Thromboelastography Parameter Predicts Outcome After Subarachnoid Hemorrhage: An Exploratory Analysis

Increased blood coagulation is associated with poor neurological outcome in aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Patients with aneurysmal subarachnoid hemorrhage (aSAH) have demonstrated increased blood coagulation which is thought to contribute to delayed cerebral ischemia (DCI) and to a worse outcome. Therefore, we sought to determine whether this increased blood coagulation, detectable with rotational thromboelastometry (ROTEM), was associated with DCI and neurological outcome.

METHODS

We conducted a prospective observational study of 60 consecutive adult aSAH patients. ROTEM's EXTEM and FIBTEM assays and D-dimer were analyzed at admission and post-bleed days (PBDs) 2-3, 4-5, 7-8, and 11-12. ROTEM's clot formation time (CFT) represents the stabilization of the clot, and the maximum clot firmness (MCF) the maximum clot strength. Glasgow Outcome Scale extended (GOSe) at three months determined the neurological outcome.

RESULTS

DCI incidence was 41.7%. EXTEM-CFT was significantly shorter in patients with unfavorable neurological outcome (GOSe 1-4) on PBDs 4-5 and 7-8, p < 0.05, respectively. FIBTEM-MCF was significantly higher in patients with unfavorable neurological outcomes on PBD 4-5 (p < 0.05), PBD 7-8 (p < 0.05), and PBD 11-12 (p < 0.05). EXTEM-CFT decreased, and FIBTEM-MCF rose during the study period in all patients. Patients with unfavorable neurological outcome had a higher D-dimer at all studied time points, p < 0.05. No difference was found in the ROTEM parameters or D-dimer when assessing patients with and without DCI.

CONCLUSIONS

Patients were in a state of increased blood coagulation after aSAH, with those with unfavorable neurological outcome being more coagulable than those with favorable outcome. However, increased blood coagulation was not associated with DCI.

CLINICALTRIALS

gov, NCT03985176.

Thromboelastography in the Perioperative Period: A Literature Review

Assessing coagulation status is essential for prompt intervention to reduce morbidity and mortality related to bleeding and thrombotic complications during the perioperative period. Traditional coagulation tests such as platelet count, activated partial thromboplastin time (aPTT), prothrombin time (PT), international normalized ratio (INR), and activated clotting time (ACT) provide only static evaluation. These tests are not designed for assessment of dynamically changing coagulation conditions during the perioperative time. However, viscoelastic coagulation testing such as thromboelastography (TEG) produces a rapid numerical and graphical representation that helps to detect and direct targeted hemostatic therapy. Searching the literature through PubMed, Medline, Ovid, CINAHL, and ClinicalTrials.gov we retrieved 210 studies, which represent the use of TEG in the perioperative period. The included studies were categorized under various settings such as trauma, obstetrics, orthopedics, intensive care unit (ICU), cardiovascular, transplant, and miscellaneous scenarios. TEG showed promising results in trauma surgeries in predicting mortality, hypercoagulability, and bleeding even when it was compared to conventional methods. TEG was also useful in monitoring anticoagulant therapy in orthopedic and obstetric surgeries; however, its role in predicting thrombotic events, hypercoagulability, or complications was questionable. In ICU patients, it showed promising results, especially in the prediction or improvement of sepsis, coagulopathy, thrombotic events, ICU duration, hospital stay, and ventilator duration. TEG parameters effectively predicted hypercoagulation in transplant surgeries. Regarding cardiovascular surgeries, they were effective in the prediction of the need for blood products, coagulopathy, thrombotic events, and monitoring anticoagulation therapy. More randomized clinical trials comparing TEG parameters with standardized tools are needed to produce robust results to standardize its use in different perioperative settings.

Incidence and Risk Model of Venous Thromboembolism in Patients with Aneurysmal Subarachnoid Hemorrhage

OBJECTIVE

Venous thromboembolism (VTE) is a significant source of morbidity and mortality in hospitalized patients. We describe our experience with VTE prophylaxis and treatment in patients with aneurysmal subarachnoid hemorrhage (aSAH), risk factors for VTE, and a hazard model describing the daily risk of VTE.

METHODS

A retrospective cohort study was performed on patients with aSAH admitted from 2014 to 2018. Patients were screened for VTE based on clinical suspicion. Demographics, perioperative data, and in-hospital data were assessed as risk factors for VTE using survival analysis with death as a competing risk.

RESULTS

Among 485 patients, the overall incidence of VTE, deep vein thrombosis, and pulmonary embolism were 5.6%, 4.3%, and 2.3%, respectively. Increasing length of stay in the intensive care unit (hazard ratio [HR], 1.79; P < 0.0001; 95% confidence interval [CI], 1.49-2.16) and ventilation immediately after aneurysm treatment was associated with VTE (HR, 8.87; P < 0.01; 95% CI, 1.86-42.38). Hunt and Hess grade was negatively associated with VTE (HR, 0.61; P = 0.045; 95% CI, 0.37-1.00) due to its increased association with the competing risk of death (HR, 2.57; P < 0.0001; 95% CI, 1.89-3.49). The adjusted 4-year cumulative incidence for VTE is 11.1% and at mean day of hospital discharge is 5.4%. Treatment of VTEs with anticoagulation and/or inferior vena cava filter placement was not associated with immediate complications.

CONCLUSIONS

We describe the largest single-institution cohort of VTEs in aSAH patients. Our hazard model quantifies the cumulative incidence of VTEs during the course of hospitalization. We suggest a standardized protocol for screening, prophylaxis, and treatment of VTEs in this patient population.

Viscoelastic Testing in the Clinical Management of Subarachnoid Hemorrhage and Intracerebral Hemorrhage

Subarachnoid hemorrhage (SAH) and intracerebral hemorrhage (ICH) are both debilitating and life-threatening incidents calling for immediate action and treatment. This review focuses on the applicability of viscoelastic testing (rotational thromboelastometry or thromboelastography [TEG]) in the management of SAH and ICH. A systematic literature search was performed in PubMed and EMBASE. Studies including patients with SAH or ICH, in which viscoelastic testing was performed, were identified. In total, 24 studies were included for analysis, and further subdivided into studies on SAH patients investigated prior to stenting or coiling (n = 12), ICH patients (n = 8) and studies testing patients undergoing stenting or coiling, or ischemic stroke patients undergoing thrombolysis or thrombectomy and developing ICH as a complication (n = 5). SAH patients had increased clot firmness, and this was associated with a higher degree of early brain injury and higher Hunt-Hess score. SAH patients with delayed cerebral ischemia had higher clot firmness than patients not developing delayed cerebral ischemia. ICH patients showed accelerated clot formation and increased clot firmness in comparison to healthy controls. Patients with hematoma expansion had longer clot initiation and lower platelet aggregation than patients with no hematoma expansion. During stent procedures for SAH, adjustment of antiplatelet therapy according to TEG platelet mapping did not change prevalence of major bleeding, thromboembolic events, or functional outcome. Viscoelastic testing prior to thrombolysis showed conflicting results in predicting ICH as complication. In conclusion, viscoelastic testing suggests hypercoagulation following SAH and ICH. Further investigation of the predictive value of increased clot firmness in SAH seems relevant. In ICH, the prediction of hematoma expansion and ICH as a complication to thrombolysis might be clinically relevant.

Clopidogrel hyper-response increases peripheral hemorrhagic complications without increasing intracranial complications in endovascular aneurysm treatments requiring dual antiplatelet therapy

Clinical significance of increased clopidogrel response measured by VerifyNow P2Y12 assay is unclear; management guidelines are lacking in the context of neuroendovascular intervention. Our objective was to assess whether increased clopidogrel response predicts complications from endovascular aneurysm treatment requiring dual antiplatelet therapy. A single-institution, 9-year retrospective study of patients undergoing endovascular treatments for ruptured and unruptured aneurysms requiring aspirin and clopidogrel was conducted. Patients were grouped according to preoperative platelet inhibition in response to clopidogrel measured by the VerifyNow P2Y12 assay (VNP; P2Y12 reactivity units, PRU). Demographic and clinical features were compared across groups. Hemorrhagic complication rates (intracranial, major extracranial, minor extracranial) and thromboembolic complications (in-stent stenosis, stroke/transient ischemic attack) were compared, controlling for potential confounders and multiple comparisons. Data were collected from 284 patients across 317 procedures. Pre-operative VNP assays identified 9 % Extreme Responders (PRU ≤ 15), 13 % Hyper-Responders (PRU 16-60), 62 % Therapeutic Responders (PRU 61-214), 16 % Hypo-Responders (PRU ≥ 215). Increased response to clopidogrel was associated with increased risk of any hemorrhagic complication (≤60 PRU vs > 60 PRU; 39 % vs 24 %, P = 0.050); all intracranial hemorrhages occurred in patients with PRU > 60. Thromboembolic complications were similar between therapeutic and subtherapeutic patients (<215 PRU vs ≥ 215 PRU; 15 % vs 16 %, P = 0.835). Increased preoperative clopidogrel response is associated with increased rate of extracranial hemorrhagic complications in endovascular aneurysm treatments. Hyper-responders (16-60 PRU) and Extreme Responders (≤15 PRU) were not associated with intracranial hemorrhagic or thrombotic complications. Hypo-responders who underwent adjustment of antiplatelet therapy and neurointerventions did not experience higher rates of complications.

Refractory Heparin-Induced Thrombocytopenia in a Patient With Subarachnoid Hemorrhage-A Clinical Conundrum

Heparin induced thrombocytopenia (HIT) often resolves with discontinuation of heparin/ heparinoid products. Severe HIT with platelet counts <20,000/µL and disseminated intravascular coagulation is frequently associated with consumptive coagulopathy and systemic thrombosis. Management of severe HIT in patients who fail to improve on discontinuing heparinoid products and argatroban infusion is not well established. We describe a patient admitted with aneurysmal subarachnoid hemorrhage (SAH) who developed severe autoimmune HIT, failed conventional anticoagulation therapy with argatroban and progressed to develop extensive deep venous thrombosis and limb ischemia. She was successfully treated using bivalirudin, immunomodulation with 2 cycles of intravenous immunoglobulin and immunosuppression with methylprednisolone. Refractory severe HIT among SAH patients is rare and pose several therapeutic challenges. We report successful treatment using alternate anticoagulant and immune suppression and modulation.

Hemostasis and Fibrinolysis following Aneurysmal Subarachnoid Hemorrhage: A Systematic Review on Additional Knowledge from Dynamic Assays and Potential Treatment Targets

Mortality after aneurysmal subarachnoid hemorrhage (aSAH) is augmented by rebleeding and delayed cerebral ischemia (DCI). A range of assays evaluating the dynamic process of blood coagulation, from activation of clotting factors to fibrinolysis, has emerged and a comprehensive review of hemostasis and fibrinolysis following aSAH may reveal targets of treatment. We conducted a systematic review of existing literature assessing coagulation and fibrinolysis following aSAH, but prior to treatment. PubMed, Embase, and Web of Science were searched on November 18, 2020, without time boundaries. In total, 45 original studies were eventually incorporated into this systematic review, divided into studies presenting data only from conventional or quantitative assays (n = 22) and studies employing dynamic assays (n = 23). Data from conventional or quantitative assays indicated increased platelet activation, whereas dynamic assays detected platelet dysfunction possibly related to an increased risk of rebleeding. Secondary hemostasis was activated in conventional, quantitative, and dynamic assays and this was related to poor neurological outcome and mortality. Studies systematically investigating fibrinolysis were sparse. Measurements from conventional or quantitative assays, as well as dynamic fibrinolysis assays, revealed conflicting results with normal or increased lysis and changes were not associated with outcome. In conclusion, dynamic assays were able to detect reduced platelet function, not revealed by conventional or quantitative assays. Activation of secondary hemostasis was found in both dynamic and nondynamic assays, while changes in fibrinolysis were not convincingly demonstrable in either dynamic or conventional or quantitative assays. Hence, from a mechanistic point of view, desmopressin to prevent rebleeding and heparin to prevent DCI may hold potential as therapeutic options. As changes in fibrinolysis were not convincingly demonstrated and not related to outcome, the use of tranexamic acid prior to aneurysm closure is not supported by this review.

Dynamic Change in Mean Platelet Volume and Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage

Background: The mean platelet volume (MPV) has been shown to predict short-term outcomes in patients who have experienced aneurysmal subarachnoid hemorrhage (aSAH). The purpose of this study was to explore the temporal variation of MPV in patients with aSAH and its relationship to the development of delayed cerebral ischemia (DCI).

Methods: Data from 197 consecutive aSAH patients who were treated at our institution between January 2017 and December 2019 were collected and analyzed. Blood samples to assess MPV were obtained at 1–3, 3–5, 5–7, and 7–9 d after the initial hemorrhage. Univariate and multivariate analyses were performed to investigate whether MPV was an independent predictor of DCI and the receiver operating characteristic (ROC) curve and area under the curve (AUC) were determined.

Results: The MPV values in patients with DCI were significantly higher compared to those without DCI at 1–3, 3–5, 5–7, and 7–9 d after hemorrhage (P < 0.001). The trend for MPV in patients with DCI was increased at first and then decreased. The transition from increases to decreases occurred at 3–5 d after hemorrhage. The optimal cutoff value for MPV to accurately predict DCI was 10.35 fL at 3–5 d after aSAH in our cohort. Furthermore, the MPV observed at 3–5 d was an independent risk factor for DCI [odds ratio (OR) = 4.508, 95% confidence interval (CI): 2.665–7.626, P < 0.001].

Conclusions: MPV is a dynamic variable that occurs during aSAH, and a high MPV at 3–5 days after hemorrhage is associated with the development of DCI.

Use of viscoelastic monitoring and prothrombin complex concentrate in a paediatric patient with polytrauma and severe traumatic brain injury

Viscoelastic monitoring (VEM) tools, such as rotational thrombelastometry, have been used extensively to measure coagulopathy in adults but have received less attention in paediatric care. The presented case involves a 5-year-old boy who was brought to the emergency department after a motor vehicle collision with a Glasgow Coma Scale score of 6T and extensive injuries, including a subdural hematoma. VEM was used to monitor the patient's coagulopathy and to inform treatment measures by allowing real-time visualisation of the patient's coagulation status. VEM was additionally used to direct blood product replacement in preparation for neurosurgical intervention, and 4-factor prothrombin complex concentrate (PCC) was used to help reverse the coagulopathy. The patient underwent successful hemicraniectomy after improvement of his coagulopathy. In paediatrics, VEM and PCC are increasingly being used for post-trauma coagulopathy, and this case highlights their potential promise and the need for further research.

Acute platelet response to aneurysmal subarachnoid hemorrhage depends on severity and distribution of bleeding: an observational cohort study

Microthrombosis after aneurysmal subarachnoid hemorrhage (aSAH) is considered to initiate neuroinflammation, vessel remodeling, and blood-brain barrier leakage. We aimed to verify the hypothesis that the intensity of thrombogenicity immediately after aSAH depends on the amount and distribution of extravasated blood. This observational cohort study included 37 consecutive aSAH patients admitted no longer than 24 h after ictus. Volumes of subarachnoid and intraventricular hemorrhages as well as the Subarachnoid Hemorrhage Early Brain Edema Scale (SEBES) score were calculated in each case. Platelet system status was described by platelet count (PLT), mean platelet volume (MPV), MPV to PLT ratio, and platelet-large cell ratio (P-LCR). Median hemorrhage volume amounted to 11.4 ml (interquartile range 2.8-26.8 ml). Patients with more severe hemorrhage had lower PLT and higher MPV to PLT ratio (ρ =  - 0.49, p < .002; ρ = 0.50, p < .002, respectively). PLT decreased by 2.80 G/l per 1 ml of hemorrhage volume (95% CL 1.30-4.30, p < .001). Further analysis revealed that intraventricular hemorrhage volume was associated with P-LCR and MPV (ρ = 0.34, p < .039; ρ = 0.33, p < .048, respectively), whereas SAH volume with PLT and MPV:PLT ratio (ρ =  - 0.40, p < .013; ρ = 0.41, p < .013, respectively). The odds of unfavorable neurological outcome increased 3.95 times per 1 fl of MPV (95% CI 1.19-13.12, p < .025). MPV was independently correlated with SEBES (ρ = 0.44, p < .006). This study demonstrated that the extent and distribution of aneurysmal subarachnoid hemorrhage are related to different types of acute platelet response, which may be interpreted as local and systemic thrombogenicity. Increased mean platelet volume measured in the acute phase of aSAH may identify patients at risk for unfavorable neurological outcomes and may serve as a marker of early brain injury.

Tracing the Lines: A Review of Viscoelastography for Emergency Medicine Clinicians

BACKGROUND

Viscoelastography (VE) is an established method to identify coagulopathies in various disease processes. Clinical decisions can be made with real-time tracings and quantitative values at the bedside. Thromboelastography (TEG®) and rotational thromboelastometry (ROTEM®) have been utilized in several disease states with clinical varying success.

OBJECTIVES

This review will summarize the literature and provide recommendations pertaining to major disease processes where VE may be beneficial, including trauma, anticoagulation reversal, liver disease, acute ischemic stroke, and acquired brain injuries.

DISCUSSION

VE has a role in many emergency medicine patients encountered by clinicians. Reduced mortality, decreased blood product utilization, and prognostication ability makes VE an intriguing tool that can be utilized by providers to improve patient care.

CONCLUSION

This review serves as a way for emergency medicine clinicians to utilize VE in their practice and provides an insightful literature overview.

Thromboelastometry as a Comprehensive Assessment of Hypercoagulation After Aneurysmal Subarachnoid Hemorrhage: A Case Report and Literature Review

Subarachnoid hemorrhage after cerebral aneurysm rupture (aSAH) leads to delayed cerebral ischemia (DCI) in 25-35% of surviving patients. It is believed that DCI has a multifactorial etiology, including vasospasm. Furthermore, aSAH is associated with the development of hypercoagulation and microthrombosis; thus, its pharmacological correction may help to prevent DCI. We encountered a case where hypercoagulation was detected using rotational thromboelastometry (ROTEM), although the standard coagulation test results were within the normal ranges. Based on reviews of viscoelastic tests in cases of aSAH, ROTEM could be more sensitive to hypercoagulation after aSAH, compared to standard coagulation testing.

Prospective Longitudinal Evaluation of Coagulation with Novel Thromboelastography Technology in Patients After Subarachnoid Hemorrhage: A Pilot Study

BACKGROUND

There is limited knowledge of whether hypercoagulability is present after subarachnoid hemorrhage (SAH) or about its timing of onset, duration, and severity. To conduct a pilot new-generation thromboelastography (TEG) technology (TEG6s)-based and conventional coagulation test-supported longitudinal assessment of coagulation in patients with SAH.

METHODS

We prospectively enrolled patients with nontraumatic SAH on admission from May 2015 to May 2016. We performed TEG6s measurements and conventional coagulation tests on days 1, 2, 3, 5, 7, 10, and 14 and compared them with TEG6s parameters in healthy volunteers.

RESULTS

We studied 14 patients and 72 TEG6s measurements. Of these patients, 10 (71.4%) were admitted to the intensive care unit. Mean age was 57.5 (±14.5) years, Acute Physiology and Chronic Health Evaluation III score 58.2 (±26.6), length of hospital stay was 23 (±11.7) days, and mortality was 14.3%. At baseline, conventional coagulation tests were within normal range. However, TEG6s parameters already showed increased coagulability. Thereafter, alpha angle, reaction time, functional fibrinogen level, and maximum amplitude rapidly and significantly increased (P < 0.01) compared with healthy controls. Ten (71.4%) patients demonstrated a >20% increase in coagulability based on TEG6s parameters from their baseline. Moreover, TEG6s hypercoagulability peaked at day 10 and only showed an initial partial decline towards normal by day 14. Similarly, platelet counts and fibrinogen levels increased over this period (P < 0.01) CONCLUSIONS: Using TEG6s technology, we found significant and progressive hypercoagulability in 70% of patients, with an early dominant contribution from hyperfibrinogenemia and increased fibrin formation and partial contribution from thrombocytosis, beginning on the first day, increasing to peak values by day 10, and then partly declining toward normal by day 14.

Thromboelastography with Platelet Mapping Detects Platelet Dysfunction in Patients with Aneurysmal Subarachnoid Hemorrhage with Rebleeding

BACKGROUND

Aneurysmal subarachnoid hemorrhage (aSAH) has high rates of disability and mortality, and aneurysm rebleeding is associated with poor functional outcomes. Thrombelastography with platelet mapping (TEG-PM) measures platelet function; however, it has not yet been researched in aSAH. We aimed to use TEG-PM to detect changes in platelet function in patients with aSAH and the difference in patients with and without rebleeding.

METHODS

We retrospectively included patients with aSAH who underwent a TEG-PM test on admission. Rebleeding was diagnosed according to clinical and imaging data. TEG-PM data of patients with unruptured intracranial aneurysms (UIA) were also obtained as controls. Univariate and multivariate logistic regression models were performed to investigate the relationship between the platelet function and rebleeding.

RESULTS

A total of 245 aSAH patients and 32 UIA patients were included in our study. Compared with controls, patients with aSAH demonstrated higher arachidonic acid (AA) and adenosine diphosphate (ADP) inhibition of platelet function (P<0.05). Among them, 27 patients with Hunt-Hess grade IV or V were classified as the severe SAH group. There was a significant correlation between the severe SAH group and the degree of pathway inhibition (P<0.05). Furthermore, AA (Spearman's r=0.264, P<0.001) and ADP (Spearman's r=0.183, P=0.004) inhibition were elevated in Hunt-Hess grade-dependent manners. The AA (Spearman's r=0.169, P=0.008) and ADP (Spearman's r=0.233, P<0.001) inhibition were also significantly correlated with Fisher grade. Thirty-five patients (14.3%) suffered rebleeding. Rebleeding was significantly correlated with systolic blood pressure (P=0.011), diastolic blood pressure (P=0.008), Hunt-Hess grade (P=0.034), Fisher grade (P=0.015), AA inhibition (P<0.001), and ADP inhibition (P<0.001). Multivariate logistic regression analysis model revealed that both AA (P=0.037) and ADP inhibition (P=0.008) were independent determinants for rebleeding.

CONCLUSION

TEG-PM may assess platelet dysfunction in patients with aSAH, and the diminished platelet response to ADP and AA may be associated with rebleeding. These findings deserve further investigation.

The role of inflammation and potential use of sex steroids in intracranial aneurysms and subarachnoid hemorrhage

Background

Aneurysmal subarachnoid hemorrhage (aSAH) continues to be a devastating neurological condition with a high risk of associated morbidity and mortality. Inflammation has been shown to increase the risk of complications associated with aSAH such as vasospasm and brain injury in animal models and humans. The goal of this review is to discuss the inflammatory mechanisms of aneurysm formation, rupture and vasospasm and explore the role of sex hormones in the inflammatory response to aSAH.

Methods

A literature review was performed using PubMed using the following search terms: "intracranial aneurysm," "cerebral aneurysm," "dihydroepiandrosterone sulfate" "estrogen," "hormone replacement therapy," "inflammation," "oral contraceptive," "progesterone," "sex steroids," "sex hormones" "subarachnoid hemorrhage," "testosterone." Only studies published in English language were included in the review.

Results

Studies have shown that administration of sex hormones such as progesterone and estrogen at early stages in the inflammatory cascade can lower the risk and magnitude of subsequent complications. The exact mechanism by which these hormones act on the brain, as well as their role in the inflammatory cascade is not fully understood. Moreover, conflicting results have been published on the effect of hormone replacement therapy in humans. This review will scrutinize the variations in these studies to provide a more detailed understanding of sex hormones as potential therapeutic agents for intracranial aneurysms and aSAH.

Conclusion

Inflammation may play a role in the pathogenesis of intracranial aneurysm formation and subarachnoid hemorrhage, and administration of sex hormones as anti-inflammatory agents has been associated with improved functional outcome in experimental models. Further studies are needed to determine the therapeutic role of these hormones in the intracranial aneurysms and aSAH.

Unique Contribution of Haptoglobin and Haptoglobin Genotype in Aneurysmal Subarachnoid Hemorrhage

Survivors of cerebral aneurysm rupture are at risk for significant morbidity and neurological deficits. Much of this is related to the effects of blood in the subarachnoid space which induces an inflammatory cascade with numerous downstream consequences. Recent clinical trials have not been able to reduce the toxic effects of free hemoglobin or improve clinical outcome. One reason for this may be the inability to identify patients at high risk for neurologic decline. Recently, haptoglobin genotype has been identified as a pertinent factor in diabetes, sickle cell, and cardiovascular disease, with the Hp 2-2 genotype contributing to increased complications. Haptoglobin is a protein synthesized by the liver that binds free hemoglobin following red blood cell lysis, and in doing so, prevents hemoglobin induced toxicity and facilitates clearance. Clinical studies in patients with subarachnoid hemorrhage indicate that Hp 2-2 patients may be a high-risk group for hemorrhage related complications and poor outcome. We review the relevance of haptoglobin in subarachnoid hemorrhage and discuss the effects of genotype and expression levels on the known mechanisms of early brain injury (EBI) and cerebral ischemia after aneurysm rupture. A better understanding of haptoglobin and its role in preventing hemoglobin related toxicity should lead to novel therapeutic avenues.

Blood clot parameters: Prejudgment of fibrinolysis in thromboelastography

BACKGROUND

Thromboelastography (TEG) is a physical method to simulate the whole process of coagulation and fibrinolysis in the human body environment, and then it also can quickly determine whether patients with hypercoagulable, low coagulation, fibrinolysis or other symptoms. The first step in the diagnosis is based on two parameters: Estimated percentage of lysis (EPL) or the Lysis at 30 min (LY30). These two parameters are used to determine whether the sample has fibrinolysis. However, the determination of LY30 takes a long time, although EPL can reflect real-time fibrinolysis, sometimes the secondary fibrinolysis is not obvious.

MATERIALS AND METHODS

We have an extensive database of results from TEG of fibrinolysis and healthy whole blood (WB). These results were generated using citrated WB, followed by the addition of CaCl₂, to initiate clot formation.

RESULTS

According to the characteristics of fibrinolysis, a new parameter clot retention time (CRT) was proposed to predict the status of fibrinolysis, and the normal range of the parameters was obtained in this paper.

CONCLUSION

It is essential for the clinician to determine the fibrinolytic and ultimately contribute to the treatment of patients. We believe this parameter will add to the standardization of TEG parameters. The new parameter will also shorten the measurement time of non-fibrinolytic samples, which has definite physiological and pathological significance.

Neurosurgical applications of viscoelastic hemostatic assays

Patients taking antithrombotic agents are very common in neurosurgical practice. The perioperative management of these patients can be extremely challenging especially as newer agents, with poorly defined laboratory monitoring and reversal strategies, become more prevalent. This is especially true with emergent cases in which rapid reversal of anticoagulation is required and the patient’s exact medical history is not available. With an aging patient population and the associated increase in diseases such as atrial fibrillation, it is expected that the use of these agents will continue to rise in coming years. Furthermore, thromboembolic complications such as deep venous thrombosis, pulmonary embolism, and myocardial infarction are common complications of major surgery. These trends, in conjunction with a growing understanding of the hemostatic process and its contribution to the pathophysiology of disease, stress the importance of the complete evaluation of a patient’s hemostatic profile in guiding management decisions. Viscoelastic hemostatic assays (VHAs), such as thromboelastography and rotational thromboelastometry, are global assessments of coagulation that account for the cellular and plasma components of coagulation. This FDA-approved technology has been available for decades and has been widely used in cardiac surgery and liver transplantation. Although VHAs were cumbersome in the past, advances in software and design have made them more accurate, reliable, and accessible to the neurosurgeon. VHAs have demonstrated utility in guiding intraoperative blood product transfusion, identifying coagulopathy in trauma, and managing postoperative thromboprophylaxis. The first half of this review aims to evaluate and assess VHAs, while the latter half seeks to appraise the evidence supporting their use in neurosurgical populations.

The Role of Thromboinflammation in Delayed Cerebral Ischemia after Subarachnoid Hemorrhage

Delayed cerebral ischemia (DCI) is a major determinant of patient outcome following aneurysmal subarachnoid hemorrhage. Although the exact mechanisms leading to DCI are not fully known, inflammation, cerebral vasospasm, and microthrombi may all function together to mediate the onset of DCI. Indeed, inflammation is tightly linked with activation of coagulation and microthrombi formation. Thromboinflammation is the intersection at which inflammation and thrombosis regulate one another in a feedforward manner, potentiating the formation of thrombi and pro-inflammatory signaling. In this review, we will explore the role(s) of inflammation and microthrombi in subarachnoid hemorrhage (SAH) pathophysiology and DCI, and discuss the potential of targeting thromboinflammation to prevent DCI after SAH.

D-dimer may predict poor outcomes in patients with aneurysmal subarachnoid hemorrhage: a retrospective study

Serum biomarkers may play a reliable role in predicting the outcomes of patients with aneurysmal subarachnoid hemorrhage. This study retrospectively analyzed the relationship between serum biomarkers on admission and outcomes in patients with aneurysmal subarachnoid hemorrhage. We recruited 146 patients with aneurysmal subarachnoid hemorrhage who were treated in Renmin Hospital of Wuhan University of China between 1 May 2014 and 30 March 2016. There were 57 males and 89 females included and average age of included patients was 57.03 years old. Serum samples were taken immediately on admission (within 48 hours after initial hemorrhage) and the levels of serum biomarkers were detected. Baseline information, complications, and outcomes at 6 months were recorded. Univariate and multivariate logistic regression analyses were used to explore the relationship between biomarkers and clinical outcomes. Receiver operating characteristic curves were obtained to investigate the possibility of the biomarkers predicting prognosis. Of the 146 patients, 102 patients achieved good outcomes and 44 patients had poor outcomes. Univariate and multivariate analyses showed that high World Federation of Neurosurgical Societies grade, high serum D-dimer levels, and high neurological complications were significantly associated with poor outcomes. Receiver operating characteristic curves verified that D-dimer levels were associated with poor outcomes. D-dimer levels strongly correlated with neurological complications. In conclusion, we suggest that D-dimer levels are a good independent prognostic factor for poor outcomes in patients with aneurysmal subarachnoid hemorrhage.