The evolution of extracorporeal life support as a bridge to lung transplantation. ASAIO J. 2013;59:3-10. [PMID: 23271390 DOI: 10.1097/mat.0b013e31827461c2]

Outcomes of Recipients Aged 65 Years and Older Bridged to Lung Transplant With Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) as a bridge to lung transplant (BTT) has been used for critically ill candidates with excellent outcomes, but data on this strategy in older recipients remain limited. We compared outcomes of no BTT, mechanical ventilation (MV)-only BTT, and ECMO BTT in recipients of greater than or equal to 65 years. Lung-only recipients of greater than or equal to 65 years in the United Network for Organ Sharing database between 2008 and 2022 were included and stratified by bridging strategy. Of the 9,936 transplants included, 226 (2.3%) were MV-only BTT and 159 (1.6%) were ECMO BTT. Extracorporeal membrane oxygenation BTT recipients were more likely to have restrictive disease pathology, had higher median lung allocation score, and spent fewer days on the waitlist (all p < 0.001). Compared to no-BTT recipients, ECMO BTT recipients were more likely to be intubated or on ECMO at 72 hours posttransplant and had longer hospital lengths of stay (all p < 0.001). Extracorporeal membrane oxygenation BTT recipients had increased risk of 3 years mortality compared to both no-BTT (adjusted hazard ratio [aHR] = 1.48 [95% confidence interval {CI}: 1.14-1.91], p = 0.003) and MV-only recipients (aHR = 1.50 [95% CI: 1.08-2.07], p = 0.02). Overall, we found that ECMO BTT in older recipients is associated with inferior posttransplant outcomes compared to MV-only or no BTT, but over half of recipients remained alive at 3 years posttransplant.

Nurses' Interventions in Minimizing Adult Patient Vulnerability During Extracorporeal Membrane Oxygenation as a Bridge to Lung Transplantation: An Integrative Review

Introduction

People during extracorporeal membrane oxygenation (ECMO) as a bridge to lung transplantation find themselves in a high degree of physical and psychological vulnerability, which could cause additional problems for their health status. Therefore, this review aims to identify the interventions that shape critical nursing care to minimize patient vulnerability during ECMO as a bridge to lung transplantation.

Method

A literature review was performed using CINAHL, MEDLINE, PubMed, Scopus and Web of Science databases with searches conducted in March 2023, with temporal restriction of articles published between 2013 and 2023. After selecting articles involving adults in critical situations on ECMO, their quality was assessed using the critical appraisal tools from the Joanna Briggs Institute. Articles with the pediatric population, reviews, and opinion articles were excluded. A spreadsheet was built for data extraction and a narrative analysis was performed.

Results

Three articles were included involving 40 participants in total. Interventions that shape critical nursing care to minimize a person's vulnerability are in the physical domain (basic precautions to prevent infection) and in the psychological domain (trusting relationships, consistent and clear communication, physical presence of nurses and family members and the use of advocacy). The Awake ECMO strategy was identified as beneficial for reducing vulnerability.

Conclusion

By recognizing and identifying the person's vulnerability during ECMO as a bridge to lung transplantation, nurses can implement effective interventions to minimize vulnerability in this population, thus contributing to the person's well-being through personalization and individualization of care. Additionally, the results of this review could be useful for developing tools to assess the degree of vulnerability and for implementing person-centered care measures and policies. However, further research is warranted given the scarcity of literature on these topics.

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.

In Vivo Testing of an Ambient Air Based, Portable, and Automated CO 2 Removal Controller for Artificial Lungs

Portable artificial lung (AL) systems are under development, but there are few technologies available that adjust the carbon dioxide (CO 2 ) removal in response to changes in patient metabolic needs. Our work describes the second generation of a CO 2 -based portable servoregulation system that automatically adjusts CO 2 removal in ALs. Four adult sheep (68 ± 14.3 kg) were used to test the servoregulator. The servoregulator controlled air sweep flow through the lung to meet a target exhaust gas CO 2 (tEGCO 2 ) level in normocapnic and hypercapnic (arterial partial pressure of CO 2 [PaCO 2 ] >60 mm Hg) conditions at varying flow rates (0.5-1.5 L/min) and at tEGCO 2 levels of 10, 20, and 40 mm Hg. In hypercapnic sheep, average post-AL blood partial pressure of CO 2 (pCO 2 ) values were 22.4 ± 3.6 mm Hg for tEGCO 2 of 10 mm Hg, 28.0 ± 4.1 mm Hg for tEGCO 2 of 20 mm Hg and 40.6 ± 4.8 mm Hg for tEGCO 2 of 40 mm Hg. The controller successfully and automatically adjusted the sweep gas flow to rapidly (<10 minutes) meet the tEGCO 2 level when challenged with changes in inlet blood flow or target EGCO 2 levels for all animals. These in vivo data demonstrate an important step toward portable ALs that can automatically modulate CO 2 removal and allow for substantial changes in patient activity or disease status in ambulatory applications.

A Portable Servoregulation Controller to Automate CO2 Removal in Artificial Lungs

Artificial lung (AL) systems provide respiratory support to patients with severe lung disease, but none can adapt to the changing respiratory needs of the patients. Precisely, none can automatically adjust carbon dioxide (CO2) removal from the blood in response to changes in patient activity or disease status. Because of this, all current systems limit patient comfort, activity level, and rehabilitation. A portable servoregulation controller that automatically modulates CO2 removal in ALs to meet the real-time metabolic demands of the patient is described. The controller is based on a proportional-integral-derivative (PID) based closed-loop feedback control system that modulates sweep gas (air) flow through the AL to maintain a target exhaust gas CO2 partial pressure (target EGCO2 or tEGCO2). The presented work advances previous research by (1) using gas-side sensing that avoids complications and clotting associated with blood-based sensors, (2) incorporating all components into a portable, battery-powered package, and (3) integrating smart moisture removal from the AL to enable long term operation. The performance of the controller was tested in vitro for ∼12 h with anti-coagulated bovine blood and 5 days with distilled water. In tests with blood, the sweep gas flow was automatically adjusted by the controller rapidly (<2 min) meeting the specified tEGCO2 level when confronted with changes in inlet blood partial pressure of CO2 (pCO2) levels at various AL blood flows. Overall, the CO2 removal from the AL showed a strong correlation with blood flow rate and blood pCO2 levels. The controller successfully operated continuously for 5 days when tested with water. This study demonstrates an important step toward ambulatory AL systems that automatically modulate CO2 removal as required by lung disease patients, thereby allowing for physiotherapy, comfort, and activity.

Acute Interstitial Pneumonia (Hamman-Rich Syndrome) in Lung Transplantation: A Case Series

BACKGROUND

Acute interstitial pneumonia (AIP), also known as Hamman-Rich syndrome, is a rare and rapidly progressive idiopathic interstitial lung disease with a high mortality rate. Treatment is limited to supportive care and empirical high-dose steroids; however, outcomes are generally poor. There are few reports of lung transplantation (LTx) in patients with AIP.

METHODS

We retrospectively identified patients with AIP among those who underwent LTx at our center between January 2008 and December 2020.

RESULTS

During the study period, 4 patients with AIP underwent bilateral LTx: 3 men and 1 woman, between 30 and 57 years of age. The lung allocation score ranged between 71 and 89. Of the 4 patients, 2 needed extracorporeal membrane oxygenation and mechanical ventilation (MV) and 1 needed MV preoperatively. Time of onset to transplant ranged from 1 to 3 months. None of the patients had primary graft dysfunction after LTx; 2 had acute cellular rejection and 1 had chronic lung allograft dysfunction. The 4 patients are alive with survival ranging between 1 and 12 years after LTx.

CONCLUSION

AIP should be considered in patients with acute respiratory failure without a clear etiology. Our study showed that LTx led to good outcomes and should be considered as a treatment option in appropriate candidates.

Toward a Servoregulation Controller to Automate CO2 Removal in Wearable Artificial Lungs

A laptop-driven, benchtop control system that automatically adjusts carbon dioxide (CO2) removal in artificial lungs (ALs) is described. The proportional-integral-derivative (PID) feedback controller modulates pump-driven air sweep gas flow through an AL to achieve a desired exhaust gas CO2 partial pressure (EGCO2). When EGCO2 increases, the servoregulator automatically and rapidly increases sweep flow to remove more CO2. If EGCO2 decreases, the sweep flow decreases to reduce CO2 removal. System operation was tested for 6 hours in vitro using bovine blood and in vivo in three proof-of-concept sheep experiments. In all studies, the controller automatically adjusted the sweep gas flow to rapidly (<1 minute) meet the specified EGCO2 level when challenged with changes in inlet blood or target EGCO2 levels. CO2 removal increased or decreased as a function of arterial pCO2 (PaCO2). Such a system may serve as a controller in wearable AL systems that allow for large changes in patient activity or disease status.

Lung Transplantation in COPD

Chronic obstructive pulmonary disease (COPD) remains one of the leading causes of morbidity and mortality both in the United States and worldwide. Despite advances in medical treatment including smoking cessation, bronchodilator therapy, oxygen administration, and pulmonary rehabilitation, patients with advanced COPD still suffer significant debility. For select patients with severe COPD, there are additional surgical options including lung volume reduction surgery and ultimately lung transplantation.This article discusses the history, clinical indications, selection of candidates, choice of procedure, and outcomes of lung transplantation in patients with advanced COPD. In addition, certain aspects of potential short- and long-term complications of transplantation will also be discussed.

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.

Effects of the duration of bridge to lung transplantation with extracorporeal membrane oxygenation

Background

Although bridge to lung transplantation (BTT) with extracorporeal membrane oxygenation (ECMO) is increasingly performed, the impact of BTT and its duration on post-transplant outcomes are unclear.

Methods

We retrospectively reviewed medical records of adult patients who underwent lung or heart-lung transplantation in our institution between January 2008 and December 2018. Data were compared in patients who did (n = 41; BTT) and did not (n = 36; non-BTT) require pre-transplant ECMO support. Data were also compared in patients who underwent short-term (<14 days; n = 21; ST-BTT) and long-term (≥14 days; n = 20; LT-BTT) BTTs.

Results

Among 77 patients included, 51 (66.2%) were male and median age was 53 years. The median bridging time in the BTT group was 13 days (interquartile range [IQR], 7–19 days). Although simplified acute physiologic score II was significantly higher in the BTT group (median, 35; IQR, 31–49 in BTT group vs. median, 12; IQR, 7–19 in non-BTT group; p<0.001), 1-year (73.2% vs. 80.6%; p = 0.361) and 5-year (61.5% vs. 61.5%; p = 0.765) post-transplant survival rates were comparable in both groups. Comparison of ST- and LT-BTT subgroups showed that 1-year (90.5% vs. 55.0%; p = 0.009) and 5-year (73.0% vs. 48.1%; p = 0.030) post-transplant survival rates were significantly higher in ST-BTT group. In age and sex adjusted model, the LT-BTT was an independent risk factor for 1-year post-transplant mortality (hazard ratio, 3.019; 95% confidence interval, 1.119–8.146; p = 0.029), whereas the ST-BTT was not.

Conclusions

Despite the severe illness, the BTT group showed favorable post-transplantation outcomes, particularly those bridged for less than 14 days.

Bioengineering Progress in Lung Assist Devices

Artificial lung technology is advancing at a startling rate raising hopes that it would better serve the needs of those requiring respiratory support. Whether to assist the healing of an injured lung, support patients to lung transplantation, or to entirely replace native lung function, safe and effective artificial lungs are sought. After 200 years of bioengineering progress, artificial lungs are closer than ever before to meet this demand which has risen exponentially due to the COVID-19 crisis. In this review, the critical advances in the historical development of artificial lungs are detailed. The current state of affairs regarding extracorporeal membrane oxygenation, intravascular lung assists, pump-less extracorporeal lung assists, total artificial lungs, and microfluidic oxygenators are outlined.

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.

Extracorporeal membrane oxygenation as a bridge to lung transplantation in a Turkish lung transplantation program: our initial experience

Lung transplantation is a life-saving treatment for patients with end-stage lung disease. Although the number of lung transplants has increased over the years, the number of available donor lungs has not increased at the same rate, leading to the death of transplant candidates on waiting lists. In this paper, we presented our initial experience with the use of extracorporeal membrane oxygenation (ECMO) as a bridge to lung transplantation. Between December 2016 and August 2018, we retrospectively reviewed the use of ECMO as a bridge to lung transplantation. Thirteen patients underwent preparative ECMO for bridging to lung transplantation, and seven patients successfully underwent bridging to lung transplantation. The average age of the patients was 45.7 years (range, 19–62 years). The ECMO support period lasted 3–55 days (mean, 18.7 days; median, 13 days). In seven patients, bridging to lung transplantation was performed successfully. The mean age of patients was 49.8 years (range 42–62). Bridging time was 3–55 days (mean, 19 days; median, 13 days). Two patients died in the early postoperative period. Five patients survived until discharge from the hospital. One-year survival was achieved in four patients. ECMO can be used safely for a long time to meet the physiological needs of critically ill patients. The use of ECMO as a bridge to lung transplantation is an acceptable treatment option to reduce the number of deaths on the waiting list. Despite the successful results achieved, this approach still involves risks and complications.

Extracorporeal Membrane Oxygenation as a Bridge to Lung Transplantation: First Polish Experience

BACKGROUND

Lung transplantation remains the only viable option for patients with end-stage lung diseases. However, due to an insufficient number of lung donors, many potential candidates die without undergoing the procedure. In the cases of some patients, bridges to transplantation can be implemented. One such method is extracorporeal membrane oxygenation (ECMO), which, depending on the type, has the ability to replace patients' circulatory and respiratory function.

CASE PRESENTATION

This case study describes 4 cases of patients, who were successfully bridged to lung transplantation. The first patient developed respiratory failure as a result of acute pulmonary embolisms. His respiratory function was insufficient and he had ECMO implanted for 84 days until he was transplanted. Another patient presented respiratory failure due to massive bleeding, which occurred during transbronchial lung biopsy. Such event led to extensive exacerbation, which resulted in using ECMO as a bridge to recovery at first, but later a bridge to lung transplantation. The patient became a lung graft recipient after 14 days on ECMO. The third patient was a woman who developed severe respiratory failure during the course of the progression of her underlying disease. She was treated with ECMO for 14 days as well, and she also underwent lung transplantation. The fourth patient was qualified for retransplantation. She was bridged to retransplantation via veno-venous ECMO.

CONCLUSION

ECMO can be used a bridge to lung transplantation for suitable patients even for a long period of time, given that it is maintained in accordance with the guidelines.

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.

Improvement in patient-reported outcomes after lung transplantation is not impacted by the use of extracorporeal membrane oxygenation as a bridge to transplantation

OBJECTIVE

Extracorporeal membrane oxygenation (ECMO) is increasingly used as a bridge to lung transplantation. The impact of preoperative ECMO on health-related quality of life (HRQL) and depressive symptoms after lung transplantation remains unknown, however.

METHODS

In a single-center prospective cohort study, we assessed HRQL and depressive symptoms before and at 3, 6, and 12 months after lung transplantation using the Short Form 12 Physical and Mental Component Scores (SF12-PCS and SF12-MCS), Airway Questionnaire 20-Revised (AQ20R), EuroQol 5D (EQ5D), and Geriatric Depression Scale (GDS). Changes in HRQL were quantified by segmented linear mixed-effects models controlling for age, sex, diagnosis, preoperative forced expiratory volume in 1 second, 6-minute walk distance, and Lung Allocation Score. We compared changes in HRQL among subjects bridged with ECMO, subjects hospitalized but not on ECMO, and subjects called in for transplantation as outpatients.

RESULTS

Out of 189 subjects, 17 were bridged to transplantation with ECMO. In all groups, improvements in HRQL following lung transplantation exceeded the minimally clinically important difference using the SF12-PCS, AQ20R, EQ5D, and GDS. HRQL defined by SF12-MCS did not change after transplantation. Improvements were generally similar among the groups, except for EQ5D, which showed a trend toward less benefit in the outpatients, possibly due to their better HRQL before lung transplantation.

CONCLUSIONS

Subjects ill enough to require ECMO as a bridge to lung transplantation appear to achieve similar improvements in HRQL and depressive symptoms as those who do not. It is reassuring to both providers and patients that lung transplantation provides substantial improvements in HRQL, even for those patients who are critically ill in the run up to transplantation.

Extracorporeal membrane oxygenation following lung transplantation: indications and survival

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is employed to rescue patients with early graft dysfunction after lung transplantation (LTx). Rates of post-LTx ECMO and subsequent outcomes have been limited to single-center reports.

METHODS

UNOS registry was queried for LTx recipients from March 2015 to March 2016; 2,001 recipients were identified and stratified by need for post-LTx ECMO. Logistic regression was used to determine variables associated with post-LTx ECMO. Cox proportional hazards modeling identified factors associated with survival. Kaplan-Meier analysis with log-rank testing was employed for survival analysis.

RESULTS

Of 2,001 recipients identified, 107 required post-LTx ECMO (5.1%). Recipients requiring ECMO were younger (56 vs 60 years, p = 0.007) and had higher body mass index (27.2 vs 25.8, p = 0.012). Recipients requiring post-LTx ECMO were more likely to have required mechanical ventilation before transplant (9.3% vs 4.9%, p = 0.049) and were more likely to have required pre-transplant ECMO (15% vs 3.7%, p < 0.001). On multivariable analysis, pre-transplant ECMO and increasing ischemic time were associated with post-LTx ECMO. Six-month survival for recipients requiring ECMO was 62.2%. On multivariable analysis, need for post-transplant dialysis was associated with mortality. Six-month survival for recipients requiring ECMO with and without dialysis was 25.8% and 86.7% (p < 0.001).

CONCLUSIONS

In a nationally representative database, ischemic time and pre-transplant ECMO and/or ventilator requirement were associated with need for post-LTx ECMO. Need for post-transplant dialysis was associated with mortality in patients requiring post-LTx ECMO. These data may permit improved prediction of graft dysfunction. Strategies to minimize renal toxicity in the perioperative phase may lead to improved early survival post-LTx.

Spontaneously Breathing Extracorporeal Membrane Oxygenation Support Provides the Optimal Bridge to Lung Transplantation

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is being increasingly used as a bridge to lung transplantation. Small, single-institution series have described increased success using ECMO in spontaneously breathing patients compared with patients on ECMO with mechanical ventilation, but this strategy has not been evaluated on a large scale.

METHODS

Using the United Network for Organ Sharing database, all adult patients undergoing isolated lung transplantation from May 2005 through September 2013 were identified. Patients were categorized by their type of pretransplant support: no support, ECMO only, invasive mechanical ventilation (iMV) only, and ECMO + iMV. Kaplan-Meier survival analysis with log-rank testing was performed to compare survival based on type of preoperative support. A Cox regression model was used to determine whether type of preoperative support was independently associated with survival, using previously established predictors of survival as covariates.

RESULTS

Approximately 12,403 primary adult pulmonary transplantations were included in this analysis. Sixty-five patients (0.52%) were on ECMO only, 612 (4.93%) required only iMV, 119 (0.96%) were on ECMO + iMV, and the remaining 11,607 (94.6%) required no invasive support before transplantation. One-year survival was decreased in all patients requiring support, regardless of type. However, mid-term survival was similar between patients on ECMO alone and those not on support but significantly worse with patients requiring iMV only or ECMO + iMV. In multivariable analysis, ECMO + iMV and iMV alone were independently associated with decreased survival compared with nonsupport patients, whereas ECMO alone was not significant.

CONCLUSIONS

In patients with worsening pulmonary disease awaiting lung transplantation, those supported via ECMO with spontaneous breathing demonstrated improved survival compared with other bridging strategies.

Back to the roots? Dual cannulation strategy for ambulatory ECMO in adolescent lung transplant candidates: An alternative?

Bridging critically ill pediatric patients to lung transplantation still remains a major challenge. Although still controversial, within the last 5 years, ECMO has been increasingly used as a bridge to lung transplantation concept in adult and pediatric patients with acceptable outcomes. The outstanding developments in the field of extracorporeal devices and the introduction of awake ECMO concepts with the avoidance of mechanical ventilation have led to a real paradigm shift in the ICU management of pretransplant candidates with severe respiratory failure. Therefore, ECMO is no longer seen as a contraindication for lung transplantation at least at our center. Nevertheless, how to bridge these patients on ECMO still remains controversial. Thus, we introduced an ambulatory ECMO approach in adolescent lung transplant candidates with acute respiratory failure using a dual cannulation strategy and hereby present first results from this procedure.

Towards a Biohybrid Lung Assist Device: N-Acetylcysteine Reduces Oxygen Toxicity and Changes Endothelial Cells' Morphology

The development of an endothelialized membrane oxygenator requires solution strategies combining the knowledge of oxygenators with endothelial cells' biology. Since it is well known that exposing cells towards pure oxygen causes oxidative stress, this aspect has to be taken into account in the development of a biohybrid oxygenator system. N-Acetylcysteine (NAC) is known for its antioxidant properties in cells. We tested its applicability for the development of an endothelialized oxygenator model. Cultivating human umbilical vein derived endothelial cells (HUVEC) up to 6 days with increasing concentrations of NAC from 1 to 30 mM revealed NAC toxicity at concentrations from 20 mM. Cell density clearly decreased after radical oxygen species exposure in non-NAC pretreated cells compared to 20 mM NAC precultured HUVEC after 3 and 6 days. Also the survival rate after ROS treatment could be restored by incubation with NAC from 15 to 25 mM for all time points. NAC treated cells changed their morphology from typical endothelial cells' cobblestone pattern to a fusiform, elongated configuration. Transformed cells were still positive for typical endothelial cell markers. Our present results show the potential of NAC for the protection of an endothelial cell layer in an endothelialized membrane oxygenator due to its antioxidative properties. Moreover, NAC induces a morphological change in HUVEC similar to dynamic cultivation procedures.

High Levels of Residue within Polymeric Hollow Fiber Membranes Used for Blood Oxygenation

A number of research teams are developing surface coatings for hollow fiber membrane (HFM) blood oxygenators to improve their biocompatibility and service life. Surface coating techniques can be quite sensitive to the presence of contaminants on the exterior surface of the hollow fibers. We found large amounts of leachable oils associated with several commercial HFMs, i.e., as much as 2.5-7.5 weight percent. Leachable residues were suspected when a surface coating, a surface-initiated atom transfer radical polymerization (s-ATRP) of poly(ethylene glycol) methacrylate, resulted in areas of 100 µm devoid of coatings on the exterior surfaces of HFMs. After leaching residual oils, s-ATRP coatings were uniform and continuous across the hollow fibers. Therefore, removal of residual material should be considered before applying coating technologies to commercial HFMs. The effects of such leachable agents on the performance of blood oxygenators are not known.

Prolonged VV ECMO (265 Days) for ARDS without technical complications

The usual duration of extracorporeal membrane oxygenation (ECMO) in patients with severe acute respiratory distress syndrome is 7-10 days. Prolonged duration ECMO (defined as greater than 14 days) is increasingly being documented with native lung recovery or as a bridge to lung transplantation. We report a case of prolonged duration ECMO (6,364 hours, 265 days) requiring no complete circuit exchange. As critical care improves, prolonged ECMO will continue to pose unique technological and ethical challenges that test our expectations of this treatment modality. There is a critical need for diagnostic modalities to provide objective assessment of native lung recovery in patients requiring prolonged duration ECMO.

A global perspective of lung transplantation: Part 1 - Recipient selection and choice of procedure

Lung transplantation has grown considerably in recent years and its availability has spread to an expanding number of countries worldwide. Importantly, survival has also steadily improved, making this an increasingly viable procedure for patients with end-stage lung disease and limited life expectancy. In this first of a series of articles, recipient selection and type of transplant operation are reviewed. Pulmonary fibrotic disorders are now the most indication in the U.S., followed by chronic obstructive pulmonary disease and cystic fibrosis. Transplant centers have liberalized criteria to include older and more critically ill candidates. A careful, systematic, multi-disciplinary selection process is critical in identifying potential barriers that may increase risk and optimize long-term outcomes.

Extracorporeal Membrane Oxygenation Applications in Cardiac Critical Care

The use of extracorporeal membrane oxygenation therapy (ECMO) in cardiac critical care has steadily increased over the past decade. Significant improvements in the technology associated with ECMO have propagated this recent resurgence and contributed to improved patient outcomes in the fields of cardiac and transplant (heart and lung) surgery. Specifically, ECMO is being increasingly utilized as a bridge to heart and lung transplantation, as well as to ventricular assist device placement. ECMO is also employed during the administration of cardiopulmonary resuscitation, known as extracorporeal life support. In this review, we examine the recent literature regarding the applications of ECMO and also describe emerging topics involving current ECMO management strategies.

Physiotherapy for Patients on Awake Extracorporeal Membrane Oxygenation: A Systematic Review

BACKGROUND AND PURPOSE

Extracorporeal membrane oxygenation (ECMO) is used as temporary life support in subjects with potentially reversible respiratory/cardiac failure. The principal purpose of this review was to assess the characteristics and potential advantages of physiotherapeutic interventions in subjects on awake ECMO support.

METHODS

Seven databases were interrogated: we searched titles, abstracts and keywords using the Medical Subject Headings terms 'extracorporeal membrane oxygenation' and 'rehabilitation' linked with the Boolean operator 'AND'.

RESULTS AND CONCLUSION

In total, 216 citations were retrieved. Nine citations satisfied our inclusion criteria and were subjected to full-text analysis. The numbers of patients enrolled in the included studies (most of which were case series) were low (n = 52). We found no prospective studies or randomized controlled trials. Overall, subjects on awake ECMO usually received a combination of passive and active physiotherapy, and most achieved an acceptable degree of autonomy after treatment. Emerging research in the field affords preliminary evidence supporting the safety of early mobilization and ambulation in patients on awake veno-venous ECMO support. Copyright © 2015 John Wiley & Sons, Ltd.

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.

Extracorporeal life support as bridge to lung transplantation: a systematic review

INTRODUCTION

Patients with acute respiratory failure requiring respiratory support with invasive mechanical ventilation while awaiting lung transplantation are at a high risk of death. Extracorporeal membrane oxygenation (ECMO) has been proposed as an alternative bridging strategy to mechanical ventilation. The aim of this study was to assess the current evidence regarding how the ECMO bridge influences patients' survival and length of hospital stay.

METHODS

We performed a systematic review by searching PubMed, EMBASE and the bibliographies of retrieved articles. Three reviewers independently screened citation titles and abstracts and agreement was reached by consensus. We selected studies enrolling patients who received ECMO with the intention to bridge lung transplant. We included randomized controlled trials (RCTs), case-control studies and case series with ten or more patients. Outcomes of interest included survival and length of hospital stay. Quantitative data summaries were made when feasible.

RESULTS

We identified 82 studies, of which 14 were included in the final analysis. All 14 were retrospective studies which enrolled 441 patients in total. Because of the broad heterogeneity among the studies we did not perform a meta-analysis. The mortality rate of patients on ECMO before lung transplant and the one-year survival ranged from 10% to 50% and 50% to 90%, respectively. The intensive care and hospital length of stay ranged between a median of 15 to 47 days and 22 to 47 days, respectively. There was a general paucity of high-quality data and significant heterogeneity among studies in the enrolled patients and technology used, which confounded analysis.

CONCLUSIONS

In most of the studies, patients on ECMO while awaiting lung transplantation also received invasive mechanical ventilation. Therefore, whether ECMO as an alternative, rather than an adjunction, to invasive mechanical ventilation is a better bridging strategy to lung transplantation still remains an unresolved issue. ECMO support as a bridge for these patients could provide acceptable one-year survival. Future studies are needed to investigate ECMO as part of an algorithm of care for patients with end-stage lung disease.

Ex vivo approach to treat failing organs: expanding the limits

BACKGROUND

Advanced organ failure is often classified as an end-stage disease where the treatment options are limited only to transplantation. As an alternative, different attempts have been undertaken to improve the outcome of the treatment of failing organs by using targeted ex vivo approaches. This may solve the issue of organ shortage by treating the donor organs before transplantation and the number of patients requiring transplantation may also be reduced by applying extensive ex vivo treatment followed by autotransplantation.

METHODS

We performed a literature review of PubMed and included articles published between 1962 and 2013. The following keywords were used (and; or): ex vivo, therapy, surgery, organ perfusion and autotransplantation. This review includes specific methods and attempts related to ex vivo organ perfusion and preservation, temporary life support systems, surgical and other therapeutic approaches, and diagnostic methods applied ex vivo to an isolated organ.

RESULTS

For the practical clinical use of ex vivo therapies, we could identify three major directions: (1) ex vivo pretransplant organ reconditioning, (2) ex vivo surgery and (3) ex vivo medical treatment. Different attempts have been made worldwide in the above-mentioned areas focusing on ex vivo organ preservation and treatment. We summarize in the present review the developments in the field of ex vivo organ recovery and evaluate the possibilities of combining and applying different technologies such as organ perfusion and storage, ex vivo exact topographical diagnosis, ex vivo locoregional medical treatment and ex vivo surgical correction.

CONCLUSION

Ex vivo therapies open new horizons in the treatment of end-stage organ pathologies.

Bridge to lung transplantation and rescue post-transplant: the expanding role of extracorporeal membrane oxygenation

Over the last several decades, the growth of lung transplantation has been hindered by a much higher demand for donor lungs than can be supplied, leading to considerable waiting time and mortality among patients waiting for transplant. This has led to the search for an alternative bridging strategy in patients with end-stage lung disease. The use of extracorporeal membrane oxygenation (ECMO) as a bridge to lung transplantation as well as a rescue strategy post-transplant for primary graft dysfunction (PGD) has been studied previously, however due to initially poor outcomes, its use was not heavily instituted. In recent years, with significant improvement in technologies, several single and multi-center studies have shown promising outcomes related to the use of ECMO as a bridging strategy as well as a therapy for patients suffering from PGD post-transplant. These results have challenged our current notion on ECMO use and hence forced us to reexamine the utility, efficacy and safety of ECMO in conjunction with lung transplantation. Through this review, we will address the various aspects related to ECMO use as a bridge to lung transplantation as well as a rescue post-transplant in the treatment of PGD. We will emphasize newer technologies related to ECMO use, examine recent observational studies and randomized trials of ECMO use before and after lung transplantation, and reflect upon our own institutional experience with the use of ECMO in these difficult clinical situations.

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.

Bilateral lung transplantation in a patient with Vascular Ehlers-Danlos syndrome

We describe the case of a 29-year-old woman with end-stage chronic obstructive pulmonary disease secondary to vascular Ehlers-Danlos syndrome. Because of critical deterioration, respiratory arrest, and complete lung failure, she required urgent implantation of a venovenous extracorporeal membrane oxygenator as a bridge to lung transplantation. After 6 days of extracorporeal life support, a successful bilateral sequential lung transplantation was performed. This is the first case of lung transplantation in a patient with a diagnosis of chronic obstructive pulmonary disease secondary to Ehlers-Danlos syndrome.

Prolonged duration ECMO for ARDS: futility, native lung recovery, or transplantation?

Extracorporeal membrane oxygenation (ECMO) is recommended as a treatment modality for severe acute respiratory distress syndrome (PaO2/FiO2 ≤ 100 mm Hg with positive end-expiratory pressure ≥ 5 cm H2O) as defined by the Berlin definition. The reported usual duration of ECMO in these patients is 7-10 days. However, increasing reports of prolonged duration ECMO (>14 days) for respiratory failure document survival rates of 50-70% with native lung recovery, and ECMO bridge to lung transplantation has been performed at many centers. At present, there are no established national criteria for when to consider futility or lung transplantation in adult patients requiring ECMO for acute respiratory failure. We report a case of prolonged duration venovenous-ECMO (1,347 hours, 56.13 days), with native lung recovery and discuss treatment strategies to optimize native lung recovery in ECMO patients. The lung may have unexpected regenerative capacity with native lung recovery after prolonged mechanical support, similar to acute kidney injury and native renal recovery. We recommend redefining irreversible lung injury and futility in ECMO.

Optimal endovascular methods for placement of bicaval dual-lumen cannulae for venovenous extracorporeal membrane oxygenation

Early mobility is associated with improved outcomes in critically ill patients with acute respiratory failure. The Avalon Elite Bicaval Dual-Lumen cannula provides support for extracorporeal membrane oxygenation through a single cannula in the internal jugular position in the neck, avoiding femoral cannulation. This allows the patient to participate in early mobility and strength exercises, facilitating early reconditioning. Placement of the Avalon bicaval cannula poses a potential risk of intracardiac placement and right ventricular rupture as a result of the flexibility of the guidewire. We present our endovascular technique for Avalon bicaval cannula placement with fluoroscopic guidance to prevent inadvertent intracardiac placement.