Extracorporeal Life Support for Adults With Respiratory Failure and Related Indications: A Review

Organ donation in patients on extracorporeal membrane oxygenation: considerations for determination of death and withdrawal of life support

The use of extracorporeal membrane oxygenation (ECMO) is increasing globally, although mortality in this setting remains high. Patients on ECMO may be potential organ donors in the context of withdrawal of life-sustaining measures (WLSM) or neurologic determination of death (NDD). Nevertheless, there are currently no Canadian standards to guide clinicians on NDD or WLSM for the purposes of organ donation in this patient population. Apnea testing remains fundamental to determining NDD and is an area where ECMO may alter routine procedures. In this review, we outline protocols for the performance of apnea testing and WLSM for patients supported with ECMO, highlighting important technical and physiologic considerations that may affect the determination of death. In addition, we review important considerations for NDD in ECMO, including management of potential confounders, strategies for controlling oxygen and carbon dioxide levels during apnea testing, and the appropriate use of ancillary tests to support NDD. In the context of ECMO support, there is limited evidence to guide NDD and WLSM for the purposes of organ donation. Drawing upon extensive clinical experience, we provide protocols for these processes and review other important considerations in an effort to maximize donor potential in this growing patient population.

Temporary circulatory support for cardiogenic shock

Cardiogenic shock can occur due to acute ischaemic or non-ischaemic cardiac events, or from progression of long-standing underlying heart disease. When addressing the cause of underlying disease, the management of cardiogenic shock consists of vasopressors and inotropes; however, these agents can increase myocardial oxygen consumption, impair tissue perfusion, and are frequently ineffective. An alternative approach is to temporarily augment cardiac output using mechanical devices. The use of these devices-known as temporary circulatory support systems-has increased substantially in recent years, despite being expensive, resource intensive, associated with major complications, and lacking high-quality evidence to support their use. This Review summarises the physiological basis underlying the use of temporary circulatory support for cardiogenic shock, reviews the evidence informing indications and contraindications, addresses ethical considerations, and highlights the need for further research.

Extracorporeal Life Support Organization Coronavirus Disease 2019 Interim Guidelines: A Consensus Document from an International Group of Interdisciplinary Extracorporeal Membrane Oxygenation Providers

The Extracorporeal Life Support Organization (ELSO) Coronavirus Disease 2019 (COVID-19) Guidelines have been developed to assist existing extracorporeal membrane oxygenation (ECMO) centers to prepare and plan provision of ECMO during the ongoing pandemic. The recommendations have been put together by a team of interdisciplinary ECMO providers from around the world. Recommendations are based on available evidence, existing best practice guidelines, ethical principles, and expert opinion. This is a living document and will be regularly updated when new information becomes available. ELSO is not liable for the accuracy or completeness of the information in this document. These guidelines are not meant to replace sound clinical judgment or specialist consultation but rather to strengthen provision and clinical management of ECMO specifically, in the context of the COVID-19 pandemic.

Physical rehabilitation in the awake patient receiving extracorporeal circulatory or gas exchange support

Intensive care unit (ICU)-acquired weakness is a common and serious sequela of critical illness. There is a growing body of evidence supporting the use of early mobilization in the ICU to mitigate this adverse effect. Recent data suggest that such a strategy may be feasible in patients with the most severe forms of cardiopulmonary failure—those requiring temporary mechanical circulatory support (TCS) or extracorporeal life support (ECLS). Both the modality of mechanical support and patient-specific characteristics must be taken into consideration when determining the appropriateness of an early mobilization strategy. The purpose of this review is to explore the current understanding of and evidence for mobilization and rehabilitation of patients receiving TCS or ECLS, including the identification of factors that may predict greater success for early mobilization and potential risks and contraindications to active physical therapy. While it is not yet known which of these patients are most likely to benefit from physical rehabilitation, a common theme is the importance of an interprofessional team approach to ensure patient safety and maximize the likelihood of successful mobilization.

Suspected Virus-Inducing Severe Acute Respiratory Distress Syndrome Treated by Multimodal Therapy Including Extracorporeal Membrane Oxygenation and Immune Modulation Therapy

A 44-year-old man who had been feeling general fatigue was found in an unconscious state on the same day. He had no remarkable medical history. On arrival at the hospital, his Glasgow Coma Scale was E1V2M3; he had tachycardia and hypertension, was afebrile, and in a severe hypoxic state. His PaO₂/FiO₂ (P/F) was under 100, even with tracheal intubation with 100% oxygen. Chest X-ray and CT revealed a bilateral ground-glass appearance with consolidation. Cardiac echo initially showed hyper-dynamic wall motion. The main results of a blood analysis suggested an acute inflammatory reaction, rhabdomyolysis, and pancreatitis. The microscopic findings of sputum and a rapid test for bacterial and viral infections were all negative. As he showed deterioration of P/F, venovenous extracorporeal membrane oxygenation (ECMO) was started. He also showed hypotension and therefore underwent vasopressor and steroid administration. Due to concerns of pneumonia, he received meropenem and azithromycin in addition to the infusion of γ-globulin and glycyrrhizin. The results of a COVID-19 test, culture of sputum, and collagen disease test were all negative. The serum virus neutralization assay as a serological test for Coxsackievirus B4 showed a four-fold increase in titer. The multimodal therapy mentioned above resulted in the improvement of his general condition, including acute respiratory distress syndrome (ARDS). In this report, we discuss the benefits of ECMO and immune modulation therapy in the treatment of severe ARDS.

Extracorporeal Membrane Oxygenation Support in a Young Patient With COVID-19 Infection

Critically ill patients with coronavirus disease 2019 (COVID-19) infection often require mechanical ventilation, and still many of them will progress to worsening hypoxia and death. Veno-venous extracorporeal membrane oxygenation (VV-ECMO) has been used in some centers, but its role in the setting of COVID-19 infection is still unclear to date. We describe a case of a young female patient with obesity but otherwise no other underlying medical conditions who was admitted with respiratory failure secondary to COVID-19. Given her severe acute respiratory distress syndrome (ARDS) with refractory hypoxemia, she was treated with VV-ECMO. After a prolonged hospital course, she improved clinically and was able to have VV-ECMO explanted, after 18 days of extracorporeal therapy.

The complexity of ECMO therapy requires a well-trained multidisciplinary team present only at expert centers. The high resource cost is a challenge to the health care system in times of a global pandemic. Considering the limitations of this resource-intensive therapy, clinical judgment is crucial to decide whether ECMO is an appropriate option for the patient. However, for young patients with no underlying conditions who are critically ill despite optimized mechanical ventilation, we believe that extracorporeal therapy represents a reasonable option when available

PCTR1 improves pulmonary edema fluid clearance through activating the sodium channel and lymphatic drainage in lipopolysaccharide-induced ARDS

Acute respiratory distress syndrome (ARDS) is a lethal clinical syndrome characterized by damage of the epithelial barriers and accumulation of pulmonary edema fluid. Protectin conjugates in tissue regeneration 1 (PCTR1), an endogenously produced lipid mediator, are believed to exert anti-inflammatory and pro-resolution effects. PCTR1 (1 µg/kg) was injected at 8 hr after lipopolysaccharide (LPS; 14 mg/kg) administration, and the rate of pulmonary fluid clearance was measured in live rats at 1 hr after PCTR1 treatment. The primary type II alveolar epithelial cells were cultured with PCTR1 (10 nmol/ml) and LPS (1 μg/ml) for 8 hr. PCTR1 effectively improved pulmonary fluid clearance and ameliorated morphological damage and reduced inflammation of lung tissue, as well as improved the survival rate in the LPS-induced acute lung injury (ALI) model. Moreover, PCTR1 markedly increased sodium channel expression as well as Na, K-ATPase expression and activity in vivo and in vitro. In addition, PCTR1i also upregulated the expression of LYVE-1 in vivo. Besides that, BOC-2, HK7, and LY294002 blocked the promoted effect of PCTR1 on pulmonary fluid clearance. Taken together, PCTR1 upregulates sodium channels' expression via activating the ALX/cAMP/P-Akt/Nedd4-2 pathway and increases Na, K-ATPase expression and activity to promote alveolar fluid clearance. Moreover, PCTR1 also promotes the expression of LYVE-1 to recover the lymphatic drainage resulting in the increase of lung interstitial fluid clearance. In summary, these results highlight a novel systematic mechanism for PCTR1 in pulmonary edema fluid clearance after ALI/ARDS, suggesting its potential role in a therapeutic approach for ALI/ARDS.

Evolving Role of Anesthesiology Intensivists in Cardiothoracic Critical Care

The role of cardiothoracic anesthesiology intensivists has expanded over the past few decades. Cardiothoracic anesthesiology intensivists are taking on larger roles in cardiac critical care specializing in cardiogenic shock and extracorporeal membrane oxygenation.

ECMO, ARDS and meta-analyses: Bayes to the rescue?

PURPOSE

A recent meta-analysis by Munshi et al. (Lancet Respiratory Medicine, 2019) claimed mortality treatment efficacy for extra corporeal membrane oxygenation (ECMO) in the acute respitratory syndrome (ARDS) despite very low meta-analytic study numbers (n = 2 (RCTs), risk-ratio (RR) 0·73 (95%CI: 0·58-0·92); n = 5 (2 RCT, 3 observational), RR 0·69 (95%CI: 0·50-0·95)). We explore this efficacy claim by a comprehensive re-analysis of the data.

METHODS

Data were sourced from the two- and five-study meta-analyses, conducted using the Der-Simonian & Laird (DSL) method. A variety of frequentist (DSL, restricted maximum likelihood (REML), Paul-Mandel (PM), with/without Hartung-Knapp-Sidik-Jonkman variance correction), a beta-binomial model (BBN)) and Bayesian models (2 finite-mixture and several Markov-Chain-Monte-Carlo) were used to estimate treatment effects. Fragility-indices, the minimum patients changing mortality outcome needed to induce a conclusion change were also applied.

RESULTS

For the 2-study and 5-study meta-analysis only the uncorrected frequentist estimators (DSL, REML, PM) demonstrated significant RR. Except for the BBN model, which was significant for the 2-study meta-analysis, intervals for all other models included the null. Both meta-analyses demonstrated fragility.

CONCLUSIONS

Having canvassed the conduct of both meta-analyses presented by Munshi et al. and proffered alternative methods, we find no certainty regarding the efficacy of ECMO in ARDS.

Intelligent classification of platelet aggregates by agonist type

Platelets are anucleate cells in blood whose principal function is to stop bleeding by forming aggregates for hemostatic reactions. In addition to their participation in physiological hemostasis, platelet aggregates are also involved in pathological thrombosis and play an important role in inflammation, atherosclerosis, and cancer metastasis. The aggregation of platelets is elicited by various agonists, but these platelet aggregates have long been considered indistinguishable and impossible to classify. Here we present an intelligent method for classifying them by agonist type. It is based on a convolutional neural network trained by high-throughput imaging flow cytometry of blood cells to identify and differentiate subtle yet appreciable morphological features of platelet aggregates activated by different types of agonists. The method is a powerful tool for studying the underlying mechanism of platelet aggregation and is expected to open a window on an entirely new class of clinical diagnostics, pharmacometrics, and therapeutics.

Platelets are small cells in the blood that primarily help stop bleeding after an injury by sticking together with other blood cells to form a clot that seals the broken blood vessel. Blood clots, however, can sometimes cause harm. For example, if a clot blocks the blood flow to the heart or the brain, it can result in a heart attack or stroke, respectively. Blood clots have also been linked to harmful inflammation and the spread of cancer, and there are now preliminary reports of remarkably high rates of clotting in COVID-19 patients in intensive care units.

A variety of chemicals can cause platelets to stick together. It has long been assumed that it would be impossible to tell apart the clots formed by different chemicals (which are also known as agonists). This is largely because these aggregates all look very similar under a microscope, making it incredibly time consuming for someone to look at enough microscopy images to reliably identify the subtle differences between them. However, finding a way to distinguish the different types of platelet aggregates could lead to better ways to diagnose or treat blood vessel-clogging diseases.

To make this possible, Zhou, Yasumoto et al. have developed a method called the “intelligent platelet aggregate classifier” or iPAC for short. First, numerous clot-causing chemicals were added to separate samples of platelets taken from healthy human blood. The method then involved using high-throughput techniques to take thousands of images of these samples. Then, a sophisticated computer algorithm called a deep learning model analyzed the resulting image dataset and “learned” to distinguish the chemical causes of the platelet aggregates based on subtle differences in their shapes. Finally, Zhou, Yasumoto et al. verified iPAC method’s accuracy using a new set of human platelet samples.

The iPAC method may help scientists studying the steps that lead to clot formation. It may also help clinicians distinguish which clot-causing chemical led to a patient’s heart attack or stroke. This could help them choose whether aspirin or another anti-platelet drug would be the best treatment. But first more studies are needed to confirm whether this method is a useful tool for drug selection or diagnosis.

The Heart and COVID-19: What Cardiologists Need to Know

In face of the pandemic of the novel coronavirus disease 2019 (COVID-19), the management of patients with cardiovascular risk factors and/or disease is challenging. The cardiovascular complications evidenced in patients with COVID-19 derive from several mechanisms, ranging from direct viral injury to complications secondary to the inflammatory and thrombotic responses to the infection. The proper care of patients with COVID-19 requires special attention to the cardiovascular system aimed at better outcomes.

Planning and provision of ECMO services for severe ARDS during the COVID-19 pandemic and other outbreaks of emerging infectious diseases

WHO interim guidelines recommend offering extracorporeal membrane oxygenation (ECMO) to eligible patients with acute respiratory distress syndrome (ARDS) related to coronavirus disease 2019 (COVID-19). The number of patients with COVID-19 infection who might develop severe ARDS that is refractory to maximal medical management and require this level of support is currently unknown. Available evidence from similar patient populations suggests that carefully selected patients with severe ARDS who do not benefit from conventional treatment might be successfully supported with venovenous ECMO. The need for ECMO is relatively low and its use is mostly restricted to specialised centres globally. Providing complex therapies such as ECMO during outbreaks of emerging infectious diseases has unique challenges. Careful planning, judicious resource allocation, and training of personnel to provide complex therapeutic interventions while adhering to strict infection control measures are all crucial components of an ECMO action plan. ECMO can be initiated in specialist centres, or patients can receive ECMO during transportation from a centre that is not specialised for this procedure to an expert ECMO centre. Ensuring that systems enable safe and coordinated movement of critically ill patients, staff, and equipment is important to improve ECMO access. ECMO preparedness for the COVID-19 pandemic is important in view of the high transmission rate of the virus and respiratory-related mortality.

Extracorporeal membrane oxygenation (ECMO): does it have a role in the treatment of severe COVID-19?

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has emerged since December 2019 in Wuhan city, and has quickly spread throughout China and other countries. To date, no specific treatment has been proven to be effective for SARS-CoV-2 infection. According to World Health Organization (WHO), management of coronavirus disease 19 (COVID-19) has mainly focused on infection prevention, case detection and monitoring, and supportive care. Given to the previous experience, extracorporeal membrane oxygenation (ECMO) has been proven to be an effective therapy in the treatment of respiratory failure or acute respiratory distress syndrome (ARDS). On the basis of similar principle, ECMO may be also an effective therapy in the treatment of severe COVID-19. In this study, we described and discussed the clinical outcomes of ECMO for ARDS patients, ECMO use for severe COVID-19 in China, the indications of ECMO use, and some important issues associated with ECMO.

Extracorporeal Membrane Oxygenation for Severe Respiratory Failure During Respiratory Epidemics and Pandemics: A Narrative Review

Introduction: Epidemics and pandemics from zoonotic respiratory viruses, such as the 2019 novel coronavirus, can lead to significant global intensive care burden as patients progress to acute respiratory distress syndrome (ARDS). A subset of these patients develops refractory hypoxaemia despite maximal conventional mechanical ventilation and require extracorporeal membrane oxygenation (ECMO). This review focuses on considerations for ventilatory strategies, infection control and patient selection related to ECMO for ARDS in a pandemic. We also summarise the experiences with ECMO in previous respiratory pandemics. Materials and Methods: A review of pertinent studies was conducted via a search using MEDLINE, EMBASE and Google Scholar. References of articles were also examined to identify other relevant publications. Results: Since the H1N1 Influenza pandemic in 2009, the use of ECMO for ARDS continues to grow despite limitations in evidence for survival benefit. There is emerging evidence to suggest that lung protective ventilation for ARDS can be further optimised while receiving ECMO so as to minimise ventilator-induced lung injury and subsequent contributions to multi-organ failure. Efforts to improve outcomes should also encompass appropriate infection control measures to reduce co-infections and prevent nosocomial transmission of novel respiratory viruses. Patient selection for ECMO in a pandemic can be challenging. We discuss important ethical considerations and predictive scoring systems that may assist clinical decision-making to optimise resource allocation. Conclusion: The role of ECMO in managing ARDS during respiratory pandemics continues to grow. This is supported by efforts to redefine optimal ventilatory strategies, reinforce infection control measures and enhance patient selection. Ann Acad Med Singapore 2020;49:199–214 Key words: Acute Respiratory Distress Syndrome, Coronavirus disease 2019, ECMO, Infection control, Mechanical ventilation

Veno-venous extracorporeal membrane oxygenation for severe pneumonia: COVID-19 case in Japan

Background

Veno‐venous extracorporeal membrane oxygenation (VV‐ECMO) is one of the ultimate treatments for acute respiratory failure. However, the effectiveness of ECMO in patients with novel coronavirus disease (COVID‐19) is unknown.

Case Presentation

A 72‐year‐old woman who was a passenger of a cruise ship tested positive for the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) while in quarantine on board using throat swab. Three days after admission, her condition deteriorated, and she was subsequently intubated. On day 6, VV‐ECMO was introduced. Lopinavir/ritonavir was given; continuous renal replacement therapy was also introduced. On day 10, her chest radiography and lung compliance improved. She was weaned off ECMO on day 12.

Conclusion

Treatment of severe pneumonia in COVID‐19 by ECMO should recognize lung plasticity considering time to ECMO introduction and interstitial biomarkers. In Japan, centralization of ECMO patients has not been sufficient. Thus, we suggest nationwide centralization and further research to respond to the crisis caused by COVID‐19.

ECLS-associated infections in adults: what we know and what we don't yet know

Extracorporeal life support (ECLS) is increasingly used in the management of patients with severe cardiopulmonary disease. Infections are frequently the etiologies underlying the respiratory, and occasionally cardiac, failure that necessitates ECLS. Just as importantly, infections are among the most commonly reported adverse events during ECLS. Infections in this setting may be the sequelae of prolonged critical illness or of underlying immune dysregulation; they may be hospital-acquired infections, and they may or may not be attributable to the presence of ECLS itself, the latter being an aspect that can be difficult to determine. Current registry data and evidence from the literature offer some insights, but also leave open many questions regarding the nature and significance of infections reported both before and during ECLS, including the question of any causal link between ECLS and the development of infections. An ongoing lack of consistency in the identification, diagnosis, management, and prevention of infections during ECLS is limiting our ability to interpret literature data and thus highlighting the need for more rigorous investigation and standardization of definitions. This review aims to characterize the current understanding of infections associated with the use of ECLS, taking into account data from the updated Extracorporeal Life Support Organization Registry, which provides important context for understanding the epidemiology and outcomes of these patients.

The Influence of Therapeutics on Prognostication After Cardiac Arrest

PURPOSE OF REVIEW

The goal of this review is to highlight the influence of therapeutic maneuvers on neuro-prognostication measures administered to comatose survivors of cardiac arrest. We focus on the effect of sedation regimens in the setting of targeted temperature management (TTM), one of the principle interventions known to improve neurological recovery after cardiac arrest. Further, we discuss the critical need for novel markers, as well as refinement of existing markers, among patients receiving extracorporeal membrane oxygenation (ECMO) in the setting of failed conventional resuscitation, known as extracorporeal cardiopulmonary resuscitation (ECPR).

RECENT FINDINGS

Automated pupillometry may have some advantage over standard pupillary examination for prognostication following TTM, sedation, or the use of ECMO after cardiac arrest. New serum biomarkers such as Neurofilament light chain have shown good predictive abilities and need further validation in these populations. There is a high-level uncertainty in brain death declaration protocols particularly related to apnea testing and appropriate ancillary tests in patients receiving ECMO. Both sedation and TTM alone and in combination have been shown to affect prognostic markers to varying degrees. The optimal approach to analog-sedation is unknown, and requires further study. Moreover, validation of known prognostic markers, as well as brain death declaration processes in patients receiving ECMO is warranted. Data on the effects of TTM, sedation, and ECMO on biomarkers (e.g., neuron-specific enolase) and electrophysiology measures (e.g., somatosensory-evoked potentials) is sparse. The best approach may be one customized to the individual patient, a precision-medicine approach.

Low-flow assessment of current ECMO/ECCO2R rotary blood pumps and the potential effect on hemocompatibility

Background

Extracorporeal carbon dioxide removal (ECCO₂R) uses an extracorporeal circuit to directly remove carbon dioxide from the blood either in lieu of mechanical ventilation or in combination with it. While the potential benefits of the technology are leading to increasing use, there are very real risks associated with it. Several studies demonstrated major bleeding and clotting complications, often associated with hemolysis and poorer outcomes in patients receiving ECCO₂R. A better understanding of the risks originating specifically from the rotary blood pump component of the circuit is urgently needed.

Methods

High-resolution computational fluid dynamics was used to calculate the hemodynamics and hemocompatibility of three current rotary blood pumps for various pump flow rates.

Results

The hydraulic efficiency dramatically decreases to 5–10% if operating at blood flow rates below 1 L/min, the pump internal flow recirculation rate increases 6–12-fold in these flow ranges, and adverse effects are increased due to multiple exposures to high shear stress. The deleterious consequences include a steep increase in hemolysis and destruction of platelets.

Conclusions

The role of blood pumps in contributing to adverse effects at the lower blood flow rates used during ECCO₂R is shown here to be significant. Current rotary blood pumps should be used with caution if operated at blood flow rates below 2 L/min, because of significant and high recirculation, shear stress, and hemolysis. There is a clear and urgent need to design dedicated blood pumps which are optimized for blood flow rates in the range of 0.5–1.5 L/min.