Ultra-Low-Field Portable MRI and Extracorporeal Membrane Oxygenation: Preclinical Safety Testing.

CONTEXT: Conventional MRI is incompatible with extracorporeal membrane oxygenation (ECMO) cannulas and pumps. Ultra-low-field portable MRI (ULF-pMRI) with 0.064 Tesla may provide a solution, but its safety and compatibility is unknown. HYPOTHESIS: ULF-pMRI does not cause significant displacement and heating of ECMO cannulas and does not affect ECMO pump function. METHODS AND MODELS: ECMO cannulas in various sizes were tested ex vivo using phantom models to assess displacement force and heating according to the American Society for Testing and Materials criteria. ECMO pump function was assessed by pump flow and power consumption. In vivo studies involved five female domestic pigs (20-42 kg) undergoing different ECMO configurations (peripheral and central cannulation) and types of cannulas with an imaging protocol consisting of T2-weighted, T1-weighted, FLuid-Attenuated Inversion Recovery, and diffusion-weighted imaging sequences. RESULTS: Phantom models demonstrated that ECMO cannulas, both single lumen with various sizes (15-24-Fr) and double lumen cannula, had average displacement force less than gravitational force within 5 gauss safety line of ULF-pMRI and temperature changes less than 1°C over 15 minutes of scanning and ECMO pump maintained stable flow and power consumption immediately outside of the 5 gauss line. All pig models showed no visible motion due to displacement force or heating of the cannulas. ECMO flow and the animals' hemodynamic status maintained stability, with no changes greater than 10%, respectively. INTERPRETATION AND CONCLUSIONS: ULF-pMRI is safe and feasible for use with standard ECMO configurations, supporting its clinical application as a neuroimaging modality in ECMO patients.

Sex-Related Differences in Utilization and Outcomes of Extracorporeal Cardio-Pulmonary Resuscitation for Refractory Cardiac Arrest.

Sparse data exist on sex-related differences in extracorporeal cardiopulmonary resuscitation (ECPR) for refractory cardiac arrest (rCA). We explored the role of sex on the utilization and outcomes of ECPR for rCA by retrospective analysis of the Extracorporeal Life Support Organization (ELSO) International Registry. The primary outcome was in-hospital mortality. Exploratory outcomes were discharge disposition and occurrence of any specific extracorporeal membrane oxygenation (ECMO) complications. From 1992 to 2020, a total of 7,460 adults with ECPR were identified: 30.5% women; 69.5% men; 55.9% Whites, 23.7% Asians, 8.9% Blacks, and 3.8% Hispanics. Women's age was 50.4 ± 16.9 years (mean ± standard deviation) and men's 54.7 ± 14.1 ( p < 0.001). Ischemic heart disease occurred in 14.6% women vs. 18.5% men ( p < 0.001). Overall, 28.5% survived at discharge, 30% women vs. 27.8% men ( p = 0.138). In the adjusted analysis, sex was not associated with in-hospital mortality (odds ratio [OR] = 0.93 [confidence interval {CI} = 0.80-1.08]; p = 0.374). Female sex was associated with decreased odds of neurologic, cardiovascular, and renal complications. Despite being younger and having fewer complications during ECMO, women had in-hospital mortality similar to men. Whether these findings are driven by biologic factors or disparities in health care warrants further investigation.

Racial disparities among patients on venovenous extracorporeal membrane oxygenation in the pre-Coronavirus Disease 2019 and Coronavirus Disease 2019 eras: A retrospective registry review.

Objectives: Although many studies have addressed such disparities caused by COVID-19, to our knowledge, no study has focused on the association of race on outcomes for patients with COVID-19 requiring venovenous extracorporeal membrane oxygenation support. The goal of this study was to assess association of race on death and duration on venovenous extracorporeal membrane oxygenation in both the pre-COVID-19 and COVID-19 eras. Methods: We retrospectively reviewed the Extracorporeal Life Support Organization registry and included adults (≥18 years) who required venovenous extracorporeal membrane oxygenation between January 2019 and April 2021. We performed descriptive statistics and multivariable logistic regression. Our primary outcomes were death and extracorporeal membrane oxygenation duration. Results: A total of 7477 patients were included after excluding 340 patients (4.3%) who were missing race data. In the COVID-19 era, 1474 of 2777 COVID-19-positive patients (53.1%) died. Our regression model suggested somewhat of a protective effect on death for Black and multiple race patients. Additionally, a diagnosis of COVID-19 and patients in the COVID-19 era in general, irrespective of COVID-19 diagnosis, had higher odds of death. Hispanic patients had the longest average venovenous extracorporeal membrane oxygenation run times. Conclusions: Our study using data from the international Extracorporeal Life Support Organization Registry provides updated data on patients supported with venovenous extracorporeal membrane oxygenation in the pre-COVID-19 and COVID-19 eras between 2019 and 2021 with a focus on race. Patients in the COVID-19 era group also had higher mortality compared with those in the pre-COVID-19 era even after being adjusted for COVID-19 diagnosis. Black and multiple races appeared somewhat protective in terms of death. Hispanic race was associated with longer venovenous extracorporeal membrane oxygenation duration.

Neuromonitoring detects brain injury in patients receiving extracorporeal membrane oxygenation support.

OBJECTIVE: There is limited evidence on standardized protocols for optimal neurological monitoring methods in patients receiving extracorporeal membrane oxygenation (ECMO). We previously introduced protocolized noninvasive multimodal neuromonitoring using serial neurological examinations, electroencephalography, transcranial Doppler ultrasound, and somatosensory evoked potentials. The purpose of this study was to examine if standardized neuromonitoring is associated with detection of acute brain injury (ABI) and improved patient outcomes. METHODS: A retrospective analysis of ECMO patients who received neurocritical care consultation was performed and outcomes were reviewed. The cohort was stratified according to those who did not receive standardized neuromonitoring (era 1: 2016-2017) and those who received standardized neuromonitoring (era 2: 2017-2020). Multivariable logistic regression was used to evaluate the association between standardized neuromonitoring and ABI. RESULTS: A total of 215 patients (mean age, 54 years; 60% male) underwent ECMO (71% venoarterial-ECMO) in our institution, 70 in era 1 and 145 in era 2. The proportion of patients diagnosed with ABI were 23% in era 1 and 33% in era 2 (P = .12). In multivariable logistic regression, standardized neuromonitoring (odds ratio, 2.24; 95% CI, 1.12-4.48; P = .02) and pre-ECMO cardiac arrest (odds ratio, 2.17; 95% CI, 1.14-4.14; P = .02) were independently associated with ABI. There was a greater proportion of patients with good neurological outcomes when discharged alive in era 2 (54% vs 30%; P = .04). CONCLUSIONS: Standardized neuromonitoring was associated with increased ABIs in ECMO patients. Although neuromonitoring does not prevent ABI from occurring, it might prevent worsening with timely interventions (eg, anticoagulation management, optimizing oxygen delivery and blood pressure), leading to improved neurological outcomes at discharge.

Pre-operative Machine Learning for Heart Transplant Patients Bridged with Temporary Mechanical Circulatory Support.

Background: Existing prediction models for post-transplant mortality in patients bridged to heart transplantation with temporary mechanical circulatory support (tMCS) perform poorly. A more reliable model would allow clinicians to provide better pre-operative risk assessment and develop more targeted therapies for high-risk patients. Methods: We identified adult patients in the United Network for Organ Sharing database undergoing isolated heart transplantation between 01/2009 and 12/2017 who were supported with tMCS at the time of transplant. We constructed a machine learning model using extreme gradient boosting (XGBoost) with a 70:30 train:test split to predict 1-year post-operative mortality. All pre-transplant variables available in the UNOS database were included to train the model. Shapley Additive Explanations was used to identify and interpret the most important features for XGBoost predictions. Results: A total of 1584 patients were included, with a median age of 56 (interquartile range: 46-62) and 74% male. Actual 1-year mortality was 12.1%. Out of 498 available variables, 43 were selected for the final model. The area under the receiver operator characteristics curve (AUC) for the XGBoost model was 0.71 (95% CI: 0.62-0.78). The most important variables predictive of 1-year mortality included recipient functional status, age, pulmonary capillary wedge pressure (PCWP), cardiac output, ECMO usage, and serum creatinine. Conclusions: An interpretable machine learning model trained on a large clinical database demonstrated good performance in predicting 1-year mortality for patients bridged to heart transplantation with tMCS. Machine learning may be used to enhance clinician judgement in the care of markedly high-risk transplant recipients.

Early withdrawal of life sustaining therapy in extracorporeal cardiopulmonary resuscitation (ECPR): Results from the Extracorporeal Life Support Organization registry.

AIMS: Although extracorporeal cardiopulmonary resuscitation (ECPR) improves survival outcomes in refractory cardiac arrest, morbidity and mortality remain significantly high. Information on causes of death in ECPR is limited; however, some evidence suggests withdrawal of life sustaining therapy (WLST) is a major factor in ECPR-associated mortality. We sought to describe the patients experiencing WLST after ECPR. METHODS: The international Extracorporeal Life Support Organization (ELSO) Registry was retrospectively queried for patients more than 18 years old supported with ECPR who underwent WLST due to family request from 2007 to 2017. These patients were split into groups for descriptive and multivariable analysis: early (WLST < 72 hours from cannulation) and routine WLST. RESULTS: Overall, 411 ECPR patients experienced WLST (median age 42 years IQR = 28-51; 31.7% female) over the 10-year period. 55.5% (n = 228) underwent early WLST with a median ECPR duration of 24 hours (IQR = 7-48) versus routine WLST (median = 147 hours; IQR = 105-238). In multivariable regression analysis, lower arterial blood gas pH (aOR = -3.1; 95% CI = 2.18-2.8; p = 0.04), arterial oxygen saturation (aOR = 1.12; 95% CI = 1.01-1.23; p = 0.02), and higher peak inspiratory pressure (aOR = 0.84; 95% CI = 0.71-1.00; p = 0.05) were independently associated with early WLST. Early WLST patients experienced higher rates of all ECMO-related complications except for infections. CONCLUSIONS: More than half of ECPR patients experienced early WLST within 72 hours. The patients with early WLST had worse markers of severe critical illness at 24 hours and experienced higher rates of complications. Further research should include an appropriate control group to better adjust confounders for ECPR-associated death and focus on prognostication.

Temporary Mechanical Circulatory Support for Transcatheter Aortic Valve Replacement.

INTRODUCTION: This study aimed to characterize the use of temporary mechanical circulatory support (tMCS) among patients undergoing transcatheter aortic valve replacement (TAVR) using a nationally representative database. MATERIALS AND METHODS: The 2012-2018 National Inpatient Sample was queried for adult patients who underwent isolated TAVR. The tMCS group was comprised of those who required extracorporeal membrane oxygenation, percutaneous ventricular assist device, or intra-aortic balloon pump during index hospitalization. We evaluated temporal trends in the utilization of tMCS using Cuzick's test. Furthermore, a multivariable logistic regression was used to identify factors associated with tMCS use and its impact on in-hospital mortality, selected complications, and nonhome discharge. RESULTS: Of an estimated 215,925 patients who underwent TAVR, 3085 (1.4%) required tMCS during their hospital course. The most common modality of tMCS was intra-aortic balloon pump (49%), followed by extracorporeal membrane oxygenation (27%) then percutaneous ventricular assist device (18%). Seven percent of tMCS patients were supported by > 1 device. The annual incidence of tMCS usage decreased over the study period, from 3% in 2012 to 1% in 2018 (P-trend < 0.01). Nonelective admission, congestive heart failure, coagulopathy, and liver disease were strong independent predictors of requiring tMCS. Patients requiring tMCS had a 31.8% in-hospital mortality rate (adjusted odds ratio = 23, 95% confidence interval 18.5-28.5), longer length of stay (9 d versus 3, P < 0.001), and higher costs ($84,600 versus $48,100, P < 0.001) than those who did not. CONCLUSIONS: The use of tMCS during TAVR has decreased over time but remains associated with a 23-fold increased mortality rate and significant clinical and resource utilization burden.

Arterial Carbon Dioxide and Acute Brain Injury in Venoarterial Extracorporeal Membrane Oxygenation.

Acute brain injury (ABI) occurs frequently in patients receiving venoarterial extracorporeal membrane oxygenation (VA-ECMO). We examined the association between peri-cannulation arterial carbon dioxide tension (PaCO 2 ) and ABI with granular blood gas data. We retrospectively analyzed adult patients who underwent VA-ECMO at a tertiary care center with standardized neuromonitoring. Pre- and post-cannulation PaCO 2 were defined as the mean of all PaCO 2 values in the 12 hours before and after cannulation, respectively. Peri-cannulation PaCO 2 drop (∆PaCO 2 ) equaled pre- minus post-cannulation PaCO 2 . ABI included intracranial hemorrhage (ICH), ischemic stroke, hypoxic-ischemic brain injury, cerebral edema, seizure, and brain death. Univariable logistic regression analysis was performed for the presence of ABI. Out of 129 VA-ECMO patients (median age = 60, 63% male), 43 (33%) patients experienced ABI. Patients had a median of 11 (interquartile range: 8-14) peri-cannulation PaCO 2 values. Comparing patients with and without ABI, pre-cannulation (39 vs. 42 mm Hg; p = 0.38) and post-cannulation (37 vs. 36 mm Hg; p = 0.82) PaCO 2 were not different. However, higher pre-cannulation PaCO 2 (odds ratio [OR] = 2.10; 95% confidence interval [CI] = 1.10-4.00; p = 0.02) and larger ∆PaCO 2 (OR = 2.69; 95% CI = 1.18-6.13; p = 0.02) were associated with ICH. In conclusion, in a cohort with granular arterial blood gas (ABG) data and a standardized neuromonitoring protocol, higher pre-cannulation PaCO 2 and larger ∆PaCO 2 were associated with increased prevalence of ICH.

Outcomes of extracorporeal membrane oxygenation following the 2018 adult heart allocation policy.

BACKGROUND: The purpose of the study was to characterize changes in waitlist and post-transplant outcomes of extracorporeal membrane oxygenation (ECMO) patients bridged to heart transplantation under the 2018 adult heart allocation policy. METHODS: All adult patients listed for isolated heart transplantation from August 2016 to December 2020 were identified using the United Network for Organ Sharing database. Patients were stratified into Eras (Era 1 and Era 2) centered around the policy change on October 18, 2018. Competing risk regression was used to evaluate waitlist death or deterioration across Eras. Cox proportional hazards models were used to determine associations between use of ECMO and 1-year post-transplant mortality within each Era. RESULTS: Of 8,902 heart transplants included in analysis, 339 (3.8%) were bridged with ECMO (Era 2: 6.1% vs Era 1: 1.2%, P<0.001). Patients bridged with ECMO in Era 2 were less frequently female (26.0% vs 42.0%, P = 0.02) and experienced shorter waitlist times (5 vs 11 days, P<0.001) along with a lower likelihood of waitlist death or deterioration (subdistribution hazard ratio, 0.45, 95% confidence interval, CI, 0.30-0.68, P<0.001) compared to those in Era 1. Use of ECMO was associated with increased post-transplant mortality at 1-year compared to all other transplants in Era 1 (hazard ratio 3.78, 95% CI 1.88-7.61, P < 0.001) but not Era 2. CONCLUSIONS: Patients bridged with ECMO in Era 2 experience improved waitlist and post-transplant outcomes compared to Era 1, giving credence to the increased use of ECMO under the new allocation policy.

Continuous Electroencephalography Markers of Prognostication in Comatose Patients on Extracorporeal Membrane Oxygenation.

BACKGROUND: We aimed to identify continuous electroencephalogram (cEEG) markers associated with survival and death in patients with extracorporeal membrane oxygenation (ECMO) support under standardized sedation cessation protocol. METHODS: Prospectively collected records of adult patients (age ≥ 18 years) who were started on ECMO support in July 2016 to December 2020 at a single tertiary center were analyzed. cEEGs were performed on patients on the basis of inclusion and exclusion criteria. Patients receiving sedation that affect cEEG reactivity at the start of cEEG recording, including propofol, ketamine, or benzodiazepines, were excluded. We allowed fentanyl and dexmedetomidine during cEEG monitoring. cEEGs were evaluated for frequency, amplitude, variability, reactivity, and state changes. RESULTS: Of 290 patients, 40 underwent cEEG in the absence of confounding sedation (median age 60 years, 85% venoarterial-ECMO, 15% venovenous-ECMO). The median length of ECMO support and analyzable cEEG were 143 h and 24 h, respectively. A total of 27 patients underwent withdrawal of life-sustaining therapies (WOLST) during ECMO support. Of the 13 who weaned off ECMO, 9 underwent WOLST later in the hospitalization and 4 survived at hospital discharge. Decisions of WOLST were not influenced by cEEG features' results. Proportions of present EEG reactivity, present state changes, and fair/good variability were significantly higher in patients who survived compared with those who died (odds ratios infinity, infinity, and 13.57, respectively; p values < 0.001, < 0.001, and 0.0299, respectively). Sensitivity and specificity for survival at discharge were 100% and 91.67% for intact reactivity, 100% and 97.20% for present state changes, and 75% and 83.3% for fair/good variability. CONCLUSIONS: Although future multicenter studies with larger patient cohorts are certainly warranted, we were able to validate the feasibility of protocolized sedation cessation and cEEG analyses in the absence of a confounding effect from sedating medications. Moreover, we demonstrate some evidence that cEEG features of intact reactivity, present state changes, and fair/good variability in comatose patients on ECMO may be associated with survival at hospital discharge.

Heart transplantation strategies in arrhythmogenic right ventricular cardiomyopathy: a tertiary ARVC centre experience.

AIMS: End-stage heart failure necessitating evaluation for heart transplantation is increasingly recognized in arrhythmogenic right ventricular cardiomyopathy (ARVC). These patients present unique challenges in pre-transplant and peri-transplant management given their predominantly right ventricular (RV) failure and propensity for ventricular arrhythmias. We sought to utilize a tertiary ARVC referral and heart transplant centre experience to describe management of a series of patients with ARVC undergoing heart transplantation at our centre. METHODS AND RESULTS: We queried the Johns Hopkins ARVC Registry for all patients who underwent heart transplantation and further studied the subset undergoing transplantation at the Johns Hopkins Hospital. Patient demographics, clinical characteristics, and pre-transplant clinical course were obtained from the registry and electronic medical records. Of the 532 patients in the ARVC Registry, 63 (12%) underwent heart transplantation. Nine (six male) of these patients both had known ARVC prior to transplant and were transplanted at Johns Hopkins Hospital between 2006 and 2020 at a mean age of 42 ± 14 years old. Pathogenic ARVC genetic variants were identified in six (67%) patients, all of whom had variants in the plakophilin-2 (PKP2) gene. RV failure was universal with median right atrial to pulmonary capillary wedge pressure (RA/PCWP) ratio of 1.4 [interquartile range (IQR) 1.2-1.5] and median right ventricular stroke work index (RVSWI) of 0 g·m/m2 /beat (IQR 0-0.3). Six had a history of catheter ablation for ventricular arrhythmia with five of the six having at least three ablations. Transplant evaluation was initiated an average of 344 ± 407 days after first developing heart failure symptoms. The most common bridge to transplant support included inotropes (n = 3) and extracorporeal membrane oxygenation (ECMO) (n = 2). Contraindication to inotropes or mechanical support was common due to ventricular arrhythmia and RV predominant cardiomyopathy. CONCLUSIONS: Heart transplantation is a curative treatment for ARVC, but due to frequent ventricular arrhythmias and RV predominant pathology, patients require unique considerations in regard to timing of evaluation, haemodynamic support options, and wait listing qualification.

Does Targeted Temperature Management Improve Neurological Outcome in Extracorporeal Cardiopulmonary Resuscitation (ECPR)?

PURPOSE: Targeted temperature management (TTM) is a standard of care in patients after cardiac arrest for neuroprotection. Currently, the effectiveness and efficacy of TTM after extracorporeal cardiopulmonary resuscitation (ECPR) is unknown. We aimed to compare neurological and survival outcomes between TTM vs non-TTM in patients undergoing ECPR for refractory cardiac arrest. METHODS: We searched PubMed and 5 other databases for randomized controlled trials and observational studies reporting neurological outcomes or survival in adult patients undergoing ECPR with or without TTM. Good neurological outcome was defined as cerebral performance category <3. Two independent reviewers extracted the data. Random-effects meta-analyses were used to pool data. RESULTS: We included 35 studies (n = 2,643) with the median age of 56 years (interquartile range [IQR]: 52-59). The median time from collapse to ECMO cannulation was 58 minutes (IQR: 49-82) and the median ECMO duration was 3 days (IQR: 2.0-4.1). Of 2,643, 1,329 (50.3%) patients received TTM and 1,314 (49.7%) did not. There was no difference in the frequency of good neurological outcome at any time between TTM (29%, 95% confidence interval [CI]: 23%-36%) vs. without TTM (19%, 95% CI: 9%-31%) in patients with ECPR (P = 0.09). Similarly, there was no difference in overall survival between patients with TTM (30%, 95% CI: 22%-39%) vs. without TTM (24%, 95% CI: 14%-34%) (P = 0.31). A cumulative meta-analysis by publication year showed improved neurological and survival outcomes over time. CONCLUSIONS: Among ECPR patients, survival and neurological outcome were not different between those with TTM vs. without TTM. Our study suggests that neurological and survival outcome are improving over time as ECPR therapy is more widely used. Our results were limited by the heterogeneity of included studies and further research with granular temperature data is necessary to assess the benefit and risk of TTM in ECPR population.

Multiinstitutional Evaluation of a Debate-Style Journal Club for Cardiothoracic Surgery Trainees.

BACKGROUND: Traditional journal clubs address individual articles and are limited in terms of breadth and depth of content covered. The present study describes the outcomes of a novel debate-style journal club in a multiinstitutional setting. METHODS: Participating institutions were recruited through the Thoracic Education Cooperative Group. The distributed curriculum included instructions, debate scenarios, suggested article lists, moderator slides, debate scoresheets, exams, and feedback surveys. RESULTS: Six institutions participated in the study (2015-2019), consisting of a total of 10 years' worth of cumulative debates. Cardiothoracic surgery trainees participated in 10 monthly debates over each academic year. Trainee performance on the written examination in the realm of evidence-based medicine and critical appraisal improved over the course of the academic year (beginning 55.2% vs end 76.3%; P = .040). Importantly, written examination after debates revealed a significant improvement in scores on questions relating to topics that were debated as compared with those that were not (+27.1% vs +2.5%; P = .006), emphasizing the importance of the debates as compared with other sources of knowledge gain. Surveys completed by trainees and faculty overall favored the debate-style journal club as compared with the traditional journal club in gaining familiarity with seminal literature in the field, improving on oral presentation skills, and applying published literature to questions encountered clinically. CONCLUSIONS: In this multiinstitutional prospective study, we demonstrate that the novel debate-style cardiothoracic surgery journal club is an effective educational intervention for cardiothoracic surgical trainees to acquire, retain, and gain practice in applying literature-based evidence to case-based scenarios.

Population Characteristics and Markers for Withdrawal of Life-Sustaining Therapy in Patients on Extracorporeal Membrane Oxygenation.

OBJECTIVE: As survival with extracorporeal membrane oxygenation (ECMO) therapy improves, it is important to study patients who do not survive secondary to withdrawal of life-sustaining therapy (WLST). The purpose of the present study was to determine the population and clinical characteristics of those who experienced short latency to WLST. DESIGN: Retrospective cohort study. SETTING: Single academic hospital center. PARTICIPANTS: Adult ECMO patients. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: During the study period, 150 patients (mean age 54.8 ± 15.9 y, 43.3% female) underwent ECMO (80% venoarterial ECMO and 20% venovenous ECMO). Seventy-three (48.7%) had WLST from ECMO support (median five days), and 33 of those (45.2%) had early WLST (≤five days). Patients who underwent WLST were older (60.3 ± 15.3 y v 49.6 ± 14.7 y; p < 0.001) than those who did not undergo WLST and had greater body mass index (31.7 ± 7.6 kg/m2v 28.3 ± 5.5 kg/m2; p = 0.002), longer ECMO duration (six v four days; p = 0.01), and higher Acute Physiology and Chronic Health Evaluation (25 v 21; p < 0.001) and Sequential Organ Failure Assessment (12 v 11; p = 0.037) scores. Family request frequently (91.7%) was cited as part of the WLST decision. WLST patients experienced more chaplaincy (89% v 65%; p < 0.001), palliative care consults (53.4% v 29.9%; p = 0.003), and code status change (do not resuscitate: 83.6% v 7.8%; p < 0.001). CONCLUSIONS: Nearly 50% of ECMO patients underwent WLST, with approximately 25% occurring in the first 72 hours. These patients were older, sicker, and experienced a different clinical context. Unlike with other critical illnesses, neurologic injury was not a primary reason for WLST in ECMO patients.

The Ethics of Extracorporeal Membrane Oxygenation: Revisiting the Principles of Clinical Bioethics.

BACKGROUND: Extracorporeal life support has become accepted as a rescue therapy for cardiopulmonary shock, and there have been over 100,000 extracorporeal membrane oxygenation (ECMO) cases since 1987. Rapid growth has presented ethical challenges and concerns. Here, we discuss core principles of bioethics in an attempt to more thoroughly appreciate the ethical concerns and considerations raised by use of this technology. METHODS: An extensive literature review was performed on current papers on ECMO and ethics. In this paper, we utilized 3 case studies to highlight 4 major tenets of bioethics as they relate to use of ECMO: autonomy, beneficence, nonmaleficence, and justice. RESULTS: Case studies presented involved unique perspectives on utilization of ECMO and a careful balance of benefits and harms as they relate to autonomy, beneficence, nonmaleficence and justice. We present nuanced interpretations of autonomy (eg, physician autonomy) and justice (eg, various providers interpret and offer ECMO differently). An additional challenge includes contending with potentially prolonged clinical courses and/or complications that either result directly from cannulation for ECMO or indirectly from being subject to ensuing extreme conditions and prolongation of life that medical science has yet to fully understand. CONCLUSIONS: ECMO programs continue to grow in number and capacity. A deep appreciation of the bioethical dimensions of this technology and its application must be pursued, understood and applied to individual patient scenarios.

The 2018 adult heart allocation policy change benefits low-volume transplant centers.

INTRODUCTION: The effect of the 2018 adult heart allocation policy change at an institution-level remains unclear. The present study assessed the impact of the policy change by transplant center volume. METHODS: The United Network for Organ Sharing database was queried for all adults undergoing isolated heart transplantation from November 2016 to September 2020. Era 1 was defined as the period before the policy change and Era 2 afterwards. Hospitals were divided into low-(LVC) medium-(MVC) and high-volume (HVC) tertiles based on annual transplant center volume. Competing-risks regressions were used to determine changes in waitlist death/deterioration, while post-transplant mortality was assessed using multivariable Cox proportional-hazards models. RESULTS: A total of 3531 (47.0%) patients underwent heart transplantation in Era 1 and 3988 (53.0%) in Era 2. At LVC, Era 2 patients were less likely to experience death/deterioration on the waitlist (subhazard ratio .74, 95% CI .63-.88), while MVC and HVC patients experienced similar waitlist death/deterioration across eras. After adjustment, transplantation in Era 2 was associated with worse 1-year mortality at MVC (hazard ratio, HR, 1.42 95% CI 1.02-1.96) and HVC (HR 1.42, 95% CI 1.02-1.98) but not at LVC. CONCLUSION: Early analysis shows that LVC may be benefitting under the new allocation scheme.

Duration of Hyperoxia and Neurologic Outcomes in Patients Undergoing Extracorporeal Membrane Oxygenation.

OBJECTIVES: To evaluate the impact of duration of hyperoxia on neurologic outcome and mortality in patients undergoing venoarterial extracorporeal membrane oxygenation. DESIGN: A retrospective analysis of venoarterial extracorporeal membrane oxygenation patients admitted to the Johns Hopkins Hospital. The primary outcome was neurologic function at discharge defined by modified Rankin Scale, with a score of 0-3 defined as a good neurologic outcome, and a score of 4-6 defined as a poor neurologic outcome. Multivariable logistic regression analysis was performed to evaluate the association between hyperoxia and neurologic outcomes. SETTING: The Johns Hopkins Hospital Cardiovascular ICU and Cardiac Critical Care Unit. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We measured first and maximum Pao2 values, area under the curve per minute over the first 24 hours, and duration of mild, moderate, and severe hyperoxia. Of 132 patients on venoarterial extracorporeal membrane oxygenation, 127 (96.5%) were exposed to mild hyperoxia in the first 24 hours. Poor neurologic outcomes were observed in 105 patients (79.6%) (102 with vs 3 without hyperoxia; p = 0.14). Patients with poor neurologic outcomes had longer exposure to mild (19.1 vs 15.2 hr; p = 0.01), moderate (14.6 vs 9.2 hr; p = 0.003), and severe hyperoxia (9.1 vs 4.0 hr; p = 0.003). In a multivariable analysis, patients with worse neurologic outcome experienced longer durations of mild (adjusted odds ratio, 1.10; 95% CI, 1.01-1.19; p = 0.02), moderate (adjusted odds ratio, 1.12; 95% CI, 1.04-1.22; p = 0.002), and severe (adjusted odds ratio, 1.19; 95% CI, 1.06-1.35; p = 0.003) hyperoxia. Additionally, duration of severe hyperoxia was independently associated with inhospital mortality (adjusted odds ratio, 1.18; 95% CI, 1.08-1.29; p < 0.001). CONCLUSIONS: In patients undergoing venoarterial extracorporeal membrane oxygenation, duration and severity of early hyperoxia were independently associated with poor neurologic outcomes at discharge and mortality.

A Comprehensive Review of Risk Factor, Mechanism, and Management of Left Ventricular Assist Device-Associated Stroke.

The use of left ventricular assist devices (LVADs) has been increasing in the last decade, along with the number of patients with advanced heart failure refractory to medical therapy. Ischemic stroke and intracranial hemorrhage remain the leading causes of morbidity and mortality in LVAD patients. Despite the common occurrence and the significant outcome impact, underlying mechanisms and management strategies of stroke in LVAD patients are controversial. In this article, we review our current knowledge on pathophysiology and risk factors of LVAD-associated stroke, outline the diagnostic approach, and discuss treatment strategies.

Decreased Nutritional Risk Index is associated with mortality after heart transplantation.

INTRODUCTION: Validated scoring tools, such as the Nutritional Risk Index (NRI), can aid clinicians in quantifying the degree of malnourishment in patients prior to an operation. We evaluated the association between NRI and outcomes after heart transplantation. METHODS: The United Network for Organ Sharing (UNOS) database was used to identify adult patients (age > 18) undergoing heart transplantation between 1987 and 2016. NRI was calculated and categorized into previously established groupings representing severity of malnutrition. Multivariate Cox proportional hazards modeling were used to assess the primary outcome of all-cause mortality. RESULTS: A total of 25,236 patients were included in the analysis. Most patients (75.4%) were male. Malnourishment was absent (NRI ≥ 100) in 11,022 (44%) patients, while 2,898 (12%) were mildly malnourished (97.5 ≤ NRI < 100), 8,685 (34%) were moderately malnourished (83.5 ≤ NRI < 97.5), and 2,631 (10%) were severely malnourished (NRI < 83.5). Moderate-to-severe malnutrition was associated with increased mortality (HR = 1.18, p < .001, 95%CI: 1.13-1.24), and post-transplant renal failure requiring dialysis (OR: 1.13, p < .001, 95%CI: 1.03-1.23). CONCLUSION: Malnourishment determined by NRI is independently associated with mortality and post-transplant dialysis after heart transplant. This is the largest study of NRI in heart transplant recipients.