What is the impact of microvascular complications of diabetes on severe COVID-19?

Evidence suggests severe coronavirus disease-19 (COVID-19) infection is characterised by pulmonary and systemic microvasculature dysfunction, specifically, acute endothelial injury, hypercoagulation and increased capillary permeability. Diabetes, which is also characterised by vascular injury in itself, confers an increased risk of adverse COVID-19 outcomes. It has been suggested that pre-existing endothelial dysfunction and microvascular disease in diabetes will exacerbate the vascular insults associated with COVID-19 and thus lead to increased severity of COVID-19 infection. In this article, we evaluate the current evidence exploring the impact of microvascular complications, in the form of diabetic retinopathy and nephropathy, in individuals with COVID-19 and diabetes. Future insights gained from exploring the microvascular injury patterns and clinical outcomes may come to influence care delivery algorithms for either of these conditions.

Endothelial contribution to COVID-19: an update on mechanisms and therapeutic implications.

The global propagation of SARS-CoV-2 leads to an unprecedented public health emergency. Despite that the lungs are the primary organ targeted by COVID-19, systemic endothelial inflammation and dysfunction is observed particularly in patients with severe COVID-19, manifested by elevated endothelial injury markers, endotheliitis, and coagulopathy. Here, we review the clinical characteristics of COVID-19 associated endothelial dysfunction; and the likely pathological mechanisms underlying the disease including direct cell entry or indirect immune overreactions after SARS-CoV-2 infection. In addition, we discuss potential biomarkers that might indicate the disease severity, particularly related to the abnormal development of thrombosis that is a fatal vascular complication of severe COVID-19. Furthermore, we summarize clinical trials targeting the direct and indirect pathological pathways after SARS-CoV-2 infection to prevent or inhibit the virus induced endothelial disorders.

Platelets Contribution to Thrombin Generation in Philadelphia-Negative Myeloproliferative Neoplasms: The "Circulating Wound" Model.

Current cytoreductive and antithrombotic strategies in MPNs are mostly based on cell counts and on patient's demographic and clinical history. Despite the numerous studies conducted on platelet function and on the role of plasma factors, an accurate and reliable method to dynamically quantify the hypercoagulability states of these conditions is not yet part of clinical practice. Starting from our experience, and after having sifted through the literature, we propose an in-depth narrative report on the contribution of the clonal platelets of MPNs-rich in tissue factor (TF)-in promoting a perpetual procoagulant mechanism. The whole process results in an unbalanced generation of thrombin and is self-maintained by Protease Activated Receptors (PARs). We chose to define this model as a "circulating wound", as it indisputably links the coagulation, inflammation, and fibrotic progression of the disease, in analogy with what happens in some solid tumours. The platelet contribution to thrombin generation results in triggering a vicious circle supported by the PARs/TGF-beta axis. PAR antagonists could therefore be a good option for target therapy, both to contain the risk of vascular events and to slow the progression of the disease towards end-stage forms. Both the new and old strategies, however, will require tools capable of measuring procoagulant or prohaemorrhagic states in a more extensive and dynamic way to favour a less empirical management of MPNs and their potential clinical complications.

Inherited and acquired thrombophilia in women of Indian ethnicity with recurrent pregnancy loss: An observational study from North India.

OBJECTIVES: The spectrum of thrombophilia in women with recurrent pregnancy loss (RPL) is different in Indian ethnicity as reported by few studies. We aimed to study the prevalence of thrombophilia in RPL patients referred to hematology department of a tertiary centre. MATERIAL AND METHODS: This is an observational study of 112 RPL patients with no apparent cause after extensive workup for non-hematological causes. The investigations performed were routine coagulogram, APLA workup, plasma homocysteine, MTHFRC677T polymorphisms, Protein C, free Protein S, Anti-thrombin III levels, test for Activated Protein C resistance (APC-R) ,Factor V Leiden and Prothrombin gene G20210A mutation. RESULTS: Of 112 patients, at least one thrombophilia was identified in 70.5% and combined thrombophilia in 12.5% patients. Hyperhomocysteinemia (30.4%) and APLA (25.9%) were the commonest thrombophilia whereas anticoagulant defects were seen in 12.5% of the population. Protein C deficiency (5.35%) was the commonest anticoagulant defect followed by APCR (3.6%). Mutational analysis revealed MTHFRC677T polymorphism in 20.5% whereas Factor V Leiden heterozygous in 1.8% patients. None of the patients had homozygous Factor V Leiden or Prothrombin gene G20210A mutation. Hyperhomocysteinemia, MTHFRC677T and Protein C deficiency were more associated with early pregnancy losses whereas Protein S deficiency, Factor V Leiden and APLA caused both early and late losses. Patients with greater number of losses were positive for homozygous MTHFRC677T, factor V Leiden and APLA. CONCLUSION: The approach to investigating Indian women with RPL should be based on the prevalence of thrombophilia which is unique to Indian ethnicity.

Shedding light on vitamin D: the shared mechanistic and pathophysiological role between hypovitaminosis D and COVID-19 risk factors and complications.

Severe acute respiratory syndrome coronavirus (SARS-COV-2) is the culprit of the Coronavirus Disease (COVID-19), which has infected approximately 173 million people and killed more than 3.73 million. At risk groups including diabetic and obese patients are more vulnerable to COVID-19-related complications and poor outcomes. Substantial evidence points to hypovitaminosis D as a risk factor for severe disease, the need for ICU, and mortality. 1,25(OH)D, a key regulator of calcium homeostasis, is believed to have various immune-regulatory roles including; promoting anti-inflammatory cytokines, down regulating pro-inflammatory cytokines, dampening entry and replication of SARS-COV-2, and the production of antimicrobial peptides. In addition, there are strong connections which suggest that dysregulated 1,25(OH)D levels play a mechanistic and pathophysiologic role in several disease processes that are shared with COVID-19 including: diabetes, obesity, acute respiratory distress syndrome (ARDS), cytokine storm, and even hypercoagulable states. With evidence continuing to grow for the case that low vitamin D status is a risk factor for COVID-19 disease and poor outcomes, there is a need now to address the public health efforts set in place to minimize infection, such as lock down orders, which may have inadvertently increased hypovitaminosis D in the general population and those already at risk (elderly, obese, and disabled). Moreover, there is a need to address the implications of this evidence and how we may apply the use of cheaply available supplementation, which has yet to overcome the near global concern of hypovitaminosis D. In our review, we exhaustively scope these shared pathophysiologic connections between COVID-19 and hypovitaminosis D.

Enoxaparina 60 mg/0, 6 mL injetável para a prevenção de tromboembolismo venoso em gestantes com trombofilia / Enoxaparin 60 mg/0. 6 mL injectable for the prevention of venous thromboembolism in pregnant women with thrombophilia

CONTEXTO: O tromboembolismo venoso (TEV) associado à gravidez, incluindo trombose venosa profunda (TVP) e embolia pulmonar (EP), embora incomum, continua sendo causa importante de morbimortalidade. Por ser uma condição próinflamatória com ativação de células endoteliais, as gestantes apresentam um risco maior de TEV quando comparado com mulheres não grávidas. Mulheres com trombofilia e aquelas que se submetem à cesariana representam a maioria das pacientes com TEV pós-parto. Atualmente, o Brasil possui um Protocolo Clínico e Diretrizes Terapêuticas (PCDT) de Profilaxia do Tromboembolismo Venoso em Gestantes com Trombofilia. O PCDT foi publicado por meio da Portaria Conjunta SAES-SCTIE nº 04, de 12 de fevereiro de 2020 e preconiza o uso do medicamento enoxaparina para prevenção e tratamento do tromboembolismo venoso em gestantes com trombofilia. Entretanto, a apresentação de 60 mg/0,6 mL de enoxaparina, necessária para uma dose precisa em grávidas ou puérperas com trombofilia com massa corporal acima de 90 kg com indicação de anticoagulação profilática ou em grávidas ou puérperas com trombofilia e indicação de esquema de anticoagulação plena, independentemente do peso corporal, atualmente não está disponível no SUS. PERGUNTA: A enoxaparina 60 mg/0,6mL é eficaz, efetiva e segura em grávidas ou puérperas com trombofilia com massa corporal acima de 90 kg que estiverem em tratamento com esquema de anticoagulação profilática ou em gestantes com indicação esquema de anticoagulação plena, independentemente do peso corporal? EVIDÊNCIAS CLÍNICAS: Foram incluídos 4 estudos descritos em 5 referências, sendo 02 ensaios clínicos randomizados (ECR) e dois estudos observacionais do tipo coorte retrospectiva. Os estudos apontam que não há diferenças significativas para os desfechos de eficácia, efetividade e segurança entre a dose mínima e o ajuste de dose de enoxaparina na Prevenção de Tromboembolismo Venoso em Gestantes com Trombofilia. Para o desfecho mais relevante que corresponde ao número de nascidos vivos por gestação, a meta-análise incluiu 165 gestantes recebendo enoxaparina com dose ajustada e 155 gestantes recebendo 40 mg/dia de enoxaparina em dose fixa. O resultado agrupado dos dois ECRs gerou um RR de 0,95 sem diferença estatisticamente significante entre os grupos no modelo de efeitos randômicos, (IC95% = 0,86 ­ 1,04; I 2 = 0%; p = 0,55). Nos efeitos indesejáveis da tecnologia, ambas as doses de enoxaparina indicam ser seguras e bem toleradas. ANÁLISE DE IMPACTO ORÇAMENTÁRIO: Foi adotado um horizonte temporal de cinco anos (2021 a 2025). No cenário mais conservador, a análise de impacto orçamentário evidenciou uma economia de R$ 55.369.020,00 diante da incorporação da enoxaparina 60 mg/0,6 mL no SUS. MONITORAMENTO DO HORIZONTE TECNOLÓGICO: Não foram detectadas tecnologias para compor o esquema terapêutico de prevenção de tromboembolismo venoso em gestantes com trombofilia. No Brasil, a enoxaparina não está sob proteção patentária. CONSIDERAÇÕES FINAIS: Considerou-se que a enoxaparina 60 mg/0,6 mL mostra-se como uma alternativa segura quando comparada à dose mínima de 40 mg/0,4 mL. Ademais, a incorporação da enoxaparina 60 mg/0,6 mL pode levar à economia de R$ 55.369.020,00 ao longo de cinco anos. RECOMENDAÇÃO PRELIMINAR DA CONITEC: O Plenário da Conitec, em sua 96ª Reunião Ordinária, no dia 07 de abril de 2021, deliberou que a matéria fosse disponibilizada em Consulta Pública com recomendação preliminar favorável à incorporação da enoxaparina 60 mg/0,6 mL injetável para a prevenção de tromboembolismo venoso em gestantes com trombofilia no SUS. Os membros da Conitec consideraram que a incorporação desta nova apresentação de enoxaparina é necessária para a prevenção de tromboembolismo venoso em gestantes com sobrepeso ou com indicação de anticoagulação plena. Além disso, considerou-se que essa incorporação potencialmente irá representar economia para o Sistema Único de Saúde. CONSULTA PÚBLICA: Foram recebidas 16 contribuições, sendo 8 técnico-científicas e 8 sobre experiência ou opinião. A grande maioria destas concordou da recomendação inicial da Conitec. Ao final, o Plenário da Conitec entendeu que não foram apresentadas novas evidências que mudassem seu entendimento sobre o tema, fazendo com que sua recomendação preliminar fosse mantida. RECOMENDAÇÃO FINAL DA CONITEC: O Plenário da Conitec, em sua 98ª Reunião Ordinária, no dia 09 de junho de 2021, deliberou por unanimidade recomendar a incorporação da enoxaparina 60 mg/0,6 mL injetável para a prevenção de tromboembolismo venoso em gestantes com trombofilia. Assim, foi assinado o Registro de Deliberação nº 622/2021. DECISÃO: Incorporar a enoxaparina 60 mg/0,6 mL injetável para a prevenção de tromboembolismo venoso em gestantes com trombofilia, no âmbito do Sistema Único de Saúde ­ SUS, conforme a Portaria nº 35, publicada no Diário Oficial da União nº 127, seção 1, página 143, em 08 de julho de 2021.

Acute Viral Illnesses and Ischemic Stroke: Pathophysiological Considerations in the Era of the COVID-19 Pandemic.

The severe acute respiratory syndrome coronavirus 2 or coronavirus disease 2019 (COVID-19) pandemic has raised concerns about the correlation with this viral illness and increased risk of stroke. Although it is too early in the pandemic to know the strength of the association between COVID-19 and stroke, it is an opportune time to review the relationship between acute viral illnesses and stroke. Here, we summarize pathophysiological principles and available literature to guide understanding of how viruses may contribute to ischemic stroke. After a review of inflammatory mechanisms, we summarize relevant pathophysiological principles of vasculopathy, hypercoagulability, and hemodynamic instability. We will end by discussing mechanisms by which several well-known viruses may cause stroke in an effort to inform our understanding of the relationship between COVID-19 and stroke.

COVID-19 infection and stroke risk.

Coronavirus disease 2019 (COVID-19), due to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in Wuhan city, China in December 2019 and rapidly spread to other countries. The most common reported symptoms are fever, dry cough, myalgia and fatigue, headache, anorexia, and breathlessness. Anosmia and dysgeusia as well as gastrointestinal symptoms including nausea and diarrhea are other notable symptoms. This virus also can exhibit neurotropic properties and may also cause neurological diseases, including epileptic seizures, cerebrovascular accident, Guillian barre syndrome, acute transverse myelitis, and acute encephalitis. In this study, we discuss stroke as a complication of the new coronavirus and its possible mechanisms of damage.

Prognostic Value of Antithrombin Levels in COVID-19 Patients and Impact of Fresh Frozen Plasma Treatment: A Retrospective Study

Objective: The defective interplay between coagulation and inflammation may be the leading cause of intravascular coagulation and organ dysfunction in coronavirus disease-19 (COVID-19) patients. Abnormal coagulation profiles were reported to be associated with poor outcomes. In this study, we assessed the prognostic values of antithrombin (AT) activity levels and the impact of fresh frozen plasma (FFP) treatment on outcome. Materials and Methods: Conventional coagulation parameters as well as AT activity levels and outcomes of 104 consecutive critically ill acute respiratory distress syndrome (ARDS) patients with laboratory-confirmed COVID-19 disease were retrospectively analyzed. Patients with AT activity below 75% were treated with FFP. Maximum AT activity levels achieved in those patients were recorded. Results: AT activity levels at admission were significantly lower in nonsurvivors than survivors (73% vs. 81%). The cutoff level for admission AT activity was 79% and 58% was the lowest AT for survival. The outcome in those patients who had AT activity levels above 75% after FFP treatment was better than that of the nonresponding group. As well as AT, admission values of D-dimer, C-reactive protein, and procalcitonin were coagulation and inflammatory parameters among the mortality risk factors. Conclusion: AT activity could be used as a prognostic marker for survival and organ failure in COVID-19-associated ARDS patients. AT supplementation therapy with FFP in patients with COVID-19-induced hypercoagulopathy may improve thrombosis prophylaxis and thus have an impact on survival.

Complement activation and coagulopathy - an ominous duo in COVID19.

INTRODUCTION: COVID-19 has similarities to the Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) outbreaks, as severe patients and non-survivors have frequently shown abnormal coagulation profiles. Immune-mediated pathology is a key player in this disease; hence, the role of the complement system needs assessment. The complement system and the coagulation cascade share an intricate network, where multiple mediators maintain a balance between both pathways. Coagulopathy in COVID-19, showing mixed features of complement-mediated and consumption coagulopathy, creates a dilemma in diagnosis and management. AREAS COVERED: Pathophysiology of coagulopathy in COVID-19 patients, with a particular focus on D-dimer and its role in predicting the severity of COVID-19 has been discussed. A comprehensive search of the medical literature on PubMed was done till May 30th, 2020 with the keywords 'COVID-19', 'SARS-CoV-2', 'Coronavirus', 'Coagulopathy', and 'D-dimer'. Twenty-two studies were taken for weighted pooled analysis of D-dimer. EXPERT OPINION: A tailored anticoagulant regimen, including intensification of standard prophylactic regimens with low-molecular-weight heparin is advisable for COVID-19 patients. Atypical manifestations and varying D-dimer levels seen in different populations bring forth the futility of uniform recommendations for anticoagulant therapy. Further, direct thrombin inhibitors and platelet inhibitors in a patient-specific manner should also be considered.

The Vasculopathy of Juvenile Dermatomyositis: Endothelial Injury, Hypercoagulability, and Increased Arterial Stiffness.

OBJECTIVE: Vasculopathy is considered central to the pathogenesis of juvenile dermatomyositis (DM) and is associated with severe extramuscular manifestations. We undertook this study to investigate the hypothesis that the vasculopathy of juvenile DM can be noninvasively tracked by examining biomarkers of endothelial injury, subclinical inflammation, hypercoagulability, and vascular arterial stiffness. METHODS: The study population was a UK cohort of children with juvenile DM. Circulating endothelial cells (CECs) and microparticles (MPs) were identified using immunomagnetic bead extraction and flow cytometry, respectively. Plasma thrombin generation was determined using a fluorogenic assay. Cytokine and chemokine levels were measured by electrochemiluminescence. Arterial stiffness was assessed using pulse wave velocity (PWV). Results were expressed as the median and interquartile range (IQR), and statistical significance was assessed using nonparametric analyses. RESULTS: Ninety patients with juvenile DM and 79 healthy control subjects were included. The median age of the patients was 10.21 years (IQR 6.68-13.40), and the median disease duration was 1.63 years (IQR 0.28-4.66). CEC counts were higher in all patients with juvenile DM compared to controls (median 96 cells/ml [IQR (40-192] and 12 cells/ml [IQR 8-24], respectively; P < 0.0001). Circulating MP numbers were also significantly higher in patients with active juvenile DM compared to controls (median 204.7 × 103 /ml [IQR 87.9-412.6] and 44.3 × 103 /ml [IQR 15.0-249.1], respectively; P < 0.0001). MPs were predominantly of platelet and endothelial origin. Enhanced plasma thrombin generation was demonstrated in patients with active juvenile DM compared to those with inactive disease (P = 0.0003) and controls (P < 0.0001). Carotid-radial PWV adjusted for age was increased in patients with juvenile DM compared to controls (P = 0.003). CONCLUSION: We observed increased endothelial injury and increased levels of proinflammatory cytokines in patients with active juvenile DM. MP profiles reflected distinct disease activity status in juvenile DM and are markers of vascular pathology, platelet activation, and thrombotic propensity. Ongoing long-term vascular injury may result in increased arterial stiffness in patients with juvenile DM.

Is Mesenteric Ischemia In COVID-19 Patients A Surprise?

Aim. The disease caused by the 2019 novel coronavirus is known predominantly for its respiratory outcomes; a subset of critically ill patients demonstrates clinically remarkable hypercoagulability in which thrombotic events range from acute pulmonary embolism in patients with COVID-19 pneumonia to extremity ischemia. Our observational study aimed to describe the incidence and characteristics, as well as clinical outcomes, of patients presenting and treated for mesenteric ischemia during the COVID-19 pandemic. Material and Methods. Between March 13 and May 13, 2020, 60 patients operated for emergency reasons were analyzed, and it was noticed that 5 of the 6 COVID-positive patients were operated due to mesenteric ischemia. Results. Five of sixty patients (83.3%) applied to our emergency clinic with COVID-19 positive and acute abdomen. Two of them (40%) did not have any comorbidities. All of them (%100) were male. There were no complications and only 1 death (20%). Mean leukocyte, neutrophil, and platelet levels were within the normal range, while the lymphocyte level was near the lower limit. C-Reactive Protein was above the limit in all patients. The mean levels of International Normalized Ratio, Platelet, and Activated Partial Thromboplastin Time were above the limits. While D-dimer levels were close to the upper limit; fibrinogen levels were above the normal limit for each patient. Conclusion. The presence of hypercoagulation status in critical COVID-19 patients should be observed closely, and anticoagulation therapy can be considered in selected patients. More clinical data are needed to examine the role of anticoagulation in COVID-19 treatment.

COVID-19-associated coagulopathy and disseminated intravascular coagulation.

The pathology of coronavirus disease 2019 (COVID-19) is exacerbated by the progression of thrombosis, and disseminated intravascular coagulation (DIC), and cytokine storms. The most frequently reported coagulation/fibrinolytic abnormality in COVID-19 is the increase in D-dimer, and its relationship with prognosis has been discussed. However, limits exist to the utility of evaluation by D-dimer alone. In addition, since the coagulation/fibrinolytic condition sometimes fluctuates within a short period of time, regular examinations in recognition of the significance of the examination are desirable. The pathophysiology of disseminated intravascular coagulation (DIC) associated with COVID-19 is very different from that of septic DIC, and both thrombotic and hemorrhagic pathologies should be noted. COVID-19 thrombosis includes macro- and microthrombosis, with diagnosis of the latter depending on markers of coagulation and fibrinolysis. Treatment of COVID-19 is classified into antiviral treatment, cytokine storm treatment, and thrombosis treatment. Rather than providing uniform treatment, the treatment method most suitable for the severity and stage should be selected. Combination therapy with heparin and nafamostat is expected to develop in the future. Fibrinolytic therapy and adsorption therapy require further study.

Instrumentación vertebral y flegmasía cerúlea dolens / Vertebral instrumentation and Phlegmasia cerulea dolens

La flegmasía cerúlea dolens es un estado muy infrecuente, secundario a trombosis venosa profunda, de origen multietiológico, que afecta usualmente a las extremidades inferiores. Se presenta con dolor en miembro inferior y edema rápidamente progresivo que puede comprometer la perfusión de la extremidad, pudiendo llevar a gangrena, amputación e incluso a la muerte. Se presenta un caso de flegmasía extremadamente raro secundario a trombosis venosa profunda masiva del eje iliofemoral izquierdo provocado por un hematoma crónico compresivo de origen traumático por cizallamiento del tornillo de S1 en una paciente intervenida hacia 3 meses de hernia discal lumbar mediante artrodesis e instrumentación vertebral L5-S1. Este artículo muestra la necesidad de realizar un escrupuloso escrutinio de los tornillos tanto intra como postoperatoriamente cuando nos encontramos cerca de los grandes vasos

Phlegmasia cerulea dolens is a very infrequent condition secondary to a deep venous thrombosis of multietiological origin usually affecting the lower extremities. It presents with pain and edema in the lower limb rapidly progressive that can compromise the perfusion of the limb, being able to cause gangrene, amputation and even death. We present an extremely rare case of a phlegmasia secondary to a massive deep venous tombosis of the left iliofemoral axis caused by chronic compressive hematoma of a traumatic origin due to a S1 screw shearing in a patient operated three months ago of a lumbar herniated disc through a L5-S1 fussion. This article shows the need to perform a scrupulously scrutinize of the screws both intra and postoperatively when we are close to the great vessels

A rat model of orthopedic injury-induced hypercoagulability and fibrinolytic shutdown.

BACKGROUND: Postinjury hypercoagulability occurs in >25% of injured patients, increasing risk of thromboembolic complications despite chemoprophylaxis. However, few clinically relevant animal models of posttraumatic hypercoagulability exist. We aimed to evaluate a rodent model of bilateral hindlimb injury as a preclinical model of postinjury hypercoagulability. METHODS: Forty Wistar rats were anesthetized with isoflurane: 20 underwent bilateral hindlimb fibula fracture, soft tissue and muscular crush injury, and bone homogenate injection intended to mimic the physiological severity of bilateral femur fracture. Twenty sham rats underwent anesthesia only. Terminal citrated blood samples were drawn at 0, 6, 12, and 24 hours (n = 5 per timed group) for analysis by native thromboelastography in the presence and absence of taurocholic acid to augment fibrinolysis. Plasminogen activator inhibitor 1 and α-2 antiplasmin levels in plasma were assessed via enzyme-linked immunosorbent assay. RESULTS: Injured rats became hypercoagulable relative to baseline by 6 hours based on thromboelastography maximal amplitude (MA) and G (p < 0.005); sham rats became hypercoagulable to a lesser degree by 24 hours (p < 0.005). Compared with sham animals, injured rats were hypercoagulable by MA and G within 6 hours of injury, remained hypercoagulable by MA and G through at least 24 hours (all p < 0.01), and showed impaired fibrinolysis by taurocholic acid LY30 at 12 hours (p = 0.019) and native LY30 at 24 hours (p = 0.045). In terms of antifibrinolytic mediators, α-2 antiplasmin was elevated in trauma animals at 24 hours (p = 0.009), and plasminogen activator inhibitor 1 was elevated in trauma animals at 6 hours (p = 0.004) and 12 hours (p < 0.001) when compared with sham. CONCLUSIONS: Orthopedic injury in rodents induced platelet and overall hypercoagulability within 6 hours and fibrinolytic impairment by 12 to 24 hours, mimicking postinjury hypercoagulability in injured patients. This rodent model of orthopedic injury may serve as a preclinical testing ground for potential therapies to mitigate hypercoagulability, maintain normal fibrinolysis, and prevent thromboembolic complications.

The hypercoagulable state in COVID-19: Incidence, pathophysiology, and management.

The 2019 coronavirus disease (COVID-19) presents with a large variety of clinical manifestations ranging from asymptomatic carrier state to severe respiratory distress, multiple organ dysfunction and death. While it was initially considered primarily a respiratory illness, rapidly accumulating data suggests that COVID-19 results in a unique, profoundly prothrombotic milieu leading to both arterial and venous thrombosis. Consistently, elevated D-dimer level has emerged as an independent risk factor for poor outcomes, including death. Several other laboratory markers and blood counts have also been associated with poor prognosis, possibly due to their connection to thrombosis. At present, the pathophysiology underlying the hypercoagulable state is poorly understood. However, a growing body of data suggests that the initial events occur in the lung. A severe inflammatory response, originating in the alveoli, triggers a dysfunctional cascade of inflammatory thrombosis in the pulmonary vasculature, leading to a state of local coagulopathy. This is followed, in patients with more severe disease, by a generalized hypercoagulable state that results in macro- and microvascular thrombosis. Of concern, is the observation that anticoagulation may be inadequate in many circumstances, highlighting the need for alternative or additional therapies. Numerous ongoing studies investigating the pathophysiology of the COVID-19 associated coagulopathy may provide mechanistic insights that can direct appropriate interventional strategies.

The pathophysiology of SARS-CoV-2: A suggested model and therapeutic approach.

In this paper, a model is proposed of the pathophysiological processes of COVID-19 starting from the infection of human type II alveolar epithelial cells (pneumocytes) by SARS-CoV-2 and culminating in the development of ARDS. The innate immune response to infection of type II alveolar epithelial cells leads both to their death by apoptosis and pyroptosis and to alveolar macrophage activation. Activated macrophages secrete proinflammatory cytokines and chemokines and tend to polarise into the inflammatory M1 phenotype. These changes are associated with activation of vascular endothelial cells and thence the recruitment of highly toxic neutrophils and inflammatory activated platelets into the alveolar space. Activated vascular endothelial cells become a source of proinflammatory cytokines and reactive oxygen species (ROS) and contribute to the development of coagulopathy, systemic sepsis, a cytokine storm and ARDS. Pulmonary activated platelets are also an important source of proinflammatory cytokines and ROS, as well as exacerbating pulmonary neutrophil-mediated inflammatory responses and contributing to systemic sepsis by binding to neutrophils to form platelet-neutrophil complexes (PNCs). PNC formation increases neutrophil recruitment, activation priming and extraversion of these immune cells into inflamed pulmonary tissue, thereby contributing to ARDS. Sequestered PNCs cause the development of a procoagulant and proinflammatory environment. The contribution to ARDS of increased extracellular histone levels, circulating mitochondrial DNA, the chromatin protein HMGB1, decreased neutrophil apoptosis, impaired macrophage efferocytosis, the cytokine storm, the toll-like receptor radical cycle, pyroptosis, necroinflammation, lymphopenia and a high Th17 to regulatory T lymphocyte ratio are detailed.