Extracorporeal membrane oxygenation seems to induce impairment of primary hemostasis pathology as measured by a Multiplate analyzer: An observational retrospective study

Acquired von Willebrand syndrome during extracorporeal membrane oxygenation support: a comprehensive review of current evidence: communication from the ISTH SSC on perioperative and critical care thrombosis and hemostasis

During extracorporeal membrane oxygenation (ECMO) support, the high shear stress in the ECMO circuit results in increased proteolysis of von Willebrand factor (VWF), loss of VWF high-molecular-weight multimers, and impaired ability to bind to platelets and collagen. These structural changes in VWF are consistent with acquired von Willebrand syndrome (AVWS) type 2A and may contribute to the bleeding diathesis frequently observed in ECMO patients. We performed a systematic review of all clinical studies evaluating the prevalence and associated outcomes of AVWS in ECMO patients. Our findings suggest that almost all ECMO patients develop partial or complete loss of VWF high-molecular-weight multimers within a few hours of device implantation. The AVWS persists as long as the patient is supported by ECMO. Weaning from ECMO rapidly and completely resolves the AVWS. Nevertheless, few studies have reported bleeding outcomes in ECMO patients with AVWS, and the extent to which AVWS contributes to the bleeding diathesis during ECMO support cannot be determined by current evidence. Data supporting the use of VWF concentrates to prevent bleeding complications in ECMO patients remain limited.

Anaesthesiologic Considerations for Intraoperative ECMO Anticoagulation During Lung Transplantation: A Single-Centre, Retrospective, Observational Study

Background: Extracorporeal membrane oxygenation (ECMO) is frequently used during lung transplantation. Unfractionated heparin (UFH) is mainly used as part of ECMO support for anticoagulation. One of the most common perioperative complications is bleeding, which high-dose UFH can aggravate. Methods: We retrospectively analyzed (n = 141) patients who underwent lung transplantation between 2020 and 2022. All subjects (n = 109) underwent central cannulated VA ECMO with successful intraoperative ECMO weaning. Patients on ECMO bridge, postoperative ECMO, heart-lung transplants and transplants without ECMO were excluded. The dose of UFH for the entire surgical procedure, blood loss and consumption of blood derivatives intraoperatively and 48 h after ICU admission were recorded. Surgical revision for postoperative bleeding were analyzed. Thrombotic complications, mortality and long-term survival were evaluated. Results: Lower doses of UFH administered for intraoperative ECMO anticoagulation contribute to a reduction in intraoperative blood derivates consumption and blood loss with no thrombotic complications related to the patient or the ECMO circuit. Lower doses of UFH may lead to a decreased incidence of surgical revision for hemothorax. Conclusion: Lower doses of UFH as part of intraoperative ECMO anticoagulation might reduce the incidence of complications and lead to better postoperative outcomes.

Interest in the new thromboelastometry device, Clot Pro®, for predicting thrombocytopenia and hypofibrinogenemia during lung transplantation

INTRODUCTION

Lung transplantation is associated with high proportion of transfusion. Monitoring of coagulopathy using viscoelastic tests could aid in the perioperative management of bleeding. The aim of the study was to assess the predictive cut-off values for thrombocytopenia and hypofibrinogenemia using the new thromboelastography analyzer, ClotPro.

METHODS

We retrospectively enrolled 65 patients who underwent lung transplantation and were sampled for both viscoelastic assays and conventional coagulation assays simultaneously during the procedure. We characterized the correlation between the EX-test (extrinsic pathway) and platelet count as well as between the FIB-test (extrinsic pathway after platelet inhibition) and fibrinogen concentration. Then, we used ROC curve analysis to determine the optimal EX-test and FIB-test values for predicting thrombocytopenia and hypofibrinogenemia.

RESULTS

All the amplitude values of the EX-test (A5, A10, A20, MCF) showed correlation with platelets count (Spearman's rank correlation coefficient ranging from 0.75 to 0.77, all p < 0.0001). We also observed a strong correlation between the amplitude values of the FIB-test (A5, A10, A20 and MCF) and the fibrinogen concentration (Spearman's rank correlation coefficient ranging from 0.68 to 0.71, all p < 0.0001). The AUCs of the EX-test values for thrombocytopenia <100 G/L and <80 G/L ranged from 0.80 to 0.93. Similarly, the AUCs of the FIB-test values for hypofibrinogenemia <1.5 g/L and <2 g/L ranged from 0.74 to 0.83. These results indicate that only the five-minute parameter of thromboelastometry is sufficient for detecting thrombocytopenia and hypofibrinogenemia in patients undergoing lung transplantation. The proposed cut off values for the EX-test to predict thrombocytopenia <80 G/L showed high sensitivity (>86 %), high specificity (>89 %) and high negative predictive value (>95 %). FIB-test cut off values predictive of fibrinogen below 1.5 g/L showed sensitivity (>78 %), specificity (>55 %) and negative predictive value (>88 %).

CONCLUSIONS

Our study provided preliminary results that are useful for developing a ClotPro-based algorithm to guide transfusion in lung transplantation. Future interventional studies will be necessary to validate these cut-off values of ClotPro for guiding transfusion.

aPTT-guided anticoagulation monitoring during ECMO support: A systematic review and meta-analysis

INTRODUCTION

The initiation of the extracorporeal membrane oxygenation (ECMO) is associated with complex coagulatory and inflammatory processes and consequently needed anticoagulation. Systemic anticoagulation bears an additional risk of serious bleeding, and its monitoring is of immense importance. Therefore, our work aims to analyze the association of anticoagulation monitoring with bleeding during ECMO support.

MATERIAL AND METHODS

Systematic literature review and meta-analysis, complying with the PRISMA guidelines (PROSPERO-CRD42022359465).

RESULTS

Seventeen studies comprising 3249 patients were included in the final analysis. Patients experiencing hemorrhage had a longer activated partial thromboplastin time (aPTT), a longer ECMO duration, and higher mortality. We could not find strong evidence of any aPTT threshold association with the bleeding occurrence, as less than half of authors reported a potential relationship. Finally, we identified the acute kidney injury (66%, 233/356) and hemorrhage (46%, 469/1046) to be the most frequent adverse events, while almost one-half of patients did not survive to discharge (47%, 1192/2490).

CONCLUSION

The aPTT-guided anticoagulation is still the standard of care in ECMO patients. We did not find strong evidence supporting the aPTT-guided monitoring during ECMO. Based on the weight of the available evidence, further randomized trials are crucial to clarify the best monitoring strategy.