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

Venovenous ECMO for Acute Chronic Heart Failure after Bilateral Lung Transplantation

ABSTRACT

Venovenous (VV) ECMO is rarely used during decompensated circulatory states. Although VA ECMO is the routine option, VV ECMO may be an option in selected patients. We present a case of pulmonary edema due to acute heart failure in a patient 4- and 12-year post-lung transplantation who received VV ECMO. Using a thoughtful cannulation strategy, VV ECMO, and aggressive ultrafiltration, the patient was successfully decannulated, extubated, and discharged from the hospital. In cardiogenic pulmonary edema, VV ECMO represents an additional, and likely under-utilized tool, especially in patients who are at high risk for ventilator-associated lung injury. Cannula location and size should be given additional consideration to potentially transition to V-AV ECMO configuration if necessary.

A single-centre analysis of lung transplantation outcomes in recipients aged 70 or older

OBJECTIVES

As life expectancies continue to increase, a greater proportion of older patients will require lung transplants (LTs). However, there are no well-defined age cutoffs for which LT can be performed safely. At our high-volume LT centre, we explored outcomes for LT recipients ≥70 vs <70 years old.

METHODS

This is a retrospective single-centre study of survival after LT among older recipients. Data were stratified by recipient age (≥70 vs <70 years old) and procedure type (single versus double LT). Demographics and clinical variables were compared using Chi-square test and 2 sample t-test. Survival was assessed by Kaplan-Meier curves and compared by log-rank test with propensity score matching.

RESULTS

A total of 988 LTs were performed at our centre over 10 years, including 289 LTs in patients ≥70 years old and 699 LTs in patients <70 years old. The recipient groups differed significantly by race (P < 0.0001), sex (P = 0.003) and disease aetiology (P < 0.0001). Older patients were less likely to receive a double LT compared to younger patients (P < 0.0001) and had lower rates of intraoperative cardiopulmonary bypass (P = 0.019) and shorter length of stay (P = 0.001). Both groups had overall high 1-year survival (85.8% vs 89.1%, respectively). Survival did not differ between groups after propensity matching (P = 0.15).

CONCLUSIONS

Our data showed high survival for older and younger LT recipients. There were no statistically significant differences observed in survival between the groups after propensity matching, however, a trend in favour of younger patients was observed.

How Would We Treat Our Own Cystic Fibrosis With Lung Transplantation?

Lung transplantation is the only therapy for patients with end-stage lung disease. In advanced lung diseases such as cystic fibrosis (CF), life expectancy increases, and it is important to recognize extrapulmonary comorbidities. Cardiovascular involvement, including pulmonary hypertension, right-heart failure, and myocardial dysfunction, are manifest in the late stages of CF disease. Besides right-heart failure, left-heart dysfunction seems to be underestimated. Therefore, an optimal anesthesia and surgical management risk evaluation in this high-risk patient population is mandatory, especially concerning the perioperative use of mechanical circulatory support. The use of an index case of an older patient with the diagnosis of cystic fibrosis demonstrates the importance of early risk stratification and strategy planning in a multidisciplinary team approach to guarantee successful lung transplantation.

Impact of delayed veno-venous extracorporeal membrane oxygenation weaning on postoperative rehabilitation of lung transplantation: a single-center comparative study

Veno-venous extracorporeal membrane oxygenation (VV-ECMO) is a reliable and effective extracorporeal life support during lung transplantation (LTx). However, the clinical benefit of delayed VV-ECMO weaning remains unclear. The current study aims to investigate whether delayed weaning of VV-ECMO is more beneficial to the rehabilitation for lung transplant patients. Patients who underwent LTx with VV-ECMO between January 2017 and January 2019 were included. Enrollment of patients was suitable for weaning off ECMO immediately after surgery. Randomization was performed in the operating room. Postoperative outcomes were compared between the two groups. Besides, univariate and multivariable logistic regressions were performed to estimate risk of postoperative complications. Compared to VV-ECMO weaning immediately after LTx, delayed weaning was associated with shorter hospital length of stay (days, 31 vs. 46; P < 0.05), lower incidence of noninvasive ventilation (4.3% vs. 24.4%; P < 0.05), primary graft dysfunction (PGD) (6.4% vs. 29.3%; P < 0.05), atrial fibrillation (AF) (4.3% vs. 22%, P < 0.05), and respiratory failure (4.3% vs. 19.5%; P < 0.05). Multivariable logistic regressions revealed that VV-ECMO weaning after LTx was independently correlated with increased risk of developing PGD [odds ratio (OR), 5.97, 95% CI 1.16-30.74], AF (OR, 6.87, 95% CI 1.66-28.47) and respiratory failure (OR, 6.02, 95% CI 1.12-32.49) by comparison of delayed VV-ECMO weaning. Patients with delayed VV-ECMO weaning are associated with lower complications and short hospital length of stay, while it relates to longer mechanical ventilation. These findings suggest that delayed VV-ECMO after LTx can facilitate rehabilitation.

The hemodynamic interplay between pulmonary ischemia-reperfusion injury and right ventricular function in lung transplantation: a translational porcine model

Lung transplantation (LTx) is a challenging procedure. Following the process of ischemia-reperfusion injury, the transplanted pulmonary graft might become severely damaged, resulting in primary graft dysfunction. In addition, during the intraoperative window, the right ventricle (RV) is at risk of acute failure. The interaction of right ventricular function with lung injury is, however, poorly understood. We aimed to address this interaction in a translational porcine model of pulmonary ischemia-reperfusion injury. Advanced pulmonary and hemodynamic assessment was used, including right ventricular pressure-volume loop analysis. The acute model was based on clamping and unclamping of the left lung hilus, respecting the different hemodynamic phases of a clinical lung transplantation. We found that forcing entire right ventricular cardiac output through a lung suffering from ischemia-reperfusion injury increased afterload (pulmonary vascular resistance from baseline to end experiment P < 0.0001) and induced right ventricular failure (RVF) in 5/9 animals. Notably, we identified different compensation patterns in failing versus nonfailing ventricles (arterial elastance P = 0.0008; stroke volume P < 0.0001). Furthermore, increased vascular pressure and flow produced by the right ventricle resulted in higher pulmonary injury, as measured by ex vivo CT density (correlation: pressure r = 0.8; flow r = 0.85). Finally, RV ischemia as measured by troponin-T was negatively correlated with pulmonary injury (r = -0.76); however, troponin-T values did not determine RVF in all animals. In conclusion, we demonstrate a delicate balance between development of pulmonary ischemia-reperfusion injury and right ventricular function during lung transplantation. Furthermore, we provide a physiological basis for potential benefit of extracorporeal life support technology.NEW & NOTEWORTHY In contrast to the abundant literature of mechanical pulmonary artery clamping to increase right ventricular afterload, we developed a model adding a biological factor of pulmonary ischemia-reperfusion injury. We did not only focus on the right ventricular behavior, but also on the interaction with the injured lung. We are the first to describe this interaction while addressing the hemodynamic intraoperative phases of clinical lung transplantation.

National Trends, Risk Factors, and Outcomes of Acute In-Hospital Stroke Following Lung Transplantation in the United States: Analysis of the United Network for Organ Sharing Registry

BACKGROUND

Lung transplantation (LTx) is the definitive treatment for end-stage lung failure. However, there have been no large, long-term studies on the impact of acute in-hospital stroke in this population.

RESEARCH QUESTION

What are the trends, risk factors, and outcomes of acute stroke in patients undergoing LTx in the United States?

STUDY DESIGN AND METHODS

We identified adult first-time isolated LTx recipients from the United Network for Organ Sharing database, which comprehensively captures every transplant in the United States, between May 2005 and December 2020. Stroke was defined as occurring at any time after LTx but prior to discharge. Multivariable logistic regression with stepwise feature elimination was used to identify risk factors for stroke. Freedom from death in patients with a stroke vs those without a stroke was evaluated with Kaplan-Meier analysis. Cox proportional hazards analysis was used to identify predictors of death at 24 months.

RESULTS

Of 28,564 patients (median age, 60 years; 60% male), 653 (2.3%) experienced an acute in-hospital stroke after LTx. Median follow-up was 1.2 (stroke) and 3.0 (non-stroke) years. Annual incidence of stroke increased (1.5% in 2005 to 2.4% in 2020; P for trend = .007), as did lung allocation score and utilization of post-LTx extracorporeal membrane oxygenation (P = .01 and P < .001, respectively). Compared with those without stroke, patients with stroke had lower survival at 1 month (84% vs 98%), 12 months (61% vs 88%), and 24 months (52% vs 80%) (log-rank test, P < .001 for all). In Cox analysis, acute stroke conferred a high hazard of mortality (hazard ratio, 3.01; 95% CI, 2.67-3.41). Post-LTx extracorporeal membrane oxygenation was the strongest risk factor for stroke (adjusted OR, 2.98; 95% CI, 2.19-4.06).

INTERPRETATION

Acute in-hospital stroke post-LTx has been increasing over time and is associated with markedly worse short- and long-term survival. As increasingly sicker patients undergo LTx as well as experience stroke, further research on stroke characteristics, prevention, and management strategies is warranted.

Regional analgesia for lung transplantation: A narrative review

Lung transplantation (LTx) is the definitive treatment for end-stage pulmonary disease. About 4500 LTxs are performed annually worldwide. It is considered challenging and complex surgery regarding anaesthesia and pain management. While providing adequate analgesia is crucial for patient comfort, early mobilisation and prevention of postoperative pulmonary complications, standardising an analgesic protocol is challenging due to the diversity of aetiologies, surgical approaches and the potential use of extracorporeal life support (ECLS). Although thoracic epidural analgesia is commonly considered the gold standard, concerns regarding procedural safety and its potential for devastating consequences have led physicians to seek safer analgesic modalities such as thoracic nerve blocks. The advantages of thoracic nerve blocks for general thoracic surgery are well established. However, their utility in LTx remains unclear. Considering paucity of relevant literature, this review aims to raise awareness about the literature gap in the field and highlight the need for further high-quality studies determining the effectiveness of available techniques.

Management of primary graft dysfunction after lung transplantation with extracorporeal life support: an evidence-based review

Primary graft dysfunction (PGD) is a complex inflammatory syndrome that can lead to respiratory failure after lung transplantation (LTx). The pathogenesis of PGD is multifactorial and can be driven by attributes of both the donor and recipient, perioperative characteristics, and technical handling of the graft. Despite significant advancements in patient and donor selection, perioperative management and surgical technique, PGD is still a major contributor to morbidity and mortality after lung transplant. Although there are no known durable treatment options for PGD after LTx, an increasing body of evidence and experience in high-volume lung transplant centers show that extracorporeal life support (ECLS) is a reliable option for both preventing PGD and supporting critically ill patients with PGD. Both veno-venous (V-V) ECLS and veno-arterial (V-A) ECLS are proven and feasible strategies for mitigating the morbidity and mortality associated with post-LTx PGD. In this evidence-based review, we provide an overview of the epidemiology and physiology of PGD as well as a growing body of data that supports ECLS as a major tool to manage PGD. We describe the role of ECMO in PGD prevention and management, worldwide outcomes of LTx with ECLS support, and outline our step-wise approach to managing this complex respiratory syndrome leading up to institution of ECLS.

Current use of extracorporeal life support in airway surgery: a narrative review

BACKGROUND AND OBJECTIVE

Extracorporeal life support (ECLS) is widely used in patients with severe respiratory or cardiocirculatory failure. The most commonly used extracorporeal membrane oxygenation (ECMO) modes are veno-venous (V-V) and veno-arterial (V-A) ECMO, which can both be achieved by various types of vascular cannulation. Within the scope of tracheobronchial surgery, intraoperative ECLS may occasionally be necessary to provide sufficient oxygenation to a patient throughout a procedure, especially when conventional ventilation strategies are limited. Additionally, V-A ECMO can provide cardiopulmonary support in emergencies and in cases where hemodynamic instability can occur.

METHODS

This narrative literature review was carried out to identify the use and the specifics of ECLS in airway surgery over the last years. Data from 168 cases were summarized according to the indication for surgery and the mode of ECLS (V-V, V-A).

KEY CONTENT AND FINDINGS

The most common tracheobronchial pathologies in which support was needed were: primary malignant disease of the airways, malignant infiltration, tracheal stenosis, injury of the airway, and congenital airway disease. With increasing experience in ECLS, the number of reported cases performed with intraoperative ECLS increased steadily over the last decade.

CONCLUSIONS

A trend favoring the use of V-V ECMO over V-A ECMO was identified. These approaches should now be considered indispensable tools for managing challenging surgical cases.

Discontinuation of ECMO-a review with a note on Indian scenario

Extracorporeal membrane oxygenation (ECMO) has strikingly progressed over the last 20 years in the management of adult and pediatric severe respiratory and cardiac dysfunctions refractory to conventional management. In this review, we will discuss the weaning strategies of veno-venous and veno-arterial ECMO including the bridge to recovery and bridge to transplant along with post-ECMO care. We will also discuss the futility and the management of bridge to nowhere from Indian perspectives.

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.

Novel Hybrid Treatment for Pulmonary Arterial Hypertension with or without Eisenmenger Syndrome: Double Lung Transplantation with Simultaneous Endovascular or Classic Surgical Closure of the Patent Ductus Arteriosus (PDA)

Patients with pulmonary arterial hypertension (PAH) become candidates for lung or lung and heart transplantation when the maximum specific therapy is no longer effective. The most difficult challenge is choosing one of the above options in the event of symptoms of right ventricular failure. Here, we present two female patients with PAH: (1) a 21-year-old patient with Eisenmenger syndrome, caused by a congenital defect-patent ductus arteriosus (PDA); and (2) a 39-year-old patient with idiopathic PAH and coexistent PDA. Their common denominator is PDA and the hybrid surgery performed: double lung transplantation with simultaneous PDA closure. The operation was performed after pharmacological bridging (conditioning) to transplantation that lasted for 33 and 70 days, respectively. In both cases, PDA closure effectiveness was 100%. Both patients survived the operation (100%); however, patient no. 1 died on the 2nd postoperative day due to multi-organ failure; while patient no. 2 was discharged home in full health. The authors did not find a similar description of the operation in the available literature and PubMed database. Hence, we propose this new treatment method for its effectiveness and applicability proven in our practice.

Right Heart Echocardiography Parameters and Other Predictors to Evaluate Mechanical Cardiac Support Necessity During Lung Transplantation

BACKGROUND

Lung transplantation (LuTx) is a challenge when right heart function fails. Mechanical circulatory support (MCS) is then necessary.

METHODS

We aimed to investigate whether preoperative transthoracic echocardiography (TTE) can predict MCS use and help to exclude the sickest patients. Between 2011 and 2018, 52 patients at our institution received LuTx and qualified for this study: 35 bilateral, 16 single, 1 lobar [1] and 1 retransplantation procedure. Of these, 22 were operated using MCS and 30 without MCS. The patients were aged between 18 and 65 years, and 23 were women. The indications were lung fibrosis for 18 patients, chronic obstructive lung disease for 16, cystic fibrosis for 15, primary pulmonary hypertension for 2 and bronchiectasis for 1. TTE was performed up to 30 days before treatment and 1 to 7 days after.

RESULTS

Patients undergoing MCS versus patients not undergoing MCS: preoperative right ventricular systolic pressure 56.5 (30) vs 37.8 (11.5) mm Hg (P = .03); tricuspid regurgitation pressure gradient 48.7 (27) vs 30.2 (10.8) mm Hg (P = .015); tricuspid annular plane systolic excursion 17.8 (4.3) vs 19.9 (2.8) mm Hg (P = .04); pulmonary artery diameter 27.5 (5.2) vs 23.9 (4.1) mm (P = .004); age 41.9 (14.1) vs 54.3 (11.8) years (P = .001). Patients who were Dead versus patients who were alive pulmonary valve acceleration time of 82.8 (24.1) vs 104.9 (27.2) ms (hazard ratio [HR] = 0.959, 95% confidence interval [CI] = 0.923-0.996 per ms, P = .02) and pulmonary artery diameter of 28.9 (5.8) vs 24.4 (4.1) mm HR = 1.225, 95% CI = 1.028-1.460 per 1 mm, P = .016 were predictors of death.

CONCLUSIONS

Preoperative TTE parameters: right ventricular systolic pressure, tricuspid regurgitation pressure gradient, tricuspid annular plane systolic excursion, and pulmonary artery diameter predicted MCS use during LuTx. Certain values of valve acceleration time and pulmonary artery diameter could help discern LuTx qualification.

Intraoperative Circulatory Support in Lung Transplantation: Current Trend and Its Evidence

Lung transplantation has a high risk of haemodynamic complications in a highly vulnerable patient population. The effects on the cardiovascular system of the various underlying end-stage lung diseases also contribute to this risk. Following a literature review and based on our own experience, this review article summarises the current trends and their evidence for intraoperative circulatory support in lung transplantation. Identifiable and partly modifiable risk factors are mentioned and corresponding strategies for treatment are discussed. The approach of first identifying risk factors and then developing an adjusted strategy is presented as the ERSAS (early risk stratification and strategy) concept. Typical haemodynamic complications discussed here include right ventricular failure, diastolic dysfunction caused by left ventricular deconditioning, and reperfusion injury to the transplanted lung. Pre- and intra-operatively detectable risk factors for the occurrence of haemodynamic complications are rare, and the therapeutic strategies applied differ considerably between centres. However, all the mentioned risk factors and treatment strategies can be integrated into clinical treatment algorithms and can influence patient outcome in terms of both mortality and morbidity.

Postoperative management of children after lung transplantation

Pediatric lung transplantation is a highly specialized treatment option at a select few hospitals caring for children. Advancements in surgical and medical approaches in the care of these children have improved their care with only minimal improvement in outcomes which remain the lowest of all solid organ transplants. A crucial time period in the management of these children is in the perioperative period after performance of the lung transplant. Supporting allograft function, preventing infection, maintaining fluid balance, achieving pain control, and providing optimal respiratory support are all key factors required for this highly complex pediatric patient population. We review commonly encountered complications that these patients often experience and provide strategies for management.

Intraoperative use of extracorporeal CO2 removal (ECCO2R) and emergency ECMO requirement in patients undergoing lung transplant: a case-matched cohort retrospective study

BACKGROUND

The use of extracorporeal carbon dioxide removal (ECCO₂R) is less invasive than extracorporeal membrane oxygenation (ECMO), and intraoperative control of gas exchange could be feasible. The aim of this study in intermediate intraoperative severity patients undergoing LT was to assess the role of intraoperative ECCO₂R on emergency ECMO requirement in patients.

METHODS

Thirty-eight consecutive patients undergoing lung transplantation (LT) with "intermediate" intraoperative severity in the intervals 2007 to 2010 or 2011 to 2014 were analyzed as historical comparison of case-matched cohort retrospective study. The "intermediate" intraoperative severity was defined as the development of intraoperative severe respiratory acidosis with maintained oxygenation function (i.e., pH <7.25, PaCO₂ >60 mmHg, and PaO₂/FiO₂ >150), not associated with hemodynamic instability. Of these 38 patients, twenty-three patients were treated in the 2007-2010 interval by receiving "standard intraoperative treatment," while 15 patients were treated in the 2011-2014 interval by receiving "standard intraoperative treatment + ECCO₂R."

RESULTS

ECMO requirement was more frequent among patients that received "standard intraoperative treatment" alone than in those treated with "standard intraoperative treatment + ECCO₂R" (17/23 vs. 3/15; p = 0.004). The use of ECCO₂R improved pH and PaCO₂ while mean pulmonary artery pressure (mPAP) decreased.

CONCLUSION

In intermediate intraoperative severity patients, the use of ECCO₂R reduces the ECMO requirement.

A Focused Review on Primary Graft Dysfunction after Clinical Lung Transplantation: A Multilevel Syndrome

Primary graft dysfunction (PGD) is the clinical syndrome of acute lung injury after lung transplantation (LTx). However, PGD is an umbrella term that encompasses the ongoing pathophysiological and -biological mechanisms occurring in the lung grafts. Therefore, we aim to provide a focused review on the clinical, physiological, radiological, histological and cellular level of PGD. PGD is graded based on hypoxemia and chest X-ray (CXR) infiltrates. High-grade PGD is associated with inferior outcome after LTx. Lung edema is the main characteristic of PGD and alters pulmonary compliance, gas exchange and circulation. A conventional CXR provides a rough estimate of lung edema, while a chest computed tomography (CT) results in a more in-depth analysis. Macroscopically, interstitial and alveolar edema can be distinguished below the visceral lung surface. On the histological level, PGD correlates to a pattern of diffuse alveolar damage (DAD). At the cellular level, ischemia-reperfusion injury (IRI) is the main trigger for the disruption of the endothelial-epithelial alveolar barrier and inflammatory cascade. The multilevel approach integrating all PGD-related aspects results in a better understanding of acute lung failure after LTx, providing novel insights for future therapies.

Anesthetic considerations in lung transplantation: past, present and future

Lung transplantation is a very complex surgical procedure with many implications for the anesthetic care of these patients. Comprehensive preoperative evaluation is an important component of the transplant evaluation as it informs many of the decisions made perioperatively to manage these complex patients effectively and appropriately. These decisions may involve pre-emptive actions like pre-habilitation and nutrition optimization of these patients before they arrive for their transplant procedure. Appropriate airway and ventilation management of these patients needs to be performed in a manner that provides an optimal operating conditions and protection from ventilatory injury of these fragile post-transplant lungs. Pain management can be challenging and should be managed in a multi-modal fashion with or without the use of an epidural catheter while recognizing the risk of neuraxial technique in patients who will possibly be systemically anticoagulated. Complex monitoring is required for these patients involving both invasive and non-invasive including the use of transesophageal echocardiography (TEE) and continuous cardiac output monitoring. Management of the patient's hemodynamics can be challenging and involves managing the systemic and pulmonary vascular systems. Some patients may require extra-corporeal lung support as a planned part of the procedure or as a rescue technique and centers need to be proficient in instituting and managing this sophisticated method of hemodynamic support.

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

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

Extracorporeal membrane oxygenation and lung transplantation

The use of extracorporeal membrane oxygenation has had a positive impact on the outcomes after lung transplantation. Extracorporeal membrane oxygenation has a role in all phases of lung transplantation-preoperative, intraoperative, and postoperative periods. It serves as a bridge to transplantation in appropriate patients awaiting lung transplantation. Extracorporeal membrane oxygenation is used as a preferred method of cardiopulmonary support in some centres during implantation; and, after lung transplantation, it can be used to salvage the implanted lung in cases of severe primary graft dysfunction or as a planned extension of intraoperative extracorporeal membrane oxygenation onto the postoperative period. It has now gained acceptance as a mandatory tool in most lung transplant units. This article reviews the history of extracorporeal membrane oxygenation and lung transplantation, their subsequent development, and the current use of extracorporeal membrane oxygenation during lung transplantation. Our institutional practice and experience are described. The implications of the current global coronavirus disease pandemic on extracorporeal membrane oxygenation and lung transplantation are also briefly discussed.

A comparison of cardiopulmonary bypass versus extracorporeal membrane oxygenation: Does intraoperative circulatory support strategy affect outcomes in pediatric lung transplantation?

OBJECTIVE

Data on adult lung transplantation suggest perioperative benefits of intraoperative extracorporeal membrane oxygenation (ECMO) compared to cardiopulmonary bypass (CPB). Information regarding their pediatric counterparts, however, is limited. This study compares outcomes of intraoperative ECMO versus CPB in pediatric lung transplantation.

METHODS

We reviewed all pediatric lung transplants at our institution from 2014 to 2019 and compared those supported intraoperatively on ECMO (n = 13) versus CPB (n = 22), plus a conditional analysis excluding re-transplantations (ECMO [n = 13] versus CPB [n = 20]). We evaluated survival, surgical times, intraoperative transfusions, postoperative support, complications, and duration of hospitalization.

RESULTS

Total time on ECMO support was significantly less than that of CPB support (P = .018). Intraoperatively, the ECMO group required fewer transfusions of fresh-frozen plasma (8.9 [5.8-22.3] vs 16.6 [11.4-39.0] mL/kg, P = .049) and platelets (4.2 [0.0-6.7] vs 8.0 [3.5-14.0] mL/kg, P = .049). When excluding re-transplantations, patients on ECMO required fewer packed red blood cells intraoperatively (12.6 [2.1-30.7] vs 28.2 [14.0-54.0] mL/kg, P = .048). There were no differences in postoperative support requirements, complications, or mortality at one, six, and twelve months.

CONCLUSIONS

Intraoperative ECMO support during pediatric lung transplantation appears to decrease intraoperative transfusion requirements when compared to CPB. Data from additional institutions may strengthen these observations.

Influence of early extubation on post-operative outcomes after pediatric lung transplantation

Lung transplantation has become an accepted therapeutic option for a select group of children with end-stage lung disease. We evaluated the impact of early extubation in a pediatric lung transplant population and its post-operative outcomes. Single-center retrospective study. PICU within a tertiary academic pediatric hospital. Patients <22 years after pulmonary transplant between January 2011 and December 2016. A total of 74 patients underwent lung transplantation. The primary pretransplantation diagnoses included cystic fibrosis (58%), pulmonary fibrosis (9%), and surfactant dysfunction disorders (10%). Of 60 patients, 36 (60%) were extubated within 24 hours and 24 patients after 24 hours (40%). A total of seven patients (11.6%) required reintubation within 24 hours. Median length of stay for the early extubation group was shorter at 3 days ([(IQR) 2.2-4.7]) compared to 5 days (IQR, 3-7) (P = .02) in the late extubation group. Median costs were lower for the early extubation group with 13,833 US dollars (IQR, 9980-22,822) vs 23 671 US dollars (IQR, 16 673-39 267) (P = .043). Fourteen patients were in the PICU prior to their transplantation; this did not affect their early extubation success. Neither did the fact of requiring invasive or non-invasive mechanical ventilation before transplantation. Early extubation appears to be safe in a pediatric population after lung transplantation and is associated with a shorter LOS and decreased hospital costs. It may prevent known complications associated with mechanical ventilation.

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.

Population Pharmacokinetics of Caspofungin among Extracorporeal Membrane Oxygenation Patients during the Postoperative Period of Lung Transplantation

Little is known about the influence of extracorporeal membrane oxygenation (ECMO) on the pharmacokinetics (PK) of caspofungin. The aim of this study was to describe population PK of caspofungin in patients with and without ECMO during the postoperative period of lung transplantation (LTx) and to investigate covariates influencing caspofungin PK. We compared ECMO patients with non-ECMO patients, and patients before and after ECMO weaning as self-controls, to analyzed changes in caspofungin PK. Eight serial blood samples were collected from each patient for PK analysis. The population PK of caspofungin was described using nonlinear mixed-effects modeling. Twelve ECMO and 7 non-ECMO lung transplant recipients were enrolled in this study. None of the patients received renal replacement therapy during any part of the study period. The PK of caspofungin was best described by a two-compartment model. There were no significant differences in the PK parameters and concentrations of caspofungin among the ECMO, non-ECMO, and self-control group. In the final covariate model, we found that there was a significant association between the male gender and increased distribution volume, that a higher sequential organ failure assessment score was related to an increase in intercompartmental clearance, and that a longer operative time was related to an increase in clearance and the volume of distribution. ECMO did not have a significant impact on the PK of caspofungin in patients after LTx. Some factors were identified as statistically significant covariates related to the PK of caspofungin; however, their impact on clinical practice of caspofungin needs to be investigated further in more studies. (This study has been registered at ClinicalTrials.gov under identifier NCT03766282.).

Treatment of right ventricular dysfunction and heart failure in pulmonary arterial hypertension

Right heart dysfunction and failure is the principal determinant of adverse outcomes in patients with pulmonary arterial hypertension (PAH). In addition to right ventricular (RV) dysfunction, systemic congestion, increased afterload and impaired myocardial contractility play an important role in the pathophysiology of RV failure. The behavior of the RV in response to the hemodynamic overload is primarily modulated by the ventricular interaction and its coupling to the pulmonary circulation. The presentation can be acute with hemodynamic instability and shock or chronic producing symptoms of systemic venous congestion and low cardiac output. The prognostic factors associated with poor outcomes in hospitalized patients include systemic hypotension, hyponatremia, severe tricuspid insufficiency, inotropic support use and the presence of pericardial effusion. Effective therapeutic management strategies involve identification and effective treatment of the triggering factors, improving cardiopulmonary hemodynamics by optimization of volume to improve diastolic ventricular interactions, improving contractility by use of inotropes, and reducing afterload by use of drugs targeting pulmonary circulation. The medical therapies approved for PAH act primarily on the pulmonary vasculature with secondary effects on the right ventricle. Mechanical circulatory support as a bridge to transplantation has also gained traction in medically refractory cases. The current review was undertaken to summarize recent insights into the evaluation and treatment of RV dysfunction and failure attributable to PAH.

Intraoperative Extracorporeal Circulatory Support in Lung Transplantation for Pulmonary Fibrosis

BACKGROUND

Venous-arterial extracorporeal membrane oxygenation (ECMO) is an established technique for intraoperative cardiopulmonary support in patients undergoing lung transplantation. Patients with pulmonary fibrosis have a higher risk to require it. The aim of this study was to identify risk factors for the need of intraoperative ECMO use.

METHODS

Records of patients undergoing lung transplantation for pulmonary fibrosis at our institution between January 2010 and May 2018 were retrospectively reviewed. Univariate logistic regression analysis was used for statistical identification of risk factors.

RESULTS

There were 105 patients (34%) who required intraoperative ECMO support (ECMO+ group), and 203 (66%) did not (ECMO- group). Preoperative proof of pulmonary hypertension was identified as a risk factor for intraoperative ECMO support (odds ratio [OR], 3.8; 95% confidence interval [CI], 2.2-6.5; P < .01). Revealed mean pulmonary arterial pressure values exceeding 50 mm Hg and pulmonary vascular resistance values exceeding 9.4 Wood units were identified as risk factors for the need of intraoperative ECMO use with a prediction probability of 70%. Increased recipient body surface area (OR, 0.2; 95% CI, 0.1-0.5; P < .01) emerged as a protective factor against intraoperative ECMO (Hosmer-Lemeshow statistic, P = .71) as well as higher cardiac output (OR, 0.7; 95% CI, 0.6-0.9; P < .01). The postoperative course was more complicated in the ECMO+ group, whereas survival at 5 years did not differ among groups (70% vs 69%, P = .79).

CONCLUSIONS

Pulmonary hypertension with elevated pulmonary vascular resistance values predicts the need of intraoperative ECMO in patients receiving lung transplantation for pulmonary fibrosis. Although the postoperative course was more complicated in the ECMO+ group, long-term survival did not differ significantly.