Extracorporeal membrane oxygenation as an adjunct treatment for primary graft failure in adult lung transplant recipients

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

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

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.

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.

Extracorporeal Life Support in Adult Patients: A Global Perspective of the Last Decade

Extracorporeal life support (ECLS) is an external medical device to treat critically ill patients with cardiovascular and respiratory failure. In a nutshell, ECLS is only a "bridging" mechanism that provides life support while the heart and/or the lungs is recovering either by therapeutic medical interventions, transplantation, or spontaneously. Extracorporeal life support has been developed since 1950s, and many studies were conducted to improve ECLS techniques, but unfortunately, the survival rate was not improved. Because of Dr Bartlett's success in using ECLS to treat neonates with severe respiratory distress in 1975, ECLS is made as a standard lifesaving therapy for neonates with severe respiratory distress. However, its use for adult patients remains debatable. The objectives of this study are to outline and provide a general overview of the use of ECLS especially for adult patients for the past 10 years and to elaborate on the challenges encountered by each stakeholder involved in ECLS. The data used for this study were extracted from the ELSO Registry Report of January 2018. Results of this study revealed that the number of ECLS centers and the use of ECLS are increasing over the year for the past decade. There was also a shift of the patient's age category from neonatal to adult patients. However, the survival rates for adult patients are relatively low especially for cardiac and extracorporeal cardiopulmonary resuscitation cases. To date, the complications are still the major challenge of ECLS. Other challenges encountered by the stakeholders in ECLS are the limited amount of well-trained and experienced ECLS teams and centers, the limited government expenditure on health, and the lack of improvement and development of ECLS techniques and devices. Further studies are needed to evaluate the value of ECLS for adult patients.

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.

Extracorporeal membrane oxygenation in the pre and post lung transplant period

Evolution in technology has resulted in rapid increase in utilization of extracorporeal membrane oxygenation (ECMO) as a bridge to recovery and/or transplantation. Although there is limited evidence for the use of ECMO, recent improvements in ECMO technology, personnel training, ambulatory practices on ECMO and lung protective strategies have resulted in improved outcomes in patients bridged to lung transplantation. This review provides an insight into the current outcomes and best practices for utilization of ECMO in the pre- and post-lung transplantation period.

Aspects of Anesthesia for Lung Transplantation

Anesthesia for lung transplantation is both a demand ing and rewarding experience. Success requires team- work, experience, knowledge of cardiorespiratory patho physiology and its anesthetic implications, appropriate use of noninvasive and invasive monitoring, and the ability to respond quickly and effectively to life- threatening perioperative events. Specific issues in clude management of a patient with end-stage lung and heart disease, lung isolation and one-lung ventilation, perioperative respiratory failure, pulmonary hyperten sion, and acute right ventricular failure. Recent ad vances include greater understanding of dynamic hyper inflation ("gas-trapping") during mechanical ventilation, perioperative use of inhaled nitric oxide and treatment of acute right ventricular failure. Successful anesthetic management leads to greater hemodynamic stability, improvement in gas exchange and a reduction in need for cardiopulmonary bypass, all of which should lead to improved patient outcome.

Critical Care Aspects of Lung Transplant Patients

Major strides have been made in lung transplantation during the 1990s and it has become an established treatment option for patients with advanced lung disease. Due to improvements in organ preservation, surgical techniques, postoperative intensive care, and immunosuppression, the risk of perioperative and early mortality (less than 3 months after transplantation) has declined [1]. The transplant recipient now has a greater chance of realizing the benefits of the long and arduous waiting period.

Despite these improvements, suboptimal long-term outcomes continue to be shaped by issues such as opportunistic infections and chronic rejection. Because of the wider use of lung transplantation and the longer life span of recipients, intensivists and ancillary intensive care unit (ICU) staff should be well versed with the care of lung transplant recipients.

In this clinical review, issues related to organ donation will be briefly mentioned. The remaining focus will be on the critical care aspects of lung transplant recipients in the posttransplant period, particularly ICU management of frequently encountered conditions. First, the groups of patients undergoing transplantation and the types of procedures performed will be outlined. Specific issues directly related to the allograft, including early graft dysfunction from ischemia-reperfusion injury, airway anastomotic complications, and infections in the setting of immunosuppression will be emphasized. Finally nonpulmonary aspects of posttransplant care and key pharmacologic points in the ICU will be covered.

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.

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.

Lung transplantation for severe pulmonary hypertension--awake extracorporeal membrane oxygenation for postoperative left ventricular remodelling

BACKGROUND

Bilateral lung transplantation (BLTx) is an established treatment for end-stage pulmonary hypertension (PH). Ventilator weaning failure and death are more common as in BLTx for other indications. We hypothesized that left ventricular (LV) dysfunction is the main cause of early postoperative morbidity or mortality and investigated a weaning strategy using awake venoarterial extracorporeal membrane oxygenation (ECMO).

METHODS

In 23 BLTx for severe PH, ECMO used during BLTx was continued for a minimum of 5 days (BLTx-ECMO group). Echocardiography, left atrial (LA) and Swan-Ganz catheters were used for monitoring. Early extubation after transplantation was attempted under continued ECMO.

RESULTS

Preoperatively, all patients had severely reduced cardiac index (mean, 2.1 L/min/m2). On postoperative day 2, reduction of ECMO flow resulted in increasing LA and decreasing systemic blood pressures. On the day of ECMO explantation (median, postoperative day 8), LV diameter had increased; LA and blood pressures remained stable. Survival rates at 3 and 12 months were 100% and 96%, respectively. Data were compared to two historic control groups of BLTx without ECMO (BLTx ventilation) or combined heart-lung transplantation for severe PH.

CONCLUSION

Early after BLTx for severe PH, the LV may be unable to handle normalized LV preload. This can be effectively bridged with awake venoarterial ECMO.

Extracorporeal membrane oxygenation as a bridge to lung transplantation in the United States: an evolving strategy in the management of rapidly advancing pulmonary disease

OBJECTIVE

Improvements in technology have led to a resurgence in the use of extracorporeal membrane oxygenation as a bridge to lung transplantation. By using a national registry, we sought to evaluate how short-term survival has evolved using this strategy.

METHODS

With the use of the United Network for Organ Sharing database, we analyzed data from 12,458 adults who underwent lung transplantation between 2000 and 2011. Patients were categorized into 2 cohorts: 119 patients who were bridged to transplantation using extracorporeal membrane oxygenation and 12,339 patients who were not. The study period was divided into four 3-year intervals: 2000 to 2002, 2003 to 2005, 2006 to 2008, and 2009 to 2011. With Kaplan-Meier analysis, 1-year survival was compared for the 2 cohorts of patients in each of the time periods. A propensity score-adjusted Cox regression model was used to estimate the risk of 1-year mortality.

RESULTS

Of the total number of recipients, 4 (3.4%) were bridged between 2000 and 2002, 17 (14.3%) were bridged between 2003 and 2005, 31 (26.1%) were bridged between 2006 and 2008, and 67 were bridged (56.3%) between 2009 and 2011. Recipients bridged using extracorporeal membrane oxygenation were more likely to be younger and diabetic and to have higher serum creatinine and bilirubin levels. The 1-year survival for those bridged with extracorporeal membrane oxygenation was significantly lower in subsequent periods: 25.0% versus 81.0% (2000-2002), 47.1% versus 84.2% (2006-2008), and 74.4% versus 85.7% (2009-2011). However, this survival progressively increased with each period, as did the number of patients bridged using extracorporeal membrane oxygenation.

CONCLUSIONS

Short-term survival with the use of extracorporeal membrane oxygenation as a bridge to lung transplantation has significantly improved over the past few years.

Extracorporeal life support in critically ill adults

Extracorporeal life support (ECLS) has become increasingly popular as a salvage strategy for critically ill adults. Major advances in technology and the severe acute respiratory distress syndrome that characterized the 2009 influenza A(H1N1) pandemic have stimulated renewed interest in the use of venovenous extracorporeal membrane oxygenation (ECMO) and extracorporeal carbon dioxide removal to support the respiratory system. Theoretical advantages of ECLS for respiratory failure include the ability to rest the lungs by avoiding injurious mechanical ventilator settings and the potential to facilitate early mobilization, which may be advantageous for bridging to recovery or to lung transplantation. The use of venoarterial ECMO has been expanded and applied to critically ill adults with hemodynamic compromise from a variety of etiologies, beyond postcardiotomy failure. Although technology and general care of the ECLS patient have evolved, ECLS is not without potentially serious complications and remains unproven as a treatment modality. The therapy is now being tested in clinical trials, although numerous questions remain about the application of ECLS and its impact on outcomes in critically ill adults.

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.

Primary graft dysfunction

Primary graft dysfunction (PGD) is a syndrome encompassing a spectrum of mild to severe lung injury that occurs within the first 72 hours after lung transplantation. PGD is characterized by pulmonary edema with diffuse alveolar damage that manifests clinically as progressive hypoxemia with radiographic pulmonary infiltrates. In recent years, new knowledge has been generated on risks and mechanisms of PGD. Following ischemia and reperfusion, inflammatory and immunological injury-repair responses appear to be key controlling mechanisms. In addition, PGD has a significant impact on short- and long-term outcomes; therefore, the choice of donor organ is impacted by this potential adverse consequence. Improved methods of reducing PGD risk and efforts to safely expand the pool are being developed. Ex vivo lung perfusion is a strategy that may improve risk assessment and become a promising platform to implement treatment interventions to prevent PGD. This review details recent updates in the epidemiology, pathophysiology, molecular and genetic biomarkers, and state-of-the-art technical developments affecting PGD.

Outcome of extracorporeal membrane oxygenation as a bridge to lung transplantation and graft recovery

BACKGROUND

Indications for extracorporeal membrane oxygenation (ECMO) use in lung transplantation are (1) temporary assistance as a bridge to transplantation, (2) stabilization of hemodynamics during transplantation in place of cardiopulmonary bypass, and (3) treatment of severe lung dysfunction and primary graft failure after transplantation. This study compares the survival of lung transplant recipients requiring ECMO support with survival of patients without ECMO.

METHODS

A retrospective database review was performed for 108 consecutive patients who underwent single-lung or bilateral-lung transplantation at our center between 2002 and 2009.

RESULTS

Of 108 transplant recipients, 27 (25%) required venoarterial ECMO compared with 81 patients who did not. Nine patients required ECMO preoperatively (87±102 hours), and ECMO was continued for 5 patients during the lung transplant operation. Seven additional patients received ECMO during transplantation. Six patients required early (<7 days) and 5 patients delayed (≥7 days) postoperative ECMO for treatment of allograft dysfunction. The subgroup with support showed the most favorable patient discharge rate (66.7%). ECMO support was a significant risk factor for death (p<0.001). Survival was significantly reduced with the use of ECMO: 30-day, 90-day, 1-year, and 5-year survival was 97%, 91%, 83%, and 58% in the patients without ECMO compared with 63%, 44%, 33%, and 21% in those with ECMO, respectively.

CONCLUSIONS

Survival after lung transplantation was significantly reduced with ECMO. However, patients who survived the first year showed similar long-term survival as those patients who did not need perioperative ECMO support.

Institution of extracorporeal membrane oxygenation late after lung transplantation - a futile exercise?

The use of and indications for extracorporeal membrane oxygenation (ECMO) are expanding as its reliability improves with widely varying results reported. A retrospective review of 24 lung transplant recipients who required ECMO support postoperatively was performed with 13 patients requiring ECMO within the first 48 h ("early" group) and 11 requiring ECMO after seven d postoperatively ("late" group). The majority of early ECMO group had primary graft failure patients and the late ECMO group comprised patients with infection or non-specific graft failure. There were significant differences in outcomes between groups, with 10/13 in the early group and 4/11 in the late group successfully weaned from ECMO (p = 0.045). Six of the 13 patients in the early group and none of the late group survived to hospital discharge (p = 0.009). The late ECMO group had a much higher incidence of death owing to complications existing prior to institution of ECMO (essentially uncontrolled infection or organ failure). There were no differences in complications arising during ECMO between groups. Late institution of ECMO in lung transplant recipients for causes other than primary graft failure is associated with such poor survival that its use should be considered only in very select cases.

Improved survival but marginal allograft function in patients treated with extracorporeal membrane oxygenation after lung transplantation

BACKGROUND

Previous reports demonstrate that 1-year survival is severely compromised in patients with severe primary graft dysfunction (PGD) after lung transplantation. We examined if advances in extracorporeal membrane oxygenation (ECMO) support, including polymethylpentene oxygenators and reliance on venovenous (VV) ECMO have improved outcomes in patients with severe PGD after lung transplantation.

METHODS

The analysis included data prospectively collected on all single-lung or double-lung transplants between November 2001 and December 2009. Heart-lung transplants were excluded. Comparisons were made between recipients who did and did not require ECMO for PGD after transplant.

RESULTS

Since November 2001, when VV ECMO became the routine treatment for severe PGD after transplant at our center, 28 of 498 patients (6%) have required VV ECMO support. Successful weaning occurred in 27 of 28 (96%). Support was withdrawn for 1 patient with irreversible neurologic injury. Survival was substantially better than in previous reports: 30 days, 82%; 1 year, 64%; and 5 years, 49%. Freedom from bronchiolitis obliterans syndrome was 88% in the ECMO survivors at 3 years, but maximum allograft function was considerably worse than in transplant recipients not requiring ECMO (peak forced expiratory volume in 1 second: 58% in ECMO vs 83% in non-ECMO, p=0.001).

CONCLUSIONS

Advances in ECMO technology, particularly VV ECMO, have greatly improved the ability to support patients with severe PGD after lung transplantation. VV ECMO is an important tool in the armamentarium of any lung transplant program to optimize patient outcomes; however, strategies to improve lung allograft function in patients experiencing severe PGD are still needed.

Extracorporeal membrane oxygenation as a bridge to lung transplant: midterm outcomes

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is used occasionally as a bridge to lung transplantation. The impact on mid-term survival is unknown. We analyzed outcomes after lung transplant over a 19-year period in patients who received ECMO support.

METHODS

From March 1991 to October 2010, 1,305 lung transplants were performed at our institution. Seventeen patients (1.3%) were supported with ECMO before lung transplant. Diagnoses included retransplantation (n = 6), pulmonary fibrosis (n = 6), cystic fibrosis (n = 4), and chronic obstructive pulmonary disease (n = 1). Fifteen patients underwent double lung transplant, one patient had single left lung transplant and one patient had a heart-lung transplant. Venovenous and venoarterial ECMO were implanted in eight and nine cases, respectively. Median duration of support was 3.2 days (range, 1 to 49 days). Mean patient follow-up was 2.3 years.

RESULTS

Thirty-day, 1-year, and 3-year survivals were 81%, 74%, and 65%, respectively, for the supported patients and 93%, 78%, and 62% in the control group (p = 0.56). Two-year survival was not affected by ECMO type, with survival of five out of nine patients supported by venoarterial ECMO vs seven out of eight patients supported by venovenous ECMO (p = 0.17). At 1- year follow-up, allograft function for the ECMO-supported patients did not differ from the control group (forced expiratory volume in one second, 2.35 L vs 2.09 L, p = 0.39) (forced vital capacity, 3.06 L vs 2.71 L, p = 0.34).

CONCLUSIONS

Extracorporeal membrane oxygenation as a bridge to lung transplantation is associated with higher perioperative mortality but acceptable mid-term survival in carefully selected patients. Late allograft function did not differ in patients who received ECMO support before lung transplant from those who did not receive ECMO.

Extracorporeal membrane oxygenation for primary graft dysfunction after lung transplantation: long-term survival

BACKGROUND

Primary graft dysfunction (PGD) after lung transplantation is a major cause of morbidity and mortality. Venovenous or venoarterial extracorporeal membrane oxygenation (ECMO) allows lung recovery; however, the optimal approach and impact on long-term survival are unknown. We analyzed outcomes after ECMO use for PGD after lung transplantation at a single center over a 15-year period and assessed long-term survival.

METHODS

From March 1991 to March 2006, 763 lung or heart-lung transplants were performed at our center. Fifty-eight patients (7.6%) required early (0 to 7 days after transplant) ECMO support for PGD. Venovenous or venoarterial ECMO was implemented (32 and 26 cases) depending on the patient's hemodynamic stability, surgeon's preference, and the era of transplantation. Mean duration of support was 5.5 days (range, 1 to 20). Mean follow-up was 4.5 years.

RESULTS

Thirty-day and 1- and 5-year survivals were 56%, 40%, and 25%, respectively, for the entire group. Thirty-nine patients were weaned from ECMO, 21 venovenous and 18 venoarterial (53.8% and 46.2%), with 1- and 5-year survivals of 59% and 33%, inferior to recipients not requiring ECMO (p = 0.05). Survival at 30 days and at 1 and 5 years was similar for the patients supported with venoarterial or venovenous ECMO (58% versus 55%, p = 0.7; 42% versus 39%, p = 0.8; 29% versus 22%, p = 0.6).

CONCLUSIONS

Extracorporeal membrane oxygenation can provide acceptable support for PGD irrespective of the method used. Long-term survival of patients with primary graft dysfunction requiring ECMO (overall and weaned) was inferior to that of patients who did not require ECMO.

Resolution of Severe Ischemia–Reperfusion Injury Post–Lung Transplantation After Administration of Endobronchial Surfactant

BACKGROUND

Ischemia-reperfusion injury (IRI) is a prominent cause of primary graft failure after lung transplantation and is associated with an altered surfactant profile. Experimental animal studies have found that replacement with exogenous surfactant administered via fiber-optic bronchoscopy (FOB) enhanced recovery from IRI with improved pulmonary compliance and gas exchange after lung transplantation. We report our clinical experience with FOB instillation of surfactant in severe IRI after human lung transplantation.

METHODS

This study is a retrospective review of 106 consecutive lung or heart-lung transplants performed at a single institution. Severe IRI was defined as diffuse roentgenographic alveolar infiltrates, worsening hypoxemia and decreased lung compliance within 72 hours of lung transplantation. One vial of surfactant (20 mg/ml phospholipid) was instilled into each segmental bronchus upon diagnosis of IRI.

RESULTS

Six patients (5 bilateral sequential and 1 re-do heart-lung transplant), mean age 46 years, were diagnosed with IRI and surfactant was administered at a mean of 37 hours (range 2.3 to 98) post-transplant. Mean graft ischemia time was 376 minutes (range 187 to 625) and cardiopulmonary bypass time 174 minutes (range 0 to 210). Mean Pao(2) [mm Hg]/Fio(2) ratio before and 48 hours after surfactant instillation was 70 and 223, respectively. Significant resolution of radiologic infiltrates was evident in all cases within 24 hours. Successful extubation occurred at a mean of 13.5 days and survival is presently 100% at 19 months (range 3 to 54).

CONCLUSIONS

Bronchoscopic instillation of surfactant improves oxygenation and prognosis after severe IRI in lung transplant recipients. It represents a cost-effective, relatively non-invasive therapeutic alternative to extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation for primary graft dysfunction after lung transplantation: analysis of the Extracorporeal Life Support Organization (ELSO) registry

BACKGROUND

Some patients with severe primary graft dysfunction (PGD) after lung transplantation (LTx) require gas exchange support using an extracorporeal membrane oxygenator (ECMO) as a life-saving therapy. A few single-center experiences have been reported with relatively few cases of ECMO after LTx.

METHODS

We reviewed outcomes of ECMO in lung transplant recipients included in the Extracorporeal Life Support Organization (ELSO) registry, which was established with the intention to improve quality and outcome of extracorporeal life support (ECLS) in patients treated with ECMO applied for all indications.

RESULTS

The ELSO registry currently includes 31,340 ECMO cases, of which 151 were post-LTx patients with primary graft dysfunction (PGD). The mean age was 35 +/- 18 years. Indications for LTx were acute respiratory distress syndrome, (15%), cystic fibrosis (15%), idiopathic pulmonary fibrosis (8%), primary pulmonary hypertension, (10%), emphysema (15%), acute lung failure (11%), other (23%), and unknown (3%). ECMO run time was 140 +/- 212 hours. Venovenous ECMO was used in 25, venoarterial in 89, and other modes in 15 patients (unknown in 22). ECMO was discontinued in 93 patients owing to lung recovery. It was also discontinued in 29 patients with multiorgan failure, in 22 patients that died with no further specification, and in 7 patients for other reasons. In total, 63 (42%) patients survived the hospital stay. Major complications during ECMO included hemorrhage (52%), hemodialysis (42%), neurologic (12%), and cardiac (28%) complications, inotropic support (77%), and sepsis (15%).

CONCLUSIONS

Although the ELSO registry was not primarily established to study ECMO in LTx, it provides valuable insights and evidence that there is indeed an appreciable salvage rate with the use of ECMO for PGD after LTx. Clearly, this is a very high-risk patient population, and no single center can accumulate a large experience of ECMO for this specific indication. These data, however, underscore the importance of developing a specific registry for patients put on ECLS devices so that we can better study the outcomes, determine optimum treatment strategies, and optimize patient and device selection, and thus improve the outcomes of patients requiring this unique therapy.

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

BACKGROUND

Primary graft dysfunction (PGD) after lung transplantation (LTx) carries a significant mortality and clinical management is controversial. Extracorporeal membrane oxygenation (ECMO) has been used infrequently for recovery from acute lung injury (ALI) in this setting. We reviewed our experience with ECMO after primary LTx.

METHODS

The present study is a retrospective analysis of all LTx patients between 1991 and 2004. Twenty-two patients sustained severe PGD with subsequent placement on ECMO. We analyzed indications and 30-day, 1-year and 3-year mortality. Complications and incidence of multiple-organ failure (MOF) were determined. Critical appraisal of the evidence available to date was performed.

RESULTS

A total of 297 LTxs were performed during the study period, with 97.5%, 88.6% and 73.8% survival at 30 days, 1 year and 3 years, respectively. Twenty-two patients (7.9%) had severe allograft dysfunction leading to ECMO support. Twelve patients received single-lung (SLTx), 8 double-lung (BLTx), 1 single-lung/kidney (SLKTx) and 1 heart/lung (HLTx) transplantation. Thirty-day, 1-year and 3-year survival of LTx recipients with ECMO support post-operatively were 74.6%, 54% and 36%, respectively. MOF was the predominant cause of death (58.3%) in patients on ECMO support for PGD.

CONCLUSIONS

Our data suggest that, in addition to prolonged ventilation and pharmacologic support, ECMO should be considered as a bridge to recovery from PGD in lung transplantation. Early institution of ECMO may lead to diminished mortality in the setting of ALI despite the high incidence of MOF. Late institution of ECMO was associated with 100% mortality in this investigation.

Improved results treating lung allograft failure with venovenous extracorporeal membrane oxygenation

BACKGROUND

Primary graft failure remains a significant source of mortality after lung transplantation. Extracorporeal membrane oxygenation (ECMO) provides treatment for affected recipients. We hypothesized that venovenous membrane oxygenation provides a safer alternative than venoarterial support for lung recipients suffering from primary graft failure.

METHODS

We conducted an analysis of 522 patients who underwent lung transplantation from April 1992 to July 2004. Twenty-three (4.5%) patients required membrane oxygenation secondary to primary graft failure unresponsive to conventional treatment. Of these recipients, 15 (65%) were treated with venoarterial, while 8 (35%) underwent venovenous membrane oxygenation.

RESULTS

Median days to initiation and duration of membrane oxygenation did not differ between groups. Eight of 15 patients (53%) from the venoarterial group were successfully weaned from life support, with one surviving greater than 45 days. This lone long-term survivor required retransplantation 4 days after initial transplant. In contrast, all venovenous patients were weaned from support, with 7 of 8 surviving greater than 30 days. The 30-day survival for venovenous recipients (88%) approximates that of all lung recipients at our center (94%, p = 0.42). Noted complications for ECMO patients included renal failure (n = 16), neurologic catastrophes (n = 8), sepsis (n = 5), and hemorrhage (n = 10). The venoarterial recipients suffered 30 of 39 total complications. Most of the complications for venovenous recipients involved renal failure, but by hospital discharge these patients demonstrated a mean creatinine of 0.9 mg/dL.

CONCLUSIONS

For lung recipients with primary graft failure, venovenous membrane oxygenation provides better outcomes, with fewer complications, than venoarterial membrane oxygenation.

Extended use of extracorporeal membrane oxygenation after lung transplantation

OBJECTIVES

Extracorporeal membrane oxygenation (ECMO) for severe graft failure after lung transplantation is accepted immediately postoperatively; extending its use is controversial. We evaluated our post-lung transplant ECMO experience, which included extended indication, to (1) determine its prevalence, risk factors, indications, and timing, (2) compare complications and outcomes of these patients with those not requiring it, and (3) identify risk factors, including indications, for mortality.

METHODS

From February 1990 to October 2005, 474 patients underwent lung transplantation; postoperative ECMO support was instituted for severe graft failure 23 times in 22 patients (4.0%). Indications for ECMO and its timing were obtained by reviewing medical records and survival by systematic follow-up.

RESULTS

No factor evaluated predicted severe graft failure leading to ECMO. The most common indication for ECMO was early graft failure (13 patients); however, it was also used for pneumonia or sepsis (6) and acute rejection (4). ECMO was initiated at a median arterial oxygen tension/inspired oxygen fraction of 59 at a median of 2 days postoperatively and was maintained for a median of 4 days. The most common complications were renal failure (57%) and bleeding (43%). ECMO was effective in salvaging patients with rejection and early graft failure (survival at 1, 3, 6, and 12 months: 62%, 54%, 49%, and 41%), but ineffective for pneumonia or sepsis (survival at these intervals: 9%, 4%, 4%, and 3%).

CONCLUSIONS

ECMO can be extended beyond early severe graft failure to acute rejection and can be considered after the immediate postoperative period. Survival after ECMO in patients with pneumonia or sepsis is poor.

Lung Transplantation: Current Status and Challenges

The lung is an anatomically complex vital organ whose normal physiology depends on actively regulated ventilation and perfusion, and maintenance of a delicate blood-air barrier over a huge surface area in direct contact with a potentially hostile environment. Despite significant progress over the past 25 years, both short- and long-term outcomes remain significantly inferior for lung recipients relative to other "solid" organs. This review summarizes the current status of lung transplantation so as to frame the principle challenges currently facing end-stage lung-failure patients and the practitioners who care for them.

Extracorporeal membrane oxygenation after lung transplantation: evolving technique improves outcomes

BACKGROUND

Severe pulmonary graft failure (PGF) is the most common cause of death within the first 30 days after lung transplantation. Extracorporeal membrane oxygenation (ECMO) may provide lifesaving temporary support; however, its longer-term efficacy is controversial.

METHODS

We reviewed the use of ECMO for severe PGF after lung transplantation, and compared the outcomes between our early (1990 to 1999) and recent (2000 to 2003) experience utilizing improved initiation timing, oxygenator technology, and surgical technique.

RESULTS

Ten transplant recipients from a total of 481 (2.1%) were managed for PGF on ECMO by a multidisciplinary team at The Alfred Hospital. Four single-lung, 3 bilateral single-lung, and 3 heart-lung recipients were supported for a mean of 96 hours (range 14 to 212 hours). In the early group (operation from 1990 to 1999, n = 4) ECMO was initiated 21 days (range 7 to 40 days) after lung transplantation and in the recent group (operation from 2000 to 2003, n = 6) after 0 to 2 days (p = 0.01). Radial-arterial blood gas analysis 12 hours after initiation of ECMO showed significantly better oxygenation in the recent group (341 +/- 90 mm Hg) than in the early group (90 +/- 23 mm Hg, p = 0.03). Four deaths occurred as a result of bleeding (two in each group). In the early group only 1 patient was weaned from ECMO but died. In the recent group 3 were successfully weaned and were discharged from the intensive care unit; of these patients, 2 were discharged from hospital.

CONCLUSIONS

Extracorporeal membrane oxygenation results have improved with advances in oxygenator technology and surgical techniques. The procedure can allow resolution of early PGF after lung transplantation.

Respiratory failure after lung transplantation

STUDY OBJECTIVES

To characterize patients who acquired postoperative respiratory failure after lung transplantation (LT), and to identify risks associated with postoperative respiratory failure and poor surgical outcome.

STUDY DESIGN

Retrospective clinical analysis in a tertiary care transplantation center.

METHODS

We reviewed the records of 80 consecutive patients who underwent LT from April 1994 to May 1999, analyzing their records for a number of preoperative and perioperative variables and complications.

RESULTS

Forty-four patients (55%) acquired postoperative respiratory failure and had a mortality rate of 45%. No difference was noted between patients with respiratory failure and those without in terms of age (mean +/- SD, 56 +/- 9 years vs 53 +/- 11 years), gender, baseline pretransplant arterial blood gas analysis (PaCO(2), 46 +/- 9 mm Hg vs 44 +/- 10 mm Hg), and cardiopulmonary exercise testing (maximum oxygen uptake, 0.76 +/- 0.44 L/min/m(2) vs 0.82 +/- 0.20 L/min/m(2)). Ischemic reperfusion lung injury (IRLI) [55%] and perioperative cardiovascular/hemorrhagic events (36%) were the major contributors to the development of respiratory failure. Preoperative pulmonary hypertension, right ventricular (RV) dysfunction, ischemic times, and need for bilateral LT and cardiopulmonary bypass (CPB) were higher in patients with respiratory failure (p < 0.05) compared to recipients without respiratory failure. However, the presence of preoperative moderate-to-severe RV dysfunction was the only independent factor (odds ratio, 21.9; 95% confidence interval, 1.6 to 309.0).

CONCLUSION

Respiratory failure after LT is common and is associated with high morbidity and mortality. Respiratory failure often occurred in patients with operative technical complications, cardiovascular events, and postoperative IRLI, which were observed most in patients requiring CPB because of RV dysfunction.

Artificial lungs: a new inspiration

An estimated 16 million Americans are afflicted with some degree of chronic obstructive pulmonary disease (COPD), accounting for 100,000 deaths per year. The only current treatment for chronic irreversible pulmonary failure is lung transplantation. Since the widespread success of single and double lung transplantation in the early 1990s, demand for donor lungs has steadily outgrown the supply. Unlike dialysis, which functions as a bridge to renal transplantation, or a ventricular assist device (VAD), which serves as a bridge to cardiac transplantation, no suitable bridge to lung transplantation exists. The current methods for supporting patients with lung disease, however, are not adequate or efficient enough to act as a bridge to transplantation. Although occasionally successful as a bridge to transplant, ECMO requires multiple transfusions and is complex, labor-intensive, time-limited, costly, non-ambulatory and prone to infection. Intravenacaval devices, such as the intravascular oxygenator (IVOX) and the intravenous membrane oxygenator (IMO), are surface area limited and currently provide inadequate gas exchange to function as a bridge-to-recovery or transplant. A successful artificial lung could realize a substantial clinical impact as a bridge to lung transplantation, a support device immediately post-lung transplant, and as rescue and/or supplement to mechanical ventilation during the treatment of severe respiratory failure.

Primary graft failure following lung transplantation: predictive factors of mortality

STUDY OBJECTIVES

To assess incidence, outcome, and early predictors of mortality for patients with primary graft failure (PGF) following lung transplantation (LTx), and to develop an injury severity score able to accurately predict ICU mortality for these patients.

DESIGN

Retrospective cohort analysis.

SETTING

Two LTx centers in Paris.

PATIENTS

Two hundred fifty-nine patients who underwent LTx over a 12-year period.

MEASUREMENTS AND RESULTS

One hundred thirty-one patients (50.6%) met PGF criteria: radiographic graft infiltrate within the first 3 days following LTx associated with gas exchange impairment (PaO(2)/fraction of inspired oxygen ratio < 300 mm Hg). This syndrome was associated with an increased duration of mechanical ventilation (9.1 +/- 1 days vs 3.1 +/- 0.6 days, mean +/- SD; p < 0.001) and ICU mortality (29% vs 10.9%; p < 0.01). The patients with PGF were randomly assigned to developmental (n = 85) and validation (n = 46) samples. Using logistic regression analysis, four variables were found associated with ICU mortality in these patients: age, degree of gas exchange impairment, graft ischemic time, and severe early hemodynamic failure. An ischemia/reperfusion injury severity score was derived using these four variables. Model calibration was good in the developmental and validation samples, as was model discrimination (area under receiver operating characteristic curves, 0.93 and 0.85, respectively).

CONCLUSION

PGF following LTx is a frequent event, with significant ICU morbidity and mortality. We demonstrate that four simple factors allow prediction of ICU mortality with good accuracy.

Extracorporeal membrane oxygenation for severe respiratory failure

The use of extracorporeal technology to accomplish gas exchange with or without cardiac support is based on the premise that "lung rest" facilitates repair and avoids the baso- or volutrauma of mechanical ventilator management. Extracorporeal membrane oxygenation (ECMO), a modified form of cardiopulmonary bypass, has been shown to decrease mortality of neonatal, pediatric and adult respiratory failure and is capable of total gas exchange. In neonates, over 20,638 patients have been treated with an overall survival of 77% in a population thought to have 78% mortality.

Leukocyte filtration in lung transplantation

Controlled reperfusion of the transplanted lung has been used in nine consecutive patients to decrease manifestations of lung reperfusion injury. An extracorporeal circuit containing a roller pump, heat exchanger and leukodepleting filter is primed with substrate-enhanced reperfusion solution mixed with approximately 2000 ml of the patient's blood. This solution is slowly recirculated to remove leukocytes prior to reperfusion. When the pulmonary anastomoses are completed, the pulmonary artery is cannulated through the untied anastomosis using a catheter containing a pressure lumen for measurement of infusion pressure. An atrial clamp is left in place on the patient's native atrial cuff to decrease the risk of systemic air embolism during the brief period of reperfusion from the extracorporeal reservoir. During reperfusion, the water bath to the heat exchanger is kept at 35 degrees C and the flow rate for reperfusion solution is between 150 and 200 m/min, keeping the pulmonary artery pressure <14 mmHg. Eight of nine patients were ventilated on 40% inspired oxygen within a few hours of operation and 7/9 were extubated on or before postoperative day 1. Six of nine patients are long-term survivors.

Surfactant function in lung transplantation after 24 hours of ischemia: advantage of retrograde flush perfusion for preservation

OBJECTIVE

Surfactant function was shown to be impaired in clinical and experimental lung transplantation. This study was designed to define the impact of retrograde flush perfusion on graft and surfactant function after an extended period of ischemia.

METHODS

Left lung transplantation was performed after 24 hours of graft ischemia in 12 pigs. In half of the grafts antegrade cold flush perfusion (Perfadex) was used for preservation. In the second group grafts were flushed in a retrograde fashion via the left atrium. Graft function was monitored for 7 hours after transplantation. Before transplantation (basal) and after 2 hours of reperfusion, bronchoalveolar lavage fluid was obtained. Minimal surface tension of bronchoalveolar lavage fluid was determined and the ratio of small and large surfactant aggregates was calculated. Lung water content was analyzed online in the reperfusion period.

RESULTS

Right-sided heart failure developed in 2 animals of group 1 (antegrade perfusion) within 2 and 4.5 hours of reperfusion, respectively. All other pigs survived the observation period. PO(2)/FIO(2) (P =.001) and dynamic lung compliance (P =.001) were superior in retrogradely flushed grafts. A comparable increase of minimal surface tension was found after reperfusion in both groups. Small/large surfactant aggregate ratio after reperfusion (P =.03), as well as extravascular lung water content, was higher in the antegrade perfusion group.

CONCLUSION

Retrograde flush perfusion for 24-hour lung preservation with low-potassium dextran (Perfadex) solution led to better initial graft function than the standard antegrade perfusion technique. A moderate impairment of surfactant function was found in both groups, which was more pronounced in the antegrade perfusion group.

Preventive effect of inhaled nitric oxide and pentoxifylline on ischemia/reperfusion injury after lung transplantation

BACKGROUND

The preventive effect of inhaled nitric oxide (NO) and pentoxifylline (PTX) administered during reperfusion has been demonstrated on experimental models of lung ischemia/reperfusion (I/R) injury but this strategy is not validated in clinical lung transplantation. The aim of this study was to assess retrospectively the protective effect of inhaled NO and PTX after lung transplantation.

METHODS

Twenty-three consecutive patients who received inhaled NO (10 ppm) and PTX (NO-PTX group) at the time of reperfusion were compared retrospectively with (1) 23 consecutive patients transplanted just before the use of NO-PTX (control group 23); (2) 95 patients representing all the patients of the series who did not receive NO-PTX (control group 95), with respect to I/R injury related complications. In particular, the incidence of pulmonary reimplantation edema and early hemodynamic failure, the PaO2/FIO2 ratio as well as the duration of mechanical ventilation and the 2-month mortality rates were compared.

RESULTS

Reimplantation edema was observed in 6/23 patients (26%) in the NO-PTX group vs. 13/23 patients (56%) in the control group 23 (P=0.035) and 48/95 patients (50%) in the control group 95 (P=0.035). The worst PaO2/FIO2 ratio during the first three postoperative days was 240-102 mmHg in the NO-PTX group vs. 162+/-88 mmHg (P=0.01) and 176+/-107 mmHg (P=0.01) in the control group 23 and the control group 95, respectively. The duration of mechanical ventilation was 2.1+/-2.4 days in the NO-PTX group vs. 7+/-9 days in the control group 23 (P=0.02) and 6+/-7 days in the control group 95 (P=0.01). The 2-month mortality rate was 4.3% in the NO-PTX group vs. 26% (P=0.04) and 21% (P=0.07) in the control group 23 and the control group 95, respectively.

CONCLUSIONS

The marked decrease in the incidence of allograft dysfunction compared with two historical control groups suggests that PTX and inhaled NO given before and throughout reperfusion are protective against I/R injury in the setting of clinical transplantation.

Lung transplantation at the turn of the century

Lung transplantation has become a viable treatment option for patients with end-stage lung disease. Donor selection and organ allocation must follow specific guidelines. Single, bilateral, and living-donor lobar transplantation have all been performed successfully for a variety of diseases. Complications include reimplantation response and airway complications. Rejection may occur in the hyperacute, acute, or chronic settings and requires judicious management with immunosuppression. Infection and malignancy remain potential complications of the commitment to lifelong systemic immunosuppression. Survival statistics have remained encouraging and continue to improve with experience. Improved exercise tolerance and quality of life have been demonstrated in the years following transplantation. Remaining obstacles include limited donor organ availability, long-term graft function, and patient survival. However, ongoing advances in immune tolerance and standardized training of physicians in the care of transplant patients should carry lung transplant forward in the twenty-first century.