. Veno-veno ECMO was then applied. After 16 days of extracorporeal life support, the patient successfully weaned from ECMO, with relatively good pulmonary recovery.

CONCLUSION

This report demonstrates that ECMO support can help treating life-threatening diseases such as H7N9-associated ARDS. Because of his special mitral and aortic valve replacement surgery history and long duration of mechanical ventilation before ECMO, we report it as a separate case, hoping to provide some reference for ECMO treatment.

Primary graft dysfunction: lessons learned about the first 72 h after lung transplantation

PURPOSE OF REVIEW

In 2005, the International Society for Heart and Lung Transplantation published a standardized definition of primary graft dysfunction (PGD), facilitating new knowledge on this form of acute lung injury that occurs within 72 h of lung transplantation. PGD continues to be associated with significant morbidity and mortality. This article will summarize the current literature on the epidemiology of PGD, pathogenesis, risk factors, and preventive and treatment strategies.

RECENT FINDINGS

Since 2011, several manuscripts have been published that provide insight into the clinical risk factors and pathogenesis of PGD. In addition, several transplant centers have explored preventive and treatment strategies for PGD, including the use of extracorporeal strategies. More recently, results from several trials assessing the role of extracorporeal lung perfusion may allow for much-needed expansion of the donor pool, without raising PGD rates.

SUMMARY

This article will highlight the current state of the science regarding PGD, focusing on recent advances, and set a framework for future preventive and treatment strategies.

Five-year experience with intraoperative extracorporeal membrane oxygenation in lung transplantation: Indications and midterm results

BACKGROUND

Since April 2010, extracorporeal membrane oxygenation (ECMO) has replaced cardiopulmonary bypass for intraoperative support during lung transplantation at our institution. The aim of this study was to present our 5-year experience with this technique.

METHODS

Records of patients who underwent transplantation between April 2010 and January 2015 were retrospectively reviewed. Patients who underwent transplantation without ECMO formed Group A. Patients in whom the indication for ECMO support was set a priori before the beginning of the operation formed Group B. The remaining patients in whom the indication for ECMO support was set during transplantation formed Group C.

RESULTS

Among 595 patients, 425 (71%) patients (Group A) did not require intraoperative ECMO; the remaining 170 (29%) patients did. Among these patients, 95 (56%) patients formed Group B, and the remaining 75 (44%) patients comprised Group C. Pulmonary fibrosis and pre-operative dilated or hypertrophied right ventricle emerged as risk factors for the indication of non-a priori intraoperative ECMO. Patients in Groups B and C showed a higher pre-operative risk profile and higher prevalence of post-operative complications than patients in Group A. Overall survival at 1 year was 93%, 83%, and 82% and at 4 years was 73%, 68%, and 69% in Groups A, B, and C (p = 0.11). The intraoperative use of ECMO did not emerge as a risk factor for in-hospital mortality or mortality after hospital discharge.

CONCLUSIONS

Intraoperative ECMO filled the gap between pre-operative and post-operative ECMO in lung transplantation. Although complications and in-hospital mortality were higher in patients who received ECMO, survival was similar among patients who underwent transplantation with or without ECMO.

Mechanical circulatory support in lung transplantation: Cardiopulmonary bypass, extracorporeal life support, and ex-vivo lung perfusion

Lung transplant is the standard of care for patients with end-stage lung disease refractory to medical management. There is currently a critical organ shortage for lung transplantation with only 17% of offered organs being transplanted. Of those patients receiving a lung transplant, up to 25% will develop primary graft dysfunction, which is associated with an 8-fold increase in 30-d mortality. There are numerous mechanical lung assistance modalities that may be employed to help combat these challenges. We will discuss the use of mechanical lung assistance during lung transplantation, as a bridge to transplant, as a treatment for primary graft dysfunction, and finally as a means to remodel and evaluate organs deemed unsuitable for transplant, thus increasing the donor pool, improving survival to transplant, and improving overall patient survival.

Proposed management algorithm for severe hypoxemia after liver transplantation in the hepatopulmonary syndrome

The hepatopulmonary syndrome (HPS) is defined as the triad of liver disease, intrapulmonary vascular dilatation, and abnormal gas exchange, and is found in 10-32% of patients with liver disease. Liver transplantation is the only known cure for HPS, but patients can develop severe posttransplant hypoxemia, defined as a need for 100% inspired oxygen to maintain a saturation of ≥85%. This complication is seen in 6-21% of patients and carries a 45% mortality. Its management requires the application of specific strategies targeting the underlying physiologic abnormalities in HPS, but awareness of these strategies and knowledge on their optimal use is limited. We reviewed existing literature to identify strategies that can be used for this complication, and developed a clinical management algorithm based on best evidence and expert opinion. Evidence was limited to case reports and case series, and we determined which treatments to include in the algorithm and their recommended sequence based on their relative likelihood of success, invasiveness, and risk. Recommended therapies include: Trendelenburg positioning, inhaled epoprostenol or nitric oxide, methylene blue, embolization of abnormal pulmonary vessels, and extracorporeal life support. Availability and use of this pragmatic algorithm may improve management of this complication, and will benefit from prospective validation.

[The place of extra-corporeal oxygenation in pulmonary diseases]

Extra-corporeal membrane oxygenation (ECMO) effectively replaces the lung in providing oxygenation and carbon dioxide (CO2) removal. For some years, and in parallel to the H1N1 influenza pandemic, this technique has gained interest in relation to significant technological improvements, leading to new concepts of "awake and mobile ECMO" or rehabilitation with ECMO. Finally, the publication of randomized controlled trials giving encouraging results in the adult respiratory distress syndrome (ARDS) has helped to validate this technique and further studies are warranted. This general review aims to outline the definition, classification and principles of ECMO and to give some current information about the indications and possibilities of the technique to the pulmonologist and intensivist. Further possible uses for this technique include extra-corporeal removal of CO2 during hypercapnic respiratory failure and assistance during lung transplantation from the preoperative to the early postoperative period.

Veno-veno-arterial extracorporeal membrane oxygenation for respiratory failure with severe haemodynamic impairment: technique and early outcomes

OBJECTIVES

Patients with respiratory failure may benefit from veno-venous and veno-arterial extracorporeal membrane oxygenation (ECMO) support. We report on our initial experience of veno-veno-arterial (v-v-a) ECMO in patients with respiratory failure.

METHODS

Between January 2012 and February 2014, 406 patients required ECMO support at our institution. Here, we retrospectively analysed the characteristics and outcomes of patients commenced on either veno-venous or veno-arterial ECMO due to respiratory failure, and then switched to v-v-a ECMO.

RESULTS

Ten (2%) patients proceeded to v-v-a ECMO. The underlying conditions were acute respiratory distress syndrome (n = 3), end-stage pulmonary fibrosis (n = 5) and respiratory failure after major thoracic surgery (n = 1) and Caesarean section (n = 1). In all of these patients, ECMO was initially started as veno-venous (n = 9) or veno-arterial (n = 1) ECMO but was switched to a veno-veno-arterial (v-v-a) approach after a mean of 2 (range, 0-7) days. Reasons for switching were: haemodynamic instability (right heart failure, n = 5; pericardial tamponade, n = 1; severe mitral valve regurgitation, n = 1; haemodynamic instability following cardiopulmonary resuscitation, n = 1 and evidence of previously unknown atrial septal defect with pulmonary hypertension and Eisenmenger syndrome, n = 1) and upper-body hypoxaemia (n = 1). ECMO-related complications were bleeding (n = 3) and leg ischaemia (n = 2). Seven patients were successfully taken off ECMO with 4 being bridged to recovery and a further 3 to lung transplantation after a mean of 11 (range, 9-18) days. Five patients survived until hospital discharge and all of them were alive at the end of the follow-up.

CONCLUSIONS

Veno-veno-arterial ECMO is a technically feasible rescue strategy in treating patients presenting with combined respiratory and haemodynamic failure.

Extracorporeal membrane oxygenation and retransplantation in lung transplantation: an analysis of the UNOS registry

BACKGROUND

Despite limited organ availability, extracorporeal membrane oxygenation (ECMO) and retransplantation are becoming more commonplace.

METHODS

Using the United Network for Organ Sharing (UNOS) database, we evaluated survival of patients treated with ECMO before lung transplantation and undergoing retransplantation. A query identified cadaveric recipients from 2001 to 2012 over the age of 6 years.

RESULTS

Of 15,772 lung recipients, 15 583 never received ECMO, whereas 189 did. Mean age was 52.1 ± 14.4 versus 46.8 ± 16.5 years for non-ECMO and ECMO groups, respectively (p < 0.0001). Using Kaplan-Meier method, there were survival differences between ECMO and non-ECMO groups (p < 0.0001) and first-time transplants with and without ECMO to retransplants with and without ECMO (p < 0.0001). The proportional hazards model identified higher risk with ECMO use in idiopathic pulmonary fibrosis (hazard ratio [HR] 1.09; 95 % confidence interval (CI), 1.02-1.17; p = 0.014) and retransplants (HR 1.77; 95 % CI, 1.55-2.03; p < 0.0001).

CONCLUSIONS

Survival for retransplantation was similar to ECMO as a primary option with significant mortality associated with ECMO use in patients with idiopathic pulmonary fibrosis and retransplants.

Clinical neurology in lung transplantation

Lung transplantation is the only established therapeutic option for several end-stage respiratory diseases. Limited mostly by lack of suitable allografts, the results have measurably improved over the last decade. Numerous surgical and pharmaceutical improvements have had positive impact on outcomes. The potential for critical care issues and the need for interdisciplinary management remains paramount. Cardiac, renal, and metabolic complications are frequently encountered in the acute postoperative phase. Allograft rejection and infectious diseases as well as problems related to immunosuppressive regimen are seen later after lung transplantation. Neurologic manifestations with a range of etiologies are discussed here in this context.