Thromboembolic and Bleeding Events in COVID-19 Patients receiving Extracorporeal Membrane Oxygenation

Immature platelets in COVID-19

Platelets play a critical role in immune response. Coronavirus disease 2019 (COVID-19) patients with a severe course often show pathological coagulation parameters including thrombocytopenia, and at the same time the proportion of immature platelets increases. In this study, the platelet count and the immature platelet fraction (IPF) of hospitalized patients with different oxygenation requirements was investigated daily over a course of 40 days. In addition, the platelet function of COVID-19 patients was analyzed. It was found that the number of platelets in patients with the most severe course (intubation and extracorporeal membrane oxygenation (ECMO)) was significantly lower (111.5 ∙ 10⁶ /mL) than in the other groups (mild (no intubation, no ECMO): 203.5 ∙ 10⁶ /mL, p < .0001, moderate (intubation, no ECMO): 208.0 ∙ 10⁶ /mL, p < .0001). IPF tended to be elevated (10.9%). Platelet function was reduced. Differentiation by outcome revealed that the deceased patients had a highly significant lower platelet count and higher IPF (97.3 ∙ 10⁶ /mL, p < .0001, 12.2%, p = .0003).

Determinants of survival in patients on extracorporeal membrane oxygenation therapy due to severe covid-19

BACKGROUND

Severe acute respiratory distress syndrome (ARDS) due to Coronavirus Disease-19 (COVID-19) is associated with high mortality. Although survival on mechanical circulatory support has improved, determinants for better prognosis are still unclear. Here, we report on the outcome of our patient population with the need for mechanical circulatory support due to severe COVID-19 (sCOVID-19) induced ARDS.

METHODS

All patients treated with extracorporeal membrane oxygenation (ECMO) for severe ARDS due to sCOVID-19 were analysed. Patients > 18 years of age at the time of initiation of ECMO were included. Pre-existing comorbidities, complications during ECMO implantation, and ECMO runtime were reviewed. The latency to intubation, proning, tracheotomy, and ECMO implantation was analysed. Furthermore, the survival and non-survival population were compared to determine factors in favour of a better outcome.

RESULTS

In total, 85 patients were treated with veno-venous membrane oxygenation (vv-ECMO) for severe ARDS in our medical centre. The patient population was predominantly male (83.5%) with a mean patient age of 54.9 years. A history of cardiovascular disease (p = .01), smoking (p < .05), need for vasopressor- (p < .05), and renal replacement therapy (p < .001) was associated with a worse prognosis. Overall survival was 50%. The survival population was significantly younger (p = .004), had a significantly higher body weight (p = .02) and body mass index (BMI) (p = .01). Furthermore, survival was significantly better when vv-ECMO was initiated within 48 h after admission (p < .001).

CONCLUSIONS

Pre-existing cardiovascular disease, higher age, history of nicotine abuse, and development of renal failure are associated with poor outcome. Early start of vv-ECMO therapy may lead to better survival in sCOVID-19 patients, although complications during ECMO therapy are associated with a worse prognosis.

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.

Intracranial hemorrhage in patients treated for SARS-CoV-2 with extracorporeal membrane oxygenation: A systematic review and meta-analysis

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is routinely used in patients with severe respiratory failure and has been increasingly needed during the COVID-19 pandemic. In patients treated with ECMO, significant intracranial hemorrhage (ICH) risk exists due to circuit characteristics, anticoagulation, and disease characteristics. ICH risk may be substantially higher in COVID-19 patients than patients treated with ECMO for other indications.

METHODS

We systematically reviewed current literature regarding ICH during ECMO treatment of COVID-19. We utilized Embase, MEDLINE, and Cochrane Library databases. Meta-analysis was performed for included comparative studies. Quality assessment was performed using MINORS criteria.

RESULTS

A total of 54 studies with 4000 ECMO patients were included, all retrospective. Risk of bias was increased via MINORS score primarily due to retrospective designs. ICH was more likely in COVID-19 patients (RR 1.72, 95% CI 1.23, 2.42). Mortality among COVID patients on ECMO with ICH was 64.0%, compared with 41% in patients without ICH (RR1.9, 95% 1.44, 2.51).

CONCLUSION

This study suggests increased hemorrhage rates in COVID-19 patients on ECMO compared to similar controls. Hemorrhage reduction strategies may include atypical anticoagulants, conservative anticoagulation strategies, or biotechnology advances in circuit design and surface coatings.

Significance of heparin induced thrombocytopenia (HIT) in COVID-19: a systematic review and meta-analysis

Heparin-induced thrombocytopenia (HIT) occurs in approximately 3% of patients receiving heparinoids. About 30-75% of patients with type 2 of HIT develop thrombosis as a result of platelet activation. The most important clinical symptom is thrombocytopenia. Patients with severe COVID-19 are among those receiving heparinoids. This meta-analysis performed to picture the current knowledge and results of published studies in this field. Three search engines were searched and 575 papers were found. After evaluation, 37 articles were finally selected of which 13 studies were quantitatively analyzed. The pooled frequency rate of suspected cases with HIT in 13 studies with 11,241 patients was 1.7%. The frequency of HIT was 8.2% in the extracorporeal membrane oxygenation subgroup with 268 patients and 0.8% in the hospitalization subgroup with 10,887 patients. The coincidence of these two conditions may increase the risk of thrombosis. Of the 37 patients with COVID-19 and confirmed HIT, 30 patients (81%) were treated in the intensive care unit or had severe COVID-19. The most commonly used anticoagulants were UFH in 22 cases (59.4%). The median platelet count before treatment was 237 (176-290) x 10³/µl and the median nadir platelet count was 52 (31-90.5) x 10³/µl.

Prognostic factors for favorable outcomes after veno-venous extracorporeal membrane oxygenation in critical care patients with COVID-19

BACKGROUND

Patients with COVID-19 and severe acute respiratory failure may require veno-venous extracorporeal membrane oxygenation (VV ECMO). Yet, this procedure is resource-intensive and high mortality rates have been reported. Thus, predictors for identifying patients who will benefit from VV ECMO would be helpful.

METHODS

This retrospective study included 129 patients with COVID-19 and severe acute respiratory failure, who had received VV ECMO at the University Medical Center Regensburg, Germany, between 1 March 2020 and 31 December 2021. Patient-specific factors and relevant intensive-care parameters at the time of the decision to start VV ECMO were investigated regarding their value as predictors of patient survival. In addition, the intensive-care course of the first 10 days of VV ECMO was compared between survivors and patients who had died in the intensive care unit.

RESULTS

The most important parameters for predicting outcome were patient age and platelet count, which differed significantly between survivors and non-survivors (age: 52.6±8.1 vs. 57.4±10.1 years, p<0.001; platelet count before VV ECMO: 321.3±132.2 vs. 262.0±121.0 /nL, p = 0.006; average on day 10: 199.2±88.0 vs. 147.1±57.9 /nL, p = 0.002). A linear regression model derived from parameters collected before the start of VV ECMO only included age and platelet count. Patients were divided into two groups by using receiver operating characteristics (ROC) analysis: group 1: 78% of patients, mortality 26%; group 2: 22% of patients, mortality 75%. A second linear regression model included average blood pH, minimum paO2, and average pump flow on day 10 of VV ECMO in addition to age and platelet count. The ROC curve resulted in two cut-off values and thus in three groups: group 1: 25% of patients, mortality 93%; group 2: 45% of patients, mortality 31%; group 3: 30% of patients, mortality 0%.

Innovative experimental animal models for real-time comparison of antithrombogenicity between two oxygenators using dual extracorporeal circulation circuits and indocyanine green fluorescence imaging

BACKGROUND

Antithrombogenicity of extracorporeal membrane oxygenation (ECMO) devices, particularly oxygenators, is a current problem, with numerous studies and developments underway. However, there has been limited progress in developing methods to accurately compare the antithrombogenicity of oxygenators. Animal experiments are commonly conducted to evaluate the antithrombogenicity of devices; however, it is challenging to maintain a steady experimental environment. We propose an innovative experimental animal model to evaluate different devices in a constant experimental environment in real-time.

METHODS

This model uses two venous-arterial ECMO circuits attached to one animal (one by jugular vein and carotid artery, one by femoral vein and artery) and real-time assessment of thrombus formation in the oxygenator by indocyanine green (ICG) fluorescence imaging. Comparison studies were conducted using three pigs: one to compare different oxygenators (MERA vs. CAPIOX) (Case 1), and two to compare antithrombotic properties of the oxygenator (QUADROX) when used under different hydrodynamic conditions (continuous flow vs. pulsatile flow) (Cases 2 and 3).

RESULTS

Thrombi, visualized using ICG imaging, appeared as black dots on a white background in each oxygenator. In Case 1, differences in the site of thrombus formation and rate of thrombus growth were observed in real-time in two oxygenators. In Case 2 and 3, the thrombus region was smaller in pulsatile than in continuous conditions.

CONCLUSIONS

We devised an innovative experimental animal model for comparison of antithrombogenicity in ECMO circuits. This model enabled simultaneous evaluation of two different ECMO circuits under the same biological conditions and reduced the number of sacrificed experimental animals.

Bleeding and thrombotic events in patients with severe COVID-19 supported with extracorporeal membrane oxygenation: a nationwide cohort study

PURPOSE

To describe bleeding and thrombotic events and their risk factors in patients receiving extracorporeal membrane oxygenation (ECMO) for severe coronavirus disease 2019 (COVID-19) and to evaluate their impact on in-hospital mortality.

METHODS

The ECMOSARS registry included COVID-19 patients supported by ECMO in France. We analyzed all patients included up to March 31, 2022 without missing data regarding bleeding and thrombotic events. The association of bleeding and thrombotic events with in-hospital mortality and pre-ECMO variables was assessed using multivariable logistic regression models.

RESULTS

Among 620 patients supported by ECMO, 29% had only bleeding events, 16% only thrombotic events and 20% both bleeding and thrombosis. Cannulation site (18% of patients), ear nose and throat (12%), pulmonary bleeding (9%) and intracranial hemorrhage (8%) were the most frequent bleeding types. Device-related thrombosis and pulmonary embolism/thrombosis accounted for most of thrombotic events. In-hospital mortality was 55.7%. Bleeding events were associated with in-hospital mortality (adjusted odds ratio (adjOR) = 2.91[1.94-4.4]) but not thrombotic events (adjOR = 1.02[0.68-1.53]). Intracranial hemorrhage was strongly associated with in-hospital mortality (adjOR = 13.5[4.4-41.5]). Ventilation duration before ECMO ≥ 7 days and length of ECMO support were associated with bleeding. Thrombosis-associated factors were fibrinogen ≥ 6 g/L and length of ECMO support.

CONCLUSIONS

In a nationwide cohort of COVID-19 patients supported by ECMO, bleeding incidence was high and associated with mortality. Intracranial hemorrhage incidence was higher than reported for non-COVID patients and carried the highest risk of death. Thrombotic events were less frequent and not associated with mortality. Length of ECMO support was associated with a higher risk of both bleeding and thrombosis, supporting the development of strategies to minimize ECMO duration.

Temporary mechanical circulatory support for COVID‐19 patients: A systematic review of literature

Objective

Myocardial damage occurs in up to 25% of coronavirus disease 2019 (COVID‐19) cases. While veno‐venous extracorporeal life support (V‐V ECLS) is used as respiratory support, mechanical circulatory support (MCS) may be required for severe cardiac dysfunction. This systematic review summarizes the available literature regarding MCS use rates, disease drivers for MCS initiation, and MCS outcomes in COVID‐19 patients.

Methods

PubMed/EMBASE were searched until October 14, 2021. Articles including adults receiving ECLS for COVID‐19 were included. The primary outcome was the rate of MCS use. Secondary outcomes included mortality at follow‐up, ECLS conversion rate, intubation‐to‐cannulation time, time on ECLS, cardiac diseases, use of inotropes, and vasopressors.

Results

Twenty‐eight observational studies (comprising both ECLS‐only populations and ECLS patients as part of larger populations) included 4218 COVID‐19 patients (females: 28.8%; median age: 54.3 years, 95%CI: 50.7–57.8) of whom 2774 (65.8%) required ECLS with the majority (92.7%) on V‐V ECLS, 4.7% on veno‐arterial ECLS and/or Impella, and 2.6% on other ECLS. Acute heart failure, cardiogenic shock, and cardiac arrest were reported in 7.8%, 9.7%, and 6.6% of patients, respectively. Vasopressors were used in 37.2%. Overall, 3.1% of patients required an ECLS change from V‐V ECLS to MCS for heart failure, myocarditis, or myocardial infarction. The median ECLS duration was 15.9 days (95%CI: 13.9–16.3), with an overall survival of 54.6% and 28.1% in V‐V ECLS and MCS patients. One study reported 61.1% survival with oxy‐right ventricular assist device.

Conclusion

MCS use for cardiocirculatory compromise has been reported in 7.3% of COVID‐19 patients requiring ECLS, which is a lower percentage compared to the incidence of any severe cardiocirculatory complication. Based on the poor survival rates, further investigations are warranted to establish the most appropriated indications and timing for MCS in COVID‐19.

Platelets in Viral Infections - Brave Soldiers or Trojan Horses

Viral infections are often associated with platelet activation and haemostatic complications. In line, low platelet counts represent a hallmark for poor prognosis in many infectious diseases. The underlying cause of platelet dysfunction in viral infections is multifaceted and complex. While some viruses directly interact with platelets and/or megakaryocytes to modulate their function, also immune and inflammatory responses directly and indirectly favour platelet activation. Platelet activation results in increased platelet consumption and degradation, which contributes to thrombocytopenia in these patients. The role of platelets is often bi-phasic. Initial platelet hyper-activation is followed by a state of platelet exhaustion and/or hypo-responsiveness, which together with low platelet counts promotes bleeding events. Thereby infectious diseases not only increase the thrombotic but also the bleeding risk or both, which represents a most dreaded clinical complication. Treatment options in these patients are limited and new therapeutic strategies are urgently needed to prevent adverse outcome. This review summarizes the current literature on platelet-virus interactions and their impact on viral pathologies and discusses potential intervention strategies. As pandemics and concomitant haemostatic dysregulations will remain a recurrent threat, understanding the role of platelets in viral infections represents a timely and pivotal challenge.

SARS-CoV-2-related and Covid-19 vaccine-induced thromboembolic events: A comparative review

Since the start of the pandemic, thrombotic events have been a well-known and severe complication associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Nevertheless, the initiation of vaccination programs brought another rare yet highly fatal thrombotic event, vaccine-induced immune thrombotic thrombocytopaenia, which has caused extensive debate regarding the safety of vaccines. This review defines the thromboembolic events following infection and vaccination, identifies their risk factors, describes their pathophysiology, and discusses their management, treatment, and prevention.

Blood Product Utilization in Patients with COVID-19 on ECMO

Introduction

Methods

Results

Conclusions

Gavage approach to oxygen supplementation with oxygen therapeutic Ox66™ in a hypoventilation rodent model of respiratory distress

Acute respiratory distress syndrome (ARDS) features pulmonary dysfunction capable of causing life-threatening hypoxaemia. Ventilation and hyperoxic therapies force oxygen through dysfunctional alveoli but risk exacerbating damage. Ox66™ is an ingestible, solid-state oxygen product designed for oxygen supplementation. Eighteen anaesthetized, ventilated rats were subjected to a 40% reduction in tidal volume to produce a hypoventilatory simulation of the hypoxia in ARDS (HV-ARDS). After 60 min, animals were randomized to receive either normal saline (Saline; volume control) or Ox66^™ gavage. Cardiovascular function and blood oximetry/chemistry were measured alongside interstitial oxygenation (P_ISFO₂) of the peripheral spinotrapezius muscle. HV-ARDS reduced mean arterial pressure by ∼20% and P_ISFO₂ by ∼35% for both groups. Ox66^™ gavage treatment at 60 min improved P_ISFO₂ over Saline (p < .0001), restoring baseline values, however, the effect was temporary. A second bolus at 120 min repeated the OX66^™ P_ISFO₂ response, which remained elevated over Saline (p < .01) until study end and was supported by systemic parameters of lactate, P_aO₂, SO₂, and base deficit. Saline remained hypotensive, whereas Ox66^™ became normotensive. Vasoconstriction was observed in the Saline, but not Ox66^™ group. Supplemental oxygenation through Ox66^™ gavage increased peripheral tissue oxygenation, warranting further study for disorders featuring dysfunction of pulmonary perfusion like ARDS.

Extracorporeal membrane oxygenation in patients with COVID-19: 1-year experience

Background

Extracorporeal membrane oxygenation (ECMO) in patients with coronavirus disease 2019 (COVID-19) showed reasonable outcomes. However, recent studies indicated a negative trend and analysis is needed.

Methods

Baseline characteristics, laboratory parameters, and outcomes of ECMO-supported patients with COVID-19 were analyzed in a retrospective single-center study. We included hospital admissions until February 28, 2021; patients were followed until discharge/death. Eventually, we compared data between patients hospitalized before and after September 1, 2020.

Results

Median age of patients treated with ECMO (n=39) was 56 years; most patients were males (n=28, 72%). Median mechanical ventilation time (prior to ECMO) was 6 days, while the median ECMO duration was 19 days. Overall survival rate was 41%. In the sub-analysis, survival until discharge in the first and second epidemic waves was 53% (n=19) and 30% (n=20), respectively (P=0.2). At baseline, compared with patients of the first wave, those of the second wave had higher median body mass index (28.2 vs. 31.1 kg/m², respectively, P=0.02), bicarbonate (27 vs. 31.8 mmol/L, respectively, P=0.033), plasma free hemoglobin (36 vs. 58 mg/L, respectively, P=0.013), alanine aminotransferase (33 vs. 52 U/L, respectively, P=0.018), and pH (7.29 vs. 7.42, respectively, P=0.005), lower rate of pulmonary hypertension (32% vs. 0%, respectively, P=0.008), lower positive end-expiratory pressure (14 vs. 12 cmH₂O, respectively, P=0.04), longer median ECMO duration (16 vs. 24.5 days, respectively, P=0.074), and more frequent major bleeding events (42% vs. 80%, respectively, P=0.022).

Conclusions

ECMO-supported patients with COVID-19 had an overall survival rate of 41%. Similar to international registries, we observed less favorable outcomes during the second wave. Further research is needed to confirm this signal and find predictors for mortality.

Thromboembolism and Bleeding in COVID-19

Coronavirus disease 2019 (COVID-19) is characterized by a coagulation dysfunction which has different underlying mechanisms and factors. Patients with severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection have an increased risk for thromboembolic and bleeding complications. Incidences are high, and mainly consist of venous thromboembolism (VTE), which significantly contributes to morbidity and mortality in affected patients. Thromboprophylaxis is recommended in all hospitalized COVID-19 patients. Therapeutic doses of antithrombotic agents are only beneficial in noncritically ill patients, and usual care thromboprophylaxis is sufficient in critically ill patients at the ICU. Regarding screening for VTE, high quality evidence is warranted to investigate the significance of asymptomatic DVT in the ICU setting and its influence on PE and mortality.

Evaluation of Bivalirudin as the Primary Anticoagulant in Patients Receiving Extracorporeal Membrane Oxygenation for SARS-CoV-2-Associated Acute Respiratory Failure

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is a potential option for the management of severe acute respiratory failure secondary to COVID-19. Conflicting the use of this therapy is the known coagulopathy within COVID-19, leading to an incidence of venous thrombotic events of 25% to 49%. To date, limited guidance is available on optimal anticoagulation strategies in this population.

OBJECTIVE

The purpose of this study was to evaluate the utilization of a pharmacist-driven bivalirudin dosing protocol for anticoagulation in the setting of ECMO for COVID-19-associated respiratory failure.

METHODS

This was a single-center retrospective chart review over a 9-month period of patients receiving bivalirudin while on ECMO. All patients with acute respiratory failure requiring ECMO with a positive SARS-CoV-2 polymerase chain reaction were included. Bivalirudin was dosed via aPTT monitoring after a starting dose of 0.2 or 0.3 mg/kg/h.

RESULTS

There were 33 patients included in this study, all receiving mechanical ventilation. The most common starting dose of bivalirudin was 0.2 mg/kg/h, with an average time to therapeutic range of 20 hours. Compared to previous reports, rates of bleeding were low at 15.1%, and 6.1% of patients developed a new venous thromboembolic event while on ECMO. ECMO survival was 51.5%, with an ICU mortality rate of 48.5%.

CONCLUSION AND RELEVANCE

In the first published report of its use within this population, bivalirudin was found to be a viable choice for anticoagulation in those patients on ECMO for severe respiratory failure secondary to COVID-19.