Not all in your head (and neck): Stroke after blunt cerebrovascular injury is associated with systemic hypercoagulability

The in-vitro influence of urea concentration on thromboelastrography in patients with and without end stage renal disease

BACKGROUND

End stage renal disease (ESRD) is associated with platelet dysfunction but also thromboembolic complications. The specific role of increased blood urea nitrogen (BUN) on coagulation is unclear. We aimed to characterize thromboelastography (TEG) parameters from males and females with ESRD and normal kidney function and evaluate if exogenous urea in vitro reproduced those TEG differences.

METHODS

We collected blood samples from 20 living kidney donors and 20 kidney recipients. TEG was performed without and with two increasing urea concentrations in vitro. TEG parameters were compared between recipients and donors.

RESULTS

Blood from kidney recipients showed baseline increased maximum amplitude (MA) and shortened time to maximum amplitude (TMA) compared to donors. These differences were not confirmed in females. In all patients, BUN was inversely correlated with TMA (r = -0.342; p = 0.031). In males, BUN and creatinine concentrations showed a direct correlation with MA (0.583; p = 0.007) and an inverse correlation with TMA (r = -0.520; p = 0.019). Urea in vitro decreased R-time (p = 0.005) and increased LY30 (p = 0.009) in donors but not recipients.

CONCLUSIONS

ESRD is associated with increased MA and decreased TMA on TEG. No change in MA was observed with increasing urea concentrations in vitro. Gender-specific variability in TEG parameters were observed.

Traumatic Brain Injury and Long-Term Risk of Stroke Among US Military Veterans

BACKGROUND

Traumatic brain injury (TBI) is associated with significant morbidity, but the association of TBI with long-term stroke risk in diverse populations remains less clear. Our objective was to examine the long-term associations of TBI with stroke and to investigate potential differences by age, sex, race and ethnicity, and time since TBI diagnosis.

METHODS

Retrospective cohort study of US military veterans aged 18+ years receiving healthcare in the Veterans Health Administration system between October 1, 2002 and September 30, 2019. Veterans with TBI were matched 1:1 to veterans without TBI on age, sex, race and ethnicity, and index date, yielding 306 796 veterans with TBI and 306 796 veterans without TBI included in the study. In primary analyses, Fine-Gray proportional hazards models adjusted for sociodemographics and medical/psychiatric comorbidities were used to estimate the association between TBI and stroke risk, accounting for the competing risk of mortality.

RESULTS

Participants were a mean age of 50 years, 9% were female, and 25% were of non-White race and ethnicity. Overall, 4.7% of veterans developed a stroke over a median follow-up of 5.2 years. Veterans with TBI had 1.69 times (95% CI, 1.64-1.73) increased risk of any stroke (ischemic or hemorrhagic) compared to veterans without TBI. This increased risk was highest in the first-year post-TBI diagnosis (hazard ratio [HR], 2.16 [95% CI, 2.03-2.29]) but remained elevated for 10+ years. Similar patterns were observed for secondary outcomes, with associations of TBI with hemorrhagic stroke (HR, 3.92 [95% CI, 3.59-4.29]) being stronger than with ischemic stroke (HR, 1.56 [95% CI, 1.52-1.61]). Veterans with both mild (HR, 1.47 [95% CI, 1.43-1.52]) and moderate/severe/penetrating injury (HR, 2.02 [95% CI, 1.96-2.09]) had increased risk of stroke compared to veterans without TBI. Associations of TBI with stroke were stronger among older compared to younger individuals (P interaction-by-age<0.001) and were weaker among Black veterans compared to other race and ethnicities (P interaction-by-race<0.001).

CONCLUSIONS

Veterans with prior TBI are at increased long-term risk for stroke, suggesting they may be an important population to target for primary stroke prevention measures.

A Review of Thromboelastography for Nurses

BACKGROUND

Thromboelastography is a viscoelastic test with multiple potential advantages over conventional coagulation tests in various disease states. Thromboelastography rapidly provides qualitative and quantitative information related to a patient's coagulation status.

OBJECTIVE

To describe recent studies of the use of thromboelastography in various clinical states and how thromboelastography is used in coagulation management.

METHODS

A literature review using the MEDLINE and PubMed databases was conducted. The updated methodology for integrated reviews by Whittemore and Knafl was followed. Coauthors evaluated separate areas that were independently reviewed by other coauthors to ensure appropriateness for inclusion.

RESULTS

The use of thromboelastography for various clinical conditions with challenging hemostatic profiles has increased. This integrative review covers the use of thromboelastography in patients with trauma, medication-induced coagulopathy, acute and chronic liver failure, and cardiothoracic surgery. Potential future directions are also discussed.

DISCUSSION

Thromboelastography has numerous potential benefits over conventional coagulation tests for assessing coagulation status in patients in various clinical states. Nurses can support clinical decisions to use the most appropriate test for their patients.

CONCLUSIONS

Each team member should be involved in assessing the usefulness of thromboelastography. Critical care nurses and the multidisciplinary team must identify patients in whom its use is warranted, interpret the results, and provide appropriate interventions in response to the results and clinical status of the patient.

Advances in the Management of Coagulopathy in Trauma: The Role of Viscoelastic Hemostatic Assays across All Phases of Trauma Care

Uncontrolled bleeding is the leading cause of preventable death following injury. Trauma-induced coagulopathy can manifest as diverse phenotypes ranging from hypocoagulability to hypercoagulability, which can change quickly during the acute phase of trauma care. The major advances in understanding coagulation over the past 25 years have resulted from the cell-based concept, emphasizing the key role of platelets and their interaction with the damaged endothelium. Consequently, conventional plasma-based coagulation testing is not accurate in predicting bleeding and does not provide an assessment of which blood products are indicated. Viscoelastic hemostatic assays (VHA), conducted in whole blood, have emerged as a superior method to guide goal-directed transfusion. The major change in resuscitation has been the shift from unbridled crystalloid loading to judicious balanced blood product administration. Furthermore, the recognition of the rapid changes from hypocoagulability to hypercoagulability has underscored the importance of ongoing surveillance beyond emergent surgery. While the benefits of VHA testing are maximized when used as early as possible, current technology limits use in the pre-hospital setting and the time to results compromises its utility in the emergency department. Thus, most of the reported experience with VHA in trauma is in the operating room and intensive care unit, where there is compelling data to support its value. This overview will address the current and potential role of VHA in the seriously injured patient, throughout the continuum of trauma management.

Routine CTA screening identifies blunt cerebrovascular injuries missed by clinical risk factors

Objectives

Current guidelines for screening for blunt cerebrovascular injury (BCVI) are commonly based on the expanded Denver criteria, a set of risk factors that identifies patients who require CT-angiographic (CTA) screening for these injuries. Based on previously published data from our center, we have adopted a more liberal screening guideline than those outlined in the expanded Denver criteria. This entails routine CTA of the neck for all blunt trauma patients already undergoing CT of the cervical spine and/or CTA of the chest. The aim of this study was to analyze the incidence of patients with BCVI who did not meet any of the risk factors included in the expanded Denver criteria.

Methods

A retrospective review of all patients diagnosed with BCVI between June 2014 and December 2019 at a Level I Trauma Center were identified from the trauma registry. Medical records were reviewed for the presence or absence of risk factors as outlined in the expanded Denver criteria. Demographic data, time to CTA and treatment, BCVI grade, Glasgow Coma Scale and Injury Severity Score were collected.

Results

During the study period, 17 054 blunt trauma patients were evaluated, and 29% (4923) underwent CTA of the neck to screen for BCVI. 191 BCVIs were identified in 160 patients (0.94% of all blunt trauma patients, 3.25% of patients screened with CTA). 16% (25 of 160) of patients with BCVI had none of the risk factors outlined in the Denver criteria.

Conclusion

Our findings indicate that reliance on the expanded Denver criteria alone for BCVI screening will result in missed injuries. We recommend CTA screening in all patients with blunt trauma undergoing CT of the cervical spine and/or CTA of the chest to minimize this risk.

Level of evidence

Level III, therapeutic/care management.

Imaging analysis of ischemic strokes due to blunt cerebrovascular injury

BACKGROUND

The timing of stroke onset among patients with blunt cerebrovascular injury (BCVI) is not well understood. All blunt trauma patients at our institution undergo a screening computed tomographic angiography (CTA) of the neck. Most patients with CTA evidence of BCVI are treated with aspirin, and all patients with clinical evidence of stroke are treated with aspirin and undergo magnetic resonance imaging (MRI) of the brain. We conducted a retrospective review to determine the incidence of stroke upon admission and following admission.

METHODS

All neck CTAs and head MRIs obtained in blunt trauma patients were reviewed from August 2017 to August 2019. All CTAs that were interpreted as showing BCVI were individually reviewed to confirm the diagnosis of BCVI. Stroke was defined as brain MRI evidence of new ischemic lesions, and each MRI was reviewed to identify the brain territory affected. We extracted the time to aspirin administration and the timing of stroke onset from patients' electronic health records.

RESULTS

Of the 6,849 blunt trauma patients, 479 (7.0%) had BCVIs. Twenty-four patients (5.0%) with BCVI had a stroke on admission. Twelve (2.6%) of the remaining 455 patients subsequently had a stroke during their hospitalization. The incidence of stroke among patients with BCVI was 7.5%; 2.6% were potentially preventable. Only 5 of the 12 patients received aspirin before the onset of stroke symptoms. All 36 patients with BCVI and stroke had thromboembolic lesions in the territory supplied by an injured vessel.

CONCLUSION

With universal screening, CTA evidence of BCVI is common among blunt trauma patients. Although acute stroke is also relatively common in this population, two thirds of strokes are already evident on admission. One third of BCVI-related strokes occur after admission and often relatively early, necessitating rapid commencement of preventative treatment. Further studies are required to demonstrate the value of antithrombotic administration in preventing stroke in BCVI patients.

LEVEL OF EVIDENCE

Prognostic and Epidemiologic; Level IV.

Evaluation of coagulation parameters in dogs with gallbladder mucoceles

BACKGROUND

Gallbladder mucocele (GBM) is a common biliary disorder in dogs. Limited information is available on the coagulation status of dogs with GBM.

HYPOTHESIS/OBJECTIVES

To determine patterns of coagulation alterations in dogs with GBM and correlate them with clinicopathologic abnormalities and ultrasonographic findings of disease severity.

ANIMALS

Twenty-three dogs with GBM identified on ultrasound examination were prospectively enrolled.

METHODS

At the time of GBM identification, blood and urine were collected for CBC, serum biochemical panel, urinalysis, prothrombin time, activated partial thromboplastin time (aPTT), factor VIII, protein C (PC), von Willebrand's factor (vWF), antithrombin activity, fibrinogen, D-dimers, and thromboelastrography (TEG). Gallbladder mucoceles were classified into ultrasound types 1 to 5. Medical records were reviewed for clinical presentation, underlying conditions and to determine if systemic inflammatory response syndrome (SIRS) was present.

RESULTS

Based on TEG parameters, maximal amplitude, and G, 19/23 (83%) of dogs with GBM had evaluations consistent with hypercoagulability. On plasma-based coagulation testing, dogs with GBM had increased total PC activity (20/23, 87%), fibrinogen (9/23, 39%), platelet count (9/23, 39%), and D-dimers (6/15, 40%) as well as prolongations in aPTT (9/22, 41%) and low vWF activity (5/21, 24%). No correlation was found between TEG G value and any coagulation or clinical pathology variables, ultrasound stage of GBM or disease severity as assessed by the presence of SIRS.

CONCLUSIONS AND CLINICAL IMPORTANCE

Dogs with ultrasonographically identified GBM have changes in whole blood kaolin-activated TEG supporting a hypercoagulable state although traditional plasma-based coagulation testing suggests that a complex state of hemostasis exists.

Trauma-induced coagulopathy

Uncontrolled haemorrhage is a major preventable cause of death in patients with traumatic injury. Trauma-induced coagulopathy (TIC) describes abnormal coagulation processes that are attributable to trauma. In the early hours of TIC development, hypocoagulability is typically present, resulting in bleeding, whereas later TIC is characterized by a hypercoagulable state associated with venous thromboembolism and multiple organ failure. Several pathophysiological mechanisms underlie TIC; tissue injury and shock synergistically provoke endothelial, immune system, platelet and clotting activation, which are accentuated by the 'lethal triad' (coagulopathy, hypothermia and acidosis). Traumatic brain injury also has a distinct role in TIC. Haemostatic abnormalities include fibrinogen depletion, inadequate thrombin generation, impaired platelet function and dysregulated fibrinolysis. Laboratory diagnosis is based on coagulation abnormalities detected by conventional or viscoelastic haemostatic assays; however, it does not always match the clinical condition. Management priorities are stopping blood loss and reversing shock by restoring circulating blood volume, to prevent or reduce the risk of worsening TIC. Various blood products can be used in resuscitation; however, there is no international agreement on the optimal composition of transfusion components. Tranexamic acid is used in pre-hospital settings selectively in the USA and more widely in Europe and other locations. Survivors of TIC experience high rates of morbidity, which affects short-term and long-term quality of life and functional outcome.

Universal screening for blunt cerebrovascular injury

BACKGROUND

Blunt cerebrovascular injury (BCVI) can result in thromboembolic stroke. Many trauma centers selectively screen patients with cervical computed tomographic angiography (CTA) based on clinical criteria. In 2016, our institution adopted universal screening for BCVI for all blunt trauma patients. The aim of this study was to accurately determine the incidence of BCVI and to evaluate the diagnostic performance of the Denver criteria (DC), expanded Denver criteria (eDC), and Memphis criteria (MC) in selecting patients for screening.

METHODS

Retrospective cohort study of adult (≥16 years) blunt trauma patients who presented to the Level I trauma center at University of Alabama at Birmingham. We reviewed all CTA reports and selected CTA images to obtain the true incidence rate of BCVI. We then evaluated the diagnostic performance of the DC, eDC, and MC.

RESULTS

A total of 6,800 patients who had suffered blunt trauma were evaluated, of whom 6,287 (92.5%) had a neck CTA. Of these, 480 (7.6%) patients had CTA evidence of BCVI. The eDC identified the most BCVI cases (sensitivity 74.7%) but had the lowest positive predictive value (14.6%). The DC and MC had slightly greater positive predictive values (19.6% and 20.6%, respectively) and had the highest diagnostic ability in terms of likelihood ratio (2.8 and 2.9) but had low sensitivity (57.5% and 47.3%). Consequently, if relying on the traditional screening criteria, the DC, eDC, and MC would have respectively resulted in 42.5%, 25.3%, and 52.7% of patients with BCVI identified by universal screening not receiving a neck CTA to screen for BCVI.

CONCLUSION

Blunt cerebrovascular injury is even more common than previously thought. The diagnostic performance of selective clinical screening criteria is poor. Consideration should be given to the implementation of universal screening for BCVI using neck CTA in all blunt trauma patients.

LEVEL OF EVIDENCE

Diagnostic, level III.

Treatment of blunt cerebrovascular injuries: Anticoagulants or antiplatelet agents?

BACKGROUND

Blunt cerebrovascular injury (BCVI) is associated with cerebrovascular accidents (CVA). Early therapy with antiplatelet agents or anticoagulants is recommended. There are limited data comparing the effectiveness of these treatments. The aim of our study was to compare outcomes between BCVI patients who received anticoagulants versus those who received antiplatelet agents.

METHODS

We performed an (2011-2015) analysis of the Nationwide Readmission Database and included all adult trauma patients 18 years or older who had an isolated BCVI (other body regions Abbreviated Injury Scale [AIS] < 3). Head injury patients or those who developed a CVA during the index admission were excluded. Patients were stratified into anticoagulants and antiplatelet agents. Propensity score matching was performed (1:1 ratio) to control for demographics, comorbidities, BCVI grade, distribution, and severity of injuries. Outcomes were readmission with CVA and mortality within 6 months.

RESULTS

A total of 725 BCVI patients were identified. A matched cohort of 370 patients (antiplatelet agents, 185; anticoagulants, 185) was obtained. Mean age was 50 ± 15 years, neck AIS was 3 (3,4), and Injury Severity Score was 12 (9-17). The majority of the patients (69%) had high-grade BCVI (AIS ≥ 3). Overall, 3.7% were readmitted with CVA and 3% died within 6 months. Patients who received anticoagulants had a lower rate of readmission with CVA (1.8% vs. 5.72%; p = 0.03), and a lower rate of 6-month mortality (1.3% vs. 4.9%; p = 0.03). There was no significant difference between the two groups reading the median time to stroke (9 days vs. 6 days; p = 0.12).

CONCLUSION

The BCVI patients on CVA prophylaxis for BCVI have a 3.7% rate of stroke after discharge. Compared with antiplatelet agents, anticoagulants are associated with lower rates of CVA in the first 6-month postdischarge. Further studies are required to identify the optimal agent to prevent CVA in this high-risk subset of trauma patients.

LEVEL OF EVIDENCE

Therapeutic, level IV.

Modern Management of Bleeding, Clotting, and Coagulopathy in Trauma Patients: What Is the Role of Viscoelastic Assays?

Purpose of Review

The purpose of this review is to briefly outline the current state of hemorrhage control and resuscitation in trauma patients with a specific focus on the role viscoelastic assays have in this complex management, to include indications for use across all phases of care in the injured patient.

Recent Findings

Viscoelastic assay use to guide blood-product resuscitation in bleeding trauma patients can reduce mortality by up to 50%. Viscoelastic assays also reduce total blood products transfused, reduce ICU length of stay, and reduce costs. There are a large number of observational and retrospective studies evaluating viscoelastic assay use in the initial trauma resuscitation, but only one randomized control trial. There is a paucity of data evaluating use of viscoelastic assays in the operating room, post-operatively, and during ICU management in trauma patients, rendering their use in these settings extrapolative/speculative based on theory and data from other surgical disciplines and settings.

Summary

Both hypocoagulable and hypercoagulable states exist in trauma patients, and better indicate what therapy may be most appropriate. Further study is needed, particularly in the operating room and post-operative/ICU settings in trauma patients.