Development and validation of primary graft dysfunction predictive algorithm for lung transplant candidates

BACKGROUND

Primary graft dysfunction (PGD) is the leading cause of early morbidity and mortality after lung transplantation. Accurate prediction of PGD risk could inform donor approaches and perioperative care planning. We sought to develop a clinically useful, generalizable PGD prediction model to aid in transplant decision-making.

METHODS

We derived a predictive model in a prospective cohort study of subjects from 2012 to 2018, followed by a single-center external validation. We used regularized (lasso) logistic regression to evaluate the predictive ability of clinically available PGD predictors and developed a user interface for clinical application. Using decision curve analysis, we quantified the net benefit of the model across a range of PGD risk thresholds and assessed model calibration and discrimination.

RESULTS

The PGD predictive model included distance from donor hospital to recipient transplant center, recipient age, predicted total lung capacity, lung allocation score (LAS), body mass index, pulmonary artery mean pressure, sex, and indication for transplant; donor age, sex, mechanism of death, and donor smoking status; and interaction terms for LAS and donor distance. The interface allows for real-time assessment of PGD risk for any donor/recipient combination. The model offers decision-making net benefit in the PGD risk range of 10% to 75% in the derivation centers and 2% to 10% in the validation cohort, a range incorporating the incidence in that cohort.

CONCLUSION

We developed a clinically useful PGD predictive algorithm across a range of PGD risk thresholds to support transplant decision-making, posttransplant care, and enrich samples for PGD treatment trials.

Ex vivo lung perfusion in donation after circulatory death: A post hoc analysis of the Normothermic Ex Vivo Lung Perfusion as an Assessment of Extended/Marginal Donors Lungs trial

OBJECTIVE

Donation after circulatory death (DCD) donors offer the ability to expand the lung donor pool and ex vivo lung perfusion (EVLP) further contributes to this ability by allowing for additional evaluation and resuscitation of these extended criteria donors. We sought to determine the outcomes of recipients receiving organs from DCD EVLP donors in a multicenter setting.

METHODS

This was an unplanned post hoc analysis of a multicenter, prospective, nonrandomized trial that took place during 2011 to 2017 with 3 years of follow-up. Patients were placed into 3 groups based off procurement strategy: brain-dead donor (control), brain-dead donor evaluated by EVLP, and DCD donors evaluated by EVLP. The primary outcomes were severe primary graft dysfunction at 72 hours and survival. Secondary outcomes included select perioperative outcomes, and 1-year and 3-years allograft function and quality of life measures.

RESULTS

The DCD EVLP group had significantly higher incidence of severe primary graft dysfunction at 72 hours (P = .03), longer days on mechanical ventilation (P < .001) and in-hospital length of stay (P = .045). Survival at 3 years was 76.5% (95% CI, 69.2%-84.7%) for the control group, 68.3% (95% CI, 58.9%-79.1%) for the brain-dead donor group, and 60.7% (95% CI, 45.1%-81.8%) for the DCD group (P = .36). At 3-year follow-up, presence observed bronchiolitis obliterans syndrome or quality of life metrics did not differ among the groups.

CONCLUSIONS

Although DCD EVLP allografts might not be appropriate to transplant in every candidate recipient, the expansion of their use might afford recipients stagnant on the waitlist a viable therapy.

Percutaneous Venopulmonary Extracorporeal Membrane Oxygenation as Bridge to Lung Transplantation

Mechanical circulatory support (MCS) as a bridge to lung transplant is an infrequent but accepted pathway in patients who have refractory end-stage pulmonary failure. The American Association of Thoracic Surgeons Expert Consensus Guidelines, published in 2023, recommends venovenous (VV) extracorporeal membrane oxygenation (ECMO) as the initial configuration for those patients who have failed conventional medical therapy, including mechanical ventilation, while waiting for lung transplantation and needing MCS. Alternatively, venoarterial (VA) ECMO can be used in patients with acute right ventricular failure, hemodynamic instability, or refractory respiratory failure. With the advancement in percutaneous venopulmonary (VP) ECMO cannulation techniques, this option is becoming an attractive configuration as bridge to lung transplantation. This configuration enhances stability of the right ventricle, prevents recirculation with direct introduction of pulmonary artery oxygenation, and promotes hemodynamic stability during mobility, rehabilitation, and sedation-weaning trials before lung transplantation. Here, we present a case series of eight percutaneous VP ECMO as bridge to lung transplant with all patients mobilized, awake, and successfully transplanted with survival to hospital discharge.

Reevaluating Rehabilitation Practice for Patients Who Were Critically Ill After COVID-19 Infection: An Administrative Case Report

OBJECTIVE

The goal of this case report is to describe the process, challenges, and opportunities of implementing rehabilitation for individuals who were critically ill and required both mechanical ventilation (MV) and extracorporeal membrane oxygenation (ECMO) support following a coronavirus 2019 (COVID-19) infection in an academic medical center.

METHODS

This administrative case report is set in a heart and vascular intensive care unit, a 35-bed critical care unit that provides services for patients with various complex cardiovascular surgical interventions, including transplantation. Patients were admitted to the heart and vascular intensive care unit with either COVID-19 acute respiratory distress syndrome or pulmonary fibrosis for consideration of bilateral orthotropic lung transplantation. The authors describe the process of establishing rehabilitation criteria for patients who, by previously established guidelines, would be considered too ill to engage in rehabilitation.

RESULTS

The rehabilitation team, in coordination with an interprofessional team of critical care providers including physicians, respiratory care providers, perfusionists, and registered nurses, collaborated to implement a rehabilitation program for patients with critical COVID-19 being considered for bilateral orthotropic lung transplantation. This was accomplished by (1) reviewing previously published guidelines and practices; (2) developing an interdisciplinary framework for the consideration of rehabilitation treatment; and (3) implementing the framework for patients in our heart and vascular intensive care unit.

CONCLUSION

In response to the growing volume of patients admitted with critical COVID-19, the team initiated and developed an interprofessional framework and successfully provided rehabilitation services to patients who were critically ill. While resource-intensive, the process demonstrates that rehabilitation can be implemented on a case-by-case basis for select patients receiving extracorporeal membrane oxygenation and MV, who would previously have been considered too critically ill for rehabilitation services.

IMPACT

Rehabilitating patients with end-stage pulmonary disease on extracorporeal membrane oxygenation and MV support is challenging but feasible with appropriate interprofessional collaboration and knowledge sharing.

TGF-βR2 signaling coordinates pulmonary vascular repair after viral injury in mice and human tissue

Disruption of pulmonary vascular homeostasis is a central feature of viral pneumonia, wherein endothelial cell (EC) death and subsequent angiogenic responses are critical determinants of the outcome of severe lung injury. A more granular understanding of the fundamental mechanisms driving reconstitution of lung endothelium is necessary to facilitate therapeutic vascular repair. Here, we demonstrated that TGF-β signaling through TGF-βR2 (transforming growth factor-β receptor 2) is activated in pulmonary ECs upon influenza infection, and mice deficient in endothelial Tgfbr2 exhibited prolonged injury and diminished vascular repair. Loss of endothelial Tgfbr2 prevented autocrine Vegfa (vascular endothelial growth factor α) expression, reduced endothelial proliferation, and impaired renewal of aerocytes thought to be critical for alveolar gas exchange. Angiogenic responses through TGF-βR2 were attributable to leucine-rich α-2-glycoprotein 1, a proangiogenic factor that counterbalances canonical angiostatic TGF-β signaling. Further, we developed a lipid nanoparticle that targets the pulmonary endothelium, Lung-LNP (LuLNP). Delivery of Vegfa mRNA, a critical TGF-βR2 downstream effector, by LuLNPs improved the impaired regeneration phenotype of EC Tgfbr2 deficiency during influenza injury. These studies defined a role for TGF-βR2 in lung endothelial repair and demonstrated efficacy of an efficient and safe endothelial-targeted LNP capable of delivering therapeutic mRNA cargo for vascular repair in influenza infection.

Predicting Acute Brain Injury in Venoarterial Extracorporeal Membrane Oxygenation Patients with Tree-Based Machine Learning: Analysis of the Extracorporeal Life Support Organization Registry

Objective

To determine if machine learning (ML) can predict acute brain injury (ABI) and identify modifiable risk factors for ABI in venoarterial extracorporeal membrane oxygenation (VA-ECMO) patients.

Design

Retrospective cohort study of the Extracorporeal Life Support Organization (ELSO) Registry (2009-2021).

Setting

International, multicenter registry study of 676 ECMO centers.

Patients

Adults (≥18 years) supported with VA-ECMO or extracorporeal cardiopulmonary resuscitation (ECPR).

Interventions

None.

Measurements and Main Results

Our primary outcome was ABI: central nervous system (CNS) ischemia, intracranial hemorrhage (ICH), brain death, and seizures. We utilized Random Forest, CatBoost, LightGBM and XGBoost ML algorithms (10-fold leave-one-out cross-validation) to predict and identify features most important for ABI. We extracted 65 total features: demographics, pre-ECMO/on-ECMO laboratory values, and pre-ECMO/on-ECMO settings.Of 35,855 VA-ECMO (non-ECPR) patients (median age=57.8 years, 66% male), 7.7% (n=2,769) experienced ABI. In VA-ECMO (non-ECPR), the area under the receiver-operator characteristics curves (AUC-ROC) to predict ABI, CNS ischemia, and ICH was 0.67, 0.67, and 0.62, respectively. The true positive, true negative, false positive, false negative, positive, and negative predictive values were 33%, 88%, 12%, 67%, 18%, and 94%, respectively for ABI. Longer ECMO duration, higher 24h ECMO pump flow, and higher on-ECMO PaO2 were associated with ABI.Of 10,775 ECPR patients (median age=57.1 years, 68% male), 16.5% (n=1,787) experienced ABI. The AUC-ROC for ABI, CNS ischemia, and ICH was 0.72, 0.73, and 0.69, respectively. The true positive, true negative, false positive, false negative, positive, and negative predictive values were 61%, 70%, 30%, 39%, 29% and 90%, respectively, for ABI. Longer ECMO duration, younger age, and higher 24h ECMO pump flow were associated with ABI.

Conclusions

This is the largest study predicting neurological complications on sufficiently powered international ECMO cohorts. Longer ECMO duration and higher 24h pump flow were associated with ABI in both non-ECPR and ECPR VA-ECMO.

Lung transplant outcomes after acute respiratory distress syndrome requiring extracorporeal life support: Lessons from the COVID-19 pandemic

OBJECTIVE

Lung transplant for acute respiratory distress syndrome in patients supported with extracorporeal membrane oxygenation was rare before 2020, but was rapidly adopted to rescue patients with COVID-19 with lung failure. This study aims to compare the outcomes of patients who underwent lung transplant for COVID-associated acute respiratory distress syndrome and non-COVID acute respiratory distress syndrome, and to assess the impact of type and duration of extracorporeal membrane oxygenation support on survival.

METHODS

Using the United Network for Organ Sharing database, we identified 311 patients with acute respiratory distress syndrome who underwent lung transplant from 2007 to 2022 and performed a retrospective analysis of the patients who required extracorporeal membrane oxygenation preoperatively, stratified by COVID-associated acute respiratory distress syndrome and non-COVID acute respiratory distress syndrome listing diagnoses. The primary outcome was 1-year survival. Secondary outcomes included the effect of type and duration of extracorporeal membrane oxygenation on survival.

RESULTS

During the study period, 236 patients with acute respiratory distress syndrome and preoperative extracorporeal membrane oxygenation underwent lung transplant; 181 patients had a listing diagnosis of COVID-associated acute respiratory distress syndrome (77%), and 55 patients had a listing diagnosis of non-COVID acute respiratory distress syndrome (23%). Patients with COVID-associated acute respiratory distress syndrome were older, were more likely to be female, had higher body mass index, and spent longer on the waitlist (all P < .02) than patients with non-COVID acute respiratory distress syndrome. The 2 groups had similar 1-year survival (85.8% vs 81.1%, P = .2) with no differences in postoperative complications. Patients with COVID-associated acute respiratory distress syndrome required longer times on extracorporeal membrane oxygenation pretransplant (P = .02), but duration of extracorporeal membrane oxygenation support was not a predictor of 1-year survival (P = .2).

CONCLUSIONS

Despite prolonged periods of pretransplant extracorporeal membrane oxygenation support, selected patients with acute respiratory distress syndrome can undergo lung transplant safely with acceptable short-term outcomes. Appropriate selection criteria and long-term implications require further analysis.

The Impact of Donor Smoking on Primary Graft Dysfunction and Mortality after Lung Transplantation

Rationale: Primary graft dysfunction (PGD) is the leading cause of early morbidity and mortality after lung transplantation. Prior studies implicated proxy-defined donor smoking as a risk factor for PGD and mortality. Objectives: We aimed to more accurately assess the impact of donor smoke exposure on PGD and mortality using quantitative smoke exposure biomarkers. Methods: We performed a multicenter prospective cohort study of lung transplant recipients enrolled in the Lung Transplant Outcomes Group cohort between 2012 and 2018. PGD was defined as grade 3 at 48 or 72 hours after lung reperfusion. Donor smoking was defined using accepted thresholds of urinary biomarkers of nicotine exposure (cotinine) and tobacco-specific nitrosamine (4-[methylnitrosamino]-1-[3-pyridyl]-1-butanol [NNAL]) in addition to clinical history. The donor smoking-PGD association was assessed using logistic regression, and survival analysis was performed using inverse probability of exposure weighting according to smoking category. Measurements and Main Results: Active donor smoking prevalence varied by definition, with 34-43% based on urinary cotinine, 28% by urinary NNAL, and 37% by clinical documentation. The standardized risk of PGD associated with active donor smoking was higher across all definitions, with an absolute risk increase of 11.5% (95% confidence interval [CI], 3.8% to 19.2%) by urinary cotinine, 5.7% (95% CI, -3.4% to 14.9%) by urinary NNAL, and 6.5% (95% CI, -2.8% to 15.8%) defined clinically. Donor smoking was not associated with differential post-lung transplant survival using any definition. Conclusions: Donor smoking associates with a modest increase in PGD risk but not with increased recipient mortality. Use of lungs from smokers is likely safe and may increase lung donor availability. Clinical trial registered with www.clinicaltrials.gov (NCT00552357).

Utilizing Machine Learning to Predict Neurological Injury in Venovenous Extracorporeal Membrane Oxygenation Patients: An Extracorporeal Life Support Organization Registry Analysis

Background

Venovenous extracorporeal membrane oxygenation (VV-ECMO) is associated with acute brain injury (ABI), including central nervous system (CNS) ischemia (defined as ischemic stroke or hypoxic-ischemic brain injury) and intracranial hemorrhage (ICH). There is limited data on prediction models for ABI and neurological outcomes in VV-ECMO.

Research Question

Can machine learning (ML) accurately predict ABI and identify modifiable factors of ABI in VV-ECMO?

Study Design and Methods

We analyzed adult (≥18 years) VV-ECMO patients in the Extracorporeal Life Support Organization Registry (2009-2021) from 676 centers. ABI was defined as CNS ischemia, ICH, brain death, and seizures. Overall, 65 total variables were extracted including clinical characteristics and pre-ECMO and on-ECMO variables. Random Forest, CatBoost, LightGBM, and XGBoost ML algorithms (10-fold leave-one-out cross-validation) were used to predict ABI. Feature Importance Scores were used to pinpoint variables most important for predicting ABI.

Results

Of 37,473 VV-ECMO patients (median age=48.1 years, 63% male), 2,644 (7.1%) experienced ABI: 610 (2%) and 1,591 (4%) experienced CNS ischemia and ICH, respectively. The median ECMO duration was 10 days (interquartile range=5-20 days). The area under the receiver-operating characteristics curves to predict ABI, CNS ischemia, and ICH were 0.67, 0.63, and 0.70, respectively. The accuracy, positive predictive, and negative predictive values for ABI were 79%, 15%, and 95%, respectively. ML identified pre-ECMO cardiac arrest as the most important risk factor for ABI while ECMO duration and bridge to transplantation as an indication for ECMO were associated with lower risk of ABI.

Interpretation

This is the first study to use machine learning to predict ABI in a large cohort of VV-ECMO patients. Performance was sub-optimal due to the low reported prevalence of ABI with lack of standardization of neuromonitoring/imaging protocols and data granularity in the ELSO Registry. Standardized neurological monitoring and imaging protocols may improve machine learning performance to predict ABI.

Interpretable machine learning-based predictive modeling of patient outcomes following cardiac surgery

BACKGROUND

The clinical applicability of machine learning predictions of patient outcomes following cardiac surgery remains unclear. We applied machine learning to predict patient outcomes associated with high morbidity and mortality after cardiac surgery and identified the importance of variables to the derived model's performance.

METHODS

We applied machine learning to the Society of Thoracic Surgeons Adult Cardiac Surgery Database to predict postoperative hemorrhage requiring reoperation, venous thromboembolism (VTE), and stroke. We used permutation feature importance to identify variables important to model performance and a misclassification analysis to study the limitations of the model.

RESULTS

The study dataset included 662,772 subjects who underwent cardiac surgery between 2015 and 2017 and 240 variables. Hemorrhage requiring reoperation, VTE, and stroke occurred in 2.9%, 1.2%, and 2.0% of subjects, respectively. The model performed remarkably well at predicting all 3 complications (area under the receiver operating characteristic curve, 0.92-0.97). Preoperative and intraoperative variables were not important to model performance; instead, performance for the prediction of all 3 outcomes was driven primarily by several postoperative variables, including known risk factors for the complications, such as mechanical ventilation and new onset of postoperative arrhythmias. Many of the postoperative variables important to model performance also increased the risk of subject misclassification, indicating internal validity.

CONCLUSIONS

A machine learning model accurately and reliably predicts patient outcomes following cardiac surgery. Postoperative, as opposed to preoperative or intraoperative variables, are important to model performance. Interventions targeting this period, including minimizing the duration of mechanical ventilation and early treatment of new-onset postoperative arrhythmias, may help lower the risk of these complications.

Infectious complications associated with bronchial anastomotic dehiscence in lung transplant recipients

INTRODUCTION

Bronchial anastomotic dehiscence (AD) is an uncommon complication following lung transplantation that carries significant morbidity and mortality. The objective of this study was to characterize fungal and bacterial infections in ADs, including whether infections following AD were associated with progression to bronchial stenosis.

METHODS

This was a single-center study of 615 lung transplant recipients between 6/1/2015 and 12/31/2021. Airway complications were defined according to ISHLT consensus guidelines.

RESULTS

22 of the 615 recipients (3.6%) developed an AD. Bronchial ischemia or necrosis was common prior to dehiscence (68.1%). Fourteen (63.6%) recipients had bacterial airway infections, most commonly with Gram-negative rods, prior to dehiscence. Thirteen (59.1%) recipients had an associated pleural infection, most commonly with Candida species (30.8%). Post-dehiscence Aspergillus species were isolated in 4 recipients, 3 of which were de novo infections. Eleven had bacterial infections prior to dehiscence resolution, most commonly with Pseudomonas aeruginosa. Eleven recipients developed airway stenosis requiring dilation and/or stenting. Development of secondary infection prior to AD resolution was not associated with progression to stenosis (OR = .41, 95% CI = .05-3.30, p = .41).

CONCLUSIONS

Gram-negative bacterial infections are common before and after AD. Pleural infection should be suspected in most cases. Infections prior to healing were not associated with subsequent development of airway stenosis.

Intracannula Thrombus Formation Associated With Dual Lumen ProtekDuo Cannula in Extracorporeal Membrane Oxygenation (ECMO)

Extracorporeal membrane oxygenation (ECMO) is used in cases of severe respiratory failure refractory to medical management. Use of ECMO is increasing, along with new cannulation strategies including oxygenated right ventricular assist devices (oxy-RVADs). Multiple dual lumen cannulas are now available, which increase the potential for patient mobility and decrease the number of vascular access sites. However, dual lumen, single cannula flow can be limited by adequate inflow, requiring the need for an additional inflow cannula to meet patient demands. This cannula configuration may result in differential flows in the inflow and outflow limbs and altered flow dynamics, increasing the risk of intracannula thrombus. We describe a series of four patients treated with oxy-RVAD for COVID-19-associated respiratory failure complicated by dual lumen ProtekDuo intracannula thrombus.

Rehabilitation Characteristics and Outcomes for Lung Transplantation for COVID-19: A Case Series

OBJECTIVE

Severe coronavirus disease 2019 (COVID-19) can result in irreversible lung damage, with some individuals requiring lung transplantation. The purpose of this case series is to describe the initial experience with the rehabilitation and functional outcomes of 9 patients receiving a lung transplant for COVID-19.

METHODS

Nine individuals, ranging in age from 37 to 68 years, received bilateral orthotopic lung transplantation (BOLT) for COVID-19 between December 2020 and July 2021. Rehabilitation was provided before and after the transplant, including in-hospital rehabilitation, postacute care inpatient rehabilitation, and outpatient rehabilitation.

RESULTS

Progress with mobility was limited in the pretransplant phase despite rehabilitation efforts. Following transplantation, 2 individuals expired before resuming rehabilitation, and 2 others had complications that delayed their progress. The remaining 5 experienced clinically important improvements in mobility and walking capacities.

CONCLUSION

Considerable rehabilitation resources are required to care for individuals both before and after BOLT for COVID-19. Rehabilitation can have a profound impact on both functional and clinical outcomes for this unique patient population.

IMPACT

There is limited literature on the rehabilitation efforts and outcomes for patients who received BOLT for COVID-19. Occupational therapists and physical therapists play an important role during the pretransplant and posttransplant recovery process for this novel patient population.

LAY SUMMARY

Patients with a bilateral orthotopic lung transplant due to COVID-19 require a unique rehabilitation process. They have significant difficulties with activities of daily living and functional mobility across the pretransplant and posttransplant continuum of care, but progressive gains in functional performance may be possible with a comprehensive multidisciplinary rehabilitation program.

Cryoablation in Lung Transplantation: Its Impact on Pain, Opioid Use, and Outcomes

Objective

To assess the effect of intraoperative cryoablation on postoperative patient-reported pain, opioid use, and clinical outcomes in lung transplantation.

Methods

We performed a single-center retrospective cohort study of adult lung transplant recipients from August 2017 to September 2018. We compared outcomes of patients who received intraoperative cryoablation of the intercostal nerves with those who did not. Primary outcomes were postoperative patient-reported pain scores and opioid use. Secondary outcomes included postoperative sedation and agitation levels and perioperative outcomes. Data were abstracted from patients' electronic health records.

Results

Of the 102 patients transplanted, 45 received intraoperative cryoablation (intervention group) and 57 received the standard of care, which did not include intercostal or serratus blocks or immediate postoperative epidural placement (control group). The intervention group had significantly lower median and maximum postoperative pain scores at days 3 and 7 and significantly lower oral opioid use at days 3, 7, and 14 compared with the control group. Chronic opioid use at 3 and 6 months' posttransplant was lower in the intervention group. Differences in perioperative outcomes, including length of mechanical ventilation, sedation and agitation levels, and hospital stay, were not clinically meaningful. Survival at 30 days and 1 year was superior in the intervention compared with the control group.

Conclusions

Findings suggest that use of intraoperative cryoablation is an effective approach for treating pain and reducing opioid use in patients who undergo lung transplant, but a randomized study across multiple institutions is needed to confirm these findings.

ISHLT consensus document on lung transplantation in patients with connective tissue disease: Part II: Cardiac, surgical, perioperative, operative, and post-operative challenges and management statements

Patients with connective tissue disease (CTD) present unique surgical, perioperative, operative, and postoperative challenges related to the often underlying severe pulmonary hypertension and right ventricular dysfunction. The International Society for Heart and Lung Transplantation-supported consensus document on lung transplantation in patients with CTD standardization addresses the surgical challenges and relevant cardiac involvement in the perioperative, operative, and postoperative management in patients with CTD.

Lung Transplantation Outcomes after Crossing Low-Level Donor Specific Antibodies Without Planned Augmented Immunosuppression

It is unknown whether some donor specific antibodies (DSA) can be crossed at the time of lung transplant without desensitization or augmented induction immunosuppression. This study assessed whether crossing low-level pre-transplant DSA (defined as mean fluorescence intensity (MFI) 1000-6000) without augmented immunosuppression is associated with worse retransplant-free or chronic lung allograft dysfunction (CLAD)-free survival. Of the 458 included recipients, low-level pre-transplant DSA was crossed in 39 (8.6%) patients. The median follow-up time was 2.2 years. There were 15 (38.5%) patients with Class I DSA and 24 (61.5%) with Class II DSA. There was no difference in adjusted overall retransplant-free survival between recipients where pre-transplant DSA was and was not crossed (HR: 0.98 (95% CI = 0.49-1.99), p = 0.96). There was also no difference in CLAD-free survival (HR: 0.71 (95% CI = 0.38-1.33), p = 0.28). There was no difference in Grade 3 PGD at 72 hours (OR: 1.13 (95% CI = 0.52-2.48), p = 0.75) or definite or probable AMR (HR: 2.22 (95% CI = 0.64-7.61), p = 0.21). Lung transplantation in the presence of low-level DSA without planned augmented immunosuppression is not associated with worse overall or CLAD-free survival among recipients with intermediate-term follow-up. This article is protected by copyright. All rights reserved.

The Surgeon's Role in Cardiogenic Shock

PURPOSE OF REVIEW

Cardiogenic shock represents a very challenging patient population due to the undifferentiated pathologies presenting as cardiogenic shock, difficult decision-making, prognostication, and ever-expanding support options. The role of cardiac surgeons on this team is evolving.

RECENT FINDINGS

The implementation of a shock team is associated with improved outcomes in patients with cardiogenic shock. Early deployment of mechanical circulatory support devices may allow an opportunity to rescue these patients. Cardiothoracic surgeons are a critical component of the shock team who can deploy timely mechanical support and surgical intervention in selected patients for optimal outcomes.

2020 EACTS/ELSO/STS/AATS Expert Consensus on Post-cardiotomy Extracorporeal Life Support in Adult Patients

Post-cardiotomy extracorporeal life support (PC-ECLS) in adult patients has been used only rarely but recent data have shown a remarkable increase in its use, almost certainly due to improved technology, ease of management, growing familiarity with its capability and decreased costs. Trends in worldwide in-hospital survival, however, rather than improving, have shown a decline in some experiences, likely due to increased use in more complex, critically ill patients rather than to suboptimal management. Nevertheless, PC-ECLS is proving to be a valuable resource for temporary cardiocirculatory and respiratory support in patients who would otherwise most likely die. Because a comprehensive review of PC-ECLS might be of use for the practitioner, and possibly improve patient management in this setting, the authors have attempted to create a concise, comprehensive and relevant analysis of all aspects related to PC-ECLS, with a particular emphasis on indications, technique, management and avoidance of complications, appraisal of new approaches and ethics, education and training.

Severe Impairment of Microcirculatory Perfused Vessel Density Is Associated With Postoperative Lactate and Acute Organ Injury After Cardiac Surgery

OBJECTIVE

Resuscitation after cardiac surgery needs to address multiple pathophysiological processes that are associated with significant morbidity and mortality. Functional microcirculatory derangements despite normal systemic hemodynamics have been previously described but must be tied to clinical outcomes. The authors hypothesized that microcirculatory dysfunction after cardiac surgery would include impaired capillary blood flow and impaired diffusive capacity and that subjects with the lowest quartile of perfused vessel density would have an increased postoperative lactate level and acute organ injury scores.

DESIGN

Prospective, observational study.

SETTING

A single, tertiary university cardiovascular surgical intensive care unit.

PARTICIPANTS

25 adults undergoing elective cardiac surgery requiring cardiopulmonary bypass.

INTERVENTION

Sublingual microcirculation was imaged using incident dark field microscopy before and 2 to 4 hours after surgery in the intensive care unit.

MEASUREMENTS AND MAIN RESULTS

Compared with baseline measurements, postoperative vessel-by-vessel microvascular flow index (2.9 [2.8-2.9] v 2.5 [2.4-2.7], p < 0.0001) and perfused vessel density were significantly impaired (20.7 [19.3-22.9] v 16.3 [12.8-17.9], p < 0.0001). The lowest quartile of perfused vessel density (<12.8 mm/mm2) was associated with a significantly increased postoperative lactate level (6.0 ± 2.9 v 1.8 ± 1.2, p < 0.05), peak lactate level (7.6 ± 2.8 v 2.8 ± 1.5, p = 0.03), and sequential organ failure assessment (SOFA) score at 24 and 48 hours.

CONCLUSION

In patients undergoing cardiac surgery, there was a significant decrease in postoperative microcirculatory convective blood flow and diffusive capacity during early postoperative resuscitation. Severely impaired perfused vessel density, represented by the lowest quartile of distribution, is significantly related to hyperlactatemia and early organ injury.

Toward a Standard Practice to Quantify von Willebrand Factor Degradation During Left Ventricular Assist Device Support

BACKGROUND

Continuous-flow left ventricular assist devices (LVADs) cause degradation of von Willebrand factor (VWF) multimers and bleeding. Multiple techniques exist to characterize VWF deficiency. However, a standard methodology has not been established in LVAD patients. Toward this goal, we evaluated 4 methods to quantify VWF multimers.

METHODS

We collected paired blood samples from patients (n = 48) before and after 1 week of LVAD support. After 652 ± 59 days of support, patients were classified as bleeders (≥1 bleeding episode) or nonbleeders. VWF multimers were resolved with electrophoresis and immunoblotting, the gold-standard to evaluate VWF multimers. We evaluated 4 quantification methods.

RESULTS

Each method demonstrated significant VWF degradation during LVAD support vs a paired, pre-LVAD sample (method 1, VWF length: 48 of 48 patients, -10% ± 1%, P < .0001; method 2, VWF density: 40 of 48, -34% (interquartile range, -46% to -8%), P < .0001; method 3, pre-LVAD to LVAD ratio: 46 of 48, 17 ± 5: 10 ± 1, P < .0001; method 4, LVAD/pre-LVAD index: 46 of 48, 57% (interquartile range, 50% to 73%), P < .0001). Bleeding occurred in 27 of 48 patients. Method 1 demonstrated significantly fewer VWF multimers in bleeders compared with nonbleeders (-11% ± 1% vs -8% ± 1%; P = .01). Other methods did not demonstrate this potentially important clinical relationship.

CONCLUSIONS

A standardized methodology is needed to quantify VWF multimer degradation with mechanical circulatory support devices. Novel method 1 successfully quantified the patient-specific change in VWF multimer length during LVAD support and demonstrated a difference in VWF multimers between bleeders and nonbleeders. Adoption of consensus methodology will assist to standardize patient-specific bleeding risk, inform anticoagulation and antiplatelet therapy, and evaluate LVAD hemocompatibility.

2020 EACTS/ELSO/STS/AATS expert consensus on post-cardiotomy extracorporeal life support in adult patients

Post-cardiotomy extracorporeal life support (PC-ECLS) in adult patients has been used only rarely but recent data have shown a remarkable increase in its use, almost certainly due to improved technology, ease of management, growing familiarity with its capability and decreased costs. Trends in worldwide in-hospital survival, however, rather than improving, have shown a decline in some experiences, likely due to increased use in more complex, critically ill patients rather than to suboptimal management. Nevertheless, PC-ECLS is proving to be a valuable resource for temporary cardiocirculatory and respiratory support in patients who would otherwise most likely die. Because a comprehensive review of PC-ECLS might be of use for the practitioner, and possibly improve patient management in this setting, the authors have attempted to create a concise, comprehensive and relevant analysis of all aspects related to PC-ECLS, with a particular emphasis on indications, technique, management and avoidance of complications, appraisal of new approaches and ethics, education and training.

2020 EACTS/ELSO/STS/AATS Expert Consensus on Post-Cardiotomy Extracorporeal Life Support in Adult Patients

Post-cardiotomy extracorporeal life support (PC-ECLS) in adult patients has been used only rarely but recent data have shown a remarkable increase in its use, almost certainly due to improved technology, ease of management, growing familiarity with its capability and decreased costs. Trends in worldwide in-hospital survival, however, rather than improving, have shown a decline in some experiences, likely due to increased use in more complex, critically ill patients rather than to suboptimal management. Nevertheless, PC-ECLS is proving to be a valuable resource for temporary cardiocirculatory and respiratory support in patients who would otherwise most likely die. Because a comprehensive review of PC-ECLS might be of use for the practitioner, and possibly improve patient management in this setting, the authors have attempted to create a concise, comprehensive and relevant analysis of all aspects related to PC-ECLS, with a particular emphasis on indications, technique, management and avoidance of complications, appraisal of new approaches and ethics, education and training.

Coronary Artery Bypass Grafting in Cardiogenic Shock: Decision-Making, Management Options, and Outcomes

Coronary artery bypass grafting is a highly efficacious mode of myocardial revascularization that reduces mortality from ischemic heart disease. The patient presenting after acute myocardial infarction in cardiogenic shock presents a unique challenge. Early revascularization is proven to reduce mortality, but many questions remain, including the optimal mode and extent of revascularization, the role of mechanical circulatory support, and which patients are candidates for surgical intervention. Unprecedented attention to the outcomes of cardiac surgery means decisions about the management of the acute myocardial infarction in cardiogenic shock patients are influenced by risk aversion. The authors here review this topic to arm the reader with a comprehensive understanding of the literature to better guide surgical decision-making and perioperative management.

Clinical and procedural characteristics predicting need for chronotropic support and permanent pacing post-heart transplantation

BACKGROUND

Postoperative bradycardia can complicate orthotopic heart transplantation (OHT). Previous studies suggested donor age and surgical technique as possible risk factors. However, risk factors in the era of bicaval anastomosis have not been elucidated.

OBJECTIVE

We sought to examine the association between donor/recipient characteristics with need for chronotropic support and permanent pacemaker (PPM) implantation in patients with OHT.

METHODS

All patients treated with OHT between January 2003 and January 2018 at the Hospital of the University of Pennsylvania were retrospectively evaluated until June 2018. Chronotropic support was given upon postoperative inability to increase the heart rate to patient's demands and included disproportionate bradycardia and junctional rhythm.

RESULTS

A total of 820 patients (mean age 51.3 ± 12.6 years; 607, 74% men) underwent 826 OHT procedures (787 patients, 95.3% bicaval anastomosis). Patients who were exposed to amiodarone (odds ratio [OR] 2.30; 95% confidence interval [CI] 1.58-3.34; P < .001) and have older donor (OR 1.02; 95% CI 1.01-1.04; P = .001) were more likely to develop need for chronotropic support. In multivariable analysis, recipient age (OR 1.03; 95% CI 1.00-1.06; P = .04) and biatrial anastomosis (OR 6.12; 95% CI 2.48-15.09) were significantly associated with PPM implantation within 6 months of OHT. No association was found between pre-OHT amiodarone use and PPM implantation. No risk factors assessed were associated with PPM implantation 6 months post-OHT.

CONCLUSION

Surgical technique and donor age were the main risk factors for the need for chronotropic support post-OHT, whereas surgical technique and recipient age were risk factors for early PPM implantation.

Structured review of post-cardiotomy extracorporeal membrane oxygenation: part 1-Adult patients

Cardiogenic shock, cardiac arrest, acute respiratory failure, or a combination of such events, are all potential complications after cardiac surgery which lead to high mortality. Use of extracorporeal temporary cardio-circulatory and respiratory support for progressive clinical deterioration can facilitate bridging the patient to recovery or to more durable support. Over the last decade, extracorporeal membrane oxygenation (ECMO) has emerged as the preferred temporary artificial support system in such circumstances. Many factors have contributed to widespread ECMO use, including the relative ease of implantation, effectiveness, versatility, low cost relative to alternative devices, and potential for full, not just partial circulatory support. While there have been numerous publications detailing the short and midterm outcomes of ECMO support, specific reports about post-cardiotomy ECMO (PC-ECMO), are limited, single-center experiences. Etiology of cardiorespiratory failure leading to ECMO implantation, associated ECMO complications, and overall patient outcomes may be unique to the PC-ECMO population. Despite the rise in PC-ECMO use over the past decade, short-term survival has not improved. This report, therefore, aims to present a comprehensive overview of the literature with respect to the prevalence of ECMO use, patient characteristics, ECMO management, and in-hospital and early post-discharge patient outcomes for those treated for post-cardiotomy heart, lung, or heart-lung failure.

Discharge frailty following lung transplantation

INTRODUCTION

Frailty at listing for lung transplant has been associated with waitlist and post-transplant mortality. Frailty trajectories following transplant, however, have been less well characterized, including whether recipient frailty improves. The objective of this study was to identify prevalence and risk factors for frailty at discharge and to evaluate changes in frail recipients enrolled in an outpatient physical therapy program.

METHODS

This was a single-center prospective cohort study of lung transplant recipients. Enrollees completed a short physical performance battery (SPPB) to assess frailty at listing and at initial hospital discharge.

RESULTS

Of the 111 enrolled recipients, none were frail at listing and 18 (16.2%) were prefrail. At discharge, however, 60 (54.1%) patients were frail. Discharge frailty was associated with prefrailty at listing, acute kidney injury post-transplant, and longer intensive care unit stay. Among the 35 patients who were frail at discharge and who were enrolled in an outpatient PT program, the median improvement in SPPB was 6 points (IQR = 5-7 points), and 85.7% became not frail over a median of 6 weeks.

CONCLUSION

Discharge frailty is common following lung transplantation. In most frail patients, an intensive outpatient physical therapy program is associated with improvement in frailty, as assessed by the SPPB.

Structured review of post-cardiotomy extracorporeal membrane oxygenation: Part 2-pediatric patients

Veno-arterial extracorporeal membrane oxygenation (ECMO) is established therapy for short-term circulatory support for children with life-treating cardiorespiratory dysfunction. In children with congenital heart disease (CHD), ECMO is commonly used to support patients with post-cardiotomy shock or complications including intractable arrhythmias, cardiac arrest, and acute respiratory failure. Cannulation configurations include central, when the right atrium and aorta are utilized in patients with recent sternotomy, or peripheral, when cannulation of the neck or femoral vessels are used in non-operative patients. ECMO can be used to support any form of cardiac disease, including univentricular palliated circulation. Although veno-arterial ECMO is commonly used to support children with CHD, veno-venous ECMO has been used in selected patients with hypoxemia or ventilatory failure in the presence of good cardiac function. ECMO use and outcomes in the CHD population are mainly informed by single-center studies and reports from collated registry data. Significant knowledge gaps remain, including optimal patient selection, timing of ECMO deployment, duration of support, anti-coagulation, complications, and the impact of these factors on short- and long-term outcomes. This report, therefore, aims to present a comprehensive overview of the available literature informing patient selection, ECMO management, and in-hospital and early post-discharge outcomes in pediatric patients treated with ECMO for post-cardiotomy cardiorespiratory failure.

Predictors and influence of goal orientation on self-management and health-related quality of life after lung transplant

Context-Lung transplant recipients are encouraged to perform self-management behaviors to maximize health outcomes; however, performance is often less than ideal. Goal orientation is known to influence achievement of academic goals, but the influence of goal orientation on performance of self-management is unknown. Objectives-To identify characteristics at transplant that are predictive of higher goal orientation and examine relationships between Goal Orientation Index (GOI) subscores (Acting, Planning, Reflecting), self-management behaviors (adhering, self-monitoring, and communicating critical changes), and health-related quality of life (HRQOL) at 1 year after transplant. Design-A descriptive, secondary analysis of data from 33 lung transplant recipients who were assessed at transplant and followed for 1 year as part of a clinical trial. GOI subscores were dichotomized at the median to categorize recipients with high and low goal orientation. Logistic regression was used to identify predictors of higher GOI subscores. Correlations between higher GOI subscores, self-management, and HRQOL were examined. Results-Lung transplant recipients reported relatively high mean GOI subscores (Acting, Planning, and Reflecting) and the 3 subscores were correlated (r=0.31-0.86). Self-care agency was the only significant predictor (P=.04) of higher GOI (Reflecting). Lung transplant recipients with higher Planning and Reflecting subscores were more likely to adhere (r = 0.36 and 0.46, respectively). Recipients with higher GOI subscores reported significantly better mental HRQOL (r = 0.42-0.36). Recipients with higher GOI Planning or Acting subscores reported significantly less anxiety (r = -0.39-0.46) and fewer depressive symptoms (r = -0.40-0.43). Conclusion-Assessing goal orientation may offer a novel approach for promoting adherence and HRQOL after lung transplant.

Is there a difference in bleeding after left ventricular assist device implant: centrifugal versus axial?

BACKGROUND

Continuous-flow left ventricular assist devices (CF-LVAD) have become the standard of care for patients with end stage heart failure. Device reliability has increased, bringing the potential for VAD, compared to transplant, into debate. However, complications continue to limit VADs as first line therapy. Bleeding is a major morbidity. A debate exists as to the difference in bleeding profile between the major centrifugal and axial flow devices. We hypothesized that there would be similar adverse bleeding event profiles between the 2 major CF-LVADs.

METHODS

We retrospectively investigated isolated CF LVADs performed at our institution between July 2010 and July 2015: HeartMateII (HMII, n = 105) and HeartWare (HVAD, n = 34). We reviewed demographic, perioperative and short- and long-term outcomes.

RESULTS

There was no significant difference in demographics or comorbidities. There was a low incidence of gastrointestinal (GI) bleed 3.9% in HMII and 2.9% in HVAD (p = 0.78). Preoperatively, the cohorts did not differ in coagulation measures (p = 0.95). Within the post-operative period, there was no difference in product transfusion: red blood cells (p = 0.10), fresh frozen plasma (p = 0.19), and platelets (p = 0.89). Post-operatively, a higher but not significantly different number of HMII patients returned to the operating room for bleeding (n = 27) compared to HVAD (n = 6, p = 0.35). There was no difference in rates of stroke (p = 0.65), re-intubation (p = 0.60), driveline infection (p = 0.05), and GI bleeding (p = 0.31). The patients had equivalent ICU LOS (p = 0.86) and index hospitalization LOS (p = 0.59).

CONCLUSION

We found no difference in the rate of bleeding complications between the current commercially available axial and centrifugal flow devices.

ISHLT Consensus Statement on adult and pediatric airway complications after lung transplantation: Definitions, grading system, and therapeutics

Airway complications remain a major cause of morbidity and mortality after cardiothoracic transplantation. The reported incidence of airway ischemic complications varies widely, contributed to by the lack of a universally accepted grading system and standardized definitions. Furthermore, the majority of the existing classification systems fail to integrate the wide range of possible bronchial complications that may develop after lung transplant. Hence, a Working Group was created by the International Society for Heart and Lung Transplantation with the aim of elaborating a universal definition of adult and pediatric airway complications and grading system. One such area of focus is to understand the problem in the context of a more standardized consensus of classifying airway ischemia. This consensus definition will have major clinical, therapeutics, and research implications.

Incidence, risk factors, and clinical implications of post-operative delirium in lung transplant recipients

BACKGROUND

Delirium significantly affects post-operative outcomes, but the incidence, risk factors, and long-term impact of delirium in lung transplant recipients have not been well studied.

METHODS

We analyzed 155 lung transplant recipients enrolled in the Lung Transplant Outcomes Group (LTOG) cohort at a single center. We determined delirium incidence by structured chart review, identified risk factors for delirium, determined whether plasma concentrations of 2 cerebral injury markers (neuron-specific enolase [NSE] and glial fibrillary acidic protein [GFAP]) were associated with delirium, and determined the association of post-operative delirium with 1-year survival.

RESULTS

Fifty-seven (36.8%) patients developed post-operative delirium. Independent risk factors for delirium included pre-transplant benzodiazepine prescription (relative risk [RR] 1.82; 95% confidence interval [CI] 1.08 to 3.07; p = 0.025), total ischemic time (RR 1.10 per 30-minute increase; 95% CI 1.01 to 1.21; p = 0.027), duration of time with intra-operative mean arterial pressure <60 mm Hg (RR 1.07 per 15-minute increase; 95% CI 1.00 to 1.14; p = 0.041), and Grade 3 primary graft dysfunction (RR 2.13; 95% CI 1.27 to 3.58; p = 0.004). Ninety-one (58.7%) patients had plasma available at 24 hours. Plasma GFAP was inconsistently detected, whereas NSE was universally detectable, with higher NSE concentrations associated with delirium (risk difference 15.1% comparing 75th and 25th percentiles; 95% CI 2.5 to 27.7; p = 0.026). One-year mortality appeared higher among delirious patients, 12.3% compared with 7.1%, but the difference was not significant (p = 0.28).

CONCLUSIONS

Post-operative delirium is common in lung transplant recipients, and several potentially modifiable risk factors deserve further study to determine their associated mechanisms and predictive values.

Extracorporeal life support in preoperative and postoperative heart transplant management

Increased experience with extracorporeal life support (ECLS) as a mode of cardiac support has expanded its use to diverse patient populations including patients requiring a bridge to heart transplantation and patients requiring posttransplant support for primary graft dysfunction (PGD). The use of ECLS is associated with acceptable outcomes in well-selected patients. While outcomes with the use of extracorporeal membrane oxygenation (ECMO) as a bridge to heart transplant have been variable, several series have confirmed the safe use of ECLS to stabilize patients prior to left ventricular assist device (LVAD) implantation. These patients are then considered later, when in stable condition, for heart transplant. When ECLS is used prior to heart transplant, mortality is greatest during the first 6 months posttransplant. Patients who are alive 6 months after transplant appear to have similar survival rates as patients who were not supported with ECLS prior to transplant. ECLS support is a reliable therapeutic option for severe PGD and early graft failure after heart transplantation. In patients who require support for severe PGD, venoarterial-ECMO appears to result in better clinical outcomes than LVAD support. ECLS use for PGD after heart transplant continues to be the first line of support. Further studies are necessary to understand the optimal role of ECLS in heart transplantation.

Continuous-Flow LVAD Support Causes a Distinct Form of Intestinal Angiodysplasia

Rationale:

The objective of this autopsy study was to determine whether gastrointestinal angiodysplasia develops during continuous-flow left ventricular assist device (LVAD) support.

Objective:

LVAD support causes pathologic degradation of von Willebrand factor (vWF) and bleeding from gastrointestinal angiodysplasia at an alarming rate. It has been speculated that LVAD support itself may cause angiodysplasia. The relationship to abnormal vWF metabolism is unknown. We tested the hypothesis that abnormal gastrointestinal vascularity develops during continuous-flow LVAD support.

Methods and Results:

Small bowel was obtained from deceased humans, cows, and sheep supported with a continuous-flow LVAD (n=9 LVAD, n=11 control). Transmural sections of jejunum were stained with fluorescein isothiocyanate–conjugated isolectin-B4 for endothelium to demarcate vascular structures and quantify intestinal vascularity. Paired plasma samples were obtained from humans before LVAD implantation and during LVAD support (n=41). vWF multimers and degradation fragments were quantified with agarose and polyacrylamide gel electrophoresis and immunoblotting. Abnormal vascular architecture was observed in the submucosa of the jejunum of human patients, cows, and sheep supported with a continuous-flow LVAD. Intestinal vascularity was significantly higher after LVAD support versus controls (5.2±1.0% versus 2.1±0.4%, P =0.004). LVAD support caused significant degradation of high–molecular-weight vWF multimers (–9±1%, P <0.0001) and accumulation of low–molecular-weight vWF multimers (+40±5%, P <0.0001) and vWF degradation fragments (+53±6%, P <0.0001).

Conclusions:

Abnormal intestinal vascular architecture and LVAD-associated vWF degradation were consistent findings in multiple species supported with a continuous-flow LVAD. These are the first direct evidence that LVAD support causes gastrointestinal angiodysplasia. Pathologic vWF metabolism may be a mechanistic link between LVAD support, abnormal angiogenesis, gastrointestinal angiodysplasia, and bleeding.

Cardiopulmonary Resuscitation in Adults and Children With Mechanical Circulatory Support: A Scientific Statement From the American Heart Association

Cardiac arrest in patients on mechanical support is a new phenomenon brought about by the increased use of this therapy in patients with end-stage heart failure. This American Heart Association scientific statement highlights the recognition and treatment of cardiovascular collapse or cardiopulmonary arrest in an adult or pediatric patient who has a ventricular assist device or total artificial heart. Specific, expert consensus recommendations are provided for the role of external chest compressions in such patients.