A prothrombotic coagulopathy is commonly found in critically ill COVID-19 patients with acute respiratory distress syndrome (ARDS). A unique feature of COVID-19 respiratory failure is a relatively preserved lung compliance and high Alveolar-arterial oxygen gradient, with pathology reports consistently demonstrating diffuse pulmo-

BACKGROUND: COVID-19 predisposes patients to a prothrombotic state with demonstrated microvascular involvement. The degree of hypercoagulability appears to correlate with outcomes; however, optimal criteria to assess for the highest-risk patients for thrombotic events remain unclear; we hypothesized that deranged thromboelastography measurements of coagulation would correlate with thromboembolic events. STUDY DESIGN: Patients admitted to an ICU with COVID-19 diagnoses who had thromboelastography analyses performed were studied. Conventional coagulation assays, D-dimer levels, and viscoelastic measurements were analyzed using a receiver operating characteristic curve to predict thromboembolic outcomes and new-onset renal failure. RESULTS:Forty-four patients with COVID-19 were included in the analysis. Derangements in coagulation laboratory values, including elevated D-dimer, fibrinogen, prothrombin time, and partial thromboplastin time, were confirmed; viscoelastic measurements showed an elevated maximum amplitude and low lysis of clot at 30 minutes. A complete lack of lysis of clot at 30 minutes was seen in 57% of patients and predicted venous thromboembolic events with an area under the receiver operating characteristic curve of 0.742 (p ¼ 0.021). A D-dimer cutoff of 2,600 ng/mL predicted need for dialysis with an area under the receiver operating characteristic curve of 0.779 (p ¼ 0.005). Overall, patients with no lysis of clot at 30 minutes and a D-dimer > 2,600 ng/mL had a venous thromboembolic event rate of 50% compared with 0% for patients with neither risk factor (p ¼ 0.008), and had a hemodialysis rate of 80% compared with 14% (p ¼ 0.004). CONCLUSIONS: Fibrinolysis shutdown, as evidenced by elevated D-dimer and complete failure of clot lysis at 30 minutes on thromboelastography predicts thromboembolic events and need for hemodialysis in critically ill patients with COVID-19. Additional clinical trials are required to ascertain the need for early therapeutic anticoagulation or fibrinolytic therapy to address this state of fibrinolysis shutdown.

Injury is the fourth leading cause of mortality worldwide, accounting for 9% of deaths globally (4.9 million people) in 2016 (ref. 1 ). Moreover, the burden is highest in individuals <50 years of age, among whom injury as a cause of death is second only to infectious diseases. Early preventable deaths after injury in civilian 2 and military 3 settings are primarily attributable to uncontrolled haemorrhage 2-8 , whereas later preventable deaths are typically due to hypercoagulability 9 . Consequently, there is intense interest worldwide in the pathogenesis of trauma-induced coagulopathy (TIC) to attenuate its adverse effects on the outcomes of seriously injured patients.Impaired coagulation following sudden death from injury has been observed for centuries 10 and, in the 1960s, the first clinical laboratory documentation of the temporal changes in coagulation following severe injury were documented 11 . However, early endogenous drivers of coagulopathy were not specifically investigated until 1982, when a case series of patients with major abdominal vascular injuries highlighted TIC as a common direct cause of early post-injury mortality: 89% of the deaths were bleeding-related, yet half occurred after mechanical control of bleeding sites -in other words, they were due to coagulopathy 12 . The remaining ongoing quagmire is the inability to distinguish between patients with exsanguinating injuries whose TIC is the result of metabolic failure (that is, who are bleeding because they are dying) from patients whose TIC is the cause of the ongoing blood loss (that is, who are dying because they are bleeding) 13 . Furthermore, not all patients with abnormalities in laboratory coagulation tests are bleeding 14 .Despite the long-term fascination with changes in coagulation resulting from shock and tissue injury 15 , there is no standard definition of TIC, which refers to abnormal coagulation capacity attributable to trauma. The term TIC was established during the Trans-Agency Consortium for Trauma Induced Coagulopathy Workshop conducted by the National Institutes of Health in April 2010 to describe the variety of phenomena that characterize this condition. TIC can manifest as a spectrum of phenotypes from hypocoagulation to hypercoagulation (fig. 1), as a function of several interactive factors, including (but not limited to) tissue injury, presence of shock and, in particular, time from injury (fig. 2).

Summary Background Plasma is integral to haemostatic resuscitation after injury, but the timing of administration remains controversial. Anticipating approval of lyophilised plasma by the US Food and Drug Administration, the US Department of Defense funded trials of prehospital plasma resuscitation. We investigated use of prehospital plasma during rapid ground rescue of patients with haemorrhagic shock before arrival at an urban level 1 trauma centre. Methods The Control of Major Bleeding After Trauma Trial was a pragmatic, randomised, single-centre trial done at the Denver Health Medical Center (DHMC), which houses the paramedic division for Denver city. Consecutive trauma patients in haemorrhagic shock (defined as systolic blood pressure [SBP] ≤70 mm Hg or 71–90 mm Hg plus heart rate ≥108 beats per min) were assessed for eligibility at the scene of the injury by trained paramedics. Eligible patients were randomly assigned to receive plasma or normal saline (control). Randomisation was achieved by preloading all ambulances with sealed coolers at the start of each shift. Coolers were randomly assigned to groups 1:1 in blocks of 20 according to a schedule generated by the research coordinators. If the coolers contained two units of frozen plasma, they were defrosted in the ambulance and the infusion started. If the coolers contained a dummy load of frozen water, this indicated allocation to the control group and saline was infused. The primary endpoint was mortality within 28 days of injury. Analyses were done in the as-treated population and by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT01838863. Findings From April 1, 2014, to March 31, 2017, paramedics randomly assigned 144 patients to study groups. The as-treated analysis included 125 eligible patients, 65 received plasma and 60 received saline. Median age was 33 years (IQR 25–47) and median New Injury Severity Score was 27 (10–38). 70 (56%) patients required blood transfusions within 6 h of injury. The groups were similar at baseline and had similar transport times (plasma group median 19 min [IQR 16–23] vs control 16 min [14–22]). The groups did not differ in mortality at 28 days (15% in the plasma group vs 10% in the control group, p=0∙37). In the intention-to-treat analysis, we saw no significant differences between the groups in safety outcomes and adverse events. Due to the consistent lack of differences in the analyses, the study was stopped for futility after 144 of 150 planned enrolments. Interpretation During rapid ground rescue to an urban level 1 trauma centre, use of prehospital plasma was not associated with survival benefit. Blood products might be beneficial in settings with longer transport times, but the financial burden would not be justified in an urban environment with short distances to mature trauma centres.

Background Fibrinolysis is a physiologic process to maintain microvascular patency by breaking down excessive fibrin clot. Hyperfibrinolysis (HF) is associated with a doubling of mortality. Fibrinolysis shutdown (SD), an acute impairment of fibrinolysis, has been recognized as a risk factor for increased mortality. The purpose of this study was to assess the incidence and outcomes of fibrinolysis phenotypes in two urban trauma centers. Study Design Injured patients admitted 2010-2013, who were ≥18 years of age, had an injury severity score (ISS) >15 were included in the analysis. Admission fibrinolysis phenotypes were determined by the clot lysis at 30 minutes (LY30): SD ≤0.8%, physiologic 0.9-2.9%, HF ≥3%. Logistic regression was used to adjust for age, arrival blood pressure, ISS, mechanism, and facility. Results 2540 patients met inclusion. Median age was 39(IQR 26-55) and median ISS was 25(IQR 20-33) with a mortality rate of 21%. Fibrinolysis shutdown was the most common phenotype (46%) followed by physiologic (36%) and hyperfibrinolysis(18%). HF was associated with the highest death rate (34%), followed by SD(22%), and physiologic (14%, p<0.001). The risk of mortality remained increased for HF(OR=3.3, 95%C: 2.4-4.6, p<0.0001) and SD(OR 1.6 95%CI 1.3-2.1, p=0.0003) compared to physiologic when adjusting for age, ISS, mechanism, head injury, and blood pressure (AUROC=0.82, 95% CI 0.80-0.84). Conclusions Fibrinolysis SD is the most common phenotype upon admission and is associated with increased mortality. Moreover, these data provide additional evidence of distinct phenotypes of coagulation impairment and that individualized hemostatic therapy may be required.