Heparin-Sparing Anticoagulation Strategies Are Viable Options for Patients on Veno-Venous ECMO

Extended perioperative use of the ProtekDuo cannula for drainage in central venopulmonary-aortic ECMO for bilateral orthotopic lung transplantation

We present the case of a 24-year-old female who was supported with ProtekDuo cannula with variations of venopulmonary (VP) extracorporeal membrane oxygenation. The patient was cannulated for acute respiratory distress syndrome and she underwent bilateral orthotopic lung transplantation. This is the first report of the ProtekDuo cannula as a drainage cannula in central (dl)VP-/AO ECMO for 5 days.

Safety and feasibility of conversion from venoarterial to venovenous extracorporeal membrane oxygenation in pediatric patients: A case series

INTRODUCTION

In children requiring venoarterial (VA) extracorporeal membrane oxygenation (ECMO) for long durations, conversion to venovenous (VV) support may be advantageous. The purpose of this study was to evaluate the feasibility and safety of conversion from VA to VV ECMO.

METHODS

This is a retrospective review of all children who underwent conversion from VA to VV ECMO at a single institution, from 2015 to 2022. Indications for and methods of conversion were examined as well as adverse events including re-operation, ischemic complications, renal failure, and mortality.

RESULTS

Of 422 pediatric patients on initial VA ECMO, 4 children (0.9%) underwent conversion from VA to VV support. The indications for cannulation were: respiratory failure due to COVID19, respiratory failure due to congenital diaphragmatic hernia, cardiac dysfunction following heart transplant, and sepsis with associated left ventricular dysfunction. The indications for conversion were bleeding from the arterial cannula and ongoing respiratory failure. The median time to conversion was 6.5 days (range 4-54 days) and the median length of ECMO run was 34.5 days. Three patients required renal replacement therapy with two progressing to long-term dialysis. There were no ischemic limb complications although one patient developed a femoral artery pseudoaneurysm that required re-operation. Three patients survived to discharge. One patient was unable to be decannulated after conversion and mechanical support was withdrawn.

CONCLUSIONS

Conversion to VV ECMO from initial VA ECMO cannulation is feasible but a rare event. For patients with cardiac stability but continued need for respiratory support, conversion to VV ECMO can be considered.

Anticoagulation Can Be Held in Traumatically Injured Patients on Veno-Venous Extracorporeal Membrane Oxygenation Support

Traumatic injury is associated with several pulmonary complications, including pulmonary contusion, transfusion-related acute lung injury (TRALI), and the development of acute respiratory distress syndrome (ARDS). There is a lack of literature on these patients supported with veno-venous extracorporeal oxygenation (VV ECMO). Understanding the safety of using VV ECMO to support trauma patients and the ability to hold anticoagulation is important to broaden utilization. This is a single-center retrospective cohort study of adult trauma patients cannulated for VV ECMO during their initial admission over an 8 year period (2014-2021). We hypothesize that anticoagulation can be held in trauma patients on VV ECMO without increasing mortality or prothrombotic complications. We also describe the coagulopathy of traumatically injured patients on VV ECMO. Withholding anticoagulation was not associated with mortality in our study population, and there were no significant differences in bleeding or clotting complications between patients who did and did not receive systemic anticoagulation. Patients in the nonsurvivor group had increased coagulopathy both pre- and post-cannulation. Our study suggests anticoagulation can be safely withheld in traumatically injured VV ECMO patients without increasing mortality, complication rates, or transfusion requirements. Future, multicenter prospective studies with larger sample sizes are required to confirm our results.

Association of anti-factor Xa-guided anticoagulation with hemorrhage during ECMO support: A systematic review and meta-analysis

BACKGROUND

The use of extracorporeal membrane oxygenation (ECMO) is associated with complex hemostatic changes. Systemic anticoagulation is initiated to prevent clotting in the ECMO system, but this comes with an increased risk of bleeding. Evidence on the use of anti-Xa-guided monitoring to prevent bleeding during ECMO support is limited. Therefore, we aimed to analyze the association between anti-factor Xa-guided anticoagulation and hemorrhage during ECMO.

METHODS

A systematic review and meta-analysis was performed (up to August 2023).

PROSPERO

CRD42023448888.

RESULTS

Twenty-six studies comprising 2293 patients were included in the analysis, with six works being part of the meta-analysis. The mean anti-Xa values did not show a significant difference between patients with and without hemorrhage (standardized mean difference -0.05; 95% confidence interval [CI]: -0.19; 0.28, p = .69). We found a positive correlation between anti-Xa levels and unfractionated heparin dose (UFH; pooled estimate of correlation coefficients 0.44; 95% CI: 0.33; 0.55, p < .001). The most frequent complications were any type of hemorrhage (pooled 36%) and thrombosis (33%). Nearly half of the critically ill patients did not survive to hospital discharge (47%).

CONCLUSIONS

The most appropriate tool for anticoagulation monitoring in ECMO patients is uncertain. Our analysis did not reveal a significant difference in anti-Xa levels in patients with and without hemorrhagic events. However, we found a moderate correlation between anti-Xa and the UFH dose, supporting its utilization in monitoring UFH anticoagulation. Given the limitations of time-guided monitoring methods, the role of anti-Xa is promising and further research is warranted.

The impact of early perioperative heparin-free anticoagulation for extracorporeal membrane oxygenation on bleeding and thrombotic events in lung transplantation: a retrospective cohort study

BACKGROUND

Perioperative heparin-free anticoagulation extracorporeal membrane oxygenation (ECMO) for lung transplantation is rarely reported.

OBJECTIVE

To evaluate the impact of a heparin-free strategy on bleeding and thrombotic events, blood transfusion, and coagulation function during the early perioperative period and on prognosis, and to observe its effect on different ECMO types.

DESIGN

A retrospective cohort study.

METHODS

Data were collected from 324 lung transplantation patients undergoing early perioperative heparin-free ECMO between August 2017 and July 2022. Clinical data including perioperative bleeding and thrombotic events, blood product transfusion, coagulation indicators and 1-year survival were analysed.

RESULTS

Patients were divided in venovenous (VV; n = 251), venoarterial (VA; n = 40) and venovenous-arterial (VV-A; n = 33) groups. The VV group had the lowest intraoperative bleeding and thoracic drainage within 24 h postoperatively. Vein thrombosis occurred in 30.2% of patients within 10 days postoperatively or 1 week after ECMO withdrawal, and no significant difference was found among the three groups. Double lung transplantation, increased intraoperative bleeding, and increased postoperative drainage were associated with vein thrombosis. Except for acute myocardial infarction in one patient, no other serious thrombotic events occurred. The VV-ECMO group had the lowest demand for blood transfusion. The highest prothrombin time and the lowest fibrinogen levels were observed in the VA group during ECMO run, while the highest platelet counts were found in the VV group. Both intraoperative bleeding and thoracic drainage within 24 h postoperatively were independent predictors for 1-year survival, and no thrombosis-related deaths occurred.

CONCLUSION

Short-term heparin-free anticoagulation, particularly VV-ECMO, did not result in serious thrombotic events or thrombosis-related deaths, indicating that it is a safe and feasible strategy for perioperative ECMO in lung transplantation.

Review of anticoagulation considerations in extracorporeal membrane oxygenation support

Since its first success in 1975, extracorporeal membrane oxygenation (ECMO) has been used with increasing frequency for pulmonary and cardiopulmonary bypass. Use in adults has increased exponentially since the early 2000s, but despite thousands of international cannulations using both veno-arterial (VA) and veno-venous (VV) ECMO, there are still significant hemocompatibility-related adverse events. Current management of anticoagulation has been based on the Extracorporeal Life Support Organization guidance published in 2014 with recent updates published in 2022. Despite this guidance, there is still limited international consensus on how to manage anticoagulation in ECMO. For this review, we completed a comprehensive search of multiple electronic databases to identify studies pertaining to anticoagulation of adult patients on VV or VA-ECMO. The highest priority was given to sources that were prospective, randomized, controlled studies, but in the absence of such resources, observational studies, retrospective uncontrolled studies, and case series/reports were considered for inclusion. This document serves to provide a comprehensive review of the current understanding of management pertaining to anticoagulation relating to ECMO.

Current knowledge gaps in extracorporeal respiratory support

Extracorporeal life support (ECLS) for acute respiratory failure encompasses veno-venous extracorporeal membrane oxygenation (V-V ECMO) and extracorporeal carbon dioxide removal (ECCO2R). V-V ECMO is primarily used to treat severe acute respiratory distress syndrome (ARDS), characterized by life-threatening hypoxemia or ventilatory insufficiency with conventional protective settings. It employs an artificial lung with high blood flows, and allows improvement in gas exchange, correction of hypoxemia, and reduction of the workload on the native lung. On the other hand, ECCO2R focuses on carbon dioxide removal and ventilatory load reduction ("ultra-protective ventilation") in moderate ARDS, or in avoiding pump failure in acute exacerbated chronic obstructive pulmonary disease. Clinical indications for V-V ECLS are tailored to individual patients, as there are no absolute contraindications. However, determining the ideal timing for initiating extracorporeal respiratory support remains uncertain. Current ECLS equipment faces issues like size and durability. Innovations include intravascular lung assist devices (ILADs) and pumpless devices, though they come with their own challenges. Efficient gas exchange relies on modern oxygenators using hollow fiber designs, but research is exploring microfluidic technology to improve oxygenator size, thrombogenicity, and blood flow capacity. Coagulation management during V-V ECLS is crucial due to common bleeding and thrombosis complications; indeed, anticoagulation strategies and monitoring systems require improvement, while surface coatings and new materials show promise. Moreover, pharmacokinetics during ECLS significantly impact antibiotic therapy, necessitating therapeutic drug monitoring for precise dosing. Managing native lung ventilation during V-V ECMO remains complex, requiring a careful balance between benefits and potential risks for spontaneously breathing patients. Moreover, weaning from V-V ECMO is recognized as an area of relevant uncertainty, requiring further research. In the last decade, the concept of Extracorporeal Organ Support (ECOS) for patients with multiple organ dysfunction has emerged, combining ECLS with other organ support therapies to provide a more holistic approach for critically ill patients. In this review, we aim at providing an in-depth overview of V-V ECMO and ECCO2R, addressing various aspects of their use, challenges, and potential future directions in research and development.

Venovenous extracorporeal membrane oxygenation experience in a community level I trauma center

BACKGROUND

There is limited literature of venovenous extracorporeal membrane oxygenation use in a community, non-university, setting in the trauma population.

METHODS

We reviewed our cases over 2 years from March 2018 to March 2020. This study was conducted in a community hospital with a General Surgery residency with no direct affiliation to a medical school. Primary outcome reviewed was survival to discharge. Secondary outcomes included duration of extracorporeal membranous oxygenation (ECMO) support, blood transfusion requirement, complications, and disposition.

RESULTS

Five patients were cannulated during this time period. All patients survived to discharge. Mean time on ECMO was 153.4 h or 6.4 days (range 60-216 h). All patients required a transfusion while cannulated, with a mean of 10 units PRBC transfused (range 3-24). One patient required CPR, one required cessation of heparin drip for bleeding, and one had clinical signs of a stroke. Three patients were discharged to long-term acute care facilities and the other two to acute rehab.

CONCLUSIONS

Community level I trauma centers are capable of handling trauma patients requiring ECMO. It does require a multi-disciplinary team of surgical intensivists and cardiothoracic surgeons along with the support of nursing, respiratory therapists, and perfusionists. The outcomes in this limited series show that ECMO can be a tool utilized in the community setting.

Research status and development trend of extracorporeal membrane oxygenation based on bibliometrics

Background

Using bibliometric method to analyze the research status and development trend of extracorporeal membrane oxygenation (ECMO), we aim to provide clinicians, scientists, and stakeholders with the most up-to-date and comprehensive overview of ECMO research.

Materials and methods

Using Excel and VOSviewer, the literature on ECMO was systematically analyzed regarding publication trends, journal source, foundation, countries, institutions, core authors, research hotspots, and market distribution.

Results

There were five important time nodes in the research process of ECMO, including the success of the first ECMO operation, the establishment of ELSO, and the outbreak of influenza A/H1N1 and COVID-19. The R&amp;D centers of ECMO were the United States, Germany, Japan, and Italy, and the attention to ECMO was gradually increasing in China. The products most used in the literature were from Maquet, Medtronic, and LivaNova. Medicine enterprises attached great importance to the funding of ECMO research. In recent years, the literature has mainly focused on the following aspects: the treatment of ARDS, the prevention of coagulation system-related complications, the application in neonatal and pediatric patients, mechanical circulatory support for cardiogenic shock, and ECPR and ECMO during the COVID-19 pandemic.

Conclusion

The frequent epidemic occurrence of viral pneumonia and the technical advancement of ECMO in recent years have caused an increase in clinical applications. The hot spots of ECMO research are shown in the treatment of ARDS, mechanical circulatory support for cardiogenic shock, and the application during the COVID-19 pandemic.

Anticoagulation in adult patients supported with extracorporeal membrane oxygenation: guidance from the Scientific and Standardization Committees on Perioperative and Critical Care Haemostasis and Thrombosis of the International Society on Thrombosis and Haemostasis

Anticoagulation of patients supported by extracorporeal membrane oxygenation is challenging because of a high risk of both bleeding and thrombotic complications, and often empirical. Practice in anticoagulation management is therefore highly variable. The scope of this guidance document is to provide clinicians with practical advice on the choice of an anticoagulant agent, dosing, and the optimal anticoagulant monitoring strategy during extracorporeal membrane oxygenation support in adult patients.

Current and future strategies to monitor and manage coagulation in ECMO patients

Extracorporeal membrane oxygenation (ECMO) can provide life-saving support for critically ill patients suffering severe respiratory and/or cardiac failure. However, thrombosis and bleeding remain common and complex problems to manage. Key causes of thrombosis in ECMO patients include blood contact to pro-thrombotic and non-physiological surfaces, as well as high shearing forces in the pump and membrane oxygenator. On the other hand, adverse effects of anticoagulant, thrombocytopenia, platelet dysfunction, acquired von Willebrand syndrome, and hyperfibrinolysis are all established as causes of bleeding. Finding safe and effective anticoagulants that balance thrombosis and bleeding risk remains challenging. This review highlights commonly used anticoagulants in ECMO, including their mechanism of action, monitoring methods, strengths and limitations. It further elaborates on existing anticoagulant monitoring strategies, indicating their target range, benefits and drawbacks. Finally, it introduces several highly novel approaches to real-time anticoagulation monitoring methods including sound, optical, fluorescent, and electrical measurement as well as their working principles and future directions for research.

Continuous renal replacement therapy and extracorporeal membrane oxygenation: implications in the COVID-19 era

The novel severe acute respiratory syndrome coronavirus 2, SARS-CoV-2 (coronavirus Disease 19 (COVID-19)) was identified as the causative agent of viral pneumonias in Wuhan, China in December 2019, and has emerged as a pandemic causing acute respiratory distress syndrome (ARDS) and multiple organ dysfunction. Interim guidance by the World Health Organization states that extracorporeal membrane oxygenation (ECMO) should be considered as a rescue therapy in COVID-19-related ARDS. International registries tracking ECMO in COVID-19 patients reveal a 21%-70% incidence of acute renal injury requiring renal replacement therapy (RRT) during ECMO support. The indications for initiating RRT in patients on ECMO are similar to those for patients not requiring ECMO. RRT can be administered during ECMO via a temporary dialysis catheter, placement of a circuit in-line hemofilter, or direct connection of continuous RRT in-line with the ECMO circuit. Here we review methods for RRT during ECMO, RRT initiation and timing during ECMO, anticoagulation strategies, and novel cytokine filtration approaches to minimize COVID-19's pathophysiological impact.

Anticoagulation Management during Extracorporeal Membrane Oxygenation-A Mini-Review

Extracorporeal membrane oxygenation (ECMO) has been established as a life-saving technique for patients with the most severe forms of respiratory or cardiac failure. It can, however, be associated with severe complications. Anticoagulation therapy is required to prevent ECMO circuit thrombosis. It is, however, associated with an increased risk of hemocoagulation disorders. Thus, safe anticoagulation is a cornerstone of ECMO therapy. The most frequently used anticoagulant is unfractionated heparin, which can, however, cause significant adverse effects. Novel drugs (e.g., argatroban and bivalirudin) may be superior to heparin in the better predictability of their effects, functioning independently of antithrombin, inhibiting thrombin bound to fibrin, and eliminating heparin-induced thrombocytopenia. It is also necessary to keep in mind that hemocoagulation tests are not specific, and their results, used for setting up the dosage, can be biased by many factors. The knowledge of the advantages and disadvantages of particular drugs, limitations of particular tests, and individualization are cornerstones of prevention against critical events, such as life-threatening bleeding or acute oxygenator failure followed by life-threatening hypoxemia and hemodynamic deterioration. This paper describes the effects of anticoagulant drugs used in ECMO and their monitoring, highlighting specific conditions and factors that might influence coagulation and anticoagulation measurements.

Comparison of Bivalirudin Versus Heparin for Anticoagulation During Extracorporeal Membrane Oxygenation

The effect and safety of bivalirudin compared with heparin in patients undergoing extracorporeal membrane oxygenation (ECMO) remains unclear. Therefore, we conducted a systematic review and meta-analysis to compare the effectiveness and safety of heparin and bivalirudin in patients who underwent ECMO. We searched Embase, the Cochrane Central Register of Controlled Trials, and MEDLINE. Inclusion criteria included patients (1) undergoing ECMO and (2) receiving bivalirudin or heparin. We excluded studies where the majority of patients switched heparin to bivalirudin or vice versa during the clinical course. The primary outcome was short-term mortality. We presented the results of all analyses with the use of random-effects models. Eleven studies reported short-term mortality. The use of bivalirudin was associated with significantly lower short-term mortality, compared with heparin (odds ratio: 0.71, 95% confidence interval, 0.55-0.92; p = 0.01, I2 = 7%). In this meta-analysis of observational studies, the use of bivalirudin was associated with significantly lower short-term mortality, compared with heparin. Further prospective studies are warranted to clarify this finding.

Satisfactory outcome with activated clotting time <160 seconds in extracorporeal cardiopulmonary resuscitation

Patients undergoing cardiopulmonary resuscitation (CPR) prior to extracorporeal membrane oxygenation (ECMO) can have severely altered physiology, including that of the coagulation pathway. This could complicate the extracorporeal cardiopulmonary resuscitation (ECPR) management. We aimed to show that targeting an activated clotting time (ACT) < 160 seconds does not affect the complication rates in these patients. In this single-centered retrospective study, the medical records of 81 adult patients who were on ECMO support from March 2017 to March 2020 were reviewed. We compared the low ACT and conventional ACT groups, which were defined on the basis of the median of the ACT values of the included patients (160 seconds). The primary outcomes included bleeding or thromboembolic events. This study included 32 patients, who were divided into the low (n = 14) and conventional (n = 18) ACT groups. There were 2 cases of gastrointestinal bleeding (P = .183), one of intracranial hemorrhage (P = .437), and one of peripheral skin color change (P = .437) in the low ACT group. There was one case of prolonged bleeding at the cannulation site (P = 1.000) reported in the conventional ACT group. The successful weaning rate differed significantly between the low and conventional ACT groups (92.9% vs 50.0%; P = .019). Maintaining the ACT lower than the conventional ACT in patients requiring ECPR did not show a significant increase in the thromboembolic risk. Therefore, targeting a low ACT should be considered for this particular group of patients.

The Efficacy and Safety of Bivalirudin Versus Heparin in the Anticoagulation Therapy of Extracorporeal Membrane Oxygenation: A Systematic Review and Meta-Analysis

Background: Bivalirudin is a direct thrombin inhibitor (DTI) that can be an alternative to unfractionated heparin (UFH). The efficacy and safety of bivalirudin in anticoagulation therapy in extracorporeal membrane oxygenation (ECMO) remain unknown. Methods: This study followed the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. A systematic literature search was performed in PubMed, EMBASE, and The Cochrane Library databases to identify all relevant original studies estimating bivalirudin's efficacy and safety versus UFH as anticoagulation therapy in ECMO. The time limit for searching is from the search beginning to June 2021. Two researchers independently screened the literature, extracted data and evaluated the risk of bias of the included studies. The meta-analysis (CRD42020214713) was performed via the RevMan version 5.3.5 Software and STATA version 15.1 Software. Results: Ten articles with 847 patients were included for the quantitative analysis. Bivalirudin can significantly reduce the incidence of major bleeding in children (I 2 = 48%, p = 0.01, odd ratio (OR) = 0.17, 95% confidence interval (CI): 0.04-0.66), patient thrombosis (I 2 = 0%, p = 0.02, OR = 0.58, 95% CI: 0.37-0.93), in-circuit thrombosis/interventions (I 2 = 0%, p = 0.0005, OR = 0.40, 95% CI: 0.24-0.68), and in-hospital mortality (I 2 = 0%, p = 0.007, OR = 0.64, 95% CI: 0.46-0.88). Also, comparable clinical outcomes were observed in the incidence of major bleeding in adults (I 2 = 48%, p = 0.65, OR = 0.87, 95% CI: 0.46-1.62), 30-day mortality (I 2 = 0%, p = 0.61, OR = 0.83, 95% CI: 0.41-1.68), and ECMO duration in adults (I 2 = 41%, p = 0.75, mean difference (MD) = -3.19, 95% CI: -23.01-16.63) and children (I 2 = 76%, p = 0.65, MD = 40.33, 95% CI:-135.45-216.12). Conclusions: Compared with UFH, bivalirudin can be a safe and feasible alternative anticoagulant option to UFH as anticoagulation therapy in ECMO, especially for heparin resistance (HR) and heparin-induced thrombocytopenia (HIT) cases.

SEDAR/SECCE ECMO management consensus document

ECMO is an extracorporeal cardiorespiratory support system whose use has been increased in the last decade. Respiratory failure, postcardiotomy shock, and lung or heart primary graft failure may require the use of cardiorespiratory mechanical assistance. In this scenario perioperative medical and surgical management is crucial. Despite the evolution of technology in the area of extracorporeal support, morbidity and mortality of these patients continues to be high, and therefore the indication as well as the ECMO removal should be established within a multidisciplinary team with expertise in the area. This consensus document aims to unify medical knowledge and provides recommendations based on both the recent bibliography and the main national ECMO implantation centres experience with the goal of improving comprehensive patient care.

Anticoagulant-free venovenous extracorporeal membrane oxygenation for diffuse alveolar hemorrhage with bowel bleeding caused by antineutrophil cytoplasmic antibody-associated vasculitis: A case report

Antineutrophil cytoplasmic antibody-associated vasculitis (AAV) is sometimes complicated by diffuse alveolar hemorrhage (DAH), which may cause respiratory failure. Venovenous extracorporeal membrane oxygenation (VV-ECMO) without an anticoagulant because of hemorrhagic status, showed the effectiveness for severe respiratory failure by DAH with AAV. A 44-year-old woman developed DAH with bowel bleeding following the onset of AAV, with positive anti-proteinase-3 (PR3) antibodies. Although ventilator management could not support her respiratory status, VV-ECMO was performed. The patient was given immunosuppressive therapy comprising a steroid pulse, plasma exchange, and cyclophosphamide. After about 10 days of VV-ECMO and immunosuppressive therapy, VV-ECMO was withdrawn, and on day 12, ventilator support was stopped. Although a thrombus developed within the inferior vena cava (IVC), which required IVC filtration, the patient was discharged on day 51. VV-ECMO support was effective for treating DAH in this patient with new-onset AAV, which takes some time to achieve remission with immunosuppressive therapy.

Increased Intracranial Hemorrhage Amid Elevated Inflammatory Markers in Those With COVID-19 Supported With Extracorporeal Membrane Oxygenation

ABSTRACT

COVID-19-related coagulopathy is a known complication of SARS-CoV-2 infection and can lead to intracranial hemorrhage (ICH), one of the most feared complications of extracorporeal membrane oxygenation (ECMO). We sought to evaluate the incidence and etiology of ICH in patients with COVID-19 requiring ECMO. Patients at two academic medical centers with COVID-19 who required venovenous-ECMO support for acute respiratory distress syndrome (ARDS) were evaluated retrospectively. During the study period, 33 patients required ECMO support; 16 (48.5%) were discharged alive, 13 died (39.4%), and 4 (12.1%) had ongoing care. Eleven patients had ICH (33.3%). All ICH events occurred in patients who received intravenous anticoagulation. The ICH group had higher C-reactive protein (P = 0.04), procalcitonin levels (P = 0.02), and IL-6 levels (P = 0.05), lower blood pH before and after ECMO (P < 0.01), and higher activated partial thromboplastin times throughout the hospital stay (P < 0.0001). ICH-free survival was lower in COVID-19 patients than in patients on ECMO for ARDS caused by other viruses (49% vs. 79%, P = 0.02). In conclusion, patients with COVID-19 can be successfully bridged to recovery using ECMO but may suffer higher rates of ICH compared to those with other viral respiratory infections.

Contraindications to the Initiation of Veno-Venous ECMO for Severe Acute Respiratory Failure in Adults: A Systematic Review and Practical Approach Based on the Current Literature

(1) Background: Extracorporeal membrane oxygenation (ECMO) is increasingly used for acute respiratory failure with few absolute but many relative contraindications. The provider in charge often has a difficult time weighing indications and contraindications to anticipate if the patient will benefit from this treatment, a decision that often decides life and death for the patient. To assist in this process in coming to a good evidence-based decision, we reviewed the available literature. (2) Methods: We performed a systematic review through a literature search of the MEDLINE database of former and current absolute and relative contraindications to the initiation of ECMO treatment. (3) Results: The following relative and absolute contraindications were identified in the literature: absolute-refusal of the use of extracorporeal techniques by the patient, advanced stage of cancer, fatal intracerebral hemorrhage/cerebral herniation/intractable intracranial hypertension, irreversible destruction of the lung parenchyma without the possibility of transplantation, and contraindications to lung transplantation; relative-advanced age, immunosuppressed patients/pharmacological immunosuppression, injurious ventilator settings > 7 days, right-heart failure, hematologic malignancies, especially bone marrow transplantation and graft-versus-host disease, SAPS II score ≥ 60 points, SOFA score > 12 points, PRESERVE score ≥ 5 points, RESP score ≤ -2 points, PRESET score ≥ 6 points, and "do not attempt resuscitation" order (DN(A)R status). (4) Conclusions: We provide a simple-to-follow algorithm that incorporates absolute and relative contraindications to the initiation of ECMO treatment. This algorithm attempts to weigh pros and cons regarding the benefit for an individual patient and hopefully assists caregivers to make better, informed decisions.

Low vs standardized dose anticoagulation regimens for extracorporeal membrane oxygenation: A meta-analysis

Background

To compare the safety and efficacy of low-dose anticoagulation (LA) with that of standardized dose anticoagulation (SA) for patients supported with extracorporeal membrane oxygenation (ECMO).

Methods

PubMed, MEDLINE, the Cochrane Library, and Web of Science were screened for original articles. Screening was performed using predefined search terms to identify cohort studies reporting the comparison of LA with SA in patients supported with ECMO from Nov 1990 to Jun 2020. The effect size was determined by the odds ratio (OR) with the 95% confidence interval (CI).

Results

An analysis of 7 studies including a total of 553 patients was performed. LA (Low-heparin group) was administered to 255 patients, whereas the other 298 patients received SA (Full-heparin group). The incidence of gastrointestinal tract hemorrhage (OR 0.36, 95% CI 0.20–0.64) and surgical site hemorrhage (OR 0.43, 95% CI 0.20–0.94) were significantly lower in patients who underwent LA compared with that in those who underwent SA. The rates of hospital mortality (OR 0.81, 95% CI 0.42–1.56), successfully weaning off of ECMO (OR 0.80, 95% CI 0.30–2.14), pulmonary embolism (OR 0.79, 95% CI 0.24–2.65), intracardiac thrombus (OR 0.34, 95% CI 0.09–1.30), intracranial hemorrhage (OR 0.62, 95% CI 0.22–1.74), and pulmonary hemorrhage (OR 0.77, 95% CI 0.30–1.93) were similar between the two groups.

Conclusions

This meta-analysis confirms that LA is a feasible and safe anticoagulation strategy in patients supported by ECMO. Future studies should focus on the long-term benefits of LA compared with SA.

Anti-Xa activity and hemorrhagic events under extracorporeal membrane oxygenation (ECMO): a multicenter cohort study

BACKGROUND

Hemorrhagic events remain a major concern in patients under extracorporeal membrane oxygenation (ECMO) support. We tested the association between anticoagulation levels and hemorrhagic events under ECMO using anti-Xa activity monitoring.

METHODS

We performed a retrospective multicenter cohort study in three ECMO centers. All adult patients treated with veno-venous (VV)- or veno-arterial (VA)-ECMO in 6 intensive care units between September 2017 and August 2019 were included. Anti-Xa activities were collected until a hemorrhagic event in the bleeding group and for the duration of ECMO in the non-bleeding group. All dosages were averaged to obtain means of anti-Xa activity for each patient, and patients were compared according to the occurrence or not of bleeding.

RESULTS

Among 367 patients assessed for eligibility, 121 were included. Thirty-five (29%) presented a hemorrhagic complication. In univariate analysis, anti-Xa activities were significantly higher in the bleeding group than in the non-bleeding group, both for the mean anti-Xa activity (0.38 [0.29-0.67] vs 0.33 [0.22-0.42] IU/mL; p = 0.01) and the maximal anti-Xa activity (0.83 [0.47-1.46] vs 0.66 [0.36-0.91] IU/mL; p = 0.05). In the Cox proportional hazard model, mean anti-Xa activity was associated with bleeding (p = 0.0001). By Kaplan-Meier analysis with the cutoff value at 0.46 IU/mL obtained by ROC curve analysis, the probability of survival under ECMO without bleeding was significantly lower when mean anti-Xa was > 0.46 IU/mL (p = 0.0006).

CONCLUSION

In critically ill patients under ECMO, mean anti-Xa activity was an independent risk factor for hemorrhagic complications. Anticoagulation targets could be revised downward in both VV- and VA-ECMO.

A Systematic Literature Review of Packed Red Cell Transfusion Usage in Adult Extracorporeal Membrane Oxygenation

Background: Blood product administration plays a major role in the management of patients treated with extracorporeal membrane oxygenation (ECMO) and may be a contributor to morbidity and mortality. Methods: We performed a systematic review of the published literature to determine the current usage of packed red cell transfusions. Predefined search criteria were used to identify journal articles reporting transfusion practice in ECMO by interrogating EMBASE and Medline databases and following the PRISMA statement. Results: Out of 1579 abstracts screened, articles reporting ECMO usage in a minimum of 10 adult patients were included. Full texts of 331 articles were obtained, and 54 were included in the final analysis. All studies were observational (2 were designed prospectively, and two were multicentre). A total of 3808 patients were reported (range 10–517). Mean exposure to ECMO was 8.2 days (95% confidence interval (CI) 7.0–9.4). A median of 5.6% was not transfused (interquartile range (IQR) 0–11.3%, 19 studies). The mean red cell transfusion per ECMO run was 17.7 units (CI 14.2–21.2, from 52 studies) or 2.60 units per day (CI 1.93–3.27, from 49 studies). The median survival to discharge was 50.8% (IQR 40.0–64.9%). Conclusion: Current evidence on transfusion practice in ECMO is mainly drawn from single-centre observational trials and varies widely. The need for transfusions is highly variable. Confounding factors influencing transfusion practice need to be identified in prospective multicentre studies to mitigate potential harmful effects and generate hypotheses for interventional trials.

Successful extracorporeal life support in a pediatric trauma patient following angioembolization of pelvic hemorrhage

Extracorporeal Life Support (ECLS) is rarely used in pediatric trauma patients due to bleeding risk, and the use of ECLS following angioembolization of traumatic hemorrhage has never been reported in a child. We report a case of a 10-year-old boy run over by a parade float resulting in severe thoracic, abdominal, and pelvic trauma, with hemorrhage from pelvic fractures requiring massive transfusion. Due to ongoing blood product requirements and contrast extravasation near the symphysis pubis, angioembolization of the internal iliac arteries was performed. Extreme hypoxemia persisted despite maximal ventilator support due to pulmonary contusions and aspiration pneumonitis. Six hours after angioembolization, venovenous ECLS was initiated. Following an initial heparin bolus, ECLS was run without anticoagulation for 12 h, but development of circuit clot required resumption of low-dose heparin. After four days, his respiratory status improved substantially and ECLS was discontinued. There were no hemorrhagic complications. The patient was discharged home in good health following inpatient rehabilitation. In this case, ECLS was successfully used in the treatment of post-traumatic respiratory failure 6 h following angioembolization of pelvic hemorrhage in a pediatric trauma patient. Further research is needed to determine the safest interval between hemorrhage control and ECLS in severely injured children.

Comparison of anticoagulation strategies for veno-venous ECMO support in acute respiratory failure

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) support in acute respiratory failure may be lifesaving, but bleeding and thromboembolic complications are common. The optimal anticoagulation strategy balancing these factors remains to be determined. This retrospective study compared two institutional anticoagulation management strategies focussing on oxygenator changes and both bleeding and thromboembolic events.

METHODS

We conducted a retrospective observational cohort study between 04/2015 and 02/2020 in two ECMO referral centres in Germany in patients receiving veno-venous (VV)-ECMO support for acute respiratory failure for > 24 h. One centre routinely applied low-dose heparinization aiming for a partial thromboplastin time (PTT) of 35-40 s and the other routinely used a high-dose therapeutic heparinization strategy aiming for an activated clotting time (ACT) of 140-180 s. We assessed number of and time to ECMO oxygenator changes, 15-day freedom from oxygenator change, major bleeding events, thromboembolic events, 30-day ICU mortality, activated clotting time and partial thromboplastin time and administration of blood products. Primary outcome was the occurrence of oxygenator changes depending on heparinization strategy; main secondary outcomes were the occurrence of severe bleeding events and occurrence of thromboembolic events. The transfusion strategy was more liberal in the low-dose centre.

RESULTS

Of 375 screened patients receiving VV-ECMO support, 218 were included in the analysis (117 high-dose group; 101 low-dose group). Disease severity measured by SAPS II score was 46 (IQR 36-57) versus 47 (IQR 37-55) and ECMO runtime was 8 (IQR 5-12) versus 11 (IQR 7-17) days (P = 0.003). There were 14 oxygenator changes in the high-dose group versus 48 in the low-dose group. Freedom from oxygenator change at 15 days was 73% versus 55% (adjusted HR 3.34 [95% confidence interval 1.2-9.4]; P = 0.023). Severe bleeding events occurred in 23 (19.7%) versus 14 (13.9%) patients (P = 0.256) and thromboembolic events occurred in 8 (6.8%) versus 19 (19%) patients (P = 0.007). Mortality at 30 days was 33.3% versus 30.7% (P = 0.11).

CONCLUSIONS

In this retrospective study, ECMO management with high-dose heparinization was associated with lower rates of oxygenator changes and thromboembolic events when compared to a low-dose heparinization strategy. Prospective, randomized trials are needed to determine the optimal anticoagulation strategy in patients receiving ECMO support.

Veno-Venous Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome During Hemorrhagic Shock

Despite overall improvements in critical care, mortality from acute respiratory distress syndrome (ARDS) remains high. Veno-venous extracorporeal membrane oxygenation (V-V ECMO) is used to rescue patients with severe ARDS. Although V-V ECMO can be life-saving, there are significant risks associated with this therapy. Hemorrhage is one of the most common complications. Therefore, some providers are reluctant to use V-V ECMO in patients with severe ARDS who concurrently have a high risk of bleeding or recent active hemorrhage. Several studies have been published detailing the safety of heparin-sparing or completely heparin-free anticoagulation strategies in patients on V-V ECMO. We present the cases of two patients with hemorrhagic shock and ongoing transfusion requirements who developed severe and refractory ARDS while in the operating room for hemorrhage control. After the massive bleeding was stopped, both patients were placed on V-V ECMO and were managed with minimal or no therapeutic anticoagulation for the duration of their course on V-V ECMO. Both patients required multiple operations and procedures while on V-V ECMO and there were no significant hemorrhagic complications. In conclusion, V-V ECMO can be considered for use in select patients with severe ARDS and high risk of hemorrhage, active hemorrhage, or ongoing transfusion requirements.

Anticoagulation strategies in extracorporeal circulatory devices in adult populations

Extracorporeal circulatory devices such as hemodialysis and extracorporeal membrane oxygenation can be lifesaving; however, they are also prone to pathologic events including device failure, venous and arterial thrombosis, hemorrhage, and an accelerated risk for atherosclerotic disease due to interactions between blood components and device surfaces of varying biocompatibility. While extracorporeal devices may be used acutely for limited periods of time (eg, extracorporeal membrane oxygenation, continuous venovenous hemofiltration, therapeutic apheresis), some patients require chronic use of these technologies (eg, intermittent hemodialysis and left ventricular assist devices). Given the substantial thrombotic risks associated with extracorporeal devices, multiple antiplatelet and anticoagulation strategies-including unfractionated heparin, low-molecular-weight heparin, citrate, direct thrombin inhibitors, and direct oral anticoagulants, have been used to mitigate the thrombotic milieu within the patient and device. In the following manuscript, we outline the current data on anticoagulation strategies for commonly used extracorporeal circulatory devices, highlighting the potential benefits and complications involved with each.

Clinical and pathophysiologic aspects of ECMO-associated hemorrhagic complications

Extracorporeal membrane oxygenation (ECMO) is increasingly used to treat severe cases of acute respiratory or cardiac failure. Hemorrhagic complications represent one of the most common complications during ECMO, and can be life threatening. The purpose of this study was to elucidate pathophysiological mechanisms of ECMO-associated hemorrhagic complications and their impact on standard and viscoelastic coagulation tests. The study cohort included 27 patients treated with VV-ECMO or VA-ECMO. Hemostasis was evaluated using standard coagulation tests and viscoelastic parameters investigated with rotational thromboelastometry. Anticoagulation and hemorrhagic complications were analyzed for up to seven days depending on ECMO duration. Hemorrhagic complications developed in 16 (59%) patients. There were 102 discrete hemorrhagic episodes among 116 24-hour-intervals, of which 27% were considered to be clinically significant. The highest number of ECMO-associated hemorrhages occurred on the 2^nd and 3^rd day of treatment. Respiratory tract bleeding was the most common hemorrhagic complication, occurring in 62% of the 24-hour intervals. All 24-hours-intervals were divided into two groups: “with bleeding” and “without bleeding”. The probability of hemorrhage was significantly associated with abnormalities of four parameters: increased international normalized ratio (INR, sensitivity 71%, specificity 94%), increased prothrombin time (PT, sensitivity 90%, specificity 72%), decreased intrinsic pathway maximal clot firmness (MCFin, sensitivity 76%, specificity 89%), and increased extrinsic pathway clot formation time (CFTex, sensitivity 77%, specificity 87%). In conclusions, early ECMO-associated hemorrhagic complications are related to one traditional and two novel viscoelastic coagulation abnormalities: PT/INR elevation, reduced maximum clot firmness due to intrinsic pathway dysfunction (MCFin), and prolonged clot formation time due to extrinsic pathway dysfunction (CFTex). When managing hemostasis during ECMO, derangements in PT/INR, MCFin and CFT_ex should be focused on.

Extracorporeal membrane oxygenation and COVID-19: The causes of failure

Introduction

Venovenous extracorporeal membrane oxygenation (VV‐ECMO) is a therapeutic strategy for the coronavirus disease 2019 (COVID‐19) induced acute respiratory distress syndrome (ARDS). There are inconclusive data in this regard and causes of VV‐ECMO failure are not yet understood well.

Case Series

Here, seven patients with COVID‐19‐induced ARDS who underwent VV‐ECMO introduced and causes of VV‐ECMO failure discussed. Medical records of seven COVID‐19 patients treated with VV‐ECMO were retrospectively evaluated to determine the clinical outcomes of VV‐ECMO. Oxygenator failure occurred in four patients whom needed to oxygenator replacement. Successful VV‐ECMO decannulation was done in three patients, however finally one patient survived.

Conclusions

Hypercoagulability state and oxygenator failure were the most main etiologies for VV‐ECMO failure in our study. All patients with COVID‐19 undergoing VV‐ECMO should be monitored for such problems and highly specialized healthcare team should monitor the patients during VV‐ECMO.