Platelet Function During Extracorporeal Membrane Oxygenation in Adult Patients: A Systematic Review

Computational fluid dynamics in cardiac surgery and perfusion: A review

Cardiovascular diseases persist as a leading cause of mortality and morbidity, despite significant advances in diagnostic and surgical approaches. Computational Fluid Dynamics (CFD) represents a branch of fluid mechanics widely used in industrial engineering but is increasingly applied to the cardiovascular system. This review delves into the transformative potential for simulating cardiac surgery procedures and perfusion systems, providing an in-depth examination of the state-of-the-art in cardiovascular CFD modeling. The study first describes the rationale for CFD modeling and later focuses on the latest advances in heart valve surgery, transcatheter heart valve replacement, aortic aneurysms, and extracorporeal membrane oxygenation. The review underscores the role of CFD in better understanding physiopathology and its clinical relevance, as well as the profound impact of hemodynamic stimuli on patient outcomes. By integrating computational methods with advanced imaging techniques, CFD establishes a quantitative framework for understanding the intricacies of the cardiac field, providing valuable insights into disease progression and treatment strategies. As technology advances, the evolving synergy between computational simulations and clinical interventions is poised to revolutionize cardiovascular care. This collaboration sets the stage for more personalized and effective therapeutic strategies. With its potential to enhance our understanding of cardiac pathologies, CFD stands as a promising tool for improving patient outcomes in the dynamic landscape of cardiovascular medicine.

Predictors of mortality and transfusion requirements in venoarterial extracorporeal membrane oxygenation patients

OBJECTIVE

The aim of this study was to evaluate the prognostic impact of variables, including thrombocytopenia and the amount of platelet transfusion, for predicting survival in venoarterial extracorporeal membrane oxygenation (ECMO) recipients. Additionally, we aimed to identify the predictors of increased transfusion requirement during venoarterial ECMO support.

METHODS

All patients who received venoarterial ECMO between December 2008 and March 2020 were retrospectively analyzed. Univariate and multivariate Cox regressions were used to evaluate in-hospital mortality according to variables including thrombocytopenia and daily average of platelet concentrate transfusion. Stepwise multiple linear regression analysis was used to identify independent predictors for transfusion requirements.

RESULTS

Analysis of 218 patients demonstrated severe thrombocytopenia as an independent predictor of in-hospital mortality (hazard ratio = 2.840, 95% CI: 1.593-5.063, P < .001), along with age, pre-ECMO cardiac arrest, and pH. In contrast, the amount of platelet transfusion was not associated with in-hospital mortality. Multiple variables, including the type of indication for ECMO were associated with transfusion requirements.

CONCLUSION

Our findings identified severe thrombocytopenia as an independent prognostic factor of in-hospital mortality. However, daily average platelet transfusion was not associated with survival outcomes. Additionally, our study identified predictive variables of increased transfusion requirements.

Improving ECMO therapy: Monitoring oxygenator functionality and identifying key indicators, factors, and considerations for changeout

INTRODUCTION

The optimal timing for extracorporeal membrane oxygenation (ECMO) circuit change-out is crucial for the successful management of patients with severe cardiopulmonary failure. This comprehensive review examines the various factors that influence the timing of oxygenator replacement in the ECMO circuit. By considering these factors, clinicians can make informed decisions to ensure timely and effective change-out, enhancing patient outcomes and optimizing the delivery of ECMO therapy.

METHODOLOGY

A thorough search of relevant studies on ECMO circuits and oxygenator change-out was conducted using multiple scholarly databases and relevant keywords. Studies published between 2017 and 2023 were included, resulting in 40 studies that met the inclusion criteria.

DISCUSSION

Thrombosis within the membrane oxygenator and its impact on dysfunction were identified as significant contributors, highlighting the importance of monitoring coagulation parameters and gas exchange. Several factors, including fibrinogen levels, pre and post-membrane blood gases, plasma-free hemoglobin, D-dimers, platelet function, flows and pressures, and anticoagulation strategy, were found to be important considerations when determining the need for an oxygenator or circuit change-out. The involvement of a multidisciplinary team and thorough preparation were also highlighted as crucial aspects of this process.

CONCLUSION

In conclusion, managing circuit change-outs in ECMO therapy requires considering factors such as fibrinogen levels, blood gases, plasma-free hemoglobin, D-dimers, platelet function, flows, pressures, and anticoagulation strategy. Monitoring these parameters allows for early detection of issues, timely interventions, and optimized ECMO therapy. Standardized protocols, personalized anticoagulation approaches, and non-invasive monitoring techniques can improve the safety and effectiveness of circuit change-outs. Further research and collaboration are needed to advance ECMO management and enhance patient outcomes.

Effect of flow rate ratio and positioning on a lighthouse tip ECMO return cannula

Extracorporeal membrane oxygenation is a life-saving support therapy in the case of cardiopulmonary refractory failure. Its use is associated to complications due to the presence of artificial surfaces and supraphysiological stress conditions. Thus, knowledge of the fluid structures associated to each component can give insight into sources of blood damage. In this study, an experimentally validated numerical study of a conventional lighthouse tip cannula in return configuration was carried out to characterize the flow structures using water or a Newtonian blood analog with different flow rate ratios and cannula positioning and their influence on hemolysis. The results showed that strong shear layers developed where the jets from the side holes met the co-flow. Stationary backflow regions at the vessel wall were also present downstream of the cannula. In the tilted case, the recirculation was much more pronounced on the wide side and almost absent on the narrow side. Small vortical backflow structures developed at the side holes which behaved like obstacles to the co-flow, creating pairs of counter-rotating vortices, which induced locally higher risk of hemolysis. However, global hemolysis index did not show significant deviations. Across the examined flow rate ratios, the holes on the narrow side consistently reinfused a larger fraction of fluid. A radial force developed in the tilted case in a direction so as to recenter the cannula in the vessel.

Bleeding patients on extracorporeal membrane oxygenation have reduced platelet aggregation and plasma fibrinogen: a longitudinal observational study

This study investigated changes in coagulation and associations with occurrence of bleeding and thrombosis during extracorporeal membrane oxygenation (ECMO) therapy. The study included 100 adult ECMO-patients. Standard coagulation parameters, platelet aggregation and thromboelastometry (ROTEM®) were compared with healthy controls. Data on bleeding and thrombosis were collected until recovery or death. Mortality data were collected 30 days after weaning from ECMO. During ECMO therapy, 53 patients experienced at least one moderate or major bleed. Among these, 42 (79%) patients experienced the first bleeding on day 1 or 2. Platelet aggregation and ROTEM® revealed a hypocoagulable state in ECMO patients when compared with healthy controls. Patients bleeding on day 1 or 2, had lower platelet count (p = 0.04), poorer platelet aggregation and lower levels of fibrinogen (p < 0.01) than patients not bleeding on day 1 or 2. Further, ROTEM® clot propagation was reduced in bleeding patients (p < 0.001). Mortality was higher among bleeding patients than patients not bleeding on day 1 or 2 (67% versus 34%, p < 0.01). Congruity existed between ROTEM® measurements and standard coagulation assays, but plasma fibrinogen had a stronger association with bleeding than ROTEM® measurements. The present study does not support ROTEM® analysis as a routine part of coagulation monitoring during ECMO therapy.

In vitro study on the effect of fibrinogen γ-chain peptide-coated ADP-encapsulated liposomes on postcardiopulmonary bypass coagulopathy using patient blood

BACKGROUND

Fibrinogen γ-chain peptide-coated, adenosine 5'-diphosphate (ADP)-encapsulated liposomes (H12-ADP-liposomes) are potent hemostatic adjuvants that promote platelet thrombi formation at bleeding sites. Although we have reported the efficacy of these liposomes in a rabbit model of cardiopulmonary bypass coagulopathy, we are yet to address the possibility of their hypercoagulative potential, especially in human beings.

OBJECTIVES

Considering its future clinical applications, we herein investigated the safety of using H12-ADP-liposomes in vitro using blood samples from patients who had received platelet transfusion after cardiopulmonary bypass surgeries.

METHODS

Ten patients receiving platelet transfusions after cardiopulmonary bypass surgery were enrolled. Blood samples were collected at the following 3 points: at the time of incision, at the end of the cardiopulmonary bypass, and immediately after platelet transfusion. After incubating the samples with H12-ADP-liposomes or phosphate-buffered saline (PBS, as a control), blood coagulation, platelet activation, and platelet-leukocyte aggregate formation were evaluated.

RESULTS

Patients' blood incubated with H12-ADP-liposomes did not differ from that incubated with PBS in coagulation ability, degree of platelet activation, and platelet-leukocyte aggregation at any of the time points.

CONCLUSION

H12-ADP-liposomes did not cause abnormal coagulation, platelet activation, or platelet-leukocyte aggregation in the blood of patients who received platelet transfusion after a cardiopulmonary bypass. These results suggest that H12-ADP-liposomes could likely be safely used in these patients, providing hemostasis at the bleeding sites without causing considerable adverse reactions. Future studies are needed to ensure robust safety in human beings.

Comparison of anticoagulation monitoring strategies for adults supported on extracorporeal membrane oxygenation: A systematic review

BACKGROUND

Anticoagulation is critical in patients supported on extracorporeal membrane oxygenation (ECMO). The appropriate monitoring strategies for heparin remain unclear.

OBJECTIVES

This systematic review aimed to compare the accuracy and safety of various monitoring strategies for patients supported on ECMO.

METHODS

The PubMed and Web of Science databases were searched for articles in March 2023 without restrictions on publication date. Anticoagulation monitoring strategies for adults supported on ECMO were compared across all included studies. The incidence of bleeding, thrombosis, mortality, blood transfusion, correlation between tests and heparin dose, and the discordance between different tests were discussed in the included studies. The risk of bias was assessed using the Newcastle-Ottawa Scale and Cochrane Collaboration's tool.

RESULTS

Twenty-six studies, including a total of 1,684 patients, met the inclusion criteria. The monitoring of anticoagulation by activated partial thromboplastin time (aPTT) resulted in less blood product transfusion than that by activated clotting time (ACT). Moreover, the monitoring of anticoagulation by anti-factor Xa (Anti-Xa) resulted in a more stable anticoagulation than that by aPTT. Anti-Xa and aPTT correlated with heparin dose better than ACT, and the discordance between different monitoring tests was common. Finally, combined monitoring showed some advantages in reducing mortality and blood product transfusion.

CONCLUSION

Anti-Xa and aPTT are more suitable for anticoagulation monitoring for patients supported on ECMO than ACT. Thromboelastography and combination strategies are less applied. Most of the studies were retrospective, and their sample sizes were relatively small; thus, more appropriate monitoring strategies and higher quality research are needed.

Numerical and experimental investigation of a lighthouse tip drainage cannula used in extracorporeal membrane oxygenation

BACKGROUND

Extracorporeal membrane oxygenation is a life-saving therapy used in case of acute respiratory/circulatory failure. Exposure of blood to non-physiological surfaces and high shear stresses is related to hemolytic damage and platelet activation. A detailed knowledge of the fluid dynamics of the components under different scenarios is thus paramount to assess the thrombogenicity of the circuit.

METHODS

An investigation of the flow structures developing in a conventional lighthouse tip (single-staged) drainage cannula was performed with cross-validated computational fluid dynamics and particle image velocimetry. The aim was to quantify the variation in drainage performance and stress levels induced by different fluid models, hematocrit and vessel-to-cannula flow rate ratios.

RESULTS

The results showed that the 90° bends of the flow through the side holes created a recirculation zone inside the cannula which increased residence time. Flow structures resembling a jet in a crossflow were also observed. The use of different hematocrits did not significantly affect drainage performances. The most proximal set of holes drained the largest fraction of fluid. However, different flow rate ratios altered the flow rate drained through the tip. The use of 2D data led to a 50% underestimation of shear rate levels. In the drainage zone the non-Newtonian behavior of blood was less relevant.

CONCLUSIONS

The most proximal holes drained the largest amount of fluid. The flow features and distribution of flow rates among the holes showed little dependence on the hematocrit. The non-Newtonian behavior of blood had a small influence on the dynamics of the flow.

Characterization of Shear Stress Mediated Platelet Dysfunction: Data from an Ex Vivo Model for Extracorporeal Circulation and a Prospective Clinical Study

Extracorporeal circulation (ECC) is frequently used in intensive care patients with impaired lung or cardiac function. Despite being a life-saving therapeutic option, ECC is associated with increased risk for both bleeding and thrombosis. The management of bleeding and thromboembolic events in ECC patients is still challenging partly due to the lack of information on the pathophysiological changes in hemostasis and platelet function during the procedure. Using a combination of an ex vivo model for shear stress and a sensitive and easy-to-use laboratory method, we analyzed platelet responsiveness during ECC. After shear stress simulation in an ex vivo closed-loop ECC model, we found a significantly decreased response of α-granules after activation with adenosine diphosphate and thrombin receptor activating peptide (TRAP-6) and CD63 expression after activation with TRAP-6. Mepacrine uptake was also significantly reduced in the ex vivo shear stress model.In the same line, platelets from patients under ECC with venovenous systems and venoarterial systems showed impaired CD62P degranulation after stimulation with ADP and TRAP-6 compared with healthy control on day 1, 6, and 10 after implantation of ECC. However, no correlation between platelet degranulation and the occurrence of bleeding or thromboembolic events was observed.The used whole blood flow cytometry with immediate fixation after drawing introduces a sensitive and easy-to-use method to determine platelet activation status and our data confirm that increased shear stress conditions under ECC can cause impaired degranulation of platelet.

Major Bleeding and Thromboembolic Events in Veno-Venous Extracorporeal Membrane Oxygenation-Patients With Isolated Respiratory Failure

Bleeding and thromboembolic events are common during veno-venous extracorporeal membrane oxygenation (vvECMO). It is unknown whether these complications are driven by the ECMO system itself, multiorgan-failure, or both. The aim of this study was to assess the prevalence of bleeding and thromboembolic events in patients with isolated respiratory failure. Patients with vvECMO were retrospectively included from March 2009 to October 2017. Exclusion included any organ failure other than respiratory. Major bleeding was defined as a decrease in hemoglobin ≥2 g/dl per 24 hours, the requirement for transfusion of ≥2 packed red blood cell concentrates per 24 hours, any retroperitoneal, pulmonary, central nervous system bleeding, or bleeding requiring surgery. Thromboembolic events were assessed by duplex sonography or CT scan. Of 601 patients, 123 patients with a mean age of 49 ± 15 years and a median Sepsis-related Organ Failure Assessment score of 8 (7-9) were eligible for the analysis. Major bleeding was observed in 73%; 35% of all bleedings occurred on the day of or after ECMO initiation. A more pronounced decrease of PaCO2 after ECMO initiation was seen in patients with intracranial bleeding (ICB) compared with those without. Thromboembolic events were noted in 30%. The levels of activated prothrombin time, fibrinogen, platelet count, or D-dimers affected neither bleeding nor the prevalence of thromboembolic events.

Platelet Transfusion and In-Hospital Mortality in Veno-Arterial Extracorporeal Membrane Oxygenation Patients

Thrombocytopenia is common during extracorporeal membrane oxygenation (ECMO), and platelets are sometimes transfused to meet arbitrary goals. We performed a retrospective cohort study of veno-arterial (VA) ECMO patients from a single academic medical center and explored the relationship between platelet transfusion and in-hospital mortality using multivariable logistic regression. One hundred eighty-eight VA ECMO patients were included in the study. Ninety-one patients (48.4%) were transfused platelets during ECMO. Patients who received platelet transfusion had more coronary artery disease, lower platelet counts at cannulation, higher predicted mortality, lower nadir platelet counts, more ECMO days, and more red blood cell (RBC) and plasma transfusion. Mortality was 19.6% for patients who received no platelets, 40.8% for patients who received 1-3 platelets, and 78.6% for patients who received 4 or more platelets ( P &lt; 0.001). After controlling for confounding variables including baseline severity of illness, central cannulation, postcardiotomy status, RBC and plasma transfusion, major bleeding, and total ECMO days, transfusion of 4 or more platelets remained associated with in-hospital mortality; OR = 4.68 (95% CI = 1.18-27.28), P = 0.03. Our findings highlight the need for randomized controlled trials that compare different platelet transfusion triggers, so that providers can better understand when platelet transfusion is indicated in VA ECMO patients.

Optimal Tests to Minimise Bleeding and Ischaemic Complications in Patients on Extracorporeal Membrane Oxygenation

Patients supported with extracorporeal membrane oxygenation (ECMO) experience a very high frequency of bleeding and ischaemic complications, including stroke and systemic embolism. These patients require systemic anticoagulation, mainly with unfractionated heparin (UFH) to prevent clotting of the circuit and reduce the risk of arterial or venous thrombosis. Monitoring of UFH can be very challenging. While most centres routinely monitor the activated clotting time and activated partial thromboplastin time (aPTT) to assess UFH, measurement of anti-factor Xa (anti-Xa) level best correlates with heparin dose, and appears to be predictive of circuit thrombosis, although aPTT may be a better predictor of bleeding. Although monitoring of prothrombin time, platelet count and fibrinogen is routinely undertaken to assess haemostasis, there is no clear guidance available regarding the optimal test.Additional tests, including antithrombin level and thromboelastography, can be used for risk stratification of patients to try and predict the risks of thrombosis and bleeding. Each has their specific role, strengths and limitations. Increased thrombin generation may have a role in predicting thrombosis. Acquired von Willebrand syndrome is frequent with ECMO, contributing to bleeding risk and can be detected by assessing the von Willebrand factor activity-to-antigen ratio, while the platelet function analyser can be used in urgent situations to detect this, with a high negative predictive value. Tests of platelet aggregation can aid in the prediction of bleeding.To personalise management, a selection of complementary tests to collectively assess heparin-effect, coagulation, platelet function and platelet aggregation is proposed, to optimise clinical outcomes in these high-risk patients.

Longitudinal Trends in Bleeding Complications on Extracorporeal Life Support Over the Past Two Decades—Extracorporeal Life Support Organization Registry Analysis

OBJECTIVES

Data about inhospital outcomes in bleeding complications during extracorporeal life support (ECLS) have been poorly investigated.

DESIGN

Retrospective observational study.

SETTING

Patients reported in Extracorporeal Life Support Organization Registry.

PATIENTS

Data of 53.644 adult patients (greater than or equal to 18 yr old) mean age 51.4 ± 15.9 years, 33.859 (64.5%) male supported with single ECLS run between 01.01.2000 and 31.03.2020, and 19.748 cannulated for venovenous (V-V) ECLS and 30.696 for venoarterial (V-A) ECLS.

INTERVENTIONS

Trends in bleeding complications, bleeding risk factors, and mortality.

MEASUREMENT AND MAIN RESULTS

Bleeding complications were reported in 14.786 patients (27.6%), more often in V-A ECLS compared with V-V (30.0% vs 21.9%; p < 0.001). Hospital survival in those who developed bleeding complications was lower in both V-V ECLS (49.6% vs 66.6%; p < 0.001) and V-A ECLS (33.9 vs 44.9%; p < 0.001). Steady decrease in bleeding complications in V-V and V-A ECLS was observed over the past 20 years (coef., -1.124; p < 0.001 and -1.661; p < 0.001). No change in mortality rates was reported over time in V-V or V-A ECLS (coef., -0.147; p = 0.442 and coef., -0.195; p = 0.139).Multivariate regression revealed advanced age, ecls duration, surgical cannulation, renal replacement therapy, prone positioning as independent bleeding predictors in v-v ecls and female gender, ecls duration, pre-ecls arrest or bridge to transplant, therapeutic hypothermia, and surgical cannulation in v-a ecls.

CONCLUSIONS

A steady decrease in bleeding over the last 20 years, mostly attributable to surgical and cannula-site-related bleeding has been found in this large cohort of patients receiving ECLS support. However, there is not enough data to attribute the decreasing trends in bleeding to technological refinements alone. Especially reduction in cannulation site bleeding is also due to changes in timing, patient selection, and ultrasound guided percutaneous cannulation. Other types of bleeding, such as CNS, have remained stable, and overall bleeding remains associated with a persistent increase in mortality.

The Underestimated Role of Platelets in Severe Infection a Narrative Review

Beyond their role in hemostasis, platelets have emerged as key contributors in the immune response; accordingly, the occurrence of thrombocytopenia during sepsis/septic shock is a well-known risk factor of mortality and a marker of disease severity. Recently, some studies elucidated that the response of platelets to infections goes beyond a simple fall in platelets count; indeed, sepsis-induced thrombocytopenia can be associated with—or even anticipated by—several changes, including an altered morphological pattern, receptor expression and aggregation. Of note, alterations in platelet function and morphology can occur even with a normal platelet count and can modify, depending on the nature of the pathogen, the pattern of host response and the severity of the infection. The purpose of this review is to give an overview on the pathophysiological interaction between platelets and pathogens, as well as the clinical consequences of platelet dysregulation. Furthermore, we try to clarify how understanding the nature of platelet dysregulation may help to optimize the therapeutic approach.

HEROES V-V-HEmorRhagic cOmplications in Veno-Venous Extracorporeal life Support-Development and internal validation of multivariable prediction model in adult patients

BACKGROUND

During extracorporeal life support (ECLS), bleeding is one of the most frequent complications, associated with high morbidity and increased mortality, despite continuous improvements in devices and patient care. Risk factors for bleeding complications in veno-venous (V-V) ECLS applied for respiratory support have been poorly investigated. We aim to develop and internally validate a prediction model to calculate the risk for bleeding complications in adult patients receiving V-V ECLS support.

METHODS

Data from adult patients reported to the extracorporeal life support organization (ELSO) registry between the years 2010 and 2020 were analyzed. The primary outcome was bleeding complications recorded during V-V ECLS. Multivariable logistic regression with backward stepwise elimination was used to develop the predictive model. The performance of the model was tested by discriminative ability and calibration with receiver operating characteristic curves and visual inspection of the calibration plot.

RESULTS

In total, 18 658 adult patients were included, of which 3 933 (21.1%) developed bleeding complications. The prediction model showed a prediction of bleeding complications with an AUC of 0.63. Pre-ECLS arrest, surgical cannulation, lactate, pO₂ , HCO₃ , ventilation rate, mean airway pressure, pre-ECLS cardiopulmonary bypass or renal replacement therapy, pre-ECLS surgical interventions, and different types of diagnosis were included in the prediction model.

CONCLUSIONS

The model is based on the largest cohort of V-V ECLS patients and reveals the most favorable predictive value addressing bleeding events given the predictors that are feasible and when compared to the current literature. This model will help identify patients at risk of bleeding complications, and decision making in terms of anticoagulation and hemostatic management.

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

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) support is often associated with bleeding complications caused by secondary or primary hemostasis pathology. However, there are limited data investigating primary hemostasis using Multiplate aggregometry with specific diagnostics tests for vWF (von Willebrand factor) deficiency.

AIMS

The aim of this study was to find out whether short-term ECMO produces the pathology of primary hemostasis that is detected by Multiplate aggregometry and to investigate the pathology of vWF.

METHODS

In this study, blood samples of 20 patients undergoing lung transplantations with short-term perioperative ECMO support were analyzed. The multimeric structure, the levels of von Willebrand factor antigen (vWF), ristocetin cofactor (RCo), collagen-binding protein (CB), and the results of multiple electrode aggregometry RISTO (ristocetin), ADP (adenosine diphosphate), ASPI (Aspirin®; arachidonic acid), and TRAP (thrombin receptor activating peptide) tests were compared to the samples obtained before and after ECMO support.

RESULTS

The Multiplate ADP and RISTO tests showed the presence of significant pathology in primary hemostasis after surgery (p < 0.05), suggesting the presence of acquired platelet dysfunction. Although the RISTO tests suggest the presence of acquired vWF deficiency, laboratory tests for vWF antigen and RCo and CB tests showed an increase in this case. The multimeric structure of vWF did not show clinically significant deterioration.

CONCLUSIONS

Multiple aggregometry ADP, ASPI, and TRAP tests seem to be able to detect primary hemostasis pathology (platelets aggregation and adhesion pathology) that is present during short-term perioperative ECMO support in lung transplantation procedures. Interestingly, RISTO tests seem to be more suitable for the diagnosis of platelet dysfunction than the diagnosis of acquired vWF deficiency in this situation.

Early platelet dysfunction in patients receiving extracorporeal membrane oxygenation is associated with mortality

Extracorporeal membrane oxygenation (ECMO) is used for patients with cardiopulmonary failure and is associated with severe bleeding and poor outcome. Platelet dysfunction may be a contributing factor. The aim of this prospective observational study was to characterize platelet dysfunction and its relation to outcome in ECMO patients. Blood was sampled from thirty ECMO patients at three timepoints. Expression of CD62P, CD63, activated GPIIb/IIIa, GPVI, GPIbα and formation platelet-leukocyte aggregates (PLA) were analyzed at rest and in response to stimulation. Delta granule storage-pool deficiency and secretion defects were also investigated. Fifteen healthy volunteers and ten patients with coronary artery disease served as controls. Results were also compared between survivors and non-survivors. Compared to controls, expression of platelet surface markers, delta granule secretion and formation of PLA was reduced, particularly in response to stimulation. Baseline CD63 expression was higher and activated GPIIb/IIIa expression in response to stimulation was lower in non-survivors on day 1 of ECMO. Logistic regression analysis revealed that these markers were associated with mortality. In conclusion, platelets from ECMO patients are severely dysfunctional predisposing patients to bleeding complications and poor outcome. Platelet dysfunction on day 1 of ECMO detected by the platelet surface markers CD63 and activated GPIIb/IIIa is associated with mortality. CD63 and activated GPIIb/IIIa may therefore serve as novel prognostic biomarkers, but future studies are required to determine their true potential.

Oseltamivir Improved Thrombocytopenia During Veno-Arterial Extracorporeal Membrane Oxygenation in Adults With Refractory Cardiac Failure: A Single-Center Retrospective Real-World Study

Background: Severe thrombocytopenia is a common complication of extracorporeal membrane oxygenation (ECMO). Oseltamivir can be used to treat infection-associated thrombocytopenia.

Objective: To evaluate the effect of oseltamivir on attenuating severe thrombocytopenia during ECMO.

Methods: This was a single-center real-world study in critically ill patients supported with venous-arterial extracorporeal membrane oxygenation (VA-ECMO). Patients suspected or confirmed with influenza received oseltamivir according to the Chinese guidelines. Thrombocytopenia and survival were compared between the oseltamivir-treated and untreated group. The factors associated with survival were analyzed by multivariable Cox analysis.

Results: A total of 82 patients were included. All patients developed thrombocytopenia after initiating VA-ECMO. Twenty-three patients received oseltamivir (O⁺ group), and 59 did not use oseltamivir (O⁻ group). During the first 8 days after VA-ECMO initiation, the platelet count in the O⁺ group was higher than that in the O⁻ group (all P < 0.05). The patients in the O⁺ group had a higher median nadir platelet count (77,000/μl, 6,000–169,000/μl) compared with the O⁻ group (49,000/μl, 2,000–168,000/μl; P = 0.04). A nadir platelet count of <50,000/μl was seen in 26% of the patients in the O⁺ group, compared with 53% in the O⁻ group (P = 0.031). No significant difference in survival from cardiac failure was seen between the O⁺ and O⁻ group (48 vs. 56%, P = 0.508). The Sequential Organ Failure Assessment (SOFA) score on initiation of VA-ECMO were independently associated with survival (OR = 1.12, 95% confidence interval (95% CI): 1.02–1.22, P = 0.015).

Conclusions: Oseltamivir could ameliorate VA-ECMO-related thrombocytopenia. These findings suggested the prophylactic potential of oseltamivir on severe thrombocytopenia associated with the initiation of VA-ECMO.

Annexin V positive microvesicles are elevated and correlate with flow rate in patients receiving veno-arterial extracorporeal membrane oxygenation

OBJECTIVES

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is used in critically ill patients requiring haemodynamic support. Microvesicles (MV) are released by activated blood cells acting as mediators of intercellular communication. We aimed to determine MV count and composition over time in patients with VA-ECMO and explore what drives MV formation.

METHODS

VA-ECMO patients and healthy controls were recruited prospectively, and blood was taken at different time points (day 0, 1, 3 after ECMO placement and after explantation) for MV analysis.

RESULTS

Annexin V positive MV were increased in patients (n = 14, mean age = 61.4 ± 9.0 years, 11 males, 3 females) compared to healthy controls (n = 6, Annexin V positive MV count per millilitre day 1 versus healthy controls: 2.3 × 106 vs 1.3 × 105, P < 0.001). Furthermore, patients had higher proportions of endothelial and leukocyte MV [leukocyte MV day 1 versus healthy controls (%): 32.8 vs 17.5, P = 0.001; endothelial MV day 1 versus healthy controls (%): 10.5 vs 5.5, P = 0.01]. Annexin V positive and leucocyte MV correlated with the flow rate (r = 0.46, P = 0.01).

CONCLUSIONS

Patients on VA-ECMO have increased levels of circulating MV and a changed MV composition. Our data support the hypothesis that MV release may be driven by higher flow rate and cellular activation in the extracorporeal circuit leading to poor outcomes in these patients.

CLINICAL TRIAL REGISTRATION NUMBER

German Clinical Trials Register-ID: DRKS00011106.

Contact Activation Inhibitor, AB023, in Heparin-Free Hemodialysis: Results of a Randomized Phase 2 Clinical Trial

End-stage renal disease (ESRD) patients on chronic hemodialysis have repeated blood exposure to artificial surfaces that can trigger clot formation within the hemodialysis circuit. Dialyzer clotting can lead to anemia despite erythropoietin and iron supplementation. Unfractionated heparin prevents clotting during hemodialysis, but it is not tolerated by all patients. Although heparin-free dialysis is performed, intradialytic blood entrapment can be problematic. To address this issue, we performed a randomized, double-blind, phase 2 study comparing AB023, a unique antibody that binds factor (F) XI and blocks its activation by factor XIIa but not by thrombin, to placebo in 24 patients with ESRD undergoing heparin-free hemodialysis (www.clinicaltrials.gov #NCT03612856). Patients were randomized to receive a single pre-dialysis dose of AB023 (0.25 or 0.5 mg/kg) or placebo in a 2:1 ratio and safety and preliminary efficacy were compared to placebo and to observations made prior to dosing within each treatment arm. AB023 administration was not associated with impaired hemostasis or other drug-related adverse events. Occlusive events requiring hemodialysis circuit exchange were less frequent and levels of thrombin-antithrombin complexes and C-reactive protein were lower after AB023 administration compared with data collected prior to dosing. AB023 also reduced potassium and iron entrapment in the dialyzers, consistent with less blood accumulation within the dialyzers. We conclude that despite the small sample size, inhibition of contact activation-induced coagulation with AB023 was well tolerated and reduced clotting within the dialyzer.

Flow Dynamics and Mixing in Extracorporeal Support: A Study of the Return Cannula

Cannulation strategies in medical treatment such as in extracorporeal life support along with the associated cannula position, orientation and design, affects the mixing and the mechanical shear stress appearing in the flow field. This in turn influences platelet activation state and blood cell destruction. In this study, a co-flowing confined jet similar to a return cannula flow configuration found in extracorporeal membrane oxygenation was investigated experimentally. Cannula diameters, flow rate ratios between the jet and the co-flow and cannula position were studied using Particle Image Velocimetry and Planar Laser Induced Fluorescence. The jet was turbulent for all but two cases, in which a transitional regime was observed. The mixing, governed by flow entrainment, shear layer induced vortices and a backflow along the vessel wall, was found to require 9–12 cannula diameters to reach a fully homogeneous mixture. This can be compared to the 22–30 cannula diameters needed to obtain a fully developed flow. Although not significantly affecting mixing characteristics, cannula position altered the development of the flow structures, and hence the shear stress characteristics.

Device-Induced Hemostatic Disorders in Mechanically Assisted Circulation

Mechanically assisted circulation (MAC) sustains the blood circulation in the body of a patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) or on ventricular assistance with a ventricular assist device (VAD) or on extracorporeal membrane oxygenation (ECMO) with a pump-oxygenator system. While MAC provides short-term (days to weeks) support and long-term (months to years) for the heart and/or lungs, the blood is inevitably exposed to non-physiological shear stress (NPSS) due to mechanical pumping action and in contact with artificial surfaces. NPSS is well known to cause blood damage and functional alterations of blood cells. In this review, we discussed shear-induced platelet adhesion, platelet aggregation, platelet receptor shedding, and platelet apoptosis, shear-induced acquired von Willebrand syndrome (AVWS), shear-induced hemolysis and microparticle formation during MAC. These alterations are associated with perioperative bleeding and thrombotic events, morbidity and mortality, and quality of life in MCS patients. Understanding the mechanism of shear-induce hemostatic disorders will help us develop low-shear-stress devices and select more effective treatments for better clinical outcomes.

Thrombocytopenia: Perioperative Considerations for Patients Undergoing Cardiac Surgery

The etiologies of thrombocytopenia in patients presenting for cardiac surgery are extensive, but clinically relevant conditions generally can be categorized by those related to decreased platelet production or increased platelet destruction. Many causes require mere acknowledgment and availability of allogeneic platelet transfusion; others have unique considerations for which providers should be familiar. The purpose of this review is to provide an overview of the common causes of thrombocytopenia, summarize the literature, and discuss perioperative considerations for patients undergoing cardiac surgery.

Evaluation of effect of scheduled fresh frozen plasma on ECMO circuit life: A randomized pilot trial

BACKGROUND

Factor consumption is common during ECMO complicating the balance of pro and anticoagulation factors. This study sought to determine whether transfusion of coagulation factors using fresh frozen plasma (FFP) increased ECMO circuit life and decreased blood product transfusion. Secondly, it analyzed the association between FFP transfusion and hemorrhagic and thrombotic complications.

STUDY DESIGN AND METHODS

Thirty-one pediatric ECMO patients between October 2013 and January 2016 at a quaternary care institution were included. Patients were randomized to FFP every 48 hours or usual care. The primary outcome was ECMO circuit change. Secondary outcomes included blood product transfusion, survival to decannulation, hemorrhagic and thrombotic complications, and ECMO costs.

RESULTS

Median (interquartile range [IQR]) number of circuit changes was 0 (0, 1). No difference was seen in percent days without a circuit change between intervention and control group, P = .53. Intervention group patients received median platelets of 15.5 mL/kg/d IQR (3.7, 26.8) vs 24.8 mL/kg/d (12.2, 30.8) for the control group (P = .16), and median packed red blood cells (pRBC) of 7.7 mL/kg/d (3.3, 16.3) vs 5.9 mL/kg/d (3.4, 18.7) for the control group, P = .60. FFP transfusions were similar with 10.2 mL/kg/d (5.0, 13.9) in the intervention group vs 8.8 (2.5, 17.7) for the control group, P = .98.

CONCLUSION

In this pilot randomized study, scheduled FFP did not increase circuit life. There was no difference in blood product transfusion of platelets, pRBCs, and FFP between groups. Further studies are needed to examine the association of scheduled FFP with blood product transfusion.

Platelet Functions During Extracorporeal Membrane Oxygenation. Platelet-Leukocyte Aggregates Analyzed by Flow Cytometry as a Promising Tool to Monitor Platelet Activation

Extracorporeal membrane oxygenation (ECMO) is an extracorporeal circulation used to manage patients with severe circulatory or respiratory failure. It is associated with both high bleeding and thrombosis risks, mainly as a result of biomaterial/blood interface phenomena, high shear stress, and complex inflammatory response involving the activation of coagulation and complement systems, endothelial cells, leukocytes, and platelets. Besides their critical role in hemostasis, platelets are important players in inflammatory reactions, especially due to their ability to bind and activate leukocytes. Hence, we reviewed studies on platelet function of ECMO patients. Moreover, we addressed the issue of platelet–leukocyte aggregates (PLAs), which is a key step in both platelet and leukocyte activation, and deserves to be investigated in these patients. A reduced expression of GPIb and GPVI was found under ECMO therapy, due to the shedding processes. However, defective platelet aggregation is inconsistently reported and is still not clearly defined. Due to the high susceptibility of PLAs to pre-analytical conditions, defining and strictly adhering to a rigorous laboratory methodology is essential for reliable and reproducible results, especially in the setting of complex inflammatory situations like ECMO. We provide results on sample preparation and flow cytometric whole blood evaluation of circulating PLAs.

Post-operative of bleeding, haemolysis and coagulation in mechanical circulatory support patients

There are unique complications arising from mechanical support devices but some of the long-term systemic haematological complications are indistinguishable from management problems affecting the care of other patients receiving intermediate to long term care in the cardiac ICU. The field of mechanical cardiac assist device (MCAD) is evolving. Despite major changes in design of these devices the most feared haematological complications have remained unchanged, namely haemolysis, pump thrombosis or thromboembolism. This review article gives an overview over the pathophysiology of MCAD related haematological complications, their management and where possible an outlook on future strategies to prevent such complications. The impact of MCAD on blood is discussed, starting with rheology, common pump mechanisms, current and future pump surface coating materials, anatomical considerations of the connection of the circuit and design of the circuit itself. Moreover, the duration of the cardiovascular support, impact of bleeding complications and other patient factors. This article also covers the impact of long term mechanical cardiac support on the properties of platelets, the anticoagulation strategies and a basic guide to the differential diagnosis of haemolysis is reviewed. The section on anaemia considers anaemia in the wider perioperative setting for patients in critical care having undergone cardiac surgery and also discusses transfusion alternatives.

COVID-19 and ECMO: the interplay between coagulation and inflammation-a narrative review

Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has presently become a rapidly spreading and devastating global pandemic. Veno-venous extracorporeal membrane oxygenation (V-V ECMO) may serve as life-saving rescue therapy for refractory respiratory failure in the setting of acute respiratory compromise such as that induced by SARS-CoV-2. While still little is known on the true efficacy of ECMO in this setting, the natural resemblance of seasonal influenza's characteristics with respect to acute onset, initial symptoms, and some complications prompt to ECMO implantation in most severe, pulmonary decompensated patients. The present review summarizes the evidence on ECMO management of severe ARDS in light of recent COVID-19 pandemic, at the same time focusing on differences and similarities between SARS-CoV-2 and ECMO in terms of hematological and inflammatory interplay when these two settings merge.

Hematologic concerns in extracorporeal membrane oxygenation

This ISTH "State of the Art" review aims to critically evaluate the hematologic considerations and complications in extracorporeal membrane oxygenation (ECMO). ECMO is experiencing a rapid increase in clinical use, but many questions remain unanswered. The existing literature does not address or explicitly state many pertinent details that may influence hematologic complications and, ultimately, patient outcomes. This review aims to broadly introduce modern ECMO practices, circuit designs, circuit materials, hematologic complications, transfusion-related considerations, age- and size-related differences, and considerations for choosing outcome measures. Relevant studies from the 2019 ISTH Congress in Melbourne, which further advanced our understanding of these processes, will also be highlighted.

Impact of high mechanical shear stress and oxygenator membrane surface on blood damage relevant to thrombosis and bleeding in a pediatric ECMO circuit

The roles of the large membrane surface of the oxygenator and the high mechanical shear stress (HMSS) of the pump in the extracorporeal membrane oxygenation (ECMO) circuit were examined under a pediatric support setting. A clinical centrifugal pump and a pediatric oxygenator were used to construct the ECMO circuit. An identical circuit without the oxygenator was constructed for comparison. Fresh human blood was circulated in the two circuits for 4 hours under the identical pump speed and flow. Blood samples were collected hourly for blood damage assessment, including platelet activation, generation of platelet-derived microparticles (PDMP), losses of key platelet hemostasis receptors (glycoprotein (GP) Ibα (GPIbα) and GPVI), and high molecular weight multimers (HMWM) of von Willebrand factor (VWF) and plasma free hemoglobin (PFH). Platelet adhesion on fibrinogen, VWF, and collagen was further examined. The levels of platelet activation and generation of PDMP and PFH exhibited an increasing trend with circulation time while the expression levels of GPIbα and GPVI receptors on the platelet surface decreased. Correspondingly, the platelets in the blood samples exhibited increased adhesion capacity to fibrinogen and decreased adhesion capacities on VWF and collagen with circulation time. Loss of HMWM of VWF occurred in both circuits. No statistically significant differences were found in all the measured parameters for blood damage and platelet adhesion function between the two circuits. The results indicate that HMSS from the pump played a dominant role in blood damage associated with ECMO and the impact of the large surface of the oxygenator on blood damage was insignificant.

Extracorporeal Membrane Oxygenation During Adult Noncardiac Surgery and Perioperative Emergencies: A Narrative Review

Over the last decade, the use of extracorporeal membrane oxygenation (ECMO) has increased significantly. In some centers, ECMO has been deployed to manage perioperative emergencies and plays a role in facilitating high-risk thoracic, airway, and trauma surgery, which may not be feasible without ECMO support. General anesthesiologists who usually manage these cases may not be familiar with the initiation and management of patients on ECMO. This review discusses the use of ECMO in the operating room for thoracic, airway, and trauma surgery, as well as obstetric and perioperative emergencies.

Platelet Phenotype and Function in the Setting of Pediatric Extracorporeal Membrane Oxygenation (ECMO): A Systematic Review

Background: Despite increasing technical improvement and extracorporeal membrane oxygenation (ECMO)-related knowledge over the past three decades, morbidity and mortality associated with bleeding and clotting complications remain high in pediatric patients undergoing ECMO. Platelets, a key element of the coagulation system, have been proposed to be the main cause of coagulopathy in the setting of ECMO. This systematic review aims to summarize and discuss the existing knowledge of platelet phenotype and function in the pediatric ECMO population. Methods: A systematic review was conducted for the Embase, Medline, and PubMed databases following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Results: The detailed study selection process yielded a total of 765 studies and only 3 studies that fulfilled the selection criteria were included in this review. Techniques used to assess platelet function in the three existing studies included platelet aggregometry, flow cytometry, and thromboelastography-platelet mapping. The finding that is common to the three studies is reduced platelet function in pediatric patients during ECMO either compared to before the initiation of ECMO or in non-survivors compared to survivors. Two studies demonstrated reduced platelet aggregation that are irreversible by platelet transfusion during ECMO. Two studies reported bleeding events and mortality in children on ECMO and none of the studies investigated thrombotic events. Conclusions: This systematic review demonstrates the extremely limited information available for platelet phenotype and function in the pediatric ECMO population. Evidence from the existing literature suggests reduced platelet aggregation and increased platelet activation in children during ECMO. However, this needs to be interpreted with care due to the limitations associated with the techniques used for platelet function testing. Furthermore, the association between platelet dysfunction and clinical outcomes in the pediatric ECMO population remains elusive. Multiple research gaps have been identified when it comes to the knowledge of platelet phenotype and function of children on ECMO, highlighting the need for robust, well-designed studies in this setting.

Sources of human infection by Salmonella enterica serotype Javiana: A systematic review

Non-typhoidal Salmonella (NTS) infection is one of the major causes of diarrheal disease throughout the world. In recent years, an increase in human S. Javiana infection has been reported from the southern part of the United States. However, the sources and routes of transmission of this Salmonella serotype are not well understood. The objective of this study was to perform a systematic review of the literature to identify risk factors for human S. Javiana infection. Using PRISMA guidelines, we conducted a systematic search in Web of Science, PubMed, and the Morbidity and Mortality Weekly Report (MMWR). Searches returned 63 potential articles, of which 12 articles met all eligibility criteria and were included in this review. A review of the literature indicated that both food and non-food (such as animal contact) exposures are responsible for the transmission of S. Javiana infection to humans. Consumption of fresh produce (tomatoes and watermelons), herbs (paprika-spice), dairy products (cheese), drinking contaminated well water and animal contact were associated with human S. Javiana infections. Based on the findings of this study, control of human S. Javiana infection should include three factors, (a) consumption of drinking water after treatment, (b) safe animal contact, and (c) safe food processing and handling procedures. The risk factors of S. Javiana infections identified in the current study provide helpful insight into the major vehicles of transmission of S. Javiana. Eventually, this will help to improve the risk management of this Salmonella serotype to reduce the overall burden of NTS infection in humans.