Comparison of Anticoagulation Strategies in Patients Requiring Venovenous Extracorporeal Membrane Oxygenation: Heparin Versus Bivalirudin

Meta-Analysis Comparing Bivalirudin Versus. Unfractionated Heparin in Adult Patients With Extracorporeal Membrane Oxygenation

Introduction: Unfractionated heparin (UFH) has traditionally been the agent of choice in patients on extracorporeal membrane oxygenation (ECMO). However, direct thrombin inhibitors (DTI) have recently garnered more attention in ECMO because of their advantages over UFH. Given the heterogeneous results of multiple recent published studies, we performed a meta-analysis to describe pooled outcomes between bivalirudin and UFH anticoagulation in patients on ECMO. Methods: Relevant studies were identified from MEDLINE and Google Scholar database searches through April 23, 2022. The primary efficacy outcome was thromboembolism (TE), and secondary efficacy outcomes included all-cause mortality and circuit thrombosis. The primary safety outcome was major bleeding. Results: A total of 6 studies were included in the meta-analysis. Bivalirudin use was associated with significantly lower risk of TE (OR 0.61; 95% CI 0.38-.99; P = .05; I2 = 0%) and circuit thrombosis (OR 0.51; 95% CI .32-.80; P = .004; I2 = 0%) compared with UFH. There was no significant difference in all-cause mortality risk (OR 0.75; 95% CI .52-1.09; P = .13; I2 = 30%) between the bivalirudin and UFH groups. No significant difference in the risk of major bleeding between 2 groups was found (OR 0.67; 95% CI 0.25-1.81; P = .43; I2 = 80%). Conclusion: These data support that bivalirudin is a reasonable alternative to UFH in patients on ECMO. Randomized controlled trials are needed to confirm bivalirudin's efficacy and safety results compared with UFH.

Comparison of bleeding and thrombotic outcomes in veno-venous extracorporeal membrane oxygenation: Heparin versus bivalirudin

OBJECTIVES

We aimed to evaluate thrombotic and hemorrhagic complications with heparin versus bivalirudin use in veno-venous extracorporeal membrane oxygenation (V-V ECMO).

METHODS

We performed a retrospective cohort study of adult patients placed on V-V ECMO with intravenous anticoagulation with either heparin or bivalirudin. Time to thrombotic event and major bleed were analyzed in addition to related outcomes.

RESULTS

We identified 95 patients placed on V-V ECMO: 61 receiving heparin, 34 bivalirudin. The bivalirudin group had a higher rate of severe COVID-19, higher BMI, and longer ECMO duration. Despite this, bivalirudin was associated with reduced risk of thrombotic event (HR 0.14, 95% CI 0.06-0.32, p < .001) and increased average lifespan of the circuit membrane lung (16 vs. 10 days, p = 0.004). While there was no difference in major bleeding, the bivalirudin group required fewer transfusions of packed red blood cells and platelets per 100 ECMO days (means of 13 vs. 39, p = 0.004; 5 vs. 19, p = .014, respectively). Lastly, the bivalirudin group had improved survival to ECMO decannulation in univariate analysis (median OS 53 vs. 26 days, p = .015).

CONCLUSIONS

In this real-world analysis of bivalirudin versus heparin, bivalirudin is a viable option for V-V ECMO and associated with lower risk of thrombotic complications and fewer transfusion requirements.

Iatrogenic blood loss from phlebotomy during adult extracorporeal membrane oxygenation: A retrospective cohort study

BACKGROUND

Adult extracorporeal membrane oxygenation (ECMO) patients are at high risk for allogeneic blood transfusion. Few studies have characterized iatrogenic blood loss from phlebotomy in adult ECMO patients. We hypothesized that iatrogenic phlebotomy would be a significant source of blood loss during ECMO.

METHODS

Adults who had their entire ECMO run at our medical center between 2020 and 2022 were included. Average daily phlebotomy volume and total phlebotomy volume during ECMO were estimated based on the total number of laboratory tests that were processed. In addition, the crude and adjusted association between total phlebotomy volume during ECMO and RBC transfusion during ECMO was evaluated using linear regression and Loess curve analysis.

RESULTS

A total of 161 patients who underwent 162 ECMO runs were included. Of the 162 ECMO runs, 88 (54.3%) were veno-arterial and 74 (45.7%) were veno-venous ECMO. Median duration of ECMO was 5 days [25th, 75th percentile = 2, 11]. Median daily phlebotomy volume was 130 mLs [25th, 75th percentile = 94, 170] and median total phlebotomy volume during ECMO was 579 mLs [25th, 75th percentile = 238, 1314]. There was a significant crude and adjusted association between total phlebotomy volume and RBC transfusion during ECMO (beta coefficient = 0.0023 and 0.0024 respectively, both p < .001) based on linear regression analysis.

DISCUSSION

Phlebotomy for laboratory testing is a significant source of blood loss during ECMO in adults. Comprehensive patient blood management for adult ECMO patients should include strategies to reduce laboratory testing and/or phlebotomy volume during ECMO.

Use of bivalirudin after initial heparin management among adult patients on long-term venovenous extracorporeal support as a bridge to lung transplant: A case series

A growing body of evidence supports the use of bivalirudin as an alternative to unfractionated heparin (UFH) for the prevention of thrombotic events in patients on venovenous (VV) extracorporeal membrane oxygenation (ECMO). However, data in patients bridged to lung transplantation are limited. In this case series, we describe the outcomes of six patients who were transitioned from UFH to bivalirudin during their course of VV ECMO support as a bridge to lung transplantation. All six patients were on VV ECMO support until transplant, with a median duration of 73 days. Bivalirudin demonstrated a shorter time to first therapeutic activated thromboplastin time (aPTT) level. Additionally, time in therapeutic range was longer while patients were receiving bivalirudin compared to UFH (median 92.9% vs. 74.6%). However, major bleeding and thrombotic events occurred while patients were receiving either anticoagulant. Based on our experience, bivalirudin appears to be a viable option for anticoagulation in VV ECMO patients bridged to lung transplantation. Larger studies evaluating the optimal anticoagulation strategy in patients bridged to transplant are needed.

Anticoagulation and Bleeding during Veno-Venous Extracorporeal Membrane Oxygenation: Insights from the PROTECMO Study

Rationale: Definitive guidelines for anticoagulation management during veno-venous extracorporeal membrane oxygenation (VV ECMO) are lacking, whereas bleeding complications continue to pose major challenges. Objectives: To describe anticoagulation modalities and bleeding events in adults receiving VV ECMO. Methods: This was an international prospective observational study in 41 centers, from December 2018 to February 2021. Anticoagulation was recorded daily in terms of type, dosage, and monitoring strategy. Bleeding events were reported according to site, severity, and impact on mortality. Measurements and Main Results: The study cohort included 652 patients, and 8,471 days on ECMO were analyzed. Unfractionated heparin was the initial anticoagulant in 77% of patients, and the most frequently used anticoagulant during the ECMO course (6,221 d; 73%). Activated partial thromboplastin time (aPTT) was the most common test for monitoring coagulation (86% of days): the median value was 52 seconds (interquartile range, 39 to 61 s) but dropped by 5.3 seconds after the first bleeding event (95% confidence interval, -7.4 to -3.2; P < 0.01). Bleeding occurred on 1,202 days (16.5%). Overall, 342 patients (52.5%) experienced at least one bleeding event (one episode every 215 h on ECMO), of which 10 (1.6%) were fatal. In a multiple penalized Cox proportional hazard model, higher aPTT was a potentially modifiable risk factor for the first episode of bleeding (for 20-s increase; hazard ratio, 1.07). Conclusions: Anticoagulation during VV ECMO was a dynamic process, with frequent stopping in cases of bleeding and restart according to the clinical picture. Future studies might explore lower aPTT targets to reduce the risk of bleeding.

Concomitant use of extracorporeal membrane oxygenation and percutaneous microaxial assist device support for cardiogenic shock

Objectives

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) with concomitant percutaneous microaxial left ventricular assist device support is an emerging treatment modality for cardiogenic shock (CS). Survival outcomes by CS etiology with this support strategy have not been well described.

Methods

This study was a retrospective, single-center analysis of patients with CS due to acute myocardial infarction (AMI-CS) or decompensated heart failure (ADHF-CS) supported with VA-ECMO with concomitant percutaneous microaxial left ventricular assist device support from December 2020 to January 2023.

Results

A total of 44 patients were included (AMI-CS, n = 20, and ADHF-CS, n = 24). Patients with AMI-CS and ADHF-CS had similar survival at 90 days postdischarge (P = .267) with similar destinations after support (P = .220). Patients with AMI-CS initially supported with VA-ECMO were less likely to survive 90 days postdischarge (P = .038) when compared with other cohorts. Limb ischemia and acute kidney injury occurred more frequently in patients presenting with AMI-CS (P =.013; P = .030). Subanalysis of ADHF-CS patients into acute-on-chronic decompensated HF and de novo HF demonstrated no difference in survival or destination.

Conclusions

VA-ECMO with concomitant percutaneous microaxial left ventricular assist device support can be used to successfully manage patients with CS. There is no difference in survival or destination for AMI-CS and ADHF-CS with this support strategy. AMI-CS patients with initial VA-ECMO support have increased mortality in comparison to other cohorts. Future multicenter studies are required to fully analyze the differences between AMI-CS and ADHF-CS with this support strategy.

Evaluation of Bivalirudin During Adult Extracorporeal Membrane Oxygenation: A Retrospective Characterization of Dosing, Efficacy and Bleeding

Objective: Although heparin is the current standard anticoagulant during venoarterial (VA) and venovenous (VV) extracorporeal membrane oxygenation (ECMO), factors including heparin-induced thrombocytopenia, heparin resistance and drug shortages necessitate alternative anticoagulants such as direct thrombin inhibitors. The aim was to characterize dosing, safety, and efficacy of bivalirudin during ECMO support. Methods: This retrospective single-center study included 24 adults on ECMO support who received ≥6 hours of bivalirudin. The primary endpoint was dose to first therapeutic activated partial thromboplastin time (aPTT). Secondary endpoints included evaluating dosing between ECMO modes, incidence of bleeding and thrombotic events, and time in therapeutic range (TTR). Results: The dose at time of first therapeutic aPTT was bivalirudin 0.05 [0.05-0.1] mg/kg/hour. Bivalirudin dosing requirements were lower in VAECMO compared to VV-ECMO patients and were not impacted by continuous venovenous hemofiltration. Time to therapeutic aPTT was 5.5 [2-13] hours for VA-ECMO and 4.5 [2-8.6] hours for VV-ECMO patients. During any mode of ECMO TTR was 58.3% [39.6-73.1]. Thrombotic events occurred in 3 (13%) patients and major bleeding occurred in 12 (50%) patients. Conclusions: Our findings demonstrated variable bivalirudin dosing requirements based on mode of ECMO and dosing modifications may not be required during CVVH. Factors including mode of ECMO, indication for bivalirudin and concomitant antiplatelet therapy may impact hematologic events. Application of this data can assist with developing a bivalirudin ECMO protocol which provides less variability in initial dosing and TTR.

Bivalirudin-hydrogel coatings of polyvinyl chloride on extracorporeal membrane oxygenation for anticoagulation

Introduction

Thromboembolic events associated with extracorporeal membrane oxygenation (ECMO) in clinical treatment are typical. Heparin coating has been widely employed as a surface modification strategy for ECMO tubes. However, its clinical application is often accompanied by unavoidable complications due to its mechanism of action. As a direct thrombin inhibitor with a single target, Bivalirudin (BV) has exhibited a lower incidence of adverse events and superior pharmacokinetic performance compared to heparin.

Methods

A gelatin methacrylate hydrogel (GelMA) coating layer with BV was successfully synthesized on polyvinyl chloride, and the drug release ratio was close to complete release within 7 days.

Results and discussion

Simulated extracorporeal circulation experiments using roller pumps in vitro and jugular arteriovenous bypass experiments in rabbits demonstrated its outstanding anticoagulant efficacy. The systemic anticoagulant assay proved that BV hydrogel coating does not affect the coagulation level, and reduces the risk of complications such as systemic bleeding compared to intravenous injection. BV-Coating GelMA hydrogel tube has exhibited good biocompatibility and significantly improved anticoagulant performance, making it an optimal choice for surface materials used in blood-contacting medical devices.

Anticoagulants in adult extracorporeal membrane oxygenation: alternatives to standardized anticoagulation with unfractionated heparin

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is a vital technique for severe respiratory or heart failure patients. Bleeding and thrombotic events are common during ECMO and negatively impact patient outcomes. Unfractionated heparin is the primary anticoagulant, but its adverse effects limit its use, necessitating alternative anticoagulants.

OBJECTIVE

Review available alternative anticoagulants for adult ECMO patients. Explore potential novel anticoagulants for future ECMO use. Aim to reduce complications (bleeding and thrombosis) and improve safety and efficacy for critically ill ECMO patients.

METHODS

Comprehensive literature review of existing and emerging anticoagulants for ECMO.

RESULTS

Identified a range of alternative anticoagulants beyond unfractionated heparin. Evaluated their potential utility in mitigating ECMO-related complications.

CONCLUSION

Diverse anticoagulant options are available and under investigation for ECMO. These alternatives may enhance patient safety and outcomes during ECMO support. Further research and clinical studies are warranted to determine their effectiveness and safety profiles.

Approaches to Precision-based Anticoagulation management in the critically Ill

Anticoagulant therapy is commonly associated with a high incidence of avoidable adverse events, especially in the acute care setting. This has led to several initiatives by key national health care stakeholders, including specific attention to The Joint Commission's National Patient Safety Goals, to improve anticoagulation management. The subject of special populations has long been identified as challenging by clinicians with the use of anticoagulants. This is driven in part by numerous variables that can contribute to hard outcomes such as bleeding, thrombosis, length of stay, hospital re-admission, morbidity, and mortality. Despite the notable effort to improve the use of anticoagulants with numerous clinical trials, guidelines, guidance statements, and other sources of published evidence, notable difficulties continue to challenge practitioners in managing this class of medications. This is especially the case with very diverse critically ill populations where countless variables exist, many of which were never explored in trials or have historically been frequently excluded. Trials evaluating anticoagulation therapy often can only account for small portions of variables that may affect thrombosis and hemostasis, and study methods often do not reflect the constantly changing dynamic conditions seen in unique critically ill patients. Clinicians providing care to the numerous critically ill populations are faced with conditions that lead to relatively small therapeutic windows, which makes designing safe optimal anticoagulation management plans difficult when dealing with complex patients and mechanical support devices. The approach to crafting a successful management plan for anticoagulant therapy must incorporate the numerous variables that are continuously assessed and revised during the patient's time in the intensive care unit. We explore considerations and approaches when developing, assessing, and implementing an individualized or precision-based management plan that involves the use of anticoagulants in the critically ill. The skills and thought process provided will assist clinicians in managing this unique, variable, and challenging population.

Louis JD, Jain A, Bailey C, Jacobs JP, Weinstein S. Variation in outcomes with extracorporeal membrane oxygenation in the era of coronavirus: A multicenter cohort evaluation

Extracorporeal membrane oxygenation (ECMO) is used in critically ill patients with coronavirus disease 2019 (COVID-19) with acute respiratory distress syndrome unresponsive to other interventions. However, a COVID-19 infection may result in a differential tolerance to both medical treatment and ECMO management. The aim of this study was to compare outcomes (mortality, organ failure, circuit complications) in patients on ECMO with and without COVID-19 infection, either by venovenous (VV) or venoarterial (VA) cannulation. This is a multicenter, retrospective analysis of a national database of patients placed on ECMO between May 2020 and January 2022 within the United States. Nine-hundred thirty patients were classified as either Pulmonary (PULM, n = 206), Cardiac (CARD, n = 279) or COVID-19 (COVID, n = 445). Patients were younger in COVID groups: PULM = 48.4 ± 15.8 years versus COVID = 44.9 ± 12.3 years, p = 0.006, and CARD = 57.9 ± 15.4 versus COVID = 46.5 ± 11.8 years, p < 0.001. Total hours on ECMO were greatest for COVID patients with a median support time two-times higher for VV support (365 [101, 657] hours vs 183 [63, 361], p < 0.001), and three times longer for VA support (212 [99, 566] hours vs 70 [17, 159], p < 0.001). Mortality was highest for COVID patients for both cannulation types (VA-70% vs 51% in CARD, p = 0.041, and VV-59% vs PULM-42%, p < 0.001). For VA supported patients hepatic failure was more often seen with COVID patients, while for VV support renal failure was higher. Circuit complications were more frequent in the COVID group as compared to both CARD and PULM with significantly higher circuit change-outs, circuit thromboses and oxygenator failures. Anticoagulation with direct thrombin inhibitors was used more often in COVID compared to both CARD (31% vs 10%, p = 0.002) and PULM (43% vs 15%, p < 0.001) groups. This multicenter observational study has shown that COVID patients on ECMO had higher support times, greater hospital mortality and higher circuit complications, when compared to patients managed for either cardiac or pulmonary lesions.

Anticoagulation strategies in patients with extracorporeal membrane oxygenation: A network meta-analysis and systematic review

OBJECTIVES

Extracorporeal membrane oxygenation (ECMO) plays an important role in providing temporary life support for patients with severe cardiac or pulmonary failure, but requires strict anticoagulation and monitoring. This network meta-analysis systematically explored the most effective anticoagulation and monitoring strategies for patients receiving ECMO.

METHODS

MEDLINE, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials were searched up to January 31, 2023, for studies comparing unfractionated heparin (UFH), argatroban (Arg), bivalirudin (Biv), and/or nafamostat mesylate (NM) in patients receiving ECMO. The primary outcomes included device-related thrombosis, patient-related thrombosis, and major bleeding events. The secondary outcomes included ECMO survival, ECMO duration, and in-hospital mortality.

RESULTS

A total of 2522 patients from 23 trials were included in the study. Biv was associated with a decreased risk of device-related thrombosis (odd ratio [OR] 0.51, 95% confidence interval [CI]: 0.33-0.84) compared with UFH, whereas NM (OR 2.2, 95% CI: 0.24-65.0) and Arg (OR 0.92, 95% CI: 0.43-2.0) did not reduce the risk of device-related thrombosis compared with UFH. Biv was superior to Arg in decreasing the risk of device-related thrombosis (OR 0.14, 95% CI: 0.03-0.51). Biv reduced the risk of patient-related thrombosis compared with UFH (OR 0.44, 95% CI: 0.18-0.85); NM (OR 0.65, 95% CI: 0.14-3.3) and Arg (OR 3.1, 95% CI: 0.94-12.0) did not decrease risk of patient-related thrombosis compared with UFH. No significant difference was observed in the risk of major bleeding between three alternatives and UFH: Biv (OR 0.54, 95% CI: 0.23-1.3), Arg (OR 1.3, 95% CI: 0.34-5.8), and NM (OR 0.60, 95% CI: 0.13-2.6). NM showed a reduced risk of in-hospital mortality compared with UFH (OR 0.27, 95% CI: 0.091-0.77), whereas Arg (OR 0.43, 95% CI: 0.15-1.2) and Biv (OR 0.75, 95% CI: 0.52-1.1) did not decrease risk of in-hospital mortality.

CONCLUSIONS

Compared with UFH and Arg, Biv reduces the risk of thrombosis and appears to be a better choice for patients requiring ECMO. NM was associated with a reduced risk of in-hospital mortality.

Update on Anticoagulation Strategies in Patients with ECMO-A Narrative Review

The use of extracorporeal membrane oxygenation (ECMO) has recently increased exponentially. ECMO has become the preferred mode of organ support in refractory respiratory or circulatory failure. The fragile balance of haemostasis physiology is massively altered by the patient's critical condition and specifically the aetiology of the underlying disease. Furthermore, an application of ECMO conveys another disturbance of haemostasis due to blood-circuit interaction and the presence of an oxygenator. The purpose of this review is to summarise current knowledge on the anticoagulation management in patients undergoing ECMO therapy. The unfractionated heparin modality with monitoring of activated partial thromboplastin tests is considered to be a gold standard for anticoagulation in this specific subgroup of intensive care patients. However, alternative modalities with other agents are comprehensively discussed. Furthermore, other ways of monitoring can represent the actual state of coagulation in a more complex fashion, such as thromboelastometric/graphic methods, and might become more frequent. In conclusion, the coagulation system of patients with ECMO is altered by multiple variables, and there is a significant lack of evidence in this area. Therefore, a highly individualised approach is the best solution today.

Anticoagulation strategies in COVID-19 infected patients receiving ECMO support

BACKGROUND

Hospitalized COVID-19 patients with hypoxemic respiratory failure may deteriorate despite invasive mechanical ventilation and thus require extracorporeal membrane oxygenation (ECMO) support. Unfractionated heparin (UFH) is the antithrombotic of choice, however, bivalirudin may offer more predictable pharmacokinetics resulting in consistent anticoagulant effects with lower bleeding and thrombotic occurrences. The aim of this study was to evaluate efficacy and safety outcomes in patients undergoing venovenous (VV) ECMO receiving bivalirudin or UFH-based anticoagulation.

METHODS

This retrospective, single-center, observational cohort study included patients with confirmed COVID-19 infection requiring VV ECMO support receiving anticoagulation with UFH or bivalirudin. Primary endpoints were time to reach therapeutic aPTT, percent time spent in aPTT range, and the occurrence of thrombotic events over the entire course of ECMO support. Secondary endpoints included the incidence of major/minor bleeding, the ability to wean off ECMO support, in-hospital mortality, and length of stay.

RESULTS

Twenty-two patients were included in the study (n = 10 UFH, n = 12 bivalirudin). Time to therapeutic aPTT was achieved faster with UFH (10 h vs. 20 h). The percentage time spent within the goal aPTT range was similar between UFH and bivalirudin (50% vs. 52%). Thrombotic events were significantly higher in the UFH group (40% DVT, 40% PE, 80% oxygenator thrombus in ECMO machine, 10% ischemic stroke) versus bivalirudin (8% DVT, 17% PE, 33% oxygenator thrombus, no ischemic strokes) (CI 95%, p = 0.04). The overall bleeding incidence was higher in the UFH arm (90% vs. 75%). The mortality rate was 90% in the UFH group and 58% in the bivalirudin group. The length of stay was similar between the two study arms.

CONCLUSION

In hospitalized patients with COVID-19-associated acute respiratory distress syndrome (ARDS) on VV ECMO support, the use of bivalirudin showed to be a viable anticoagulation alternative in terms of efficacy compared to UFH and resulted in a favorable safety profile with lower rates of bleeding and thrombotic events.

Bivalirudin versus heparin anticoagulation in patients receiving extracorporeal membrane oxygenation

OBJECTIVE

Bivalirudin has been suggested as an alternative to heparin for anticoagulation in patients receiving extracorporeal membrane oxygenation (ECMO). Nevertheless, there is limited evidence about the benefit of bivalirudin in ECMO patients compared with heparin. Hence, we conducted a meta-analysis to assess the effect of bivalirudin versus heparin on clinical outcomes in patients receiving ECMO.

METHODS

PubMed, Embase, and the Cochrane Library were systematically searched from inception up to 1 April 2022 for cohort studies and randomized controlled trials comparing bivalirudin versus heparin in patients who received ECMO. The primary outcome was short-term death. Secondary outcomes included thrombotic events and bleeding events.

RESULTS

We selected 12 retrospective cohort studies with 1232 ECMO patients focusing on bivalirudin anticoagulation (n = 497) versus heparin anticoagulation (n = 735). Two hundred and one of 497 patients (40.4%) in the bivalirudin group versus 350 of 735 patients (47.6%) in the heparin group did not survive to hospital discharge. Compared with the heparin group, bivalirudin anticoagulation did not significantly decrease in-hospital mortality in patients receiving ECMO (RR, 0.95; 95% CI, 0.79-1.13; p = 0.546). Fifty-seven of 374 patients (15.2%) in the bivalirudin versus 99 of 381 patients (26.0%) in the heparin group suffered from thrombotic events. Compared with the heparin group, bivalirudin anticoagulation did not significantly decrease the rate of thrombotic events for patients receiving ECMO (RR, 0.78; 95% CI, 0.45-1.35; p = 0.378). However, bivalirudin anticoagulation significantly decreased the incidence of bleeding events compared to the heparin group (RR, 0.48; 95% CI, 0.25-0.95; p = 0.035).

CONCLUSIONS

Compared with heparin anticoagulation, bivalirudin did not decrease the rates of short-term mortality and thrombotic events, but reduced the incidence of bleeding events in patients receiving ECMO.

Is it time to switch to bivalirudin for ECMO anticoagulation?

For decades, unfractionated heparin (hereafter, heparin) has been the primary anticoagulant used for extracorporeal membrane oxygenation (ECMO) support. More recently, however, bivalirudin, a direct thrombin inhibitor, has emerged as an alternative. This systematic review based on PRISMA guidelines, aims to summarize 16 comparative studies and 8 meta-analysis and review articles published from January, 2011 till May, 2023 which directly compares ECMO courses using heparin versus bivalirudin as the anticoagulant. While this comparison is complicated by the lack of a standardized definition of major bleeding or thrombosis, our overall findings suggest there is no statistical difference between heparin and bivalirudin in incidence of bleeding and thrombosis. That said, some studies found a statistical significance favoring bivalirudin in reducing major bleeding, thrombosis, and the need for transfusions. We also offer essential guidance for appropriately selecting an anticoagulant and monitoring its effect in ECMO settings.

Extracorporeal membrane oxygenation for COVID-19 and influenza associated acute respiratory distress syndrome: a systematic review

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) has been used extensively for H1N1 influenza and coronavirus disease 2019 (COVID-19)-related acute respiratory distress syndrome (ARDS) to improve gas exchange and quickly correct hypoxemia and hypercapnia. This systematic review summarized the evidence on ECMO for the treatment of COVID-19 and influenza-associated ARDS.

RESEARCH DESIGN AND METHODS

This is a systematic review and meta-analysis of studies to compare the efficacy and safety of ECMO with conventional mechanical ventilation in adults with COVID-19 and influenza-associated ARDS. The study performed a structured search on PubMed, Embase, Web of Science, Scopus and The Cochrane Library. The primary outcome was hospital mortality.

RESULTS

The study included 15 observational studies with 5239 patients with COVID-19 and influenza-associated ARDS. The use of ECMO significantly reduced in-hospital mortality in COVID-19-associated ARDS (OR = 0.40; 95% CI = 0.27-0.58; P < 0.00001) but did not reduce influenza-related mortality (OR = 1.08; 95% CI = 0.41-2.87; P = 0.87). Moreover, ECMO treatment meaningfully increased the incidence of bleeding complications (OR = 7.66; 95% CI = 2.47-23.72; P = 0.0004).

CONCLUSION

The use of ECMO significantly reduced in-hospital mortality in COVID-19- associated ARDS, which may be related to the advances in ECMO-related techniques and the increased experience of clinicians. However, the incidence of bleeding complications remains high. [Figure: see text].

Comparison of bivalirudin versus heparin in adult extracorporeal membrane oxygenation anticoagulant therapy: A retrospective case-control study

INTRODUCTION

There were controversial opinions on the use of bivalirudin versus heparin for anticoagulant therapy in extracorporeal membrane oxygenation. The aim of our present study is to evaluate the efficacy and safety of bivalirudin versus heparin for the maintenance of systemic anticoagulation during adult veno-venous extracorporeal membrane oxygenation (V-V ECMO).

METHODS

Adult patients who received V-V ECMO support in our center between February 2018and February 2022 were retrospectively recruited. We analyzed their ECMO support time, platelet count, coagulation indicators, blood product infusion volume, the incidence of thrombosis and bleeding, probability of successful weaning of ECMO, and in-hospital mortality.

RESULTS

A total of 58 patients received V-V ECMO support. Thirty-four patients were finally included according to the exclusion and inclusion criteria, 14 and 20 accepted bivalirudin and heparin for anticoagulant therapy, respectively. The Minimum platelet value (98.50 × 10⁹/L (85.50, 123.75) vs 49.50 × 10⁹/L (31.25, 83.00), p = 0.002) and mean platelet value (149.90 × 10⁹/L (127.40, 164.80) vs 74.55 × 10⁹/L (62.45, 131.60), p = 0.03) and the ratio of successful weaning of ECMO (92.8% vs 60.0%, p = 0.033) in bivalirudin group were significantly higher than those in heparin group. The red blood cell infusion volume (7.00 U (3.00, 13.25) vs 13.75 U (7.25, 22.63), p = 0.039), platelet infusion volume (0.00 mL (0.00, 75.00) vs 300 mL (0.00, 825.00), p = 0.027), and the incidence of major bleeding (0.00% vs 30%, p = 0.024) in bivalirudin group were significantly lower than those in heparin group.

CONCLUSIONS

In V-V ECMO-supported adult patients, systemic anticoagulation with bivalirudin has achieved the same anticoagulation targets as heparin with less frequency of major bleeding events and lower requirement for blood products without significantly increased risk of thrombosis. Bivalirudin most likely is a safe and effective anticoagulation method for adult patients supported by V-V ECMO.

Correlation between partial thromboplastin time and thromboelastography in adult critically ill patients requiring bivalirudin for extracorporeal membrane oxygenation

STUDY OBJECTIVE

Thromboelastography (TEG) offers a more dynamic assessment of hemostasis over activated partial thromboplastin time (aPTT). However, the clinical utility of TEG in monitoring bivalirudin during extracorporeal membrane oxygenation (ECMO) remains unknown. The purpose of this study was to evaluate the correlation between aPTT and TEG in adult ECMO patients anticoagulated with bivalirudin.

DESIGN

Multicenter, retrospective, cohort study conducted over a 2-year period.

SETTING

Two academic university medical centers (Banner University Medical Center) in Phoenix and Tucson, AZ.

PATIENTS

Adult patients requiring ECMO and bivalirudin therapy with ≥1 corresponding standard TEG and aPTT plasma samples drawn ≤4 h of each other were included. The primary endpoint was to determine the correlation coefficient between the standard TEG reaction (R) time and bivalirudin aPTT serum concentrations.

MEASUREMENTS AND MAIN RESULTS

A total of 104 patients consisting of 848 concurrent laboratory assessments of R time and aPTT were included. A moderate correlation between TEG R time and aPTT was demonstrated in the study population (r = 0.41; p < 0.001). Overall, 502 (59.2%) concurrent assessments of TEG R time and aPTT values showed agreement on whether they were sub-, supra-, or therapeutic according to the institution's classification for bivalirudin. The 42.2% (n = 271/642) discordant TEG R times among "therapeutic" aPTT were almost equally distributed between subtherapeutic and supratherapeutic categories.

CONCLUSIONS

Moderate correlation was found between TEG R time and aPTT associated with bivalirudin during ECMO in critically ill adults. Further research is warranted to address the optimal test to guide clinical decision-making for anticoagulation dosing in ECMO patients.

Bivalirudin vs. Enoxaparin in Intubated COVID-19 Patients: A Pilot Multicenter Randomized Controlled Trial

(1) Background: In COVID-19 patients, the occurrence of thromboembolic complications contributes to disease progression and mortality. In patients at increased risk for thrombotic complications, therapeutic enoxaparin should be considered. However, critically ill COVID-19 patients could develop resistance to enoxaparin. Bivalirudin, a thrombin inhibitor, may be an alternative. This pilot multicenter randomized controlled trial aims to ascertain if bivalirudin may reduce the time spent under invasive mechanical ventilation, as compared to enoxaparin. (2) Methods: Intubated COVID-19 patients at risk for thrombo-embolic complications were randomized to receive therapeutic doses of enoxaparin or bivalirudin. We ascertained the time spent under invasive mechanical ventilation during the first 28 days from Intensive Care Unit (ICU) admission. A standardized weaning protocol was implemented in all centers. In addition, we assessed the occurrence of thromboembolic complications, the number of patients requiring percutaneous tracheostomy, the gas exchange, the reintubation rate, the ICU length of stay, the ICU and 28-days mortalities. (3) Results: We enrolled 58 consecutive patients. Bivalirudin did not reduce the time spent under invasive mechanical ventilation as compared to enoxaparin (12 [8; 13] vs. 13 [10; 15] days, respectively; p = 0.078). Thrombotic (p = 0.056) and embolic (p = 0.423) complications, need for tracheostomy (p = 0.423) or reintubation (p = 0.999), the ICU length of stay (p = 0.076) and mortality (p = 0.777) were also similar between treatments. Patients randomized to bivalirudin showed a higher oxygenation at day 7 and 15 after randomization, when compared to enoxaparin group. (4) Conclusions: In intubated COVID-19 patients at increased risk for thromboembolic complications, bivalirudin did not reduce the time spent under invasive mechanical ventilation, nor improved any other clinical outcomes.

Evaluation of clinical outcomes in patients treated with heparin or direct thrombin inhibitors during extracorporeal membrane oxygenation: a systematic review and meta-analysis

BACKGROUND

The number of patients treated with extracorporeal membrane oxygenation (ECMO) devices is increasing. Anticoagulation therapy is crucial to prevent thrombosis during ECMO therapy. Predominantly, heparin has been used as primary anticoagulant but direct thrombin inhibitors (DTI) have been established as alternatives. The aim of this systematic review and meta-analysis was to evaluate clinical outcomes in patients treated with heparin compared to different DTI during ECMO.

METHODS

A systematic search was conducted. Full scientific articles were sought for inclusion if heparin anticoagulation was compared to DTI (argatroban/bivalirudin) in ECMO patients. Risk of bias was assessed by Newcastle Ottawa scale. Primary endpoint was in-hospital mortality. Bleeding events, thrombotic events, hours of ECMO support, days of hospital stay, percentage of time within therapeutic range and time to therapeutic range were extracted from full texts as secondary endpoints. Results were presented as Forrest-plots. GRADE was used for confidence assessment in outcomes.

RESULTS

Systematic search identified 4.385 records, thereof 18 retrospective studies for a total of 1942 patients, complied with the predefined eligibility criteria:15 studies investigated bivalirudin and 3 studies investigated argatroban versus heparin. Risk of bias was high for most studies. In-hospital mortality, major bleeding events and pump-related thrombosis were less frequent in DTI group as compared to heparin [mortality-OR 0.69, 95% CI 0.54-0.86; major bleeding-OR 0.48, 95% CI 0.29-0.81; pump thrombosis-OR 0.55, 95% CI 0.40-0.76]. Additionally, percentage of time within therapeutic range was higher for DTI [SMD 0.54, 95% CI 0.14-0.94]. GRADE approach revealed a very low level of certainty for each outcome.

CONCLUSION

In this meta-analysis, DTI and especially bivalirudin showed beneficial effects on clinical outcomes in ECMO patients as compared to heparin. However, due to the lack of randomized trials, certainty of evidence is low.

TRIAL REGISTRATION

This systematic review and meta-analysis was prospectively registered at PROSPERO data base (reference number CRD42021237252 ).

The Changing Landscape of Anticoagulation in Pediatric Extracorporeal Membrane Oxygenation: Use of the Direct Thrombin Inhibitors

Bleeding and thrombosis frequently occur in pediatric patients with extracorporeal membrane oxygenation (ECMO) therapy. Until now, most patients are anticoagulated with unfractionated heparin (UFH). However, heparin has many disadvantages, such as binding to other plasma proteins and endothelial cells in addition to antithrombin, causing an unpredictable response, challenging monitoring, development of heparin resistance, and risk of heparin-induced thrombocytopenia (HIT). Direct thrombin inhibitors (DTIs), such as bivalirudin and argatroban, might be a good alternative. This review will discuss the use of both UFH and DTIs in pediatric patients with ECMO therapy.

Evaluation of anticoagulation with bivalirudin for heparin-induced thrombocytopenia during extracorporeal membrane oxygenation

INTRODUCTION

Unfractionated heparin is the most commonly utilized anticoagulant in extracorporeal membrane oxygenation (ECMO) due to clinician familiarity, ease of reversal, and low cost compared to alternative agents. However, heparin's anticoagulant effect can be unpredictable and its use accompanies a risk of heparin induced thrombocytopenia (HIT). Successful use of bivalirudin as an alternative to heparin in non-HIT ECMO patients has previously been described. However, there is a paucity of data regarding its utilization in patients with confirmed HIT on ECMO.

METHODS

This single-center retrospective chart review at Cleveland Clinic Main Campus included 12 ECMO patients who were managed with bivalirudin for a new diagnosis of HIT. Descriptive statistical analyses were performed utilizing median with interquartile range and number with percent as appropriate.

RESULTS

Of the 12 patients included, median ECMO duration was 328.5 (218.8-502.1) h and venoarterial ECMO was the most common configuration. No patients experienced the primary outcome of in-circuit thrombosis while on bivalirudin. One patient developed a deep vein thrombosis 22.5 h after switching from heparin to bivalirudin. Major bleeding occurred during bivalirudin therapy in 8 (66.7%) patients.

CONCLUSIONS

Overall, our study results suggest that bivalirudin is effective for the management of HIT and did not show evidence of in-circuit thrombosis. A high incidence of major bleeding was observed with bivalirudin use within this study. Clinicians should view bivalirudin as an acceptable agent for the treatment of HIT in the ECMO population, but must consider bleeding risk given the lack of effective reversal agents.

Direct Thrombin Inhibition in Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) is a widely used technique to provide circulatory and/or respiratory support in critically ill patients. ECMO treatment usually necessitates systemic anticoagulation. Unfractionated Heparin (UFH) is a commonly used anticoagulant in patients on ECMO support. In situations where UFH is contraindicated, alternative anticoagulation strategies can be applied, such as the use of direct thrombin inhibitors (DTI). Bivalirudin and argatroban are the most widely used DTIs. In this report we give account of the current evidence regarding dosing, monitoring and complications associated with the use of these agents in ECMO dependent patients.

Bivalirudin versus Heparin in Pediatric and Adult Patients on Extracorporeal Membrane Oxygenation: A Meta-analysis

AIMS

Unfractionated heparin (UFH) has been the primary anticoagulant of choice on extracorporeal membrane oxygenation (ECMO). However, it is debatable whether bivalirudin (BIV), a direct thrombin inhibitor, may be considered a better alternative anticoagulant option.

METHODS

We searched Embase, Pubmed, Cochrane library, Clinicaltrials.gov, CNKI, and Wanfang databases up to June 15, 2021. Randomized controlled trials (RCTs) and observational studies were considered eligible for inclusion. Random-effects meta-analyses, including subgroup analyses, were conducted.

RESULTS

A total of 9 studies containing 994 patients were enrolled. All articles were retrospective cohort studies. Compared with UFH, BIV was associated with lower risks of major bleeding (risk ratio [RR]: 0.32, 95% confidence interval [CI] 0.22-0.49), ECMO in-circuit thrombosis (RR: 0.57, 95% CI 0.43-0.74), stroke (RR: 0.52, 95% CI 0.29-0.95), in-hospital mortality (RR: 0.82, 95% CI 0.69-0.99) and higher rates of survival to ECMO decannulation (RR: 1.18, 95% CI 1.03-1.34). Pooled risk estimates did not show a significant association with clinical thrombotic events (RR: 0.69, 95% CI 0.45-1.07). Moreover, BIV was associated with a lower risk of ECMO in-circuit thrombosis and in-hospital mortality in the adult subgroup but not in the pediatric subgroup. However, leave-one-out sensitivity analyses indicated that the results of stroke, survival to ECMO decannulation and in-hospital mortality should be interpreted with caution.

CONCLUSIONS

BIV appears to be a potential alternative to UFH in pediatric and adult patients requiring ECMO.

A comprehensive review of vascular complications in COVID-19

This study aims to review the available literature pertinent to vascular complications in COVID-19. A systematic search was performed using PubMed and Google Scholar to identify all relevant studies based on our study objective. Multiple studies have reported widespread systemic inflammation and procoagulant/hypercoagulable state in COVID-19, including thrombotic microangiopathy, endothelial dysfunction, bleeding disorder, and thrombosis. However, large specialised studies on vascular complications are lacking despite current evidence indicating dysfunctional coagulation pathways. Furthermore, there are no clear and definitive recommendations regarding thromboprophylaxis or full therapeutic anticoagulation in COVID-19. Several studies have reported hypercoagulability and vascular complications as important predictors of patient outcome in COVID-19. Therefore, it is important to understand the pathogenesis, epidemiology, management, and outcomes of patients who develop venous or arterial thrombosis and those with a pre-existing thrombotic disease who contract COVID-19 for risk stratification, thromboprophylaxis, optimal antithrombotic therapy during active infection and long-term anticoagulation following discharge or recovery.

Efficacy of Bivalirudin for Therapeutic Anticoagulation in COVID-19 Patients Requiring ECMO Support

Objectives

The Coronavirus Disease 2019 (COVID-19) pandemic has been associated with cases of refractory acute respiratory distress syndrome (ARDS) sometimes requiring support with extracorporeal membrane oxygenation (ECMO). Bivalirudin can be used for anticoagulation in patients on ECMO support, but its efficacy and safety in patients with COVID-19 is unknown. The authors set out to compare the pharmacologic characteristics and dosing requirements of bivalirudin in patients requiring ECMO support for ARDS due to COVID-19 versus ARDS from other etiologies.

Design and Setting

This retrospective case-control study was performed at Indiana University Health Methodist Hospital in Indianapolis, Indiana.

Participants

Patients were included if they were on venovenous ECMO support between June 2019 and June 2020, and divided into two groups: ARDS secondary to COVID-19 and those with ARDS from another etiology (Non-COVID).

Interventions

Patient demographics, such as age, sex, weight, chronic comorbid conditions, baseline antiplatelet and anticoagulant use, antiplatelet use during ECMO, and need for renal replacement therapy were collected, and compared between groups. Time to activated partial thromboplastin time (aPTT) goal, percentage of time at aPTT goal, bivalirudin rates, total bivalirudin requirements, total duration on bivalirudin, total duration on ECMO, mortality, and complications associated with ECMO were collected and compared between groups.

Measurements and Main Results

A total of 42 patients met inclusion criteria (n = 19 COVID-19, n = 23 non-COVID). However, percentages of aPTTs at goal were maintained more consistently in patients with COVID-19 versus non-COVID (86% v 74%: p < 0.01). Higher median (IQR) daily rates (3.1 μg/kg/min [2.3-5.2] v 2.4 μg/kg/min [1.7-3.3]: p = 0.05) and higher median (IQR) maximum rates of bivalirudin (5 μg/kg/min [3.7-7.5] v 3.8 μg/kg/min [2.5-5]: p = 0.03) were required in the COVID-19 group versus the non-COVID group. Time to goal aPTT was similar between groups. There were no differences in complications associated with anticoagulation, as demonstrated by similar rates of bleeding and thrombosis between both groups.

Conclusions

Patients on ECMO with ARDS from COVID-19 require more bivalirudin overall and higher rates of bivalirudin to maintain goal aPTTs compared with patients without COVID-19. However, COVID-19 patients more consistently maintain goal aPTT. Future randomized trials are needed to support efficacy and safety of bivalirudin for anticoagulation of COVID-19 patients on ECMO.

Eleven Years of Venovenous Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome: From H1N1 to SARS-CoV-2. Experience and Perspectives of a National Referral Center

OBJECTIVE

Despite growing expertise and wide application of venovenous extracorporeal membrane oxygenation (VV ECMO) treatment for acute respiratory distress syndrome (ARDS) of different origin and during pandemics (H1N1 Influenza A virus and SARS-CoV-2), large reports are few and pertain mostly to multicenter registries, and randomized trials are difficult to perform. The aim of this study was to report outcomes, trends, and innovations of VV ECMO treatment over the last 11 years.

DESIGN, SETTING, AND PARTICIPANTS

Observational study on 142 patients treated at the IRCCS San Raffaele Hospital in Milan from June 2009 (year of the H1N1 pandemic) to May 2020 (SARS-CoV-2 pandemic).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The main causes of ARDS were H1N1 pneumonia in 36% of patients, bacterial pneumonia in 17%, and SARS-CoV-2 in 9%. Seventy-two percent of patients were centralized from remote hospitals, of whom 33% had implanted VV ECMO before transport. The most common cannulation strategy was the dual-lumen catheter cannulation system (55%), and anticoagulation was performed with bivalirudin in most patients (79%). Refractory hypoxia was treated with intravenous beta-blockers (64%), nitric oxide (20%), and pronation (8%). Almost one-third of patients (32%) were extubated while on ECMO. Forty-nine percent of patients were discharged from the intensive care unit, and hospital discharge was 46%; survival was lower in patients requiring VV ECMO for more than three weeks compared with shorter support duration (23% v 56%, p = 0.007). Anticoagulation with bivalirudin was associated with higher survival, compared with heparin (55% v 31%, p = 0.03), and lower thrombocytopenia incidence (69% v 35%, p = 0.003).

CONCLUSION

VV ECMO is the pivotal rescue treatment for refractory ARDS-timely treatment and optimal care are needed to optimize therapy, as duration of support is associated with outcome. Anticoagulation with bivalirudin may improve outcome.

Acute Kidney Injury and Extracorporeal Membrane Oxygenation: Review on Multiple Organ Support Options

Extracorporeal membrane oxygenation (ECMO) is a temporary life support system used to assist patients with life-threatening severe cardiac and/or respiratory insufficiency. Patients requiring ECMO can be considered the sickest patients admitted to the intensive care unit (ICU). Acute kidney injury (AKI) represents a frequent complication during ECMO, affecting up to 70% of patients, with multifactorial pathophysiology and an independent risk factor for mortality. Severe AKI requiring Continuous Renal Replacement Therapy (CRRT) occurs in 20% of ECMO patients, but multiple indications and different timing may imply a significantly higher application rate in different centers. CRRT can be run in parallel to ECMO through different vascular access, or it can be conducted in series by connecting the circuits. Anticoagulation of ECMO is typically managed with systemic heparin, but several approaches can be applied for the CRRT circuit, from no anticoagulation to the addition of intra-filter heparin or regional citrate anticoagulation. The combination of CRRT and ECMO can be considered a form of multiple organ support therapy, but this approach still requires optimization in timing, set-up, anticoagulation, prescription and delivery. The aim of this report is to review the pathophysiology of AKI, the CRRT delivery, anticoagulation strategies and outcomes of patients with AKI treated with ECMO.

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.