Extracorporeal life support as a bridge to lung transplantation

Lung transplantation in pulmonary sarcoidosis

Sarcoidosis is a systemic inflammatory disease of unknown etiology and variable clinical course. Pulmonary sarcoidosis is the most common presentation and accounts for most morbidity and mortality related to sarcoidosis. While sarcoidosis generally has good outcomes, few patients experience chronic disease. A minority of patients progress to a specific phenotype of sarcoidosis referred to advanced pulmonary sarcoidosis (APS) which includes advanced fibrosis, pulmonary hypertension and respiratory failure, leading to high morbidity and mortality. In patients with advanced disease despite medical therapy, lung transplantation may be the last viable option for improvement in quality of life. Though post-transplant survival is similar to that of other end-stage lung diseases, it is imperative that patients are evaluated and referred early to transplant centers with experience in APS. A multidisciplinary approach and clinical experience are crucial in detecting the optimal timing of referral, initiating comprehensive transplantation evaluation and listing, discussing surgical approach, and managing perioperative and post-transplant care. This review article seeks to address these aspects of lung transplantation in APS.

Dynamic logistic state space prediction model for clinical decision making

Prediction modeling for clinical decision making is of great importance and needed to be updated frequently with the changes of patient population and clinical practice. Existing methods are either done in an ad hoc fashion, such as model recalibration or focus on studying the relationship between predictors and outcome and less so for the purpose of prediction. In this article, we propose a dynamic logistic state space model to continuously update the parameters whenever new information becomes available. The proposed model allows for both time-varying and time-invariant coefficients. The varying coefficients are modeled using smoothing splines to account for their smooth trends over time. The smoothing parameters are objectively chosen by maximum likelihood. The model is updated using batch data accumulated at prespecified time intervals, which allows for better approximation of the underlying binomial density function. In the simulation, we show that the new model has significantly higher prediction accuracy compared to existing methods. We apply the method to predict 1 year survival after lung transplantation using the United Network for Organ Sharing data.

In Vitro and In Vivo Feasibility Study for a Portable VV-ECMO and ECCO2R System

Extracorporeal membrane oxygenation (ECMO) is an established rescue therapy for patients with chronic respiratory failure waiting for lung transplantation (LTx). The therapy inherent immobilization may result in fatigue, consecutive deteriorated prognosis, and even lost eligibility for transplantation. We conducted a feasibility study on a novel system designed for the deployment of a portable ECMO device, enabling the physical exercise of awake patients prior to LTx. The system comprises a novel oxygenator with a directly connected blood pump, a double-lumen cannula, gas blender and supply, as well as control and energy management. In vitro experiments included tests regarding performance, efficiency, and blood damage. A reduced system was tested in vivo for feasibility using a novel large animal model. Six anesthetized pigs were first positioned in supine position, followed by a 45° angle, simulating an upright position of the patients. We monitored performance and vital parameters. All in vitro experiments showed good performance for the respective subsystems and the integrated system. The acute in vivo trials of 8 h duration confirmed the results. The novel portable ECMO-system enables adequate oxygenation and decarboxylation sufficient for, e.g., the physical exercise of designated LTx-recipients. These results are promising and suggest further preclinical studies on safety and efficacy to facilitate translation into clinical application.

Intraoperative support during lung transplantation

The role of intraoperative mechanical support during lung transplantation (LTx) is essential to provide a safe hemodynamic and ventilatory status during critical intraoperative events. This hemodynamic and ventilatory stability is vital to minimize the odds of suboptimal outcomes, especially considering that, due to the scarcity of donors and the fact that more and more patients with significant comorbidities are being considered for this therapy, a more aggressive approach is often needed by the transplant centers. Hence, the attenuation of any potential injury that can happen during this complex event is paramount. While a thorough assessment of the donor and optimization of postoperative care is pursued, certainly protective intraoperative management would also contribute to better outcomes. Understanding each patient’s underlying anatomy and cardiopulmonary physiology, associated with awareness of critical events during a complicated procedure like LTx, is essential for a precise indication and safe use of support. Cardiopulmonary bypass (CPB) and veno-arterial extracorporeal membrane oxygenation (VA ECMO) have been the most common approaches used, with the latter gaining popularity more recently and we have used VA ECMO exclusively for the last decade. New technologies certainly contributed to more liberal use of VA ECMO intraoperatively, enabling a protecting and physiologic environment for the newly implanted grafts. In this setting, potential prophylactic use for lung protection during a critical period is also considered.

CFTR Modulator Therapy and Its Impact on Lung Transplantation in Cystic Fibrosis

Cystic fibrosis (CF) is the most common autosomal recessive disorder in Caucasian people and is caused by mutations in the gene encoding for the CF transmembrane conductance regulator (CFTR) protein. It is a multisystem disorder; however, CF lung disease causes most of its morbidity and mortality. Although survival for CF has improved over time due to a multifaceted symptomatic management approach, CF remains a life-limiting disease. For individuals with progressive advanced CF lung disease (ACFLD), lung transplantation is considered the ultimate treatment option if compatible with goals of care. Since 2012, newer drugs, called CFTR modulators, have gradually become available, revolutionizing CF care, as these small-molecule drugs target the underlying defect in CF that causes decreased CFTR protein synthesis, function, or stability. Because of their extremely high efficacy and overall respectable tolerability, CFTR modulator drugs have already proven to have a substantial positive impact on the lives of individuals with CF. Individuals with ACFLD have generally been excluded from initial clinical trials. Now, however, these drugs are being used in clinical practice in selected individuals with ACFLD, showing promising results, although randomized controlled trial data for CFTR modulators in this subgroup of patients are lacking. Such data need to be gathered, ideally in randomized controlled trials including patients with ACFLD. Furthermore, the efficacy and tolerability of the newer modulator therapies in individuals with ACFLD need to be monitored, and their impact on lung disease progression and the need for lung transplantation as the ultimate therapy call for an objective evaluation in larger patient cohorts. As of today, guidelines for referral and listing of lung transplant candidates with CF have not incorporated the status of the new CFTR modulator therapies in the referral and listing process. The purpose of this review article, therefore, is threefold: first, to describe the effects of new therapies, with a focus on the subgroup of individuals with ACFLD; second, to provide an update on the recent outcomes after lung transplantation for individuals with CF; and third, to discuss the referral, evaluation, and timing for lung transplantation as the ultimate therapeutic option in view of the new treatments available in CF.

Long- and short-term clinical impact of awake extracorporeal membrane oxygenation as bridging therapy for lung transplantation

Background

As lung transplantation (LTx) is becoming a standard treatment for end-stage lung disease, the use of bridging with extracorporeal membrane oxygenation (ECMO) is increasing. We examined the clinical impact of being awake during ECMO as bridging therapy in patients awaiting LTx.

Methods

In this single-center study, we retrospectively reviewed 241 consecutive LTx patients between October 2012 and March 2019; 64 patients received ECMO support while awaiting LTx. We divided into awake and non-awake groups and compared.

Results

Twenty-five patients (39.1%) were awake, and 39 (61.0%) were non-awake. The median age of awake patients was 59.0 (interquartile range, 52.5–63.0) years, and 80% of the group was men. The awake group had better post-operative outcomes than the non-awake group: statistically shorter post-operative intensive care unit length of stay [awake vs. non-awake, 6 (4–8.5) vs. 18 (11–36), p < 0.001], longer ventilator free days [awake vs. non-awake, 24 (17–26) vs. 0 (0–15), p < 0.001], and higher gait ability after LTx (awake vs. non-awake, 92% vs. 59%, p = 0.004), leading to higher 6-month and 1-year lung function (forced expiratory volume in 1 s: awake vs. non-awake, 6-month, 77.5% vs. 61%, p = 0.004, 1-year, 75% vs. 57%, p = 0.013). Furthermore, the awake group had significantly lower 6-month and 1-year mortality rates than the non-awake group (6-month 12% vs. 38.5%, p = 0.022, 1-year 24% vs. 53.8%, p = 0.018).

Conclusions

In patients with end-stage lung disease, considering the long-term and short-term impacts, the awake ECMO strategy could be useful compared with the non-awake ECMO strategy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-021-01905-7.

Pediatric lung transplantation as standard of care

For infants, children, and adolescents with progressive advanced lung disease, lung transplantation represents the ultimate therapy option. Fortunately, outcomes after pediatric lung transplantation have improved in recent years now producing good long-term outcomes, no less than comparable to adult lung transplantation. The field of pediatric lung transplantation has rapidly advanced; thus, this review aims to update on important issues such as transplant referral and assessment, and extra-corporal life support as "bridge to transplantation". In view of the ongoing lack of donor organs limiting the success of pediatric lung transplantation, donor acceptability criteria and surgical options of lung allograft size reduction are discussed. Post-transplant, immunosuppression is vital for prevention of allograft rejection; however, evidence-based data on immunosuppression are scarce. Drug-related side effects are frequent, close therapeutic drug monitoring is highly advised with an individually tailored patient approach. Chronic lung allograft dysfunction (CLAD) remains the Achilles' heel of pediatric lung transplant limiting its long-term success. Unfortunately, therapy options for CLAD are still restricted. The last option for progressive CLAD would be consideration for lung re-transplant; however, numbers of pediatric patients undergoing lung re-transplantation are very small and its success depends highly on the optimal selection of the most suitable candidate.

Lung transplantation for emphysema

Lung transplantation (LT) is proved to be effective in patients with end-stage lung disease who are failing optimal therapy. Chronic obstructive pulmonary disease (emphysema) is the most common indication for adult lung transplantation. As most patients with emphysema (EMP) can survive long term, it could be difficult to decide which patient should be listed for LT. LT is a complex surgery. Therefore, it is extremely important to choose a recipient in whom expected survival is at less equal or comparable to the survival without surgery. This paper reviews patient selection, bridging strategies until lung transplantation, surgical approach and choice of the procedure, and functional outcome in emphysema recipients.

Bridging to Lung Transplantation

Lung transplantation is the gold standard for treating patients with end-stage lung disease. Such patients can present with severe illness on the waitlist and may deteriorate before a lung donor is available. Bridging strategies with extracorporeal membrane oxygenation (ECMO) are valuable for getting patients to transplant and provide a chance at survival. The current article describes the indications, contraindications, and techniques involved in bridging to lung transplantation with ECMO.

Lung transplantation for idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with a poor prognosis. Lung transplantation is the only intervention shown to increase life expectancy for patients with IPF, but it is associated with disease-specific challenges. In this Review, we discuss the importance of a proactive approach to the management of IPF comorbidities, including gastro-oesophageal reflux, pulmonary hypertension, coronary artery disease, and malignancy. With a donor pool too small to meet demand and unacceptably high mortality on transplant waiting lists, we discuss different systems used internationally to facilitate organ allocation. We explore the rapidly evolving landscape of transplantation for patients with IPF with regards to antifibrotic therapy, technological advances in extracorporeal life support, advances in understanding of the genetics of the disease, and the importance of a holistic multidisciplinary approach to care. Finally, we consider potential advances over the next decade that are envisaged to improve transplantation outcomes in patients with advanced IPF.

Lung Transplantation as a Therapeutic Option in Acute Respiratory Distress Syndrome

BACKGROUND

Lung transplantation (LTPL) is considered as a salvage therapeutic option in patients with end-stage lung disease. However, there is a lack of sufficient data on the use of LTPL in patients with acute respiratory distress syndrome (ARDS). Although there are few case reports on lung transplant for ARDS, no case series exists up to date. The aim of this study was to evaluate the clinical outcomes of patients with ARDS in accordance with the LTPL status.

METHODS

Patients who had severe ARDS (PaO2/FiO2 ratio ≤ 100 mm Hg with positive end-expiratory pressure ≥ 5 cm H2O) and were listed for LTPL with no underlying end-stage lung disease were included in this single-center retrospective study. Demographic and clinical data of the patients were collected and analyzed.

RESULTS

Fourteen patients were listed for LTPL due to severe ARDS. All patients received mechanical ventilation, and 12 (86%) patients underwent extracorporeal membrane oxygenation. Of the 9 patients who underwent LTPL, 8 (89%) survived, whereas only 1 (20%) patient out of those who did not receive LTPL survived. The median survival time of the patients who underwent LTPL was 1996 days (interquartile range [IQR], 872-2239), compared with 49 days (IQR, 872-2239) in patients who did not undergo LTPL. The median survival time after LTPL was 64 months (IQR, 28-72). The 3-year survival rate of the recipients was 78%.

CONCLUSIONS

LTPL may be considered as a therapeutic option in a select group of patients with severe ARDS. However, the irreversibility of the patient's lung status should be considered.

Use of extracorporeal membrane oxygenation in cystic fibrosis in an Australian cystic fibrosis centre

Extracorporeal membrane oxygenation (ECMO) support is used in selected patients with cystic fibrosis (CF) as a bridge to transplantation. Our aim was to describe briefly treatment and outcomes of six CF patients who received ECMO. One patient received a lung transplant and another recovered from acute respiratory failure. Four died despite ECMO support. Lack of timely availability of suitable donor lungs and patient selection are contributing factors.

Lung transplantation: indications and contraindications

The selection of appropriate recipients for lung transplantation is an evolving discipline. As experience with the procedure has developed over the last decades, the identification of transplant candidates has also changed as transplant centers strive to safely provide the therapy to as many patients possible. The International Society for Heart and Lung Transplantation (ISHLT) has developed three editions of recipient selection guidelines. Published in 1998, 2006, and 2015, these guidelines represented the best information relevant to the appropriate selection of lung transplant candidates. A discussion of areas supported by the most robust scientific data will be undertaken, but in many aspects of recipient selection, there is a paucity of data upon which to rely. Therefore, it is ultimately the prerogative and responsibility of individual centers to determine, after carefully weighing the best evidence available, whether a patient is deemed a suitable candidate at a specific program. All possible indications and contraindications for transplantation will be reviewed with attention also given to the appropriate timing of referral and listing of patients with advanced lung disease to a transplant center.

Extracorporeal Life Support in Lung Transplantation

Extracorporeal life support in lung transplantation has been associated with poor posttransplant outcomes. However, recent advances have resulted in more favorable posttransplant outcomes. The increased use of this technology must be weighed against the risks inherent in its use, especially when complications arising in extracorporeal membrane oxygenation (ECMO)-dependent patients result in loss of transplant candidacy, leaving them with no viable alternative for long-term support. Existing and emerging data support the judicious use of this technology in carefully selected patients at high-volume transplant and ECMO centers that prioritize minimization of sedation, avoidance of endotracheal intubation, and early mobilization.

Pediatric lung transplantation

Pediatric lung transplantation has been undertaken since the 1980s, and it is today considered an accepted therapy option in carefully selected children with end-stage pulmonary diseases, providing carefully selected children a net survival benefit and improved health-related quality of life. Nowadays, >100 pediatric lung transplants are done worldwide every year. Here, specific pediatric aspects of lung transplantation are reviewed such as the surgical challenge, effects of immunosuppression on the developing pediatric immune system, and typical infections of childhood, as it is vital to comprehend that children undergoing lung transplants present a real challenge as children are not 'just small adults'. Further, an update on the management of the pediatric lung transplant patient is provided in this review, and future challenges outlined. Indications for lung transplantation in children are different compared to adults, the most common being cystic fibrosis (CF). However, the primary diagnoses leading to pediatric lung transplantation vary considerably by age group. Furthermore, there are regional differences regarding the primary indication for lung transplantation in children. Overall, early referral, careful patient selection and appropriate timing of listing are crucial to achieve real survival benefit. Although allograft function is to be preserved, immunosuppressant-related side effects are common in children post-transplantation. Strategies need to be put into practice to reduce drug-related side effects through careful therapeutic drug monitoring and lowering of target levels of immunosuppression, to avoid acute-reversible and chronic-irreversible renal damage. Instead of a "one fits all approach", tailored immunosuppression and a personalized therapy is to be advocated, particularly in children. Further, infectious complications are a common in children of all ages, accounting for almost 50% of death in the first year post-transplantation. However, chronic lung allograft dysfunction (CLAD) remains the major obstacle for improved long-term survival.

Physical rehabilitation for lung transplant candidates and recipients: An evidence-informed clinical approach

Physical rehabilitation of lung transplant candidates and recipients plays an important in optimizing physical function prior to transplant and facilitating recovery of function post-transplant. As medical and surgical interventions in lung transplantation have evolved over time, there has been a demographic shift of individuals undergoing lung transplantation including older individuals, those with multiple co-morbidites, and candidates with respiratory failure requiring bridging to transplantation. These changes have an impact on the rehabilitation needs of lung transplant candidates and recipients. This review provides a practical approach to rehabilitation based on research and clinical practice at our transplant centre. It focuses on functional assessment and exercise prescription during an uncomplicated and complicated clinical course in the pre-transplant, early and late post-transplant periods. The target audience includes clinicians involved in pre- and post-transplant patient care and rehabilitation researchers.

How to minimise ventilator-induced lung injury in transplanted lungs: The role of protective ventilation and other strategies

Lung transplantation is the treatment of choice for end-stage pulmonary diseases. In order to avoid or reduce pulmonary and systemic complications, mechanical ventilator settings have an important role in each stage of lung transplantation. In this respect, the use of mechanical ventilation with a tidal volume of 6 to 8 ml  kg(-1) predicted body weight, positive end-expiratory pressure of 6 to 8 cmH2O and a plateau pressure lower than 30 cmH2O has been suggested for the donor during surgery, and for the recipient both during and after surgery. For the present review, we systematically searched the PubMed database for articles published from 2000 to 2014 using the following keywords: lung transplantation, protective mechanical ventilation, lung donor, extracorporeal membrane oxygenation, recruitment manoeuvres, extracorporeal CO2 removal and noninvasive ventilation.

Vascular access for extracorporeal life support: tips and tricks

In thoracic surgery, extracorporeal life support (ECLS) techniques are performed to (I) provide a short to mid term extracorporeal mechanical support; (II) realize the gas exchanges; and (III)-depending the configuration of the circuit-substitute the failed heart function. The objective of this review is to describe the rational of the different ECLS techniques used in thoracic surgery and lung transplantation (LTx) with a specific attention to the vascular access. Venovenous extracorporeal membrane oxygenation (VV ECMO) is the most common ECLS technique used in thoracic surgery and represents the best strategy to support the lung function. VV ECMO needs peripheral vascular access. The selection between his double-site or single-site configuration should be decided according the level of O2 requirements, the nosological context, and the interest to perform an ECLS ambulatory strategy. Venoarterial (VA) ECMO uses peripheral and/or central cannulation sites. Central VA ECMO is mainly used in LTx instead a conventional cardiopulmonary bypass (CPB) to decrease the risk of hemorrhagic issues and the rate of primary graft dysfunction (PGD). Peripheral VA ECMO is traditionally realized in a femoro-femoral configuration. Femoro-femoral VA ECMO allows a cardiocirculatory support but does not provide an appropriate oxygenation of the brain and the heart. The isolated hypercapnic failure is currently supported by extracorporeal CO2 removal (ECCO2R) devices inserted in jugular or subclavian veins. The interest of the Novalung (Novalung GmbH, Hechingen, Germany) persists due to his central configuration indicated to bridge to LTx patients suffering from pulmonary hypertension. The increasing panel of ECLS technologies available in thoracic surgery is the results of a century of clinical practices, engineering progress, and improvements of physiological knowledges. The selection of the ECLS technique-and therefore the vascular access to implant the device-for a given nosological context trends to be defined according an evidence-based medicine.

Long-Term Extracorporeal Membrane Oxygenation as Bridging Strategies to Lung Transplantation in Rapidly Devastating Isolated Langerhans Cell Histiocytosis

Isolated pulmonary involvement in pediatric Langerhans cell histiocytosis (LCH) is extremely rare. While the multisystem-LCH course varies from spontaneous remission to rapid deterioration with lethal outcome, single system involvement is generally associated with favorable prognosis. A child with isolated pulmonary LCH had an extremely rapid progression leading to respiratory failure, despite treatment with prednisone and vinblastine. Since lung hyperinflation and cystic degeneration contraindicated conventional mechanical ventilation, extracorporeal membrane oxygenation (ECMO) was chosen for 50 days as a bridge to lung transplantation. The mechanisms involved in disease progression and the usefulness of long-term ECMO are discussed.

Safety of Nurse-Led Ambulation for Patients on Venovenous Extracorporeal Membrane Oxygenation

PURPOSE

Venovenous extracorporeal membrane oxygenation (VV ECMO) is an effective therapy in patients with acute lung injury and end-stage lung disease. Although immobility increases the risk of complications, ambulation of patients on VV ECMO is not the standard of care in many institutions. Staff concerns for patient safety remain a barrier to ambulation. In this case series, we present our experience utilizing a nurse-driven ambulatory VV ECMO process to safely rehabilitate patients.

METHODS

We retrospectively reviewed all VV ECMO cases at our institution between January 1, 2011, and November 1, 2013. Inclusion criteria for this study required patients to be cannulated in the right internal jugular vein and ambulated while on VV ECMO.

RESULTS

During the period from January 1, 2011, to November 1, 2013, 18 patients (mean age 49 ± 15 years, 12 male) were ambulated while on ECMO. Eight received a transplant and survived to discharge. Of the remaining patients, 4 were successfully weaned from VV ECMO and 6 died following decisions by the family to withdraw care. The mean duration of VV ECMO support was 18 ± 16 days with the maximum duration being 61 days. All patients received physical therapy, range of motion at the bedside, and ambulated in the hospital. There were no patient falls, decannulations, or any other complications related to ambulation.

CONCLUSION

The adoption of a nurse-driven program to ambulate patients on VV ECMO is safe and may reduce other complications associated with immobility.

Special considerations for the use of lung transplantation in pediatrics

Lung transplantation has become an accepted therapy in infants, children and adolescents suffering from end-stage lung diseases, an impaired quality of life as well as a reduced life expectancy. Within Europe, pediatric lung transplantation is largely performed in predominantly adult centers due to a relatively low overall case volume. Children do represent a specific and challenging cohort facing a transplant procedure, where the selection of potential candidates becomes a crucial step to maximize net survival benefit. Therefore, interdisciplinary evaluation and early listing in view of current indications and contraindications, adequate preoperative education of the child and family members, discussion of possibly required bridging procedures in case of deterioration, appropriate technical planning of the operation, adherence to postoperative medical treatment and follow-up are all crucial steps in this demanding puzzle. In this article, the authors review recent advances in the field of pediatric lung transplantation and outline challenges in the future.

Cardiopulmonary Bypass and Extracorporeal Life Support for Emergent Intraoperative Thoracic Situations

Intraoperative thoracic surgical catastrophes may require extracorporeal circulation modes to support the patient while the appropriate repair is made. Teamwork is key and, given the evidence supporting better performance with the use of simulation and surgical-crisis checklists, their use should be encouraged. Anticipation is another important factor because the results of intrathoracic malignancy resection are clearly superior in the setting of planned cardiopulmonary support. In addition, familiarity with the different modes of support that are currently available can direct the decision-making process toward the best option to facilitate resolution of the intraoperative catastrophe with the least related morbidity.

Biocompatibility Assessment of the CentriMag-Novalung Adult ECMO Circuit in a Model of Acute Pulmonary Hypertension

Extracorporeal membrane oxygenation (ECMO) is rarely used in patients with severe pulmonary hypertension (PH) as a bridge to lung transplantation. In this study, we assess the blood biocompatibility of the integrated CentriMag-Novalung ECMO system (venoarterial) in an acute model of PH. Severe PH (≥2/3 systemic) was induced in eight sheep through progressive ligation of the main pulmonary artery. System performance, platelet activation, thromboelastography (TEG) parameters, fibrinogen, plasma-free hemoglobin, and total plasma protein were measured at initiation, 3, and 6 hr of support in the ECMO (N = 4) and sham (N = 4) groups. A stable ECMO flow (2.2 ± 0.1 L/min), low transmembrane pressure gradient, and steady blood O2 and CO2 levels were maintained. Platelet activation was low (<4%) in both the groups, whereas platelet responsiveness to agonist (platelet activating factor) was reduced in the sham group when compared with the ECMO group. There were no differences in the TEG parameters, fibrinogen concentration, plasma-free hemoglobin (<10 mg/dl), and plasma total protein between the two groups. The findings of low levels of platelet activation and plfHb suggest adequate blood biocompatibility of the integrated CentriMag-Novalung circuit use for short-term support in a model of PH.

Successful extracorporeal membrane oxygenation therapy as a bridge to sequential bilateral lung transplantation for a patient after severe paraquat poisoning

CONTEXT

Paraquat is a widely used herbicide that can cause severe to fatal poisoning in humans. The irreversible and rapid progression of pulmonary fibrosis associated with respiratory failure is the main cause of death in the later stages of poisoning. There are infrequent reports of successful lung transplants for cases of severe paraquat poisoning. We expect that this successful case will provide a reference for other patients in similar circumstances.

CASE DETAILS

A 24-year-old female was sent to the hospital approximately 2 hours after ingesting 50 ml of paraquat. She experienced rapidly aggravated pulmonary fibrosis and severe respiratory failure. On the 34th day after ingestion, she underwent intubation and invasive mechanical ventilation. The patient was evaluated for lung transplantation, and veno-venous extracorporeal membrane oxygenation (ECMO) was established as a bridge to lung transplantation on the 44th day. On the 56th day, she successfully underwent a bilateral sequential lung transplantation. Through respiratory and physical rehabilitation and nutrition support, the patient was weaned from mechanical ventilation and extubated on the 66th day. On the 80th day, she was discharged. During the 1-year follow-up, the patient was found to be in good condition, and her pulmonary function improved gradually.

CONCLUSION

We suggest that lung transplantation may be an effective treatment in the end stages of paraquat-induced pulmonary fibrosis and consequential respiratory failure. For patients experiencing a rapid progression to a critical condition in whom lung transplantation cannot be performed immediately (e.g., while awaiting a viable donor or toxicant clearance), ECMO should be a viable bridge to lung transplantation.

Successful Semi-Ambulatory Veno-Arterial Extracorporeal Membrane Oxygenation Bridge to Heart-Lung Transplantation in a Very Small Child

Lung transplantation (LTx) may be denied for children on extracorporeal membrane oxygenation (ECMO) due to high risk of cerebral hemorrhage. Rarely has successful LTx been reported in children over 10 years of age receiving awake or ambulatory veno-venous ECMO. LTx following support with ambulatory veno-arterial ECMO (VA ECMO) in children has never been reported to our knowledge. We present the case of a 4-year-old, 12-kg child with heritable pulmonary artery hypertension and refractory right ventricular failure. She was successfully bridged to heart-lung transplantation (HLTx) using ambulatory VA ECMO. Initial resuscitation with standard VA ECMO was converted to an ambulatory circuit using Berlin heart cannulae. She was extubated and ambulating around her bed while on VA ECMO for 40 days. She received an HLTx from an oversized marginal lung donor. Despite a cardiac arrest and Grade 3 primary graft dysfunction, she made a full recovery without neurological deficits. She achieved 104% force expiratory volume in 1 s 33 months post-HLTx. Ambulatory VA ECMO may be a useful strategy to bridge very young children to LTx or HLTx. Patient tailored ECMO cannulation, minimization of hemorrhage, and thrombosis risks while on ECMO contributed to a successful HLTx in our patient.

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.

Extracorporeal membrane oxygenation in adults: a brief review and ethical considerations for nonspecialist health providers and hospitalists

Given the pace, distribution, and uptake of technological innovation, patients experiencing respiratory failure, heart failure, or cardiac arrest are, with greater frequency, being treated with extracorporeal membrane oxygenation (ECMO). Although most hospitalists will not be responsible for ordering or managing ECMO, in-hospital healthcare providers continue to be a vital source of patient referral and, accordingly, need to understand the rudiments of these technologies so as to co-manage patients, counsel families, and help ensure that the provision of ECMO is consistent with patient preferences and appropriate goals of care. In an effort to prepare hospitalists for these clinical responsibilities, we review the history and technology behind modern-day ECMO, including venoarterial extracorporeal membrane oxygenation (VA-ECMO) and venovenous extracorporeal membrane oxygenation. Building upon that foundation, we further highlight special ethical considerations that may arise in VA-ECMO, and present an ethically grounded approach to the initiation, continuation, and discontinuation of treatment.

Outcomes of intraoperative extracorporeal membrane oxygenation versus cardiopulmonary bypass for lung transplantation

OBJECTIVE

The study objective was to compare the outcomes of intraoperative extracorporeal membrane oxygenation versus cardiopulmonary bypass support in lung transplantation.

METHODS

We performed a retrospective cohort study from a prospective database of adult lung transplantations performed at the University of Toronto from 2007 to 2013. Among 673 lung transplantations performed in the study period, 267 (39.7%) required cardiopulmonary support. There were 39 cases of extracorporeal membrane oxygenation (2012-2013) and 228 cases of cardiopulmonary bypass (2007-2013). Patients who were bridged with extracorporeal life support, underwent a concomitant cardiac procedure, received a combined liver or heart transplant, were colonized with Burkholderia cenocepacia, or required emergency cannulation for cardiopulmonary support were excluded. Finally, 33 extracorporeal membrane oxygenation cases were matched with 66 cases of cardiopulmonary bypass according to age (±10 years), lung transplantation indication, and procedure type (bilateral vs single lung transplantation).

RESULTS

Recipient factors such as body mass index and gender were not different between extracorporeal membrane oxygenation and cardiopulmonary bypass groups. Furthermore, donor variables were similar, including age, body mass index, last PaO2/FiO2 ratio, smoking history, positive airway cultures, and donor type (brain death and donation after cardiac death). Early outcomes, such as mechanical ventilation requirement, length of intensive care unit stay, and length of hospital stay, significantly favored extracorporeal membrane oxygenation (median 3 vs 7.5 days, P = .005; 5 vs 9.5 days, P = .026; 19 vs 27 days, P = .029, respectively). Perioperative blood product transfusion requirement was lower in the extracorporeal membrane oxygenation group. The 90-day mortality for the extracorporeal membrane oxygenation group was 6% versus 15% for cardiopulmonary bypass (P = .32).

CONCLUSIONS

Extracorporeal membrane oxygenation may be considered as the first choice of intraoperative cardiorespiratory support for lung transplantation.

Feasibility of perflutren microsphere contrast transthoracic echocardiography in the visualization of ventricular endocardium during venovenous extracorporeal membrane oxygenation in a validated ovine model

BACKGROUND

Transthoracic echocardiography (TTE) during extra corporeal membrane oxygenation (ECMO) is important but can be technically challenging. Contrast-specific TTE can improve imaging in suboptimal studies. These contrast microspheres are hydrodynamically labile structures. This study assessed the feasibility of contrast echocardiography (CE) during venovenous (VV) ECMO in a validated ovine model.

METHOD

Twenty-four sheep were commenced on VV ECMO. Parasternal long-axis (Plax) and short-axis (Psax) views were obtained pre- and postcontrast while on VV ECMO. Endocardial definition scores (EDS) per segment were graded: 1 = good, 2 = suboptimal 3 = not seen. Endocardial border definition score index (EBDSI) was calculated for each view. Endocardial length (EL) in the Plax view for the left ventricle (LV) and right ventricle (RV) was measured.

RESULTS

Summation EDS data for the LV and RV for unenhanced TTE (UE) versus CE TTE imaging: EDS 1 = 289 versus 346, EDS 2 = 38 versus 10, EDS 3 = 33 versus 4, respectively. Wilcoxon matched-pairs rank-sign tests showed a significant ranking difference (improvement) pre- and postcontrast for the LV (P < 0.0001), RV (P < 0.0001) and combined ventricular data (P < 0.0001). EBDSI for CE TTE was significantly lower than UE TTE for the LV (1.05 ± 0.17 vs. 1.22 ± 0.38, P = 0.0004) and RV (1.06 ± 0.22 vs. 1.42 ± 0.47, P = 0.0.0006) respectively. Visualized EL was significantly longer in CE versus UE for both the LV (58.6 ± 11.0 mm vs. 47.4 ± 11.7 mm, P < 0.0001) and the RV (52.3 ± 8.6 mm vs. 36.0 ± 13.1 mm, P < 0.0001), respectively.

CONCLUSIONS

Despite exposure to destructive hydrodynamic forces, CE is a feasible technique in an ovine ECMO model. CE results in significantly improved EDS and increased EL.

Fate of patients with extracorporeal lung assist as a bridge to lung transplantation versus patients without--a single-center experience

OBJECTIVES

Mechanical lung assist (MLA; extracorporeal membrane oxygenation (ECMO) or extracorporeal lung assist (ECLA)) is increasingly used as a temporary bridge to lung transplantation (LTx). This study was designed to evaluate the impact of preoperative MLA on the operative outcome, including longer-term survival, in comparison to patients undergoing LTx without preoperative MLA.

METHODS

A total of 143 patients underwent LTx at our institution from 2002 to 2011. Forty-three percent (n=62) of patients presented with idiopathic pulmonary fibrosis and 71% (n=102) presented with severely elevated pulmonary artery pressure.

RESULTS

Thirteen patients (9.1%) required pre-LTx MLA support (age 44 ±13 years, double LTx 73.3%, female gender 53%) whereas 130 patients did not (age 52 ±11 years, double LTx 41.5%, female gender 36.9%). In one patient, MLA was successfully weaned and the patient underwent subsequent LTx. All patients in the MLA group were intraoperatively supported with continuous ECMO. One patient had to be supported with MLA after LTx for a period of 8 days. The short-term and mid-term postoperative survival of the MLA patient group was not significantly different from the non-MLA group (LogRank p=0.28). The 30-day, 90-day and 1-year survivals were 95%, 90% and 71%, respectively, in the patients without MLA compared to 85%, 77% and 68% in the MLA group.

CONCLUSIONS

MLA has no impact on long-term survival rate in LTx patients, but has an influence in postoperative survival. MLA support is a valuable tool to bridge unstable patients to LTx.

A consensus document for the selection of lung transplant candidates: 2014--an update from the Pulmonary Transplantation Council of the International Society for Heart and Lung Transplantation

The appropriate selection of lung transplant recipients is an important determinant of outcomes. This consensus document is an update of the recipient selection guidelines published in 2006. The Pulmonary Council of the International Society for Heart and Lung Transplantation (ISHLT) organized a Writing Committee of international experts to provide consensus opinion regarding the appropriate timing of referral and listing of candidates for lung transplantation. A comprehensive search of the medical literature was conducted with the assistance of a medical librarian. Writing Committee members were assigned specific topics to research and discuss. The Chairs of the Writing Committee were responsible for evaluating the completeness of the literature search, providing editorial support for the manuscript, and organizing group discussions regarding its content. The consensus document makes specific recommendations regarding the timing of referral and of listing for lung transplantation. These recommendations include discussions not present in previous ISHLT guidelines, including lung allocation scores, bridging to transplant with mechanical circulatory and ventilator support, and expanded indications for lung transplantation. In the absence of high-grade evidence to support decision making, these consensus guidelines remain part of a continuum of expert opinion based on available studies and personal experience. Some positions are immutable. Although transplant is rightly a treatment of last resort for end-stage lung disease, early referral allows proper evaluation and thorough patient education. Subsequent waiting list activation implies a tacit agreement that transplant offers a significant individual survival advantage. It is both the challenge and the responsibility of the transplant community globally to ensure organ allocation maximizes the potential benefits of a scarce resource, thereby achieving that advantage.

Experience of extracorporeal membrane oxygenation as a bridge to lung transplantation in France

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is increasingly used as a bridge to lung transplantation (LTx). However, data concerning this approach remain limited.

METHODS

We retrospectively reviewed the medical records of all patients in France who received ECMO as a bridge to LTx from 2007 to 2011. Post-transplant survival and associated factors were assessed by the Kaplan-Meier method and the Cox model.

RESULTS

Included were 36 patients from 11 centers. Indications for LTx were cystic fibrosis (CF) in 20 (56%), pulmonary fibrosis (PF) in 11 (30%), and other diagnoses in 5 (14%). ECMO was venovenous for 27 patients (75%) and venoarterial for 9 (25%). Mean follow-up was 17 months. Bridging to LTx was achieved in 30 patients (83%); however, only 27 patients (75%) survived the LTx procedure, and 20 (56%) were discharged from hospital. From ECMO initiation, 2-year survival rates were 50.4% overall, 71.0% for CF patients, 27.3% for PF patients, and 20.0% for other patients (p < 0.001). From LTx, 2-year survival rates were 60.5% overall, 71.0% for CF patients, 42.9% for PF patients, and 33.0% for other patients (p = 0.04).

CONCLUSIONS

Our study confirms that the use of ECMO as a bridge to LTx in France could provide a medium-term survival benefit for LTx recipients with critical conditions. Survival differed by underlying respiratory disease. Larger studies are needed to further define the optimal use of ECMO.

Extracorporeal life support for adults with severe acute respiratory failure

Extracorporeal life support (ECLS) is an artificial means of maintaining adequate oxygenation and carbon dioxide elimination to enable injured lungs to recover from underlying disease. Technological advances have made ECLS devices smaller, less invasive, and easier to use. ECLS might, therefore, represent an important step towards improved management and outcomes of patients with acute respiratory distress syndrome. Nevertheless, rigorous evidence of the ability of ECLS to improve short-term and long-term outcomes is needed before it can be widely implemented. Moreover, how to select patients and the timing and indications for ECLS in severe acute respiratory distress syndrome remain unclear. We describe the physiological principles, the putative risks and benefits, and the clinical evidence supporting the use of ECLS in patients with acute respiratory distress syndrome. Additionally, we discuss controversies and future directions, such as novel technologies and indications, mechanical ventilation of the native lung during ECLS, and ethics considerations.