Risk Factors of Ischemic and Hemorrhagic Strokes During Venovenous Extracorporeal Membrane Oxygenation: Analysis of Data From the Extracorporeal Life Support Organization Registry

Ultra-Low-Field Portable Brain Magnetic Resonance Imaging in Patients With Cardiac Devices: Current Evidence and Future Directions

The use of cardiac devices, including mechanical circulatory support (MCS), cardiac implantable electronic devices (CIEDs), and pacing wires, has increased and significantly improved survival in patients with severe cardiac failure. However, these devices are frequently associated with acute brain injuries (ABIs) including ischemic strokes, intracranial hemorrhages, seizures, and hypoxic-ischemic brain injury which contribute substantially to morbidity and mortality. Computed tomography (CT) and magnetic resonance imaging (MRI), the standard imaging modalities for ABI diagnosis, can pose significant challenges in this patient population due to the risks associated with patient transportation and the incompatibility of ferromagnetic components of certain cardiac devices with high magnetic field of the MRI. This review discusses the application of Ultralow-field portable MRI (ULF-pMRI), which operates at much lower magnetic field (0.064 T), with the potential to allow safe bedside imaging of critically ill patients. In this review, we detail the clinical studies and research findings defining the safety, feasibility, and diagnostic utility of ULF-pMRI in detecting ABI in the critically ill. We further discuss the potential broader applications of ULF-pMRI, as a standard diagnostic tool for neurocritical care in patients with cardiac devices. The integration of such technology into current practice promises to enhance diagnostic accuracy, improve patient outcomes, and optimize healthcare resources.

Development and external validation of a machine learning model for brain injury in pediatric patients on extracorporeal membrane oxygenation

BACKGROUND

Patients supported by extracorporeal membrane oxygenation (ECMO) are at a high risk of brain injury, contributing to significant morbidity and mortality. This study aimed to employ machine learning (ML) techniques to predict brain injury in pediatric patients ECMO and identify key variables for future research.

METHODS

Data from pediatric patients undergoing ECMO were collected from the Chinese Society of Extracorporeal Life Support (CSECLS) registry database and local hospitals. Ten ML methods, including random forest, support vector machine, decision tree classifier, gradient boosting machine, extreme gradient boosting, light gradient boosting machine, Naive Bayes, neural networks, a generalized linear model, and AdaBoost, were employed to develop and validate the optimal predictive model based on accuracy and area under the curve (AUC). Patients were divided into retrospective cohort for model development and internal validation, and one cohort for external validation.

RESULTS

A total of 1,633 patients supported by ECMO were included in the model development, of whom 181 experienced brain injury. In the external validation cohort, 30 of the 154 patients experienced brain injury. Fifteen features were selected for the model construction. Among the ML models tested, the random forest model achieved the best performance, with an AUC of 0.912 for internal validation and 0.807 for external validation.

CONCLUSION

The Random Forest model based on machine learning demonstrates high accuracy and robustness in predicting brain injury in pediatric patients supported by ECMO, with strong generalization capabilities and promising clinical applicability.

Prognostic Factors Associated With Intracranial Hemorrhage and Ischemic Stroke During Venovenous Extracorporeal Membrane Oxygenation: A Systematic Review

OBJECTIVES

Venovenous extracorporeal membrane oxygenation (ECMO) is a life-preserving intervention for patients with respiratory failure refractory to conventional mechanical ventilation. Intracranial hemorrhage (ICH) and ischemic stroke are life-threatening complications associated with venovenous ECMO. Despite this, little is known regarding the prognostic factors associated with these adverse neurologic events. We conducted a systematic review that characterizes these predictors of ICH and ischemic stroke during venovenous ECMO.

DATA SOURCES

We conducted a comprehensive search of MEDLINE and Embase via the Ovid interface.

STUDY SELECTION

We developed and performed a literature search to identify articles that evaluated ICH and ischemic stroke in adult patients undergoing venovenous ECMO. We excluded studies based on design, target population, and outcomes.

DATA EXTRACTION

Data were extracted manually by one reviewer. Risk of bias assessment was completed using the Quality in Prognostic Studies approach for each included study. Prognostic factors associated with ICH and ischemic stroke that were identified in two or more included studies were evaluated through the Grading of Recommendations, Assessment, Development, and Evaluation approach.

DATA SYNTHESIS

Three hundred thirty-three studies met criteria for screening. Seventeen studies met final inclusion criteria. Seventeen studies addressed predictors of ICH. Five studies demonstrated an increased risk of ICH with lower pH before venovenous ECMO (moderate certainty). Five studies demonstrated an increased risk of ICH with greater decreases in Paco2 pre- to post-venovenous ECMO cannulation (moderate certainty). Four studies addressed predictors of ischemic stroke; however, there were no predictors of ischemic stroke identified in two or more of the included studies.

CONCLUSIONS

This systematic review demonstrates that abnormalities and changes in blood gas parameters from pre- to post-venovenous ECMO cannulation are probably associated with increased risk of ICH. Additional high-quality studies dedicated to probable predictors of these adverse neurologic events are crucial to understanding the pathophysiology of ICH and ischemic stroke in this population and informing clinical practice to mitigate the risk of these life-threatening events.

Neurological Monitoring and Management for Adult Extracorporeal Membrane Oxygenation Patients: Extracorporeal Life Support Organization Consensus Guidelines

BACKGROUND

Critical care of patients on extracorporeal membrane oxygenation (ECMO) with acute brain injury (ABI) is notable for a lack of high-quality clinical evidence. Here, we offer guidelines for neurological care (neurological monitoring and management) of adults during and after ECMO support.

METHODS

These guidelines are based on clinical practice consensus recommendations and scientific statements. We convened an international multidisciplinary consensus panel including 30 clinician-scientists with expertise in ECMO from all chapters of the Extracorporeal Life Support Organization (ELSO). We used a modified Delphi process with three rounds of voting and asked panelists to assess the recommendation levels.

RESULTS

We identified five key clinical areas needing guidance: (1) neurological monitoring, (2) post-cannulation early physiological targets and ABI, (3) neurological therapy including medical and surgical intervention, (4) neurological prognostication, and (5) neurological follow-up and outcomes. The consensus produced 30 statements and recommendations regarding key clinical areas. We identified several knowledge gaps to shape future research efforts.

CONCLUSIONS

The impact of ABI on morbidity and mortality in ECMO patients is significant. Particularly, early detection and timely intervention are crucial for improving outcomes. These consensus recommendations and scientific statements serve to guide the neurological monitoring and prevention of ABI, and management strategy of ECMO-associated ABI.

Spinal Cord Infarction During Extracorporeal Membrane Oxygenation：A Case Series and Review of the Literature

Background: Little is known about extracorporeal membrane oxygenation (ECMO)-related spinal cord infarction (SCI), and reports regarding this rare and catastrophic complication are rare. Here, we report two cases of ECMO-related SCI that occurred between April and December 2023. Data were collected from patients' medical records, with SCI as the endpoint. We reviewed previously published reports by searching PubMed and summarizing the findings. Case summary: One female patient presenting with multiple traumas required oxygenation support through veno-venous ECMO (VV ECMO) due to pulmonary hemorrhage, while one male patient required circulatory support via veno-arterial ECMO (VA ECMO) concurrently with an intra-aortic balloon pump due to cardiac arrest. Neither patient had preexisting neurological deficits; however, upon weaning from ECMO, they presented with severe neurological deficits of uncertain etiology, subsequently confirmed as SCI using magnetic resonance imaging. Conclusion: ECMO-related SCI remains elusive and intricate, and this is the first report of adult VV ECMO-related SCI.

Association of early changes in arterial carbon dioxide with acute brain injury in adult patients with extracorporeal membrane oxygenation: A ten-year retrospective study in a German tertiary care hospital

PURPOSE

To assess the association between fluctuations of arterial carbon dioxide early after start of extracorporeal membrane oxygenation (ECMO) with intracranial hemorrhage (ICH) or ischemic stroke (IS).

MATERIALS AND METHODS

This single-center retrospective study included patients who required ECMO for circulatory or respiratory failure between January 2011 and April 2021 and for whom a cerebral computed tomography (cCT) scan was available. Multivariable logistic regression models were fitted to evaluate the association between the relative change of arterial carbon dioxide (RelΔPaCO2) and ICH, IS or a composite of ICH, IS, and mortality.

RESULTS

In 618 patients (venovenous ECMO: n = 295; venoarterial ECMO: n = 323) ICH occurred more frequently in patients with respiratory failure (19.0%) compared with patients with circulatory failure (6.8%). Conversely, the incidence of IS was higher in patients with circulatory failure (19.2%) compared with patients with respiratory failure (4.7%). While patients with ECMO for respiratory failure were more likely to have ICH (OR 3.683 [95% CI: 1.855;7.309], p < 0.001), they had a lower odds for IS (OR 0.360 [95%CI: 0.158;0.820], p = 0.015) compared with patients with circulatory failure. There was no significant association between RelΔPaCO2 and ICH or IS.

CONCLUSIONS

Irrespective of the indication for ECMO, we did not find a significant association between the relative change in PaCO2 early after ECMO initiation and acute brain injury. Aside from early PaCO2 decline at cannulation, future studies should address fluctuations of PaCO2 throughout the course of ECMO support and their effect on acute brain injury.

Acute Ischemic Stroke during Extracorporeal Membrane Oxygenation (ECMO): A Narrative Review of the Literature

Ischemic stroke (IS) is a severe complication and leading cause of mortality in patients under extracorporeal membrane oxygenation (ECMO). The aim of our narrative review is to summarize the existing evidence and provide a deep examination of the diagnosis and treatment of acute ischemic stroke patients undergoing ECMO support. The incidence rate of ISs is estimated to be between 1 and 8%, while the mortality rate ranges from 44 to 76%, depending on several factors, including ECMO type, duration of support and patient characteristics. Several mechanisms leading to ISs during ECMO have been identified, with thromboembolic events and cerebral hypoperfusion being the most common causes. However, considering that most of the ECMO patients are severely ill or under sedation, stroke symptoms are often underdiagnosed. Multimodal monitoring and daily clinical assessment could be useful preventive techniques. Early recognition of neurological deficits is of paramount importance for prompt therapeutic interventions. All ECMO patients with suspected strokes should immediately receive brain computed tomography (CT) and CT angiography (CTA) for the identification of large vessel occlusion (LVO) and assessment of collateral blood flow. CT perfusion (CTP) can further assist in the detection of viable tissue (penumbra), especially in cases of strokes of unknown onset. Catheter angiography is required to confirm LVO detected on CTA. Intravenous thrombolytic therapy is usually contraindicated in ECMO as most patients are on active anticoagulation treatment. Therefore, mechanical thrombectomy is the preferred treatment option in cases where there is evidence of LVO. The choice of the arterial vascular access used to perform mechanical thrombectomy should be discussed between interventional radiologists and an ECMO team. Anticoagulation management during the acute phase of IS should be individualized after the thromboembolic risk has been carefully balanced against hemorrhagic risk. A multidisciplinary approach is essential for the optimal management of ISs in patients treated with ECMO.

Using machine learning to predict neurologic injury in venovenous extracorporeal membrane oxygenation recipients: An ELSO 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 [HIBI]) and intracranial hemorrhage (ICH). Data on prediction models for neurologic outcomes in VV-ECMO are limited.

Methods

We analyzed adult (age ≥18 years) VV-ECMO patients in the Extracorporeal Life Support Organization (ELSO) Registry (2009-2021) from 676 centers. ABI was defined as CNS ischemia, ICH, brain death, and seizures. Data on 67 variables were extracted, including clinical characteristics and pre-ECMO/on-ECMO variables. Random forest, CatBoost, LightGBM, and XGBoost machine learning (ML) algorithms (10-fold leave-one-out cross-validation) were used to predict ABI. Feature importance scores were used to pinpoint the most important variables for predicting ABI.

Results

Of 37,473 VV-ECMO patients (median age, 48.1 years; 63% male), 2644 (7.1%) experienced ABI, including 610 (2%) with CNS ischemia and 1591 (4%) with ICH. The areas under the receiver operating characteristic curve for predicting ABI, CNS ischemia, and ICH were 0.70, 0.68, and 0.70, respectively. The accuracy, positive predictive value, and negative predictive value for ABI were 85%, 19%, and 95%, respectively. ML identified higher center volume, pre-ECMO cardiac arrest, higher ECMO pump flow, and elevated on-ECMO serum lactate level as the most important risk factors for ABI and its subtypes.

Conclusions

This is the largest study of VV-ECMO patients to use ML to predict ABI reported to date. Performance was suboptimal, likely due to lack of standardization of neuromonitoring/imaging protocols and data granularity in the ELSO Registry. Standardized neurologic monitoring and imaging are needed across ELSO centers to detect the true prevalence of ABI.

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.

Neurological complications in oncology and their monitoring and management in clinical practice: a narrative review

IMPORTANCE

New anti-tumor treatments, such as immune checkpoint inhibitors and CAR T-cell therapy, are associated with an increasing number of neurological issues linked to tumors not arising from nervous system such as neurological and neuropsychological side effects that can significantly impair quality of life in the short or long term. The science of pathomechanisms, therapeutic approaches, and preventive measures is still in its early stages, and the progress is hampered by the lack of studied connection between neurological and oncological disciplines.

OBJECTIVES

This work aimed to provide an overview of the questions raised in the field of clinical neuroscience that concern the outcomes of oncological diseases and their treatment. Furthermore, we give an outline of how a collaborative approach between neurology and oncology, with the implementation of neuroscience techniques including up-to-date diagnostics and therapy, can help to improve the quality of oncological patients' lives.

EVIDENCE REVIEW

The covered areas of investigation in the evaluated articles primarily encompassed the review of known neurological complications of oncological diseases caused by neurotoxic mechanisms of performed therapies or those linked to concurrent pathological conditions. Similarly, the methods of their diagnostics were assessed.

FINDINGS

Our literature review of 65 articles, including clinical trials, cohort studies, reviews, and theoretically based in vitro studies published between 1998 and 2023, outlines the broad spectrum of neurological complications primarily associated with malignant diseases and the anti-tumor therapies employed. Notably, immune-mediated complications, whose incidence is increasing due to the expanding use of new immunotherapies, require early detection and targeted treatment to prevent severe progression. In this context, neurological complications mediated by immune checkpoint inhibitors are often associated with significant impairments and high mortality, necessitating specialist consultation for early detection and differentiation from other phenotypically similar syndromes. Current data on the pathophysiology of these neurological complications are not reliable due to the limited number of studies. Moreover, there is a lack of evidence regarding the appropriate oncological approach in the event of therapy-related complications. Initial study results suggest that the establishment of interdisciplinary treatment interfaces for the management of oncology patients could improve the safety of these therapies and enhance the patients' quality of life.

CONCLUSIONS AND RELEVANCE

The accumulated knowledge on neurotoxicity caused by oncological diseases shows that the challenges in diagnosing and managing this condition are expanding in tandem with the growing array of therapies being employed. Therefore, it requires interdisciplinary approach with the introduction of new facilities enabling more personalized patient care.

Neurological monitoring and management for adult extracorporeal membrane oxygenation patients: Extracorporeal Life Support Organization consensus guidelines

BACKGROUND

Critical care of patients on extracorporeal membrane oxygenation (ECMO) with acute brain injury (ABI) is notable for a lack of high-quality clinical evidence. Here, we offer guidelines for neurological care (neurological monitoring and management) of adults during and after ECMO support.

METHODS

These guidelines are based on clinical practice consensus recommendations and scientific statements. We convened an international multidisciplinary consensus panel including 30 clinician-scientists with expertise in ECMO from all chapters of the Extracorporeal Life Support Organization (ELSO). We used a modified Delphi process with three rounds of voting and asked panelists to assess the recommendation levels.

RESULTS

We identified five key clinical areas needing guidance: (1) neurological monitoring, (2) post-cannulation early physiological targets and ABI, (3) neurological therapy including medical and surgical intervention, (4) neurological prognostication, and (5) neurological follow-up and outcomes. The consensus produced 30 statements and recommendations regarding key clinical areas. We identified several knowledge gaps to shape future research efforts.

CONCLUSIONS

The impact of ABI on morbidity and mortality in ECMO patients is significant. Particularly, early detection and timely intervention are crucial for improving outcomes. These consensus recommendations and scientific statements serve to guide the neurological monitoring and prevention of ABI, and management strategy of ECMO-associated ABI.

Short-Term Neurologic Complications in Patients Undergoing Extracorporeal Membrane Oxygenation Support: A Review on Pathophysiology, Incidence, Risk Factors, and Outcomes

Regardless of the type, extracorporeal membrane oxygenation (ECMO) requires the use of large intravascular cannulas and results in multiple abnormalities including non-physiologic blood flow, hemodynamic perturbation, rapid changes in blood oxygen and carbon dioxide levels, coagulation abnormalities, and a significant systemic inflammatory response. Among other sequelae, neurologic complications are an important source of mortality and long-term morbidity. The frequency of neurologic complications varies and is likely underreported due to the high mortality rate. Neurologic complications in patients supported by ECMO include ischemic and hemorrhagic stroke, hypoxic brain injury, intracranial hemorrhage, and brain death. In addition to the disease process that necessitates ECMO, cannulation strategies and physiologic disturbances influence neurologic outcomes in this high-risk population. For example, the overall documented rate of neurologic complications in the venovenous ECMO population is lower, but a higher rate of intracranial hemorrhage exists. Meanwhile, in the venoarterial ECMO population, ischemia and global hypoperfusion seem to compose a higher percentage of neurologic complications. In what follows, the literature is reviewed to discuss the pathophysiology, incidence, risk factors, and outcomes related to short-term neurologic complications in patients supported by ECMO.

Epidemiology of Seizures and Association With Mortality in Adult Patients Undergoing ECMO: A Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVES

Extracorporeal membrane oxygenation (ECMO) provides lifesaving support to patients with cardiopulmonary failure. Although seizures increase mortality risks among critically ill patients broadly, studies specific to adult ECMO patients have largely been limited to single-center studies. Thus, we aimed to perform a systematic review and meta-analyses of seizure prevalence, mortality, and their associations in adult ECMO patients.

METHODS

PubMed, EMBASE, Cochrane trial registry, Web of Science, and SCOPUS were searched on August 5, 2023. Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, we included studies of adults undergoing venovenous ECMO (VV-ECMO), venoarterial ECMO (VA-ECMO), or extracorporeal cardiopulmonary resuscitation (ECPR) that reported seizures during ECMO. The extracted data included study characteristics, patient demographics, ECMO support, EEG monitoring, and seizures, organized by ECMO types. Forest plot and meta-regression analyses were performed. Bias assessment was performed with the Egger test and Newcastle-Ottawa Scale.

RESULTS

Twenty-three studies (n = 40,420, mean age = 51.8 years, male = 62%) were included. Data were extracted by ECMO type as follows: VV-ECMO (n = 16,633), non-ECPR VA-ECMO (n = 11,082), ECPR (n = 3,369), combination of VA-ECMO and ECPR (n = 240), and combination of all types (n = 9,096). The pooled seizure prevalence for all ECMO types was 3.0%, not significantly different across ECMO types (VV-ECMO = 2.0% [95% CI 0.8-4.5]; VA-ECMO = 3.5% [95% CI 1.7-7.0]; ECPR = 4.9% [95% CI 1.3-17.2]). The pooled mortality was lower for VV-ECMO (46.2% [95% CI 39.3-53.2]) than VA-ECMO (63.4% [95% CI 56.6-69.6]) and ECPR (61.5% [95% CI 57.3-65.6]). Specifically, for VV-ECMO, the pooled mortality of patients with and without seizures was 55.1% and 36.7%, respectively (relative risk = 1.5 [95% CI 1.3-1.7]). Similarly, for VA-ECMO, the pooled mortality of patients with and without seizures was 74.4% and 56.1%, respectively (relative risk = 1.3 [95% CI 1.2-1.5]). Meta-regression analyses demonstrated that seizure prevalence was not associated with prior neurologic comorbidities, adjusted for ECMO type and study year.

DISCUSSION

Seizures are infrequent during ECMO support. However, they were associated with increased mortality when present. Multi-institutional, larger-scale studies using standardized EEG monitoring are necessary to further understand the risk factors of specific classes of seizures for individual ECMO types, and their effects on mortality. Limitations of our study include missing data for details on seizure types, sedating/antiseizure medications used during ECMO, other ECMO-related complications, and EEG recording protocols.

Machine Learning from Veno-Venous Extracorporeal Membrane Oxygenation Identifies Factors Associated with Neurological Outcomes

BACKGROUND

Neurological complications are common in patients receiving veno-venous extracorporeal membrane oxygenation (VV-ECMO) support. We used machine learning (ML) algorithms to identify predictors for neurological outcomes for these patients.

METHODS

All demographic, clinical, and circuit-related variables were extracted for adults with VV-ECMO support at a tertiary care center from 2016 to 2022. The primary outcome was good neurological outcome (GNO) at discharge defined as a modified Rankin Scale of 0-3.

RESULTS

Of 99 total VV-ECMO patients (median age = 48 years; 65% male), 37% had a GNO. The best performing ML model achieved an area under the receiver operating characteristic curve of 0.87. Feature importance analysis identified down-trending gas/sweep/blender flow, FiO2, and pump speed as the most salient features for predicting GNO.

CONCLUSION

Utilizing pre- as well as post-initiation variables, ML identified on-ECMO physiologic and pulmonary conditions that best predicted neurological outcomes.

Characterizing the Racial Discrepancy in Hypoxemia Detection in Venovenous Extracorporeal Membrane Oxygenation: An Extracorporeal Life Support Organization Registry Analysis

PURPOSE

Skin pigmentation influences peripheral oxygen saturation (SpO2) compared to arterial saturation of oxygen (SaO2). Occult hypoxemia (SaO2 ≤ 88% with SpO2 ≥ 92%) is associated with increased in-hospital mortality in venovenous-extracorporeal membrane oxygenation (VV-ECMO) patients. We hypothesized VV-ECMO cannulation, in addition to race/ethnicity, accentuates the SpO2-SaO2 discrepancy due to significant hemolysis.

METHODS

Adults (≥ 18 years) supported with VV-ECMO with concurrently measured SpO2 and SaO2 measurements from over 500 centers in the Extracorporeal Life Support Organization Registry (1/2018-5/2023) were included. Multivariable logistic regressions were performed to examine whether race/ethnicity was associated with occult hypoxemia in pre-ECMO and on-ECMO SpO2-SaO2 calculations.

RESULTS

Of 13,171 VV-ECMO patients, there were 7772 (59%) White, 2114 (16%) Hispanic, 1777 (14%) Black, and 1508 (11%) Asian patients. The frequency of on-ECMO occult hypoxemia was 2.0% (N = 233). Occult hypoxemia was more common in Black and Hispanic patients versus White patients (3.1% versus 1.7%, P < 0.001 and 2.5% versus 1.7%, P = 0.025, respectively). In multivariable logistic regression, Black patients were at higher risk of pre-ECMO occult hypoxemia versus White patients (adjusted odds ratio [aOR] = 1.55, 95% confidence interval [CI] = 1.18-2.02, P = 0.001). For on-ECMO occult hypoxemia, Black patients (aOR = 1.79, 95% CI = 1.16-2.75, P = 0.008) and Hispanic patients (aOR = 1.71, 95% CI = 1.15-2.55, P = 0.008) had higher risk versus White patients. Higher pump flow rates (aOR = 1.29, 95% CI = 1.08-1.55, P = 0.005) and on-ECMO 24-h lactate (aOR = 1.06, 95% CI = 1.03-1.10, P < 0.001) significantly increased the risk of on-ECMO occult hypoxemia.

CONCLUSION

SaO2 should be carefully monitored if using SpO2 during ECMO support for Black and Hispanic patients especially for those with high pump flow and lactate values at risk for occult hypoxemia.

Impact of Extracorporeal Membrane Oxygenation Bridging Duration on Lung Transplant Outcomes

BACKGROUND

We sought to characterize the association between venovenous extracorporeal membrane oxygenation (VV-ECMO) bridging duration and outcomes in patients listed for lung transplantation.

METHODS

A retrospective observational study was conducted using the Organ Procurement and Transplantation Network (OPTN) database to identify adults (aged ≥18 years) who were listed for lung transplantation between 2016 and 2020 and were bridged with VV-ECMO. Patients were then stratified into groups, determined by risk inflection points, depending on the amount of time spent on pretransplant ECMO: group 1 (≤5 days), group 2 (6-10 days), group 3 (11-20 days), and group 4 (>20 days). Waiting list survival between groups was analyzed using Fine-Gray competing risk models. Posttransplant survival was compared using Cox regression.

RESULTS

Of 566 eligible VV-ECMO bridge-to-lung-transplant patients (median age, 54 years, 49% men), 174 (31%), 124 (22%), 130 (23%), and 138 (24%) were categorized as groups 1, 2, 3, and 4, respectively. Overall, median duration of VV-ECMO was 10 days (interquartile range, 1-211 days), and 178 patients (31%) died on the waiting list. In the Fine-Gray model, compared with group 1, patients bridged with longer ECMO durations in group 2 (subdistribution hazard ratio [SHR], 2.95; 95% CI, 1.63-5.35), group 3 (SHR, 3.96; 95% CI, 2.36-6.63), and group 4 (SHR, 4.33; 95% CI, 2.59-7.22, all P < .001) were more likely to die on the waiting list. Of 388 patients receiving a transplant, pretransplant ECMO duration was not associated with 1-year survival in Cox regression.

CONCLUSIONS

Prolonged duration of ECMO bridging was associated with worse waiting list mortality but did not impact survival after lung transplant. Prioritization of very early transplantation may improve waiting list outcomes in this population.

Neurophysiologic Features Reflecting Brain Injury During Pediatric ECMO Support

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) provides lifesaving support to critically ill patients who experience refractory cardiopulmonary failure but carries a high risk for acute brain injury. We aimed to identify characteristics reflecting acute brain injury in children requiring ECMO support.

METHODS

This is a prospective observational study from 2019 to 2022 of pediatric ECMO patients undergoing neuromonitoring, including continuous electroencephalography, cerebral oximetry, and transcranial Doppler ultrasound (TCD). The primary outcome was acute brain injury. Clinical and neuromonitoring characteristics were collected. Multivariate logistic regression was implemented to model odds ratios (ORs) and identify the combined characteristics that best discriminate risk of acute brain injury using the area under the receiver operating characteristic curve.

RESULTS

Seventy-five pediatric patients requiring ECMO support were enrolled in this study, and 62 underwent neuroimaging or autopsy evaluations. Of these 62 patients, 19 experienced acute brain injury (30.6%), including seven (36.8%) with arterial ischemic stroke, four (21.1%) with hemorrhagic stroke, seven with hypoxic-ischemic brain injury (36.8%), and one (5.3%) with both arterial ischemic stroke and hypoxic-ischemic brain injury. A univariate analysis demonstrated acute brain injury to be associated with maximum hourly seizure burden (p = 0.021), electroencephalographic suppression percentage (p = 0.022), increased interhemispheric differences in electroencephalographic total power (p = 0.023) and amplitude (p = 0.017), and increased differences in TCD Thrombolysis in Brain Ischemia (TIBI) scores between bilateral middle cerebral arteries (p = 0.023). Best subset model selection identified increased seizure burden (OR = 2.07, partial R2 = 0.48, p = 0.013), increased quantitative electroencephalographic interhemispheric amplitude differences (OR = 2.41, partial R2 = 0.48, p = 0.013), and increased interhemispheric TCD TIBI score differences (OR = 4.66, partial R2 = 0.49, p = 0.006) to be independently associated with acute brain injury (area under the receiver operating characteristic curve = 0.92).

CONCLUSIONS

Increased seizure burden and increased interhemispheric differences in both quantitative electroencephalographic amplitude and TCD MCA TIBI scores are independently associated with acute brain injury in children undergoing ECMO support.

Long-Term Neuropsychiatric, Neurocognitive, and Functional Outcomes of Patients Receiving ECMO: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Despite the common occurrence of neurologic complications during extracorporeal membrane oxygenation (ECMO) support, data on long-term neuropsychiatric, neurocognitive, and functional outcomes are sparse. We aimed to determine the prevalence of long-term neuropsychiatric symptoms, neurocognitive and functional impairment, and favorable neurologic outcomes in adult patients who receive ECMO.

METHODS

PubMed, Embase, Cochrane, Web of Science, and Scopus were searched for text related to ECMO and neuropsychiatric, neurocognitive, and functional outcomes from inception to May 3, 2023. Our primary outcome was the prevalence of neuropsychiatric symptoms (pain/discomfort, anxiety, depression, posttraumatic stress disorder [PTSD], and sleep disturbance) at long-term (≥6 months) follow-up. Our secondary outcomes were the prevalence of neurocognitive impairment (memory, attention, and reasoning), functional impairment (daily activities, physical activity/mobility, and personal/self-care), and favorable neurologic outcomes (Cerebral Performance Category ≤2, modified Rankin scale ≤3, or Glasgow Outcome Scale ≥4). This study was registered in PROSPERO (CRD42023420565).

RESULTS

We included 59 studies with 3,280 patients (median age 54 years, 69% male). The cohort consisted of 86% venoarterial (VA)-ECMO (n = 2,819) and 14% venovenous (VV)-ECMO (n = 461) patients. More than 10 tools were used to assess neuropsychiatric and neurocognitive outcomes, indicating a lack of standardization in assessment methodologies. The overall prevalence of neuropsychiatric symptoms was 41% (95% CI 33%-49%): pain/discomfort (52%, 95% CI 42%-63%), sleep disturbance (37%, 95% CI 0%-98%), anxiety (36%, 95% CI 27%-46%), depression (31%, 95% CI 22%-40%), and PTSD (18%, 95% CI 9%-29%). The prevalence of neurocognitive impairment was 38% (95% CI 13%-65%). The prevalence of functional impairment was 52% (95% CI 40%-64%): daily activities (54%, 95% CI 41%-66%), mobility (41%, 95% CI 28%-54%), and self-care (21%, 95% CI 13%-31%). The prevalence of neuropsychiatric symptoms in VV-ECMO patients was higher than that in VA-ECMO patients (55% [95% CI 34%-75%] vs 32% [95% CI 23%-41%], p = 0.01), though the prevalence of neurocognitive and functional impairment was not different between the groups. The prevalence of favorable neurologic outcomes was not different at various follow-ups: 3 months (23%, 95% CI 12%-36%), 6 months (25%, 95% CI 16%-35%), and ≥1 year (28%, 95% CI 21%-36%, p = 0.68).

DISCUSSION

A substantial proportion of ECMO patients seemed to experience neuropsychiatric symptoms and neurocognitive and functional impairments at long-term follow-up. Considerable heterogeneity in methodology for gauging these outcomes exists, warranting the need for standardization. Multicenter prospective observational studies are indicated to further investigate risk factors for these outcomes in ECMO-supported patients.

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.

Stroke and Mechanical Circulatory Support in Adults

PURPOSE OF THE REVIEW

Short-term and durable mechanical circulatory support (MCS) devices represent life-saving interventions for patients with cardiogenic shock and end-stage heart failure. This review will cover the epidemiology, risk factors, and treatment of stroke in this patient population.

RECENT FINDINGS

Short-term devices such as intra-aortic balloon pump, Impella, TandemHeart, and Venoatrial Extracorporal Membrane Oxygenation, as well as durable continuous-flow left ventricular assist devices (LVADs), improve cardiac output and blood flow to the vital organs. However, MCS use is associated with high rates of complications, including ischemic and hemorrhagic strokes which carry a high risk for death and disability. Improvements in MCS technology have reduced but not eliminated the risk of stroke. Mitigation strategies focus on careful management of anti-thrombotic therapies. While data on therapeutic options for stroke are limited, several case series reported favorable outcomes with thrombectomy for ischemic stroke patients with large vessel occlusions, as well as with reversal of anticoagulation for those with hemorrhagic stroke. Stroke in patients treated with MCS is associated with high morbidity and mortality. Preventive strategies are targeted based on the specific form of MCS. Improvements in the design of the newest generation device have reduced the risk of ischemic stroke, though hemorrhagic stroke remains a serious complication.

Characterizing the Racial Discrepancy in Hypoxemia Detection in VV-ECMO: An ELSO Registry Analysis

Importance

Skin pigmentation influences peripheral oxygen saturation (SpO2) measured by pulse oximetry compared to the arterial saturation of oxygen (SaO2) measured via arterial blood gas analysis. However, data on SpO2-SaO2 discrepancy are limited in venovenous-extracorporeal membrane oxygenation (VV-ECMO) patients.

Objective

To determine whether there is racial/ethnical discrepancy between SpO2 and SaO2 in patients receiving VV-ECMO. We hypothesized VV-ECMO cannulation, in addition to race/ethnicity, accentuates the SpO2-SaO2 discrepancy due to significant hemolysis.

Design

Retrospective cohort study of the Extracorporeal Life Support Organization Registry from 1/2018-5/2023.

Setting

International, multicenter registry study including over 500 ECMO centers.

Participants

Adults (≥ 18 years) supported with VV-ECMO with concurrently measured SpO2 and SaO2 measurements.

Exposure

Race/ethnicity and ECMO cannulation.

Main outcomes and measures

Occult hypoxemia (SaO2 ≤ 88% with SpO2 ≥ 92%) was our primary outcome. Multivariable logistic regressions were performed to examine whether race/ethnicity was associated with occult hypoxemia in pre-ECMO and on-ECMO SpO2-SaO2 calculations. Covariates included age, sex, temporary mechanical circulatory support, pre-vasopressors, and pre-inotropes for pre-ECMO analysis, plus single-lumen versus double-lumen cannulation, hemolysis, hyperbilirubinemia, ECMO pump flow rate, and on-ECMO 24h lactate for on-ECMO analysis.

Results

Of 13,171 VV-ECMO patients (median age = 48.6 years, 66% male), there were 7,772 (59%) White, 2,114 (16%) Hispanic, 1,777 (14%) Black, and 1,508 (11%) Asian patients. The frequency of on-ECMO occult hypoxemia was 2.0% (N = 233). Occult hypoxemia was more common in Black and Hispanic versus White patients (3.1% versus 1.7%, P < 0.001 and 2.5% versus 1.7%, P = 0.025, respectively).In multivariable logistic regression, Black patients were at higher risk of pre-ECMO occult hypoxemia versus White patients (adjusted odds ratio [aOR] = 1.55, 95% confidence interval [CI] = 1.18-2.02, P = 0.001). For on-ECMO occult hypoxemia, Black patients (aOR = 1.79, 95%CI = 1.16-2.75, P = 0.008) and Hispanic patients (aOR = 1.71, 95%CI = 1.15-2.55, P = 0.008) had higher risk versus White patients. Furthermore, higher pump flow rate (aOR = 1.29, 95%CI = 1.08-1.55, P = 0.005) and higher on-ECMO 24h lactate (aOR = 1.06, 95%CI = 1.03-1.10, P < 0.001) significantly increased the risk of on-ECMO occult hypoxemia.

Conclusions and Relevance

Hispanic and Black VV-ECMO patients experienced occult hypoxemia more than White patients. SaO2 should be carefully monitored during ECMO support for Black and Hispanic patients especially for those with high pump flow and lactate values at risk for occult hypoxemia.

Epidemiology of ischemic stroke and hemorrhagic stroke in venoarterial extracorporeal membrane oxygenation

BACKGROUND

While venoarterial extracorporeal membrane oxygenation (V-A ECMO) provides lifesaving support for cardiopulmonary failure, complications may increase mortality, with few studies focusing on ischemic/hemorrhagic stroke. We aimed to determine the trends and associations of stroke incidence and mortality, and their risk factors, including the effects of annual case volumes of ECMO centers.

METHODS

Retrospective analysis was performed on the Extracorporeal Life Support Organization (ELSO) registry, including adult V-A ECMO patients from 534 international centers between 2012 and 2021, excluding extracorporeal cardiopulmonary resuscitation. Temporal trend analyses were performed for stroke incidence and mortality. Univariate testing, multivariable regression, and survival analysis were used to evaluate the associations of stroke, 90-day mortality, and impact of annual center volume.

RESULTS

Of 33,041 patients, 20,297 had mortality data, and 12,327 were included in the logistic regression. Between 2012 and 2021, ischemic stroke incidence increased (p < 0.0001), hemorrhagic stroke incidence remained stable, and overall 90-day mortality declined (p < 0.0001). Higher 24-h PaO2 and greater decrease between pre-ECMO PaCO2 and post-cannulation 24-h PaCO2 were associated with greater ischemic stroke incidence, while annual case volume was not. Ischemic/hemorrhagic strokes were associated with increased 90-day mortality (both p < 0.0001), while higher annual case volume was associated with lower 90-day mortality (p = 0.001). Hazard of death was highest in the first several days of V-A ECMO.

CONCLUSION

In V-A ECMO patients between 2012 and 2021, 90-day mortality decreased, while ischemic stroke incidence increased. ELSO centers with higher annual case volumes had lower mortality, but were not associated with ischemic/hemorrhagic stroke incidence. Both ischemic/hemorrhagic strokes were associated with increased mortality.

Predictors and Outcomes of Extracorporeal Membrane Oxygenation in COVID-19 Patients With ARDS: A Propensity-Matched Analysis of National Inpatient Sample

Extracorporeal membrane oxygenation (ECMO) is a significant treatment modality for COVID-19 patients on ventilators. The current data is limited for understanding the indicators and outcomes of ECMO in COVID-19 patients with acute respiratory distress syndrome (ARDS). The National Inpatient Sample (NIS) database from 2020 was queried in this study. Among 1,666,960 patients admitted with COVID-19, 99,785 (5.98%) patients developed ARDS, and 60,114 (60.2%) were placed on mechanical ventilation. Of these mechanically ventilated COVID-ARDS patients, 2580 (4.3%) were placed on ECMO. Patients with ECMO intervention had higher adjusted odds (aOR) of blood loss anemia (aOR 9.1, 95% CI: 6.16-13.5, propensity score-matched (PSM) 42% vs 5.4%, P < 0.001), major bleeding (aOR 3.79, 95% CI: 2.5-5.6, PSM 19.9% vs 5.9%, P < 0.001) and acute liver injury (aOR 1.7, 95% CI: 1.14-2.6 PSM 14% vs 6%, P = 0.009) compared to patients without ECMO intervention. However, in-hospital mortality, acute kidney injury, transfusions, acute MI, and cardiac arrest were insignificant. On subgroup analysis, patients placed on veno-arterial ECMO had higher odds of cardiogenic shock (aOR 13.4, CI 3.95-46, P < 0.0001), cardiac arrest (aOR 3.5, CI 1.45-8.47, P = 0.0057), acute congestive heart failure (aOR 4.18, CI 1.05-16.5, P = 0.042) and lower odds of major bleeding (aOR 0.26, CI 0.07-0.92). However, there was no significant difference in mortality, intracranial hemorrhage, and acute MI. Further studies are needed before considering COVID-19 ARDS patients for placement on ECMO.

Ischemic stroke and intracranial hemorrhage in extracorporeal membrane oxygenation for COVID-19: A systematic review and meta-analysis

PURPOSE

Extracorporeal membrane oxygenation (ECMO) is employed to support critically ill COVD-19 patients. The occurrence of ischemic stroke and intracranial hemorrhage (ICH), as well as the implementation of anticoagulation strategies under the dual influence of ECMO and COVID-19 remain unclear. We conducted a systematic review and meta-analysis to describe the ischemic stroke, ICH and overall in-hospital mortality in COVID-19 patients receiving ECMO and summarize the anticoagulation regimens.

METHODS

EMBASE, PubMed, Cochrane, and Scopus were searched for studies examining ischemic stroke, ICH, and mortality in COVID-19 patients supported with ECMO. The outcomes were incidences of ischemic stroke, ICH, overall in-hospital mortality and anticoagulation regimens. We calculated the pooled proportions and 95% confidence intervals (CIs) to summarize the results.

RESULTS

We analyzed 12 peer-reviewed studies involving 6039 COVID-19 patients. The incidence of ischemic stroke had a pooled estimate of 2.2% (95% CI: 1.2%-3.2%). The pooled prevalence of ICH was 8.0% (95% CI: 6.3%-9.6%). The pooled estimate of overall in-hospital mortality was 40.3% (95% CI: 33.1%-47.5%). The occurrence of ICH was significantly higher in COVID-19 patients supported with ECMO than in other respiratory ECMO [relative risk=1.75 (95% CI: 1.00-3.07)]. Unfractionated heparin was the most commonly used anticoagulant, and anticoagulation monitoring practice varied among centers.

CONCLUSIONS

Ischemic stroke and ICH were common under the double "hit" of COVID-19 and ECMO. The prevalence of ICH was significantly higher in COVID-19 patients supported with ECMO than non-COVID-19 patients requiring ECMO. Individualized anticoagulation regimens may be a good choice to balance thrombosis and bleeding. More detailed research and further exploration are needed to clarify the underlying mechanism and clinical management decisions.

Clinical impact of screening computed tomography in extracorporeal membrane oxygenation: a retrospective cohort study

BACKGROUND

Data on the prevalence and clinical impact of extrapulmonary findings at screening computed tomography (CT) on initiation of veno-venous extracorporeal membrane oxygenation (V-V ECMO) are limited. We aimed to identify the prevalence of extrapulmonary findings on screening CT following V-V ECMO initiation. We hypothesized that extrapulmonary findings would influence clinical management and outcome.

METHODS

Retrospective analysis (2011-2021) of admission screening CT including head, abdomen and pelvis with contrast of consecutive patients on initiation of V-V ECMO. CT findings identified by the attending consultant radiologist were extracted. Demographics, admission physiological and laboratory data, clinical decision-making following CT and ECMO ICU mortality were recorded from the electronic medical record. We used multivariable logistic regression and Kaplan-Meier curves to evaluate associations between extrapulmonary findings and ECMO ICU mortality.

RESULTS

Of the 833 patients receiving V-V ECMO, 761 underwent routine admission CT (91.4%). ECMO ICU length of stay was 19 days (IQR 12-23); ICU mortality at the ECMO centre was 18.9%. An incidental extrapulmonary finding was reported in 227 patients (29.8%), leading to an invasive procedure in 12/227 cases (5.3%) and a change in medical management (mainly in anticoagulation strategy) in 119/227 (52.4%). Extrapulmonary findings associated with mortality were intracranial haemorrhage (OR 2.34 (95% CI 1.31-4.12), cerebral infarction (OR 3.59 (95% CI 1.26-9.86) and colitis (OR 2.80 (95% CI 1.35-5.67).

CONCLUSIONS

Screening CT frequently identifies extrapulmonary findings of clinical significance. Newly detected intracranial haemorrhage, cerebral infarction and colitis were associated with increased ICU mortality.

R. Whitman G, Cho SM. A recommended preclinical extracorporeal cardiopulmonary resuscitation model for neurological outcomes: A scoping review

Background

Despite the high prevalence of neurological complications and mortality associated with extracorporeal cardiopulmonary resuscitation (ECPR), neurologically-focused animal models are scarce. Our objective is to review current ECPR models investigating neurological outcomes and identify key elements for a recommended model.

Methods

We searched PubMed and four other engines for animal ECPR studies examining neurological outcomes. Inclusion criteria were: animals experiencing cardiac arrest, ECPR/ECMO interventions, comparisons of short versus long cardiac arrest times, and neurological outcomes.

Results

Among 20 identified ECPR animal studies (n = 442), 13 pigs, 4 dogs, and 3 rats were used. Only 10% (2/20) included both sexes. Significant heterogeneity was observed in experimental protocols. 90% (18/20) employed peripheral VA-ECMO cannulation and 55% (11/20) were survival models (median survival = 168 hours; ECMO duration = 60 minutes). Ventricular fibrillation (18/20, 90%) was the most common method for inducing cardiac arrest with a median duration of 15 minutes (IQR = 6-20). In two studies, cardiac arrests exceeding 15 minutes led to considerable mortality and neurological impairment. Among seven studies utilizing neuromonitoring tools, only four employed multimodal devices to evaluate cerebral blood flow using Transcranial Doppler ultrasound and near-infrared spectroscopy, brain tissue oxygenation, and intracranial pressure. None examined cerebral autoregulation or neurovascular coupling.

Conclusions

The substantial heterogeneity in ECPR preclinical model protocols leads to limited reproducibility and multiple challenges. The recommended model includes large animals with both sexes, standardized pre-operative protocols, a cardiac arrest time between 10-15 minutes, use of multimodal methods to evaluate neurological outcomes, and the ability to survive animals after conducting experiments.

Lactate Dehydrogenase and Hemorrhagic Stroke During Extracorporeal Membrane Oxygenation for COVID-19

PURPOSE

Hemorrhagic stroke (HS) is a devastating complication during extracorporeal membrane oxygenation (ECMO) but markers of risk stratification during COVID-19 are unknown. Lactate dehydrogenase (LDH) is a readily available biomarker of cell injury and permeability. We sought to determine whether an elevated LDH before ECMO placement is related to the occurrence of HS during ECMO for COVID-19.

METHODS

Adult patients with COVID-19 requiring ECMO between March 2020 and February 2022 were included. LDH values prior to ECMO placement were captured. Patients were categorized into high (> 750 U/L) or low (≤ 750 U/L) LDH groups. Multivariable regression modeling was used to determine the association between LDH and HS during ECMO.

RESULTS

There were 520 patients that underwent ECMO placement in 17 centers and 384 had an available LDH. Of whom, 122 (32%) had a high LDH. The overall incidence of HS was 10.9%, and patients with high LDH had a higher incidence of HS than those with low LDH level (17% vs 8%, p = 0.007). At 100 days, the probability of a HS was 40% in the high LDH group and 23% in those with a low LDH, p = 0.002. After adjustment for clinical covariates, high LDH remained associated with subsequent HS (aHR: 2.64, 95% CI 1.39-4.92). Findings were similar when restricting to patients supported by venovenous ECMO only.

CONCLUSION

Elevated LDH prior to ECMO cannulation is associated with a higher incidence of HS during device support. LDH can risk stratify cases for impending cerebral bleeding during ECMO.

Epidemiology of Ischemic Stroke and Hemorrhagic Stroke in Venoarterial Extracorporeal Membrane Oxygenation

Background

While venoarterial extracorporeal membrane oxygenation (VA-ECMO) provides lifesaving support for cardiopulmonary failure, complications may arise that increase mortality, with few studies focusing on ischemic/hemorrhagic stroke. We aimed to determine the trends of stroke incidence and mortality, associations with each other, and associations with total case volume at each Extracorporeal Life Support Organization (ELSO) center.

Methods

Retrospective analysis of ELSO registry, including adult VA-ECMO patients from 534 international centers between 2012-2021, excluding extracorporeal cardiopulmonary resuscitation. Cochran-Armitage test and Poisson regression were used for trend analysis of stroke incidence and mortality. Kaplan-Meier curves, hazard functions, and multivariable logistic regression were used to study the impact of stroke on 90-day mortality.

Results

Of 33,041 patients (median age = 58 years, female = 32%), 4% developed ischemic stroke, and 2% developed hemorrhagic stroke. Ischemic stroke incidence increased (×1.21/year, p < 0.0001), while hemorrhagic stroke incidence remained stable, and overall 90-day mortality declined (1.78%/year, p < 0.0001). Ischemic/hemorrhagic strokes were associated with increased overall 90-day mortality (OR = 3.29, 3.99 respectively, both p < 0.0001) after controlling for pre-selected covariates, including age, pre/post-cannulation lab values, ECMO duration, center volume, and on-ECMO complications. Total center volume was associated positively with ischemic/hemorrhagic stroke incidences (OR = 1.039, 1.053 per-additional-100-cases respectively, both p = 0.022), but inversely with 90-day mortality (OR = 0.909 per-additional-100-cases, p < 0.0001). Hazard of death was highest in the first several days of VA-ECMO.

Conclusion

In VA-ECMO patients, while the reported ischemic stroke incidence steadily increased over time, 90-day mortality decreased. ELSO centers with higher case volumes reported greater stroke incidence, but lower mortality. Both ischemic/hemorrhagic strokes were associated with increased mortality.

Optic Nerve Ultrasound for Monitoring Deteriorating Intracranial Hemorrhage in a Patient on Extracorporeal Membrane Oxygenation: A Case Report

We present a 52-year-old male patient with cardiogenic shock who was placed on veno-arterial extracorporeal membrane oxygenation (ECMO) as a bridge to an orthotopic heart transplant. While on ECMO, the patient developed an acute intracranial bleed confirmed on computerized tomography (CT). However, his clinical status deteriorated and he was unstable for transport to evaluate for worsening hemorrhage. Instead, optic nerve sheath (ONS) ultrasonography was utilized to confirm increased intracranial pressure, which guided the goals of care until he stabilized enough to transport for advanced imaging. Repeat CT confirmed the worsening of his cerebellar bleed with obstructing hydrocephalus and brainstem compression. This case demonstrates how ONS ultrasound can be utilized in a cardiothoracic intensive care unit to evaluate sedated patients for new or worsening intracranial hemorrhage. In ECMO patients, who are often unstable with the risks of transportation for CT outweighing potential benefits, ONS ultrasonography can provide the care team with meaningful data on a patient's neurologic status.

Hypoxic-Ischemic Brain Injury in ECMO: Pathophysiology, Neuromonitoring, and Therapeutic Opportunities

Extracorporeal membrane oxygenation (ECMO), in conjunction with its life-saving benefits, carries a significant risk of acute brain injury (ABI). Hypoxic-ischemic brain injury (HIBI) is one of the most common types of ABI in ECMO patients. Various risk factors, such as history of hypertension, high day 1 lactate level, low pH, cannulation technique, large peri-cannulation PaCO2 drop (∆PaCO2), and early low pulse pressure, have been associated with the development of HIBI in ECMO patients. The pathogenic mechanisms of HIBI in ECMO are complex and multifactorial, attributing to the underlying pathology requiring initiation of ECMO and the risk of HIBI associated with ECMO itself. HIBI is likely to occur in the peri-cannulation or peri-decannulation time secondary to underlying refractory cardiopulmonary failure before or after ECMO. Current therapeutics target pathological mechanisms, cerebral hypoxia and ischemia, by employing targeted temperature management in the case of extracorporeal cardiopulmonary resuscitation (eCPR), and optimizing cerebral O2 saturations and cerebral perfusion. This review describes the pathophysiology, neuromonitoring, and therapeutic techniques to improve neurological outcomes in ECMO patients in order to prevent and minimize the morbidity of HIBI. Further studies aimed at standardizing the most relevant neuromonitoring techniques, optimizing cerebral perfusion, and minimizing the severity of HIBI once it occurs will improve long-term neurological outcomes in ECMO patients.

Lower Oxygen Tension and Intracranial Hemorrhage in Veno-venous Extracorporeal Membrane Oxygenation

INTRODUCTION AND METHODS

We examined the relationship between 24-h pre- and post-cannulation arterial oxygen tension (PaO2) and arterial carbon dioxide tension (PaCO2) and subsequent acute brain injury (ABI) in patients receiving veno-venous extracorporeal membrane oxygenation (VV-ECMO) with granular arterial blood gas (ABG) data and institutional standardized neuromonitoring.

RESULTS

Eighty-nine patients underwent VV-ECMO (median age = 50, 63% male). Twenty (22%) patients experienced ABI; intracranial hemorrhage (ICH) was the most common diagnosis (n = 14, 16%). Lower post-cannulation PaO2 levels were significantly associated with ICH (66 vs. 81 mmHg, p = 0.007) and a post-cannulation PaO2 level < 70 mmHg was more frequent in these patients (71% vs. 33%, p = 0.007). PaCO2 parameters were not associated with ABI. By multivariable logistic regression, hypoxemia post-cannulation increased the odds of ICH (OR = 5.06, 95% CI:1.41-18.17; p = 0.01).

CONCLUSION

In summary, lower oxygen tension in the 24-h post-cannulation was associated with ICH development. The precise roles of peri-cannulation ABG changes deserve further investigation, as they may influence the management of VV-ECMO patients.

Recognition of Strokes in the ICU: A Narrative Review

Despite the remarkable progress in acute treatment for stroke, in-hospital stroke is still devastating. The mortality and neurological sequelae are worse in patients with in-hospital stroke than in those with community-onset stroke. The leading cause of this tragic situation is the delay in emergent treatment. To achieve better outcomes, early stroke recognition and immediate treatment are crucial. In general, in-hospital stroke is initially witnessed by non-neurologists, but it is sometimes challenging for non-neurologists to diagnose a patient's state as a stroke and respond quickly. Therefore, understanding the risk and characteristics of in-hospital stroke would be helpful for early recognition. First, we need to know "the epicenter of in-hospital stroke". Critically ill patients and patients who undergo surgery or procedures are admitted to the intensive care unit, and they are potentially at high risk for stroke. Moreover, since they are often sedated and intubated, evaluating their neurological status concisely is difficult. The limited evidence demonstrated that the intensive care unit is the most common place for in-hospital strokes. This paper presents a review of the literature and clarifies the causes and risks of stroke in the intensive care unit.

Neurological manifestations of COVID-19 in adults and children

Different neurological manifestations of coronavirus disease 2019 (COVID-19) in adults and children and their impact have not been well characterized. We aimed to determine the prevalence of neurological manifestations and in-hospital complications among hospitalized COVID-19 patients and ascertain differences between adults and children. We conducted a prospective multicentre observational study using the International Severe Acute Respiratory and emerging Infection Consortium (ISARIC) cohort across 1507 sites worldwide from 30 January 2020 to 25 May 2021. Analyses of neurological manifestations and neurological complications considered unadjusted prevalence estimates for predefined patient subgroups, and adjusted estimates as a function of patient age and time of hospitalization using generalized linear models. Overall, 161 239 patients (158 267 adults; 2972 children) hospitalized with COVID-19 and assessed for neurological manifestations and complications were included. In adults and children, the most frequent neurological manifestations at admission were fatigue (adults: 37.4%; children: 20.4%), altered consciousness (20.9%; 6.8%), myalgia (16.9%; 7.6%), dysgeusia (7.4%; 1.9%), anosmia (6.0%; 2.2%) and seizure (1.1%; 5.2%). In adults, the most frequent in-hospital neurological complications were stroke (1.5%), seizure (1%) and CNS infection (0.2%). Each occurred more frequently in intensive care unit (ICU) than in non-ICU patients. In children, seizure was the only neurological complication to occur more frequently in ICU versus non-ICU (7.1% versus 2.3%, P < 0.001). Stroke prevalence increased with increasing age, while CNS infection and seizure steadily decreased with age. There was a dramatic decrease in stroke over time during the pandemic. Hypertension, chronic neurological disease and the use of extracorporeal membrane oxygenation were associated with increased risk of stroke. Altered consciousness was associated with CNS infection, seizure and stroke. All in-hospital neurological complications were associated with increased odds of death. The likelihood of death rose with increasing age, especially after 25 years of age. In conclusion, adults and children have different neurological manifestations and in-hospital complications associated with COVID-19. Stroke risk increased with increasing age, while CNS infection and seizure risk decreased with age.

Neurologic Complications of Patients With COVID-19 Requiring Extracorporeal Membrane Oxygenation: A Systematic Review and Meta-Analysis

In COVID-19 patients requiring extracorporeal membrane oxygenation (ECMO), our primary objective was to determine the frequency of intracranial hemorrhage (ICH). Secondary objectives were to estimate the frequency of ischemic stroke, to explore association between higher anticoagulation targets and ICH, and to estimate the association between neurologic complications and in-hospital mortality.

DATA SOURCES

We searched MEDLINE, Embase, PsycINFO, Cochrane, and MedRxiv databases from inception to March 15, 2022.

STUDY SELECTION

We identified studies that described acute neurological complications in adult patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection requiring ECMO.

DATA EXTRACTION

Two authors independently performed study selection and data extraction. Studies with 95% or more of its patients on venovenous or venoarterial ECMO were pooled for meta-analysis, which was calculated using a random-effects model.

DATA SYNTHESIS

Fifty-four studies (n = 3,347) were included in the systematic review. Venovenous ECMO was used in 97% of patients. Meta-analysis of ICH and ischemic stroke on venovenous ECMO included 18 and 11 studies, respectively. The frequency of ICH was 11% (95% CI, 8-15%), with intraparenchymal hemorrhage being the most common subtype (73%), while the frequency of ischemic strokes was 2% (95% CI, 1-3%). Higher anticoagulation targets were not associated with increased frequency of ICH (p = 0.06). In-hospital mortality was 37% (95% CI, 34-40%) and neurologic causes ranked as the third most common cause of death. The risk ratio of mortality in COVID-19 patients with neurologic complications on venovenous ECMO compared with patients without neurologic complications was 2.24 (95% CI, 1.46-3.46). There were insufficient studies for meta-analysis of COVID-19 patients on venoarterial ECMO.

CONCLUSIONS

COVID-19 patients requiring venovenous ECMO have a high frequency of ICH, and the development of neurologic complications more than doubled the risk of death. Healthcare providers should be aware of these increased risks and maintain a high index of suspicion for ICH.

Mechanical Thrombectomy for Ischemic Stroke Secondary to Large Vessel Occlusions in Patients on Extracorporeal Membrane Oxygenation

INTRODUCTION

The use of short-term mechanical circulatory support (MCS) devices and procedures for function- and life-sustaining therapy is becoming a routine practice at many centers. Concomitant with the increasing use of MCS is the increasing recognition of acute brain injuries, including acute ischemic stroke, which may be caused by a myriad of MCS-driven factors. The aim of this case series was to document our experience with mechanical thrombectomy (MT) for ischemic stroke in extracorporeal membrane oxygenation (ECMO) patients.

METHODS

We retrospectively reviewed a prospectively maintained database of patients undergoing endovascular thrombectomy for large vessel occlusion at our institution. We identified patients that were on ECMO and underwent thrombectomy. Baseline demographics and procedural and functional outcomes were collected.

RESULTS

Three patients on ECMO were identified to have a large vessel occlusion and underwent thrombectomy. Two patients had an internal carotid artery terminus occlusion and one had a basilar artery occlusion. An mTICI 3 recanalization was achieved in all patients without postoperative hemorrhagic complications. Two patients achieved a 3-month mRS of 1, while one had mRS 4.

CONCLUSION

Ischemic stroke can be associated with significant morbidity in MCS patients. We demonstrate that MT can be safely performed in this patient population with good outcomes.

Characterization of Cerebral Hemodynamics with TCD in Patients Undergoing VA-ECMO and VV-ECMO: a Prospective Observational Study

BACKGROUND

Extracorporeal membrane oxygenation has a high risk of acute brain injury and resultant mortality. Transcranial Doppler characterizes cerebral hemodynamics in real time, but limited data exist on its interpretation in ECMO. Here, we report TCD mean flow velocity and pulsatility index in a large ECMO population.

METHODS

This was a prospective cohort study at a tertiary care center. The patients were adults on venoarterial ECMO or venovenous ECMO undergoing TCD studies.

RESULTS

A total of 135 patients underwent a total of 237 TCD studies while on VA-ECMO (n = 95, 70.3%) or VV-ECMO (n = 40, 29.6%). MFVs were captured reliably (approximately 90%) and were similar to a published healthy cohort in all vessels except the internal carotid artery. Presence of a recordable PI was strongly associated with ECMO mode (57% in VA vs. 95% in VV, p < 0.001). Absence of TCD pulsatility was associated with intraparenchymal hemorrhage (14.7 vs. 1.6%, p = 0.03) in VA-ECMO patients.

CONCLUSIONS

Transcranial Doppler analysis in a single-center cohort of VA-ECMO and VV-ECMO patients demonstrates similar MFVs and PIs. Absence of PIs was associated with a higher frequency of intraparenchymal hemorrhage and a composite bleeding event. However, cautious interpretation and external validation is necessary for these findings with a multicenter study with a larger sample size.

Safety of Bedside Portable Low-Field Brain MRI in ECMO Patients Supported on Intra-Aortic Balloon Pump

(1) Background: Fifty percent of patients supported on veno-arterial extracorporeal membrane oxygenation (VA-ECMO) are concurrently supported with an intra-aortic balloon pump (IABP). Acute brain injury (ABI) is a devastating complication related to ECMO and IABP use. The standard of care for ABI diagnosis requires transport to a head CT (HCT) scanner. Recent data suggest that point-of-care (POC) magnetic resonance imaging (MRI) is safe and may be effective in diagnosing ABI in ECMO patients; however, no data exist in patients supported on ECMO with an IABP. We report pre-clinical safety data and a case series to evaluate the safety and feasibility of POC brain MRI in ECMO patients supported with IABP. (2) Methods: Prior to patient use, ex vivo testing with an IABP catheter within the Swoop^® Portable MRI (0.064 T) System™ was conducted. After IRB approval, clinical testing was performed for the safety and feasibility of early ABI detection. (3) Results: No deflection force was measured with a 7.5 French Maquet Linear IABP within the 0.064 T field. Three adult ECMO patients (average age: 40 years; 67% female) supported with IABP completed four POC brain MRI exams (median exam time: 30 min). Multiple signal abnormalities were detected on the POC brain MRI, corresponding to HCT results. (4) Conclusions: Our preliminary results suggest that adult VA-ECMO patients with IABP support can be safely imaged with low-field POC brain MRI in the intensive care unit, allowing for the early and bedside imaging of patients.

A phased intervention bundle to decrease the mortality of patients with extracorporeal membrane oxygenation in intensive care unit

Aim

To evaluate whether a phased multidimensional intervention bundle would decrease the mortality of patients with extracorporeal membrane oxygenation (ECMO) and the complication incidence.

Materials and methods

We conducted a prospective observational study in comparison with a retrospective control group in six intensive care units (ICUs) in China. Patients older than 18 years supported with ECMO between March 2018 to March 2022 were included in the study. A phased intervention bundle to improve the outcome of patients with ECMO was developed and implemented. Multivariable logistic regression modeling was used to compare the mortality of patients with ECMO and the complication incidence before, during, and up to 18 months after implementation of the intervention bundle.

Results

The cohort included 297 patients in 6 ICUs, mostly VA ECMO (68.7%) with a median (25th–75th percentile) duration in ECMO of 9.0 (4.0–15.0) days. The mean (SD) APECHII score was 24.1 (7.5). Overall, the mortality of ECMO decreased from 57.1% at baseline to 21.8% at 13–18 months after implementation of the study intervention (P < 0.001). In multivariable analysis, even after excluding the confounding factors, such as age, APECHII score, pre-ECMO lactate, and incidence of CRRT during ECMO, the intervention bundle still can decrease the mortality independently, which also remained true in the statistical analysis of V-V and V-A ECMO separately. Among all the ECMO-related complications, the incidence of bloodstream infection and bleeding decreased significantly at 13–18 months after implementation compared with the baseline. The CUSUM analysis revealed a typical learning curve with a point of inflection during the implementation of the bundle.

Conclusion

A phased multidimensional intervention bundle resulted in a large and sustained reduction in the mortality of ECMO that was maintained throughout the 18-month study period.

Clinical trial registration

[ClinicalTrials.gov], identifier [NCT05024786].

Transcranial Doppler microemboli and acute brain injury in extracorporeal membrane oxygenation: A prospective observational study

Objective

Extracorporeal membrane oxygenation (ECMO) carries a high morbidity of acute brain injury (ABI) with resultant mortality increase. Transcranial Doppler (TCD) allows real-time characterization of regional cerebral hemodynamics, but limited data exist on the interpretation of microembolic signals (MES) in ECMO.

Methods

This prospective cohort study was conducted at a single tertiary care center, November 2017 through February 2022, and included all adult patients receiving venoarterial (VA) and venovenous (VV) ECMO undergoing TCD examinations, which all included MES monitoring.

Results

Of 145 patients on ECMO who underwent at least 1 TCD examination, 100 (68.9%) patients on VA-ECMO received 187 examinations whereas 45 (31.1%) patients on VV-ECMO received 65 examinations (P = .81). MES were observed in 35 (35.0%) patients on VA-ECMO and 2 (4.7%) patients on VV-ECMO (P < .001), corresponding to 46 (24.6%) and 2 (3.1%) TCD examinations, respectively. MES were present in 29.4% of patients on VA-ECMO without additional cardiac support, compared with 38.1% with intra-aortic balloon pump and 57.1% with left ventricular assist device, but these differences were not statistically significant (P = .39; P = .20, respectively). Presence or number of MES was not associated with VA-ECMO cannulation mode (23.4% MES presence in peripheral cannulation vs 25.8% in central cannulation, P = .80). In both VA- and VV-ECMO, MES presence or number was not associated with presence of clot or fibrin in the ECMO circuit or with any studied hemodynamic, laboratory, or ECMO parameters at the time of TCD. ABI occurred in 38% and 31.1% of patients on VA- and VV-ECMO, respectively. In multivariable logistic regression analyses, neither ABI nor a composite outcome of arterial thromboembolic events was associated with presence or number of MES in VA- ECMO.

Conclusions

TCD analysis in a large cohort of patients on ECMO demonstrates a significant number of MES, especially in patients on VA-ECMO with intra-aortic balloon pump, and/or left ventricular assist device. However, clinical associations and significance of TCD MES remain unresolved and warrant further correlation with systematic imaging and long-term neurologic follow-up.

Assessing the SAfety and FEasibility of bedside portable low-field brain Magnetic Resonance Imaging in patients on ECMO (SAFE-MRI ECMO study): study protocol and first case series experience

BACKGROUND

To assess the safety and feasibility of imaging of the brain with a point-of-care (POC) magnetic resonance imaging (MRI) system in patients on extracorporeal membrane oxygenation (ECMO). Early detection of acute brain injury (ABI) is critical in improving survival for patients with ECMO support.

METHODS

Patients from a single tertiary academic ECMO center who underwent head CT (HCT), followed by POC brain MRI examinations within 24 h following HCT while on ECMO. Primary outcomes were safety and feasibility, defined as completion of MRI examination without serious adverse events (SAEs). Secondary outcome was the quality of MR images in assessing ABIs.

RESULTS

We report 3 consecutive adult patients (median age 47 years; 67% male) with veno-arterial (n = 1) and veno-venous ECMO (n = 2) (VA- and VV-ECMO) support. All patients were imaged successfully without SAEs. Times to complete POC brain MRI examinations were 34, 40, and 43 min. Two patients had ECMO suction events, resolved with fluid and repositioning. Two patients were found to have an unsuspected acute stroke, well visualized with MRI.

CONCLUSIONS

Adult patients with VA- or VV-ECMO support can be safely imaged with low-field POC brain MRI in the intensive care unit, allowing for the assessment of presence and timing of ABI.

Neurological Complications in COVID-19 Patients With ECMO Support: A Systematic Review and Meta-Analysis

BACKGROUND

Patients with Coronavirus disease 2019 (COVID-19)-related acute respiratory disease (ARDS) increasingly receive extracorporeal membrane oxygenation (ECMO) support. While ECMO has been shown to increase risk of stroke, few studies have examined this association in COVID-19 patients.

OBJECTIVE

We conducted a systematic review to characterise neurological events during ECMO support in COVID-19 patients.

DESIGN

Systematic review of cohort and large case series of COVID-19 patients who received ECMO support.

DATA SOURCES

Studies retrieved from PubMed, EMBASE, Cochrane, Cochrane COVID-19 Study Register, Web of Science, Scopus, Clinicaltrials.gov, and medRχiv from inception to November 11, 2020.

ELIGIBILITY CRITERIA

Inclusion criteria were a) Adult population (>18 year old); b) Positive PCR test for SARS-CoV-2 with active COVID-19 disease; c) ECMO therapy due to COVID-19 ARDS; and d) Neurological events and outcome described while on ECMO support. We excluded articles when no details of neurologic events were available.

RESULTS

1,322 patients from 12 case series and retrospective cohort studies were included in our study. The median age was 49.2, and 75% (n=985) of the patients were male. Diabetes mellitus and dyslipidaemia were the most common comorbidities (24% and 20%, respectively). Most (95%, n=1,241) patients were on venovenous ECMO with a median P:F ratio at the time of ECMO cannulation of 69.1. The prevalence of intracranial haemorrhage (ICH), ischaemic stroke, and hypoxic ischaemic brain injury (HIBI) was 5.9% (n=78), 1.1% (n=15), and 0.3% (n=4), respectively. The overall mortality of the 1,296 ECMO patients in the 10 studies that reported death was 36% (n=477), and the mortality of the subset of patients who had a neurological event was 92%.

CONCLUSIONS

Neurological injury is a concern for COVID-19 patients who receive ECMO. Further research is required to explore how neuromonitoring protocols can inform tailored anticoagulation management and improve survival in COVID-19 patients with ECMO support.

Association of COVID-19 with Intracranial Hemorrhage during Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome: A 10-Year Retrospective Observational Study

Extracorporeal membrane oxygenation (ECMO) is potentially lifesaving for patients with acute respiratory distress syndrome (ARDS) but may be accompanied by serious adverse events, including intracranial hemorrhage (ICRH). We hypothesized that ICRH occurs more frequently in patients with COVID-19 than in patients with ARDS of other etiologies. We performed a single-center retrospective analysis of adult patients treated with venovenous (vv-) ECMO for ARDS between January 2011 and April 2021. Patients were included if they had received a cranial computed tomography (cCT) scan during vv-ECMO support or within 72 h after ECMO removal. Cox regression analysis was used to identify factors associated with ICRH. During the study period, we identified 204 patients with vv-ECMO for ARDS, for whom a cCT scan was available. We observed ICRH in 35.4% (n = 17/48) of patients with COVID-19 and in 16.7% (n = 26/156) of patients with ARDS attributable to factors other than COVID-19. COVID-19 (HR: 2.945; 95%; CI: 1.079–8.038; p = 0.035) and carboxyhemoglobin (HR: 0.330; 95%; CI: 0.135–0.806; p = 0.015) were associated with ICRH during vv-ECMO. In patients receiving vv-ECMO, the incidence of ICRH is doubled in patients with COVID-19 compared to patients suffering from ARDS attributable to other causes. More studies on the association between COVID-19 and ICRH during vv-ECMO are urgently needed to identify risk patterns and targets for potential therapeutic interventions.

Ischemic and Hemorrhagic Stroke Among Critically Ill Patients With Coronavirus Disease 2019: An International Multicenter Coronavirus Disease 2019 Critical Care Consortium Study

OBJECTIVES

Stroke has been reported in observational series as a frequent complication of coronavirus disease 2019, but more information is needed regarding stroke prevalence and outcomes. We explored the prevalence and outcomes of acute stroke in an international cohort of patients with coronavirus disease 2019 who required ICU admission.

DESIGN

Retrospective analysis of prospectively collected database.

SETTING

A registry of coronavirus disease 2019 patients admitted to ICUs at over 370 international sites was reviewed for patients diagnosed with acute stroke during their stay.

PATIENTS

Patients older than 18 years old with acute coronavirus disease 2019 infection in ICU.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 2,699 patients identified (median age 59 yr; male 65%), 59 (2.2%) experienced acute stroke: 0.7% ischemic, 1.0% hemorrhagic, and 0.5% unspecified type. Systemic anticoagulant use was not associated with any stroke type. The frequency of diabetes, hypertension, and smoking was higher in patients with ischemic stroke than in stroke-free and hemorrhagic stroke patients. Extracorporeal membrane oxygenation support was more common among patients with hemorrhagic (56%) and ischemic stroke (16%) than in those without stroke (10%). Extracorporeal membrane oxygenation patients had higher cumulative 90-day probabilities of hemorrhagic (relative risk = 10.5) and ischemic stroke (relative risk = 1.7) versus nonextracorporeal membrane oxygenation patients. Hemorrhagic stroke increased the hazard of death (hazard ratio = 2.74), but ischemic stroke did not-similar to the effects of these stroke types seen in noncoronavirus disease 2019 ICU patients.

CONCLUSIONS

In an international registry of ICU patients with coronavirus disease 2019, stroke was infrequent. Hemorrhagic stroke, but not ischemic stroke, was associated with increased mortality. Further, both hemorrhagic stroke and ischemic stroke were associated with traditional vascular risk factors. Extracorporeal membrane oxygenation use was strongly associated with both stroke and death.

What Determines the Arterial Partial Pressure of Carbon Dioxide on Venovenous Extracorporeal Membrane Oxygenation?

Rapid reductions in PaCO2 during extracorporeal membrane oxygenation (ECMO) are associated with poor neurologic outcomes. Understanding what factors determine PaCO2 may allow a gradual reduction, potentially improving neurologic outcome. A simple and intuitive arithmetic expression was developed, to describe the interactions between the major factors determining PaCO2 during venovenous ECMO. This expression was tested using a wide range of input parameters from clinically feasible scenarios. The difference between PaCO2 predicted by the arithmetic equation and PaCO2 predicted by a more robust and complex in-silico mathematical model, was <10 mm Hg for more than 95% of the scenarios tested. With no CO2 in the sweep gas, PaCO2 is proportional to metabolic CO2 production and inversely proportional to the "total effective expired ventilation" (sum of alveolar ventilation and oxygenator ventilation). Extracorporeal blood flow has a small effect on PaCO2, which becomes more important at low blood flows and high recirculation fractions. With CO2 in the sweep gas, the increase in PaCO2 is proportional to the concentration of CO2 administered. PaCO2 also depends on the fraction of the total effective expired ventilation provided via the oxygenator. This relationship offers a simple intervention to control PaCO2 using titration of CO2 in the sweep gas.

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.

Narrative Review of Neurologic Complications in Adults on ECMO: Prevalence, Risks, Outcomes, and Prevention Strategies

Extracorporeal membrane oxygenation (ECMO), a life-saving technique for patients with severe respiratory and cardiac diseases, is being increasingly utilized worldwide, particularly during the coronavirus disease 2019(COVID-19) pandemic, and there has been a sharp increase in the implementation of ECMO. However, due to the presence of various complications, the survival rate of patients undergoing ECMO remains low. Among the complications, the neurologic morbidity significantly associated with venoarterial and venovenous ECMO has received increasing attention. Generally, failure to recognize neurologic injury in time is reportedly associated with poor outcomes in patients on ECMO. Currently, multimodal monitoring is increasingly utilized in patients with devastating neurologic injuries and has been advocated as an important approach for early diagnosis. Here, we highlight the prevalence and outcomes, risk factors, current monitoring technologies, prevention, and treatment of neurologic complications in adult patients on ECMO. We believe that an improved understanding of neurologic complications presumably offers promising therapeutic solutions to prevent and treat neurologic morbidity.

Brain injury in extracorporeal cardiopulmonary resuscitation: translational to clinical research

The addition of extracorporeal membrane oxygenation (ECMO) to conventional cardiopulmonary resuscitation (CPR), termed extracorporeal cardiopulmonary resuscitation (ECPR), has significantly improved survival in selected patient populations. Despite this advancement, significant neurological impairment persists in approximately half of survivors. ECPR represents a potential advancement for patients who experience refractory cardiac arrest (CA) due to a reversible etiology and do not regain spontaneous circulation. Important risk factors for acute brain injury (ABI) in ECPR include lack of perfusion, reperfusion, and altered cerebral autoregulation. The initial hypoxic-ischemic injury caused by no-flow and low-flow states after CA and during CPR is compounded by reperfusion, hyperoxia during ECMO support, and nonpulsatile blood flow. Additionally, ECPR patients are at risk for Harlequin syndrome with peripheral cannulation, which can lead to preferential perfusion of cerebral vessels with deoxygenated blood. Lastly, the oxygenator membrane is prothrombotic and requires systemic anticoagulation. The two competing phenomena result in thrombus formation, hemolysis, and thrombocytopenia, increasing the risk of ischemic and hemorrhagic ABI. In addition to clinical studies, we assessed available ECPR animal models to identify the mechanisms underlying ABI at the cellular level. Standardized multimodal neurological monitoring may facilitate early detection of and intervention for ABI. With the increasing use of ECPR, it is critical to understand the pathophysiology of ABI, its prevention, and the management strategies for improving the outcomes of ECPR. Translational and clinical research focusing on acute ABI immediately after ECMO cannulation and its short- and long-term neurological outcomes are warranted.

Diagnosis of Suspected Small Bowel Bleeding by Capsule Endoscopy in Patients with COVID-19

The current study evaluated the application of small-bowel capsule endoscopy (SBCE) in SARS-CoV-2-infected patients with suspected small bowel bleeding. We analyzed the clinical characteristics, SBCE procedures, examination results, and treatment for cases of suspected small bowel bleeding in two patients with critical COVID-19. SBCE showed active spotting bleeding in the jejunum and ileum with no identifiable lesions in case 1, while multiple small bowel ulcers were detected in case 2. Two patients had relevant changes in their management plans and received specific treatment based on SBCE findings. In summary, SBCE proved to be a non-invasive diagnostic tool for critical COVID-19 patients with suspected small bowel bleeding.

Extracorporeal Membrane Oxygenation Complications in Heparin- and Bivalirudin-Treated Patients

Supplemental Digital Content is available in the text.

OBJECTIVES:

Extracorporeal membrane oxygenation is a potentially life-saving intervention in refractory cardiopulmonary failure, but it requires anticoagulation to prevent circuit thromboses, which exposes the patient to hemorrhagic complications. Heparin has traditionally been the anticoagulant of choice, but the direct thrombin inhibitor bivalirudin is routinely used in cases of heparin-induced thrombocytopenia and has been suggested as a superior choice. We sought to examine the timing of hemorrhagic and thrombotic complications after extracorporeal membrane oxygenation cannulation and to compare the rates of such complications between patients anticoagulated with heparin versus bivalirudin.

DESIGN:

Retrospective cohort study.

SETTING:

Johns Hopkins Hospital patients between January 2016 and July 2019.

PATIENTS:

Adult (> 18 yr) extracorporeal membrane oxygenation patients.

INTERVENTIONS:

Patients were anticoagulated either with heparin or bivalirudin.

MEASUREMENTS AND MAIN RESULTS:

We compared rates of hemorrhagic and thrombotic complications by time on heparin versus bivalirudin and characterized the average time to each complication. Of 144 extracorporeal membrane oxygenation patients (mean age 55.3 yr; 58% male), 41% were on central venoarterial extracorporeal membrane oxygenation, 40% on peripheral venoarterial extracorporeal membrane oxygenation, and 19% on venovenous extracorporeal membrane oxygenation. Thirteen patients (9%) received bivalirudin during their extracorporeal membrane oxygenation run, due to concern for (n = 8) or diagnosis of (n = 4) heparin-induced thrombocytopenia or for heparin resistance (n = 1). The rate of hemorrhagic or thrombotic complications did not differ between heparin (0.13/d) and bivalirudin (0.06/d; p = 0.633), but patients on bivalirudin received significantly fewer blood transfusions (1.0 U of RBCs/d vs 2.9/d on heparin; p < 0.001).

CONCLUSIONS:

Our results confirm the safety and efficacy of bivalirudin as an alternative anticoagulant in extracorporeal membrane oxygenation and suggest a potential benefit in less blood product transfusion, although prospective studies are needed to evaluate the true effect of bivalirudin versus the disease processes that prompted its use in our study population.