Adenosine diphosphate platelet dysfunction on thromboelastogram is independently associated with increased morality in traumatic brain injury

The Impact of ADP Inhibition on Traumatic Brain Injury Outcomes

Platelet inhibition correlates with severity of traumatic brain injury and may be associated with mortality. Adenosine diphosphate participates in platelet aggregation via the activation of the ADP receptors, P2Y1 and P2Y12. Prior work suggests this ADP pathway is significant in managing patients with head injuries. This study aimed to measure the influence of ADP inhibition on outcomes after a traumatic brain injury (TBI), as measured by thromboelastography with platelet mapping (TEG-PM). Outcomes were defined as (a) hospital length of stay; (b) ICU length of stay, (c) mortality, and (d) progression of hemorrhage on CT. The resulting cohort was split into quartiles to compare the effect of increasingly inhibited ADP values on the identified outcomes. Comparisons of 2 groups of patients were also conducted, one defined by ADP inhibition less than or equal to 60% and the other group by ADP inhibition of greater than 60%. 98 patients were included in final analysis, with 72.4% having ADP inhibition less than 60%. These patients were significantly older and had lower global injury severity scores (ISSs), although their head-specific ISS was equivalent. Compared to the group with ADP inhibition over 60%, there was no significant difference in mortality, hospital or ICU length of stay, or progression of lesion on CT. Patients with ADP less than 60% inhibited had smaller ISS and higher GCS, indicating they were less injured than those with greater ADP inhibition, consistent with prior literature. The equivalent ICU and hospital length of stay and mortality suggests that ADP inhibition plays a smaller role in outcomes. Additional study with a larger sample size and guideline-based assessments is necessary to further define the impact of ADP inhibition and to determine the role of platelet transfusion in this population.

Coagulopathy in Isolated Traumatic Brain Injury: Myth or Reality

INTRODUCTION

Traumatic Brain Injury (TBI) has been shown to be associated with altered hemostasis and coagulopathy, that correlates with worsening secondary injury and clinical outcomes. Isolated Traumatic Brain Injury (iTBI), that is TBI without significant extracranial injuries, has also been shown to be associated with systemic coagulopathy and derangements in hemostasis.

METHODS

Literature Review.

RESULTS

Present your results in logical sequence in the text, tables, and figures, giving the main or most important findings first. Do not repeat all the data in the tables or figures in the text; emphasize or summarize only the most important observations. Provide data on all primary and secondary outcomes identified in the Methods section. Give numeric results not only as derivatives (e.g. percentages) but also as the absolute numbers from which the derivatives were calculated, and specify the statistical significance attached to them, if any.

DISCUSSION

In this review, we provide an overview of the pathophysiology of the hemostatic disturbances caused by iTBI, review key clinical findings and discrepancies in the way this question has been approached, describe the use and role of global viscoelastic assays such as the thromboelastrogram, and detail principles for reversal of pre-injury blood thinners.

CONCLUSIONS

iTBI is clearly associated with the development of coagulopathy, but the extent to which it occurs is confounded by the fact that many of the studies have included patients with moderate extracranial trauma into the iTBI category. The coagulopathy itself has been better studied in preclinical models, and the mechanisms driving it suggest a pattern consistent with disseminated intravascular coagulation with hyperfibrinolysis. We provide pragmatic clinical takeaways and suggestions for future research.

Effects of Guideline-Based Correction of Platelet Inhibition on Outcomes in Moderate to Severe Isolated Blunt Traumatic Brain Injury

Platelet dysfunction has been demonstrated after traumatic brain injury (TBI) regardless of the use of platelet inhibitors. The purpose of this study was to determine the efficacy of a platelet-mapping thromboelastography (PM-TEG) in predicting TBI patients who would benefit from platelet transfusion. We hypothesized that adenosine diphosphate (ADP) and arachadonic acid (AA) inhibition in patients with TBI is associated with increased mortality and can be corrected with platelet transfusion. This is a retrospective review of patients admitted to a level 1 trauma center from January 2016 through September 2017 with moderate to severe blunt TBI (msTBI), defined by an initial Glasgow Coma Scale (GCS) ≤12 with intracranial hemorrhage. Patients received PM-TEG. Those with platelet dysfunction (ADP or AA inhibition ≥60%) received one unit of platelets followed by repeat PM-TEG, until inhibition <60% or three units of platelets. Cohorts were defined as patients initially without (NPI) and with (PI) inhibition and subdivided into those whose inhibition corrected (PI-C) versus those whose did not correct (PI-NC). From 69 patients with isolated blunt TBI, 40 (58%) presented with NPI, 29 (42%) with PI. Of those with PI, 16 (55%) were with PI-C and 13 (45%) with PI-NC. Platelet inhibition in msTBI patients undergoing guideline-based transfusion is associated with age and GCS and an increase in mortality. Platelet inhibition seems to have a more adverse effect on patients >55 years of age or with GCS <8. Correction of platelet inhibition normalized mortality to that of NPI.

Traumatic brain injury patients with platelet inhibition receiving platelet transfusion demonstrate decreased need for neurosurgical intervention and decreased mortality

BACKGROUND

Platelet dysfunction is known to occur in patients with traumatic brain injury (TBI), and the correction of platelet dysfunction may prevent hemorrhagic progression in TBI. Thromboelastography with platelet mapping (TEG-PM; Haemonetics) evaluates the degree of platelet function inhibition through the adenosine diphosphate (ADP) and arachidonic acid (AA) pathways. We hypothesized that ADP and AA inhibition would improve with the transfusion of platelets in patients with TBI.

METHODS

A retrospective review was conducted at a Level I trauma center of all patients presenting with TBI from December 2019 to December 2020. Per a practice management guideline, a platelet mapping assay was obtained on all patients with TBI upon admission. If ADP or AA was found to be inhibited (>60%), the patient was transfused 1 unit of platelets and a repeat platelet mapping assay was ordered. Demographic data, laboratory values, and outcomes were analyzed.

RESULTS

Over the 13-month study period, 453 patients with TBI underwent TEG-PM with a protocol adherence rate of 66.5% resulting in a total of 147 patients who received platelets for ADP and/or AA inhibition; of those, 107 underwent repeat TEG-PM after platelets were administered. With the administration of platelets, ADP (p < 0.0001), AA (p < 0.0001), and MA (p = 0.0002) all significantly improved. Of 330 patients with TBI not taking antiplatelet medications, 50.9% showed inhibition in ADP and/or AA. If AA or ADP inhibition was noted on admission, mortality was increased (p = 0.0108). If ADP improved with platelet administration, the need for neurosurgical intervention was noted to decrease (p = 0.0182).

CONCLUSION

Patients with TBI and platelet inhibition may benefit from the administration of platelets to correct platelet dysfunction. Thromboelastography with platelet mapping may be implemented in the initial workup of patients presenting with TBI to assess platelet dysfunction and provide prognostic information, which may guide treatment.

LEVEL OF EVIDENCE

Therapeutic / Care Management, level III.

A Prognostic Model Incorporating Red Cell Distribution Width to Platelet Ratio for Patients with Traumatic Brain Injury

BACKGROUND

As an inflammation-based marker, red cell distribution width to platelet ratio (RPR) has been verified to be associated with disease severity and outcome in many clinical settings. We designed this study to evaluate the prognostic value of RPR in patients with traumatic brain injury (TBI).

METHODS

A total of 420 patients admitted with TBI were included in this study. Laboratory and clinical data were collected from an electronic medical record system. Univariate and multivariate logistic regression analyses were sequentially performed to discover risk factors of in-hospital mortality. Receiver operating characteristic (ROC) curves were drawn to confirm the predictive value of different markers including RPR in training set and testing set.

RESULTS

Non-survivors had higher level of RPR than survivors (P<0.001). Logistic regression analysis showed that RPR was significantly associated with mortality even after adjusting for confounding factors (P<0.001). The area under the ROC curve (AUC) value of Glasgow Coma Scale (GCS) for predicting mortality was 0.761 and 0775 in training set and testing set, respectively. And the constructed predictive model incorporating RPR had the highest AUC value of 0.858 and 0.884 in training set and testing set.

CONCLUSION

RPR is significantly associated with mortality in TBI patients. Utilizing RPR to construct a predictive model is valuable to evaluate prognosis of TBI patients.

Thromboelastography with platelet mapping: Limited predictive ability in detecting preinjury antiplatelet agent use

BACKGROUND

Preinjury antiplatelet agent (APA) use in trauma patients can increase traumatic hemorrhage and worsen outcomes. Thromboelastography with platelet mapping (TEGPM) has characterized platelet function via arachidonic acid (AA) and adenosine diphosphate (ADP) inhibition in nontrauma settings, but limited data exist in the acute trauma population.

METHODS

A prospective observational study of adult trauma patients with suspected preinjury APA use who received TEGPM testing from 2017 to 2020 was performed. Patients on anticoagulants were excluded. Patients were grouped according to preinjury APA regimen: 81 mg or 325 mg of aspirin daily, 81 mg of aspirin and 75 mg of clopidrogrel daily, 75 mg of clopidrogrel daily, or no antiplatelet. Ability of TEGPM to detect APA use was assessed using predictive statistics and area under receiver operating characteristic curves (AUROCs).

RESULTS

A total of 824 patients were included with most patients taking 81 mg of aspirin (n = 558). Patients on no antiplatelet were younger and had higher baseline platelet counts, while patients on 75 mg of clopidrogrel were more likely to be admitted after ground level fall. All other baseline characteristics were balanced. Admission TEG values were similar between groups. Median AA inhibition was higher in patients on aspirin containing regimens (p < 0.0001). Median ADP inhibition was higher in patients on clopidogrel containing regimens and those taking 325 mg of aspirin (p < 0.0001). Arachidonic acid inhibition accurately detected preinjury APA use and aspirin use (AUROC, 0.89 and 0.84, respectively); however, ADP inhibition performed poorly (AUROC, 0.58). Neither AA nor ADP inhibition was able to discern specific APA regimens or rule out APA use entirely.

CONCLUSION

High AA inhibition accurately detects preinjury APA use in trauma patients. High ADP inhibition after trauma is common, limiting its utility to accurately identify preinjury APA use. Further study is needed to identify assays that can reliably detect and further characterize preinjury APA use in trauma populations.

LEVEL OF EVIDENCE

Diagnostic test, level II.

Viscoelastic Testing and Coagulopathy of Traumatic Brain Injury

A unique coagulopathy often manifests following traumatic brain injury, leading the clinician down a difficult decision path on appropriate prophylaxis and therapy. Conventional coagulation assays—such as prothrombin time, partial thromboplastin time, and international normalized ratio—have historically been utilized to assess hemostasis and guide treatment following traumatic brain injury. However, these plasma-based assays alone often lack the sensitivity to diagnose and adequately treat coagulopathy associated with traumatic brain injury. Here, we review the whole blood coagulation assays termed viscoelastic tests and their use in traumatic brain injury. Modified viscoelastic tests with platelet function assays have helped elucidate the underlying pathophysiology and guide clinical decisions in a goal-directed fashion. Platelet dysfunction appears to underlie most coagulopathies in this patient population, particularly at the adenosine diphosphate and/or arachidonic acid receptors. Future research will focus not only on the utility of viscoelastic tests in diagnosing coagulopathy in traumatic brain injury, but also on better defining the use of these tests as evidence-based and/or precision-based tools to improve patient outcomes.

Use of Thromboelastography in the Evaluation and Management of Patients With Traumatic Brain Injury: A Systematic Review and Meta-Analysis

Supplemental Digital Content is available in the text.

Traumatic brain injury is associated with coagulopathy that increases mortality risk. Viscoelastic hemostatic assays such as thromboelastography (Haemonetics SA, Signy, Switzerland) provide rapid coagulopathy assessment and may be particularly useful for goal-directed treatment of traumatic brain injury patients. We conducted a systematic review to assess thromboelastography in the evaluation and management of coagulopathy in traumatic brain injury patients.

Critical traumatic brain injury is associated with worse coagulopathy

OBJECTIVES

As thromboelastography (TEG) becomes the standard of care in patients with hemorrhagic shock (HS), an association between concomitant traumatic brain injury (TBI) and coagulopathy by TEG parameters is not well understood and is thus investigated.

METHODS

Retrospective analysis of trauma registry data at a single level 1 trauma center of 772 patients admitted with head Abbreviated Injury Scale (AIS) score of 3 and TEG studies between 2014 and 2017. Patients were stratified to moderate-severe TBI by head AIS scores of 3 and 4 (435 patients) and critical TBI by head AIS score of 5 (328 patients). Hemorrhagic shock was defined by base deficit of 4 or shock index of 0.9. Statistical analysis with unpaired t tests compared patients with critical TBI with patients with moderate-severe TBI, and patients were grouped by presence or absence of HS. A comparison of TBI data with conventional coagulation studies was also evaluated.

RESULTS

In the setting of HS, critical TBI versus moderate-severe TBI was associated with longer R time (p = 0.004), longer K time (p < 0.05), less acute angle (p = 0.001), and lower clot strength and stability (maximum amplitude [MA]) (p = 0.01). Worse TBI did not correlate with increased fibrinolysis by clot lysis measured by the percentage decrease in amplitude at 30 minutes after MA (p = 0.3). Prothrombin time and international normalized ratio failed to demonstrate more severe coagulopathy, while partial thromboplastin time was found to correlate with severity of TBI (p = 0.01). In patients with critical TBI, the presence of HS correlated with a statistically significant worsening of all parameters (p < 0.05) except for clot lysis measured by the percentage decrease in amplitude at 30 minutes after MA (LY-30).

CONCLUSION

Thromboelastography demonstrates that, with and without hemorrhagic shock, critical TBI correlates with a significant worsening of traumatic coagulopathy in comparison with moderate/severe TBI. In HS, critical TBI correlates with impaired clot initiation, impaired clot kinetics, and impaired platelet-associated clot strength and stability versus parameters found in moderate-severe TBI. Hemorrhagic shock correlates with worse traumatic coagulopathy in all evaluated patient groups with TBI. Conventional coagulation studies underestimate TBI-associated coagulopathy. Traumatic brain injury-associated coagulopathy is not associated with fibrinolysis.

LEVEL OF EVIDENCE

Prognostic/epidemiological, level IV; prognostic/epidemiological, level III.

Platelet Dysfunction after Traumatic Brain Injury: A Review

Coagulopathy is a known sequela of traumatic brain injury (TBI) and can lead to increased morbidity and mortality. Platelet dysfunction has been identified as one of several etiologies of coagulopathy following TBI and has been associated with poor outcomes. Regardless of whether the platelet dysfunction occurs as a direct consequence of the injury or because of pre-existing medical comorbidities or medication use, accurate detection and monitoring of response to therapy is key to optimal patient care. Platelet transfusion has been proposed as a potential therapeutic intervention to treat platelet dysfunction, with several studies using platelet function assays to monitor response. The development of increasingly precise diagnostic testing is providing enhanced understanding of the specific derangement in the hemostatic process, allowing clinicians to provide patient-specific treatment plans. There is wide variability in the currently available literature on the incidence and clinical significance of platelet dysfunction following TBI, which creates challenges with developing evidence-based management guidelines. The relatively high prevalence of platelet inhibitor therapy serves as an additional confounding factor. In addition, the data are largely retrospective in nature. We performed a literature review to provide clarity on this clinical issue. We reviewed 348 abstracts, and included 97 manuscripts in our final literature review. Based on the currently available research, platelet dysfunction has been consistently demonstrated in patients with moderate-severe TBI. We recommend the use of platelet functional assays to evaluate patients with TBI. Platelet transfusion directed at platelet dysfunction may lead to improved clinical outcome. A randomized trial guided by implementation science could improve the applicability of these practices.

Effect of Chronic Alcoholism on Traumatic Intracranial Hemorrhage

BACKGROUND

Traumatic intracranial hemorrhage (TICH) is one of the commonest indications for neurosurgical consultation after trauma. Worsening neurologic examination results, size of initial TICH, presence of displaced skull fracture, and concomitant anticoagulant use at the time of injury drive the recommendations for repeat computed tomography of head (RCTH), to assess for stability of intracranial hemorrhage. Chronic alcohol use is not generally considered an indication for repeat head computed tomography (CT).

METHODS

A retrospective study of 423 patients with TICH with normal admission platelet (PLT) counts was reviewed for this study, taken as a subset of 1330 patients with TICH admitted to Lahey Hospital and Medical Center over a 3-year period. Of these 423 patients, 330 were classified as nonalcoholics and 93 were classified as alcoholics, based on whether alcohol use disorder was documented in the patient's medical record, present before injury. The normal PLT level was defined as ≥100,000 μ/L. Patients were excluded from review if they had comorbid conditions that could cause PLT dysfunction or coagulopathy. Continuous and categorical variables were compared using independent t test and χ², respectively. Binary logistic regression was used to predict outcome: stable versus worsening of TICH on RCTH. Statistical analysis was conducted using SPSS version 25.

RESULTS

The mean age of the nonalcoholic and alcoholic cohorts were 71.9 years and 54.8 years, respectively. A significantly higher percentage of alcoholics were male. There was a statistically significant difference (χ² = 8.14; P < 0.004) in radiologic progression of TICH between the 2 groups, with the alcoholics having a worsening RCTH 16.1% of the time compared with only 6.7% in nonalcoholics. Chronic alcohol use was an independent predictor of radiologic progression in patients with normal PLT level (odds ratio, 2.69; confidence interval, 1.34-5.43; P < 0.006).

CONCLUSIONS

Chronic alcohol use was an independent predictor of radiologic progression of TICH in the setting of normal PLT level. Modification of this risk of progression with transfusion of fresh PLTs in chronic alcoholic patients with TICH needs to be investigated in a prospective trial.

Thromboelastography and rotational thromboelastometry for the surgical intensivist: A narrative review

BACKGROUND

Viscoelastic tests (VETs), specifically thromboelastography (TEG) and rotational thromboelastometry (ROTEM), are gaining popularity in the management of critically ill surgical patients with hemorrhage or thrombosis due to their comprehensive characterization of the coagulation process and point-of-care availability in comparison to conventional coagulation tests (CCTs). We review current evidence for VET use in patients in the surgical intensive care unit (SICU).

METHODS

We searched PUBMED, EMBASE and the Cochrane Library through May 30, 2018 for articles that evaluated the use of VETs in patient populations and clinical scenarios germane to the surgical intensivist. Individual articles were critically evaluated for relevance and appropriate methodology using a structured technique. Information on patient characteristics, timing and methods of CCTs/VETs, and outcomes was collected and summarized in narrative form.

RESULTS

Of 2,589 identified articles, 36 were included. Five (14%) were interventional studies and 31 (86%) were observational. Twenty-five (69%) evaluated TEG, 11 (31%) ROTEM and 18 (50%) CCTs. Investigated outcomes included quantitative blood loss (13 (36%)), blood product transfusion (9 (25%)), thromboembolic events (9 (25%)) and mortality (6 (17%)). We identified 12 clinical scenarios with sufficient available evidence, much of which was of limited quantity and poor methodological quality. Nonetheless, research supports the use of VETs for guiding early blood product administration in severe traumatic hemorrhage and for the prediction of abstract excess bleeding following routine cardiac surgery. In contrast, evidence suggests VET-based heparin dosing strategies for venous thromboembolism prophylaxis are not superior to standard dosing in SICU patients.

CONCLUSION

While VETs have the potential to impact the care of critically ill surgical patients in many ways, current evidence for their use is limited, mainly because of poor methodological quality of most available studies. Further high-quality research, including several ongoing randomized controlled trials, is needed to elucidate the role of TEG/ROTEM in the SICU population.

LEVEL OF EVIDENCE

Systematic review, level IV.

Altered monocyte and NK cell phenotypes correlate with posttrauma infection

BACKGROUND

Trauma induces a complex immune response, requiring a systems biology approach to capture multicellular changes. Using mass cytometry by time-of-flight (CyTOF), we evaluated time-dependent changes in peripheral blood in trauma patients to identify changes correlated with infection.

METHODS

Total leukocytes were prepared via red blood cell lysis using peripheral blood samples from trauma patients with an Injury Severity Score greater than 20 at Days 1, 3, and 5 after injury, and from age- and sex-matched uninjured controls. Cells were stained using a 33-marker immunophenotyping CyTOF panel. Statistics were calculated using one-way analysis of variance with multiple comparisons.

RESULTS

The CyTOF staining demonstrated changes in many cell subsets. The mean expression intensity of CD86 on monocytes decreased significantly at all time points after injury. When the patients were stratified based on development of infection, there was a trend to decreased CD86 expression on monocytes of those patients that developed subsequent infection. Based on stratification, we identified significantly increased expression of CD39 on NK cells only in patients that developed an infection.

CONCLUSION

This study used a systems biology approach to identify novel changes in circulating immune cell subsets in trauma patients correlating with post-traumatic infection. Decreased expression of CD86, a costimulatory molecule, on monocytes demonstrates that trauma affects the innate system's ability to control T-cell immunity. We also found that CD39 expression on NK cells increased significantly in patients with subsequent infection. CD39 is a protein that generates adenosine, which has immunosuppressive effects on several immune cell types including NK cells. In summary, our results point to pathways that may be central to second-hit infections and further study to delineate these pathways could be key to generating clinical biomarkers or targeted immune therapies for trauma patients.

LEVEL OF EVIDENCE

Prognostic study, level II.

Goal-directed platelet transfusions correct platelet dysfunction and may improve survival in patients with severe traumatic brain injury

BACKGROUND

Platelet dysfunction, defined as adenosine diphosphate inhibition greater than 60% on thromboelastogram, is an independent predictor of increased mortality in patients with severe traumatic brain injury (TBI). We changed our practice to transfuse platelets for all patients with severe TBI and platelet dysfunction. We hypothesized that platelet transfusions would correct platelet dysfunction and improve mortality in patients with severe TBI.

METHODS

This retrospective review included adult trauma patients admitted to our Level I trauma center from July 2015 to October 2016 with severe TBI (head Abbreviated Injury Scale score ≥ 3) who presented with platelet dysfunction and subsequently received a platelet transfusion. Serial thromboelastograms were obtained to characterize the impact of platelet transfusion on clot strength. Subsequently, the platelet transfusion group was compared to a group of historical controls with severe TBI patients and platelet dysfunction who did not receive platelet transfusion.

RESULTS

A total of 35 patients with severe TBI presented with platelet dysfunction. Following platelet transfusion clot strength improved as represented by decreased K time, increased α angle, maximum amplitude, and G-value, as well as correction of adenosine diphosphate inhibition. When comparing to 51 historic controls with severe TBI and platelet dysfunction, the 35 study patients who received a platelet transfusion had a lower mortality (9% vs. 35%; p = 0.005). In stepwise logistic regression, platelet transfusion was independently associated with decreased mortality (odds ratio, 0.23; 95% confidence interval, 0.06-0.92; p = 0.038).

CONCLUSION

In patients with severe TBI and platelet dysfunction, platelet transfusions correct platelet inhibition and may be associated with decreased mortality.

LEVEL OF EVIDENCE

Therapeutic, level II.

Current state of transfusion in traumatic brain injury and associated coagulopathy

Traumatic brain injury (TBI)-induced coagulopathy has long been recognized as a significant risk for poor outcomes in patients with TBI, but its pathogenesis remains poorly understood. As a result, current treatment options for the condition are limited and ineffective. The lack of information is most significant for the impact of blood transfusions on patients with isolated TBI and in the absence of confounding influences from trauma to the body and limbs and the resultant hemorrhagic shock. Here we discuss recent progress in understanding the pathogenesis of TBI-induced coagulopathy and the current state of blood transfusions for patients with TBI and associated coagulopathy.

The European guideline on management of major bleeding and coagulopathy following trauma: fifth edition

BACKGROUND

Severe traumatic injury continues to present challenges to healthcare systems around the world, and post-traumatic bleeding remains a leading cause of potentially preventable death among injured patients. Now in its fifth edition, this document aims to provide guidance on the management of major bleeding and coagulopathy following traumatic injury and encourages adaptation of the guiding principles described here to individual institutional circumstances and resources.

METHODS

The pan-European, multidisciplinary Task Force for Advanced Bleeding Care in Trauma was founded in 2004, and the current author group included representatives of six relevant European professional societies. The group applied a structured, evidence-based consensus approach to address scientific queries that served as the basis for each recommendation and supporting rationale. Expert opinion and current clinical practice were also considered, particularly in areas in which randomised clinical trials have not or cannot be performed. Existing recommendations were re-examined and revised based on scientific evidence that has emerged since the previous edition and observed shifts in clinical practice. New recommendations were formulated to reflect current clinical concerns and areas in which new research data have been generated.

RESULTS

Advances in our understanding of the pathophysiology of post-traumatic coagulopathy have supported improved management strategies, including evidence that early, individualised goal-directed treatment improves the outcome of severely injured patients. The overall organisation of the current guideline has been designed to reflect the clinical decision-making process along the patient pathway in an approximate temporal sequence. Recommendations are grouped behind the rationale for key decision points, which are patient- or problem-oriented rather than related to specific treatment modalities. While these recommendations provide guidance for the diagnosis and treatment of major bleeding and coagulopathy, emerging evidence supports the author group's belief that the greatest outcome improvement can be achieved through education and the establishment of and adherence to local clinical management algorithms.

CONCLUSIONS

A multidisciplinary approach and adherence to evidence-based guidance are key to improving patient outcomes. If incorporated into local practice, these clinical practice guidelines have the potential to ensure a uniform standard of care across Europe and beyond and better outcomes for the severely bleeding trauma patient.

Consumption of alcohol leads to platelet inhibition in men

INTRODUCTION

Alcohol consumption has been shown to alter coagulation. However, thromboelastography with platelet mapping (TEG PM) to evaluate platelet function has not been studied.

METHODS

A prospective, non-randomized study of healthy volunteers was conducted. Baseline TEG PM were collected. Subjects consumed alcoholic or non-alcoholic beverages for 2 h. Repeat TEG PM was collected.

RESULTS

Fifty-four volunteers entered either the experimental group (EG, 17 women and 16 men) or control group (CG, 11 women and 10 men). After 2 h of alcohol or non-alcoholic drink consumption the median breath alcohol level was 0.08 [IQR 0.05, 0.12] in the EG and 0.00 in the CG. After consumption of alcohol, male EG subjects demonstrated higher median Adenosine Diphosphate (ADP) inhibition of platelet function (15.7% [3.9, 39.3] vs 8.2% [0, 30.1), p = 0.035), but female subjects did not. There was no evidence of increased arachidonic acid (AA) platelet inhibition in the EG compared to CG. Clot strength (TEG maximum amplitude) was not different between groups.

CONCLUSION

After consumption of alcohol, healthy male volunteers demonstrate ADP platelet inhibition by TEG PM.

Effects of platelet dysfunction and platelet transfusion on outcomes in traumatic brain injury patients

OBJECTIVE

Platelet inhibition in traumatic brain injury (TBI) may be due to injury or antiplatelet medication use pre-injury. This study aims to identify factors associated with increased platelet arachidonic acid (AA) and adenosine diphosphate (ADP) inhibition and determine if platelet transfusion reduces platelet dysfunction and affects outcome.

METHODS

Prospective thromboelastography (TEG) assays were collected on adult patients with TBI with intracranial injuries detected by computed tomography (CT). Outcomes included in-hospital mortality, and CT lesion expansion.

RESULTS

Of 153 patients, ADP inhibition was increased in moderate and severe TBI compared to mild TBI (p = 0.0011). P2Y12 inhibiting medications had increased ADP inhibition (p = 0.0077). Admission ADP inhibition was not associated with in-hospital mortality (p = 0.24) or CT lesion expansion (p = 0.94). Mean reduction of ADP inhibition from platelet transfusion (-15.1%) relative to no transfusion (+ 11.7%) was not statistically different (p = 0.0472).

CONCLUSIONS

Mild TBI results in less ADP inhibition compared to moderate and severe TBI, suggesting a dose response relationship between TBI severity and degree of platelet dysfunction. Further, study is warranted to determine efficacy and parameters for platelet transfusion in patients with TBI.

Coagulopathy induced by traumatic brain injury: systemic manifestation of a localized injury

Traumatic brain injury (TBI)-induced coagulopathy is a common and well-recognized risk for poor clinical outcomes, but its pathogenesis remains poorly understood, and treatment options are limited and ineffective. We discuss the recent progress and knowledge gaps in understanding this lethal complication of TBI. We focus on (1) the disruption of the brain-blood barrier to disseminate brain injury systemically by releasing brain-derived molecules into the circulation and (2) TBI-induced hypercoagulable and hyperfibrinolytic states that result in persistent and delayed intracranial hemorrhage and systemic bleeding.

Nonhuman primate model of polytraumatic hemorrhagic shock recapitulates early platelet dysfunction observed following severe injury in humans

BACKGROUND

Platelet dysfunction has been described as an early component of trauma-induced coagulopathy. The platelet component of trauma-induced coagulopathy remains to be fully elucidated and translatable animal models are required to facilitate mechanistic investigations. We sought to determine if the early platelet dysfunction described in trauma patients could be recapitulated in a nonhuman primate model of polytraumatic hemorrhagic shock.

METHODS

Twenty-four male rhesus macaques weighting 7 to 14 kg were subjected to 60 minutes (min) of severe pressure-targeted controlled hemorrhagic shock (HS) with and without other injuries. After 60 min, resuscitation with 0.9% NaCl and whole blood was initiated. Platelet counts and platelet aggregation assays were performed at baseline (BSLN), end of shock (EOS; T = 60 min), end of resuscitation (EOR; T = 180 min), and T = 360 min on overall cohort. Results are reported as mean ± standard deviation (SD) or median (interquartile range). Statistical analysis was conducted using Spearmen correlation, one-way analysis of variance, two-way repeated-measures analysis of variance, paired t-test or Wilcoxon nonparametric test, with p < 0.05 considered significant.

RESULTS

Platelet count in all injury cohorts decreased over time, but no animals developed thrombocytopenia. Correlations were observed between platelet aggregation and platelet count for all agonists: adenosine diphosphate, thrombin recognition-activating peptide-6, collagen, and arachidonic acid. Overall, compared to BSLN, platelet aggregation decreased for all agonist at EOS, EOR, and T = 360 min. When normalized to platelet count, platelet aggregation in response to agonist thrombin recognition-activating peptide-6 demonstrated no change from BSLN at subsequent time points. Aggregation to adenosine diphosphate was significantly less at EOR but not EOS or T = 360 min compared to BSLN. Platelet aggregation to collagen and arachidonic acid was not significantly different at EOS compared to BSLN but was significantly less at EOR and T = 360 min.

CONCLUSION

Nonhuman primates manifest early platelet dysfunction in response to polytraumatic hemorrhagic shock, consistent with that reported in severely injured human patients. Nonhuman primate models potentially are translationally valuable for understanding the mechanisms and pathophysiology of trauma-induced platelet dysfunction.