Sympathoadrenal Activation is Associated with Acute Traumatic Coagulopathy and Endotheliopathy in Isolated Brain Injury

Decreased antithrombin activity in the early phase of trauma is strongly associated with extravascular leakage, but not with antithrombin consumption: a prospective observational study

Background

We conducted a prospective observational study for investigating coagulofibrinolytic changes and mechanisms of antithrombin (AT) alternations in trauma.

Methods

Trauma patients hospitalized for more than seven days were analyzed for coagulofibrinolytic biomarkers. The patients were stratified into two groups according to AT activity level on admission (day 0), comprising normal AT and low AT patients.

Results

Thirty-nine patients (median Injury Severity Score 20) exhibited initial coagulatory activation and triphasic fibrinolytic changes. AT activity did not show a negative linear correlation with levels of thrombin-antithrombin complex (TAT), a marker of coagulation activity and AT consumption, but was strongly correlated with levels of albumin (Alb), an index of vascular permeability, on day 0 (r = 0.702, p <  0.001). Furthermore, Alb was one of the independent predictors for AT on day 0. IL-6 on day 0 and thrombomodulin (TM) levels during the study period, reflecting systemic inflammation and endothelial cell injury, respectively, were significantly higher in the lower AT group (n = 10) than in the normal group (n = 29) (IL-6, p = 0.004; TM, p = 0.017). On days 2 and 4, TAT levels in the lower AT group were significantly higher than in the normal group.

Conclusions

Trauma caused clear triphasic coagulofibrinolytic changes. Decreased AT in the later phase might lead to a prolonged hypercoagulation. AT reduction in the initial phase of trauma is strongly associated with extravascular leakage as suggested by the association of Alb depletion with IL-6 and TM elevation, but not with AT consumption.

Neuroinflammation as a Target for Intervention in Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a sub-type of hemorrhagic stroke associated with the highest rates of mortality and long-term neurological disabilities. Despite the improvement in the management of SAH patients and the reduction in case fatality in the last decades, disability and mortality remain high in this population. Brain injury can occur immediately and in the first days after SAH. This early brain injury can be due to physical effects on the brain such as increased intracranial pressure, herniations, intracerebral, intraventricular hemorrhage, and hydrocephalus. After the first 3 days, angiographic cerebral vasospasm (ACV) is a common neurological complication that in severe cases can lead to delayed cerebral ischemia and cerebral infarction. Consequently, the prevention and treatment of ACV continue to be a major goal. However, most treatments for ACV are vasodilators since ACV is due to arterial vasoconstriction. Other targets also have included those directed at the underlying biochemical mechanisms of brain injury such as inflammation and either independently or as a consequence, cerebral microthrombosis, cortical spreading ischemia, blood–brain barrier breakdown, and cerebral ischemia. Unfortunately, no pharmacologic treatment directed at these processes has yet shown efficacy in SAH. Enteral nimodipine and the endovascular treatment of the culprit aneurysm, remain the only treatment options supported by evidence from randomized clinical trials to improve patients’ outcome. Currently, there is no intervention directly developed and approved to target neuroinflammation after SAH. The goal of this review is to provide an overview on anti-inflammatory drugs tested after aneurysmal SAH.

Traumatic Brain Injury Leads to Accelerated Atherosclerosis in Apolipoprotein E Deficient Mice

Traumatic brain injury (TBI) has been associated with atherosclerosis and cardiovascular mortality in humans. However the causal relationship between TBI and vascular disease is unclear. This study investigated the direct role of TBI on vascular disease using a murine model of atherosclerosis. Apolipoprotein E deficient mice were placed on a western diet beginning at 10 weeks of age. Induction of TBI or a sham operation was performed at 14 weeks of age and mice were sacrificed 6 weeks later at 20 weeks of age. MRI revealed evidence of uniform brain injury in all mice subjected to TBI. There were no differences in total cholesterol levels or blood pressure between the groups. Complete blood counts and flow cytometry analysis performed on peripheral blood 6 weeks following TBI revealed a higher percentage of Ly6C-high monocytes in mice subjected to TBI compared to sham-treated mice. Mice with TBI also showed elevated levels of plasma soluble E-selectin and bone marrow tyrosine hydroxylase. Analysis of atherosclerosis at the time of sacrifice revealed increased atherosclerosis with increased Ly6C/G immunostaining in TBI mice compared to sham-treated mice. In conclusion, progression of atherosclerosis is accelerated following TBI. Targeting inflammatory pathways in patients with TBI may reduce subsequent vascular complications.

Isolated Brain Trauma in Cats Triggers Rapid Onset of Hypovolemia

Background

Hemodynamic instability responsive to fluid resuscitation is common after a traumatic brain injury (TBI), also in the absence of systemic hemorrhage. The present study tests if an isolated severe TBI induces a decrease in plasma volume (PV).

Methods

The study was performed in three groups of anesthetized and tracheostomized male cats (n = 21). In one group (n = 8), the cats were prepared with a cranial borehole (10 mm i.d) used to expose the brain to a fluid percussion brain injury (FPI) (1.90–2.20 bar), and two smaller cranial boreholes (4 mm i.d) for insertion of an intracranial pressure (ICP) and a microdialysis catheter. To differentiate the effect of FPI from that of the surgical preparation, a sham group was exposed to the same surgical preparation but no FPI trauma (n = 8). A control group had no brain trauma and no surgical preparation (n = 5). PV was determined by a ¹²⁵I-albumin dilution technique. PV, electrolytes, pH, BE (base excess), hematocrit (Hct), P_aO₂, and P_aCO₂ were measured at baseline and after 3 h. Mean arterial pressure (MAP) was measured continuously. ICP was measured in the FPI and the sham group.

Results

In the FPI group, PV decreased by 11.2 mL/kg from 31.7 mL/kg (p < 0.01) with a simultaneous increase in Hct and decrease in pH. In the sham group, PV decreased by 5.7 mL/kg from 32.7 mL/kg (p < 0.01). The control group showed no PV reduction.

Conclusions

The results support that an isolated severe head trauma triggers a significant and rapid reduction in PV, most likely due to vascular leak.

Innate immune responses to trauma

Trauma can affect any individual at any location and at any time over a lifespan. The disruption of macrobarriers and microbarriers induces instant activation of innate immunity. The subsequent complex response, designed to limit further damage and induce healing, also represents a major driver of complications and fatal outcome after injury. This Review aims to provide basic concepts about the posttraumatic response and is focused on the interactive events of innate immunity at frequent sites of injury: the endothelium at large, and sites within the lungs, inside and outside the brain and at the gut barrier.

Acute Traumatic Endotheliopathy in Isolated Severe Brain Injury and Its Impact on Clinical Outcome

Study design: Prospective observational cohort. Objective: To investigate the difference in plasma levels of syndecan-1 (due to glycocalyx degradation) and soluble thrombomodulin (due to endothelial damage) in isolated severe traumatic brain injury (TBI) patients with/without early coagulopathy. A secondary objective was to compare the effects of the degree of TBI endotheliopathy on hospital mortality among patients with TBI-associated coagulopathy (TBI-AC). Methods: Data was prospectively collected on isolated severe TBI (sTBI) patients with Glasgow Coma Scale (GCS) ≤8 less than 12 h after injury admitted to a level I trauma centre. Isolated sTBI patients with samples withdrawn prior to blood transfusion were stratified by conventional coagulation tests as coagulopathic (prothrombin time (PT) ≥ 16.7 s, international normalized ratio (INR) ≥ 1.27, and activated partial thromboplastin time (aPTT) ≥ 28.8 s) and non-coagulopathic. Twenty healthy controls were also included. Plasma levels of thrombomodulin and syndecan-1 were estimated by ELISA. With receiver operating characteristic curve (ROC) analysis, we defined endotheliopathy as a syndecan-1 cut-off level that maximized the sum of sensitivity and specificity for predicting TBI-AC. Results: Inclusion criteria were met in 120 cases, with subjects aged 35.5 ± 12.6 years (88.3% males). TBI-AC was identified in 50 (41.6%) patients, independent of age, gender, and GCS, but there was an association with acidosis (60%; p = 0.01). Following isolated sTBI, we found insignificant changes in soluble thrombomodulin (sTM) levels between patients with isolated TBI and controls, and sTM levels were lower in coagulopathic compared to non-coagulopathic patients. Elevations in plasma syndecan-1 (ng/mL) levels were seen compared to control (31.1(21.5–30.6) vs. 24.8(18.5–30.6); p = 0.08). Syndecan-1(ng/mL) levels were significantly elevated in coagulopathic compared to non-coagulopathic patients (33.7(21.6–109.5) vs. 29.9(19.239.5); p = 0.03). Using ROC analysis (area under the curve = 0.61; 95% Confidence Interval (CI) 0.50 to 0.72), we established a plasma syndecan-1 level cutoff of ≥30.5 ng/mL (sensitivity % = 55.3, specificity % = 52.3), with a significant association with TBI-associated coagulopathy. Conclusion: Subsequent to brain injury, elevated syndecan-1 shedding and endotheliopathy may be associated with early coagulation abnormalities. A syndecan-1 level ≥30.5 ng/mL identified patients with TBI-AC, and may be of importance in guiding management and clinical decision-making.

Preoperative elevated FDP may predict severe intraoperative hypotension after dural opening during decompressive craniectomy of traumatic brain injury

Purpose

Coagulation disorder and intraoperative hypotension are representative complications of traumatic brain injury which cause worse perioperative outcome. The aim of this study was to survey the relation of coagulation disorder and intraoperative hypotension (IH) during decompressive craniectomy.

Method

Patients who underwent emergency decompressive craniectomy due to traumatic brain injury were retrospectively surveyed. The relation between preoperative coagulation date and intraoperative hypotension (systolic blood pressure < 60 mmHg after dural opening) was analyzed.

Results

Of 41 patients screened, 12 patients (27.9%) developed IH. Fibrinogen degradation products (314 vs 64.4 μg/mL; p = 0.01) were significantly higher in the IH group. In contrast, fibrinogen (181 vs 239 mg/dL; p = 0.01) was significantly lower in the IH group. Reduction rate of sBRP before and after dural opening (%) was higher in IH group than in non-IH group (49.1 vs 27.6%: p = 0.001).

Conclusions

Preoperative elevated FDP may predict IH after dural opening during traumatic decompressive craniectomy.

Disseminated intravascular coagulation with increased fibrinolysis during the early phase of isolated traumatic brain injury

Background

There is evidence to demonstrate that the coagulopathy which occurs in patients with traumatic brain injury coincides with disseminated intravascular coagulation (DIC). We hypothesized that DIC with increased fibrinolysis during the early stage of isolated traumatic brain injury (iTBI) affects the outcome of the patients and that hypoperfusion contributes to hyperfibrinolysis in the DIC.

Methods

This retrospective study included 92 patients with iTBI who were divided into DIC and non-DIC groups according to the Japanese Association Acute Medicine DIC scoring system. The DIC patients were subdivided into those with and without hyperfibrinolysis. The platelet counts and global markers of coagulation and fibrinolysis were measured. Systemic inflammatory response syndrome (SIRS), organ dysfunction (assessed by the Sequential Organ Failure Assessment score), tissue hypoperfusion (assessed by the lactate levels) and the transfusion volume were also evaluated. The outcome measure was all-cause hospital mortality.

Results

DIC patients showed consumption coagulopathy, lower antithrombin levels and higher fibrin/fibrinogen degradation products (FDP) and D-dimer levels than non-DIC patients. All of the DIC patients developed SIRS accompanied by organ dysfunction and required higher blood transfusion volumes, leading to a worse outcome than non-DIC patients. These changes were more prominent in DIC with hyperfibrinolysis. A higher FDP/D-dimer ratio suggests that DIC belongs to the fibrinolytic phenotype and involves fibrin(ogen)olysis. The mean blood pressures of the patients with and without DIC on arrival were identical. Hypoperfusion and the lactate levels were not identified as independent predictors of hyperfibrinolysis.

Conclusions

DIC, especially DIC with hyperfibrinolysis, affects the outcome of patients with iTBI. Low blood pressure-induced tissue hypoperfusion does not contribute to hyperfibrinolysis in this type of DIC.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1808-9) contains supplementary material, which is available to authorized users.

Symptom correlates of cerebral blood flow following acute concussion

Concussion is associated with significant symptoms within hours to days post-injury, including disturbances in physical function, cognition, sleep and emotion. However, little is known about how subjective impairments correlate with objective measures of cerebrovascular function following brain injury. This study examined the relationship between symptoms and cerebral blood flow (CBF) in individuals following sport-related concussion. Seventy university level athletes had CBF measured using Arterial Spin Labelling (ASL), including 35 with acute concussion and 35 matched controls and their symptoms were assessed using the Sport Concussion Assessment Tool 3 (SCAT3). For concussed athletes, greater total symptom severity was associated with elevated posterior cortical CBF, although mean CBF was not significantly different from matched controls (p = 0.46). Examining symptom clusters, athletes reporting greater cognitive symptoms also had lower frontal and subcortical CBF, relative to athletes with greater somatic symptoms. The "cognitive" and "somatic" subgroups also exhibited significant differences in CBF relative to controls (p ≤ 0.026). This study demonstrates objective CBF correlates of symptoms in recently concussed athletes and shows that specific symptom clusters may have distinct patterns of altered CBF, significantly extending our understanding of the neurobiology of concussion and traumatic brain injury.

Coagulopathy and haemorrhagic progression in traumatic brain injury: advances in mechanisms, diagnosis, and management

Normal haemostasis depends on an intricate balance between mechanisms of bleeding and mechanisms of thrombosis, and this balance can be altered after traumatic brain injury (TBI). Impaired haemostasis could exacerbate the primary insult with risk of initiation or aggravation of bleeding; anticoagulant use at the time of injury can also contribute to bleeding risk after TBI. Many patients with TBI have abnormalities on conventional coagulation tests at admission to the emergency department, and the presence of coagulopathy is associated with increased morbidity and mortality. Further blood testing often reveals a range of changes affecting platelet numbers and function, procoagulant or anticoagulant factors, fibrinolysis, and interactions between the coagulation system and the vascular endothelium, brain tissue, inflammatory mechanisms, and blood flow dynamics. However, the degree to which these coagulation abnormalities affect TBI outcomes and whether they are modifiable risk factors are not known. Although the main challenge for management is to address the risk of hypocoagulopathy with prolonged bleeding and progression of haemorrhagic lesions, the risk of hypercoagulopathy with an increased prothrombotic tendency also warrants consideration.

Catecholamines as outcome markers in isolated traumatic brain injury: the COMA-TBI study

Background

Elevated catecholamine levels might be associated with unfavorable outcome after traumatic brain injury (TBI). We investigated the association between catecholamine levels in the first 24 h post-trauma and functional outcome in patients with isolated moderate-to-severe TBI.

Methods

A cohort of 174 patients who sustained isolated blunt TBI was prospectively enrolled from three Level-1 Trauma Centers. Epinephrine (Epi) and norepinephrine (NE) concentrations were measured at admission (baseline), 6, 12 and 24 h post-injury. Outcome was assessed at 6 months by the extended Glasgow Outcome Scale (GOSE) score. Fractional polynomial plots and logistic regression models (fixed and random effects) were used to study the association between catecholamine levels and outcome. Effect size was reported as the odds ratio (OR) associated with one logarithmic change in catecholamine level.

Results

At 6 months, 109 patients (62.6%) had an unfavorable outcome (GOSE 5–8 vs. 1–4), including 51 deaths (29.3%). Higher admission levels of Epi were associated with a higher risk of unfavorable outcome (OR, 2.04, 95% CI: 1.31–3.18, p = 0.002) and mortality (OR, 2.86, 95% CI: 1.62–5.01, p = 0.001). Higher admission levels of NE were associated with higher risk of unfavorable outcome (OR, 1.59, 95% CI: 1.07–2.35, p = 0.022) but not mortality (OR, 1.45, 95% CI: 0.98–2.17, p = 0.07). There was no relationship between the changes in Epi levels over time and mortality or unfavorable outcome. Changes in NE levels with time were statistically associated with a higher risk of mortality, but the changes had no relation to unfavorable outcome.

Conclusions

Elevated circulating catecholamines, especially Epi levels on hospital admission, are independently associated with functional outcome and mortality after isolated moderate-to-severe TBI.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1620-6) contains supplementary material, which is available to authorized users.

Shock induced endotheliopathy (SHINE) in acute critical illness - a unifying pathophysiologic mechanism

One quarter of patients suffering from acute critical illness such as severe trauma, sepsis, myocardial infarction (MI) or post cardiac arrest syndrome (PCAS) develop severe hemostatic aberrations and coagulopathy, which are associated with excess mortality. Despite the different types of injurious “hit”, acutely critically ill patients share several phenotypic features that may be driven by the shock. This response, mounted by the body to various life-threatening conditions, is relatively homogenous and most likely evolutionarily adapted. We propose that shock-induced sympatho-adrenal hyperactivation is a critical driver of endothelial cell and glycocalyx damage (endotheliopathy) in acute critical illness, with the overall aim of ensuring organ perfusion through an injured microvasculature. We have investigated more than 3000 patients suffering from different types of acute critical illness (severe trauma, sepsis, MI and PCAS) and have found a potential unifying pathologic link between sympatho-adrenal hyperactivation, endotheliopathy, and poor outcome. We entitled this proposed disease entity, shock-induced endotheliopathy (SHINE). Here we review the literature and discuss the pathophysiology of SHINE.