Does enoxaparin interfere with HMGB1 signaling after TBI? A potential mechanism for reduced cerebral edema and neurologic recovery

Venous thromboembolism chemoprophylaxis after severe polytrauma: timing and type of prophylaxis matter

In this review, we provide recommendations as well as summarize available data on the optimal time to initiate venous thromboembolism chemoprophylaxis after severe trauma. A general approach to the severe polytrauma patient is provided as well as in-depth reviews of three high-risk injury subgroups: patients with traumatic brain injury, solid organ injury, and pelvic fractures.

Propensity weighted analysis of chemical venous thromboembolism prophylaxis agents in isolated severe traumatic brain injury: An EAST sponsored multicenter study

BACKGROUND

In patients with severe traumatic brain injury (TBI), clinicians must balance preventing venous thromboembolism (VTE) with the risk of intracranial hemorrhagic expansion (ICHE). We hypothesized that low molecular weight heparin (LMWH) would not increase risk of ICHE or VTE as compared to unfractionated heparin (UH) in patients with severe TBI.

METHODS

Patients ≥ 18 years of age with isolated severe TBI (AIS ≥ 3), admitted to 24 level I and II trauma centers between January 1, 2014 to December 31, 2020 and who received subcutaneous UH and LMWH injections for chemical venous thromboembolism prophylaxis (VTEP) were included. Primary outcomes were VTE and ICHE after VTEP initiation. Secondary outcomes were mortality and neurosurgical interventions. Entropy balancing (EBAL) weighted competing risk or logistic regression models were estimated for all outcomes with chemical VTEP agent as the predictor of interest.

RESULTS

984 patients received chemical VTEP, 482 UH and 502 LMWH. Patients on LMWH more often had pre-existing conditions such as liver disease (UH vs LMWH 1.7 % vs. 4.4 %, p = 0.01), and coagulopathy (UH vs LMWH 0.4 % vs. 4.2 %, p < 0.001). There were no differences in VTE or ICHE after VTEP initiation. There were no differences in neurosurgical interventions performed. There were a total of 29 VTE events (3 %) in the cohort who received VTEP. A Cox proportional hazards model with a random effect for facility demonstrated no statistically significant differences in time to VTE across the two agents (p = 0.44). The LMWH group had a 43 % lower risk of overall ICHE compared to the UH group (HR = 0.57: 95 % CI = 0.32-1.03, p = 0.062), however was not statistically significant.

CONCLUSION

In this multi-center analysis, patients who received LMWH had a decreased risk of ICHE, with no differences in VTE, ICHE after VTEP initiation and neurosurgical interventions compared to those who received UH. There were no safety concerns when using LMWH compared to UH.

LEVEL OF EVIDENCE

Level III, Therapeutic Care Management.

Venous thromboembolism chemoprophylaxis in geriatric trauma patients with isolated severe traumatic brain injury

PURPOSE

Low-molecular-weight-heparin (LMWH) has been shown to be associated with a decreased risk of venous thromboembolism (VTE) and mortality compared to unfractionated heparin (UH) in severe traumatic brain injury (TBI). The aim of this study was to see if this association persists among a subset of patients, namely elderly patients with isolated TBI.

METHODS

This Trauma Quality Improvement Project (TQIP) database study included patients ≥ 65 years old with severe TBI (Abbreviated injury score [AIS] ≥ 3) that received either LMWH or UH for VTE prophylaxis. Patients with associated severe injuries (extracranial AIS ≥ 3), transferals, deaths < 72-h, hospitalization < 2 days, VTE chemoprophylaxis other than UH or LMWH, or with a history of bleeding diathesis were excluded. The association between VTE, deep vein thrombosis (DVT), and pulmonary embolism (PE) with VTE chemoprophylaxis was analyzed with multivariable analysis, subset analyses of different grades of AIS-head injury, and a 1:1 matched LWMH:UH cohort of patients.

RESULTS

Out of 14,926 patients, 11,036 (73.9%) received LMWH. Multivariate analysis showed that patients receiving LMWH had a decreased risk of mortality (OR 0.81, 95% CI 0.67-0.97, p < 0.001) but a similar risk of VTE (OR 0.83, 95% CI 0.63-1.08). Analysis according to head-AIS showed that LMWH was associated with a decreased risk of PE in patients AIS-3 but not in AIS 4 or 5. In a 1:1 matched cohort of LMWH:UH patients, the risk of PE, DVT and VTE were all similar but LMWH continued to be associated with a decreased risk of mortality (OR 0.81, CI 0.67-0.97, p = 0.023).

CONCLUSION

LMWH was associated with a decreased risk of overall mortality and reduced risk of PE compared to UH among geriatric patients with a severe head injury.

Roles and therapeutic potential of different extracellular vesicle subtypes on traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of injury-related disability and death around the world, but the clinical stratification, diagnosis, and treatment of complex TBI are limited. Due to their unique properties, extracellular vesicles (EVs) are emerging candidates for being biomarkers of traumatic brain injury as well as serving as potential therapeutic targets. However, the effects of different extracellular vesicle subtypes on the pathophysiology of traumatic brain injury are very different, or potentially even opposite. Before extracellular vesicles can be used as targets for TBI therapy, it is necessary to classify different extracellular vesicle subtypes according to their functions to clarify different strategies for EV-based TBI therapy. The purpose of this review is to discuss contradictory effects of different EV subtypes on TBI, and to propose treatment ideas based on different EV subtypes to maximize their benefits for the recovery of TBI patients. Video Abstract.

Neuroinflammatory Biomarkers for Traumatic Brain Injury Diagnosis and Prognosis: A TRACK-TBI Pilot Study

The relationship between systemic inflammation and secondary injury in traumatic brain injury (TBI) is complex. We investigated associations between inflammatory markers and clinical confirmation of TBI diagnosis and prognosis. The prospective TRACK-TBI Pilot (Transforming Research and Clinical Knowledge in Traumatic Brain Injury Pilot) study enrolled TBI patients triaged to head computed tomography (CT) and received blood draw within 24 h of injury. Healthy controls (HCs) and orthopedic controls (OCs) were included. Thirty-one inflammatory markers were analyzed from plasma. Area under the receiver operating characteristic curve (AUC) was used to evaluate discriminatory ability. AUC >0.7 was considered acceptable. Criteria included: TBI diagnosis (vs. OC/HC); moderate/severe vs. mild TBI (Glasgow Coma Scale; GCS); radiographic TBI (CT positive vs. CT negative); 3- and 6-month Glasgow Outcome Scale-Extended (GOSE) dichotomized to death/greater relative disability versus less relative disability (GOSE 1-4/5-8); and incomplete versus full recovery (GOSE <8/ = 8). One-hundred sixty TBI subjects, 28 OCs, and 18 HCs were included. Markers discriminating TBI/OC: HMGB-1 (AUC = 0.835), IL-1b (0.795), IL-16 (0.784), IL-7 (0.742), and TARC (0.731). Markers discriminating GCS 3-12/13-15: IL-6 (AUC = 0.747), CRP (0.726), IL-15 (0.720), and SAA (0.716). Markers discriminating CT positive/CT negative: SAA (AUC = 0.767), IL-6 (0.757), CRP (0.733), and IL-15 (0.724). At 3 months, IL-15 (AUC = 0.738) and IL-2 (0.705) discriminated GOSE 5-8/1-4. At 6 months, IL-15 discriminated GOSE 1-4/5-8 (AUC = 0.704) and GOSE <8/ = 8 (0.711); SAA discriminated GOSE 1-4/5-8 (0.704). We identified a profile of acute circulating inflammatory proteins with potential relevance for TBI diagnosis, severity differentiation, and prognosis. IL-15 and serum amyloid A are priority markers with acceptable discrimination across multiple diagnostic and outcome categories. Validation in larger prospective cohorts is needed. ClinicalTrials.gov Registration: NCT01565551.

LPS-Induced Coagulation and Neuronal Damage in a Mice Model Is Attenuated by Enoxaparin

Background. Due to the interactions between neuroinflammation and coagulation, the neural effects of lipopolysaccharide (LPS)-induced inflammation (1 mg/kg, intraperitoneal (IP), n = 20) and treatment with the anti-thrombotic enoxaparin (1 mg/kg, IP, 15 min, and 12 h following LPS, n = 20) were studied in C57BL/6J mice. Methods. One week after LPS injection, sensory, motor, and cognitive functions were assessed by a hot plate, rotarod, open field test (OFT), and Y-maze. Thrombin activity was measured with a fluorometric assay; hippocampal mRNA expression of coagulation and inflammation factors were measured by real-time-PCR; and serum neurofilament-light-chain (NfL), and tumor necrosis factor-α (TNF-α) were measured by a single-molecule array (Simoa) assay. Results. Reduced crossing center frequency was observed in both LPS groups in the OFT (p = 0.02), along with a minor motor deficit between controls and LPS indicated by the rotarod (p = 0.057). Increased hippocampal thrombin activity (p = 0.038) and protease-activated receptor 1 (PAR1) mRNA (p = 0.01) were measured in LPS compared to controls, but not in enoxaparin LPS-treated mice (p = 0.4, p = 0.9, respectively). Serum NfL and TNF-α levels were elevated in LPS mice (p < 0.05) and normalized by enoxaparin treatment. Conclusions. These results indicate that inflammation, coagulation, neuronal damage, and behavior are linked and may regulate each other, suggesting another pharmacological mechanism for intervention in neuroinflammation.

Delayed Cranial Decompression Rates After Initiation of Unfractionated Heparin versus Low-Molecular-Weight Heparin in Traumatic Brain Injury

BACKGROUND

Both unfractionated heparin (UH) and low-molecular-weight heparin (LMWH) are routinely used prophylactically after traumatic brain injury (TBI) to prevent deep vein thrombosis (DVT). Their comparative risk for development or worsening of intracranial hemorrhage necessitating cranial decompression is unclear. Furthermore, the absence of a specific antidote for LMWH may lead to UH being used more often for high-risk patients. This study aims to compare the incidence of delayed cranial decompression occurring after initiation of prophylactic UH versus LMWH using the National Trauma Data Bank.

METHODS

Cranial decompression procedures included craniotomy and craniectomy. Multiple imputation was used for missing data. Propensity score matching was used to account for selection bias between UH and LMWH. The 1:1 matched groups were compared using logistic regression for the primary outcome of postprophylaxis cranial decompression.

RESULTS

A total of 218,594 patients with TBI were included, with 61,998 (28.3%) receiving UH and 156,596 (71.7%) receiving LMWH as DVT prophylaxis. The UH group had higher patient age, body mass index, comorbidity rates, Injury Severity Score, and worse motor Glasgow Coma Scale score. After the UH and LMWH groups were matched for these factors, logistic regression showed lower rates of postprophylaxis cranial decompression for the LMWH group (odds ratio, 0.13; 95% confidence interval, 0.11-0.16; P < 0.001).

CONCLUSIONS

Despite the absence of a specific antidote, LMWH was associated with lower rates of need for post-DVT-prophylaxis in craniotomy/craniectomy. This finding questions the notion of UH being safer for patients with TBI because it can be readily reversed. Randomized studies are needed to elucidate causality.

Low-Molecular Weight Heparin is Superior to Unfractionated Heparin for Elderly Trauma Patients

BACKGROUND

Several studies have demonstrated that low-molecular weight heparin (LMWH) is superior to unfractionated heparin (UFH) in trauma patients. The superiority of either one has not been established for the elderly. In this study, we compared LMWH to UFH in elderly trauma patients.

METHODS

A retrospective analysis of the American College of Surgeons' Trauma Quality Improvement Program database was performed for patients aged ≥65 y. Propensity score matching was performed to minimize confounders between the two groups. Outcomes included venous thromboembolic (VTE) and bleeding events.

RESULTS

Overall, 93,987 patients were identified (mean age 77.1 ± 7.3 y, females 55,035 [58.6%]), of which 67,738 (72.1%) patients received LMWH and 26,249 (27.9%) received UFH. After Propensity score matching, LMWH was associated with a lower incidence of deep venous thrombosis (1.7% versus 2.1%, P = 0.007) and pulmonary embolisms (0.6% versus 1%, P< 0.001). LMWH was also associated with fewer bleeding complications (transfusions: 2.8% versus 3.5%, P< 0.001, procedures: 0.7% versus 0.9%, P = 0.007). Sub-analyses showed that differences in VTE rates were identified in patients with mild injuries (Injury Severity Score [ISS] <16, 0.6% versus 1.9%, P< 0.001). Differences in bleeding complications were identified in patients with injuries of mild (ISS <16, transfusions: 3% versus 3.8%, P< 0.001, surgeries: 0.3% versus 0.4%, P= 0.015) and moderate severity (ISS 16-24, transfusions: 1.9% versus 2.7%, P= 0.038, surgeries: 1% versus 1.7%, P= 0.013).

CONCLUSION

LMWH prophylaxis is superior to UFH for VTE prevention among elderly trauma patients. LMWH prophylaxis is associated with fewer bleeding complications compared to UFH in patients with injuries of mild or moderate severity.

Timing of venous thromboembolic pharmacological prophylaxis in traumatic combined subdural and subarachnoid hemorrhage

BACKGROUND

The combination of subdural and subarachnoid hemorrhage is the most common intracranial bleeding. The present study evaluated the timing and type of venous thromboembolic chemoprophylaxis (VTEp) for efficacy and safety in patients with blunt head trauma with combined acute subdural and subarachnoid hemorrhage.

METHODS

Patients with isolated combined acute subdural and subarachnoid hemorrhage were extracted from the ACS-TQIP database (2013-2017). After 1:1 cohort matching of patients receiving early prophylaxis (EP, ≤48 h) versus late prophylaxis (LP, >48 h) outcomes were compared with univariable and multivariable regression analysis.

RESULTS

Multivariable regression analysis identified EP as an independent protective factor for VTE complications (OR 0.468, CI 0.293-0.748) but not mortality (p = 0.485). The adjusted risk for delayed craniectomy was not associated with EP compared to LP (p = 0.283). The type of VTEp was not associated with VTE complications (p = 0.301), mortality (p = 0.391) or delayed craniectomy (p = 0.126).

CONCLUSIONS

Early VTEp (≤48 h) was associated with fewer VTE complications in patients and did not increase the risk for craniectomies in patients with combined acute subdural and subarachnoid hemorrhage.

Venous thromboembolic pharmacological prophylaxis in severe traumatic acute subdural hematomas: Early prophylaxis is effective and safe

BACKGROUND

The purpose of this study was to evaluate the optimal timing and type of pharmacological venous thromboembolism prophylaxis (VTEp) in patients with severe blunt head trauma with acute subdural hematomas (ASDH).

METHODS

Matched cohort study using ACS-TQIP database (2013-2016) including patients with isolated ASDH. Outcomes of matched patients receiving early prophylaxis (EP, ≤48 h) and late prophylaxis (LP, >48 h) were compared with univariable and multivariable regression analysis.

RESULTS

In 1,660 matched cases VTE complications (3.1% vs 0.5%, p < 0.001) were more common in the LP compared to the EP group. Multivariable regression analysis identified EP as an independent protective factor for VTE complications (OR 0.169, p < 0.001) but not mortality (p = 0.260). The adjusted risk for delayed craniectomy was not associated with EP compared to LP (p = 0.095). LMWH was independently associated with a lower mortality (OR 0.480, p = 0.008) compared to UH.

CONCLUSIONS

Early VTEp (≤48 h) does not increase the risk for craniectomies and is independently associated with fewer VTE complications in patients with isolated ASDH. LMWH was independently associated with a lower mortality compared to UH.

Low-molecular-weight heparin versus unfractionated heparin in pediatric traumatic brain injury

OBJECTIVE

The incidence of venous thromboembolism (VTE) in patients with traumatic brain injury (TBI) has increased significantly. The Eastern Association for the Surgery of Trauma recommends using low-molecular-weight heparin (LMWH) over unfractionated heparin (UH) in pediatric patients requiring VTE prophylaxis, although this strategy is unsupported by the literature. In this study, the authors compare the outcomes of pediatric TBI patients receiving LMWH versus UH.

METHODS

The authors performed a 4-year (2014-2017) analysis of the pediatric American College of Surgeons Trauma Quality Improvement Program. All trauma patients (age ≤ 18 years) with TBI requiring thromboprophylaxis with UH or LMWH were potentially eligible for inclusion. Patients who had been transferred, had died in the emergency department, or had penetrating trauma were excluded. Patients were stratified into either the LMWH or the UH group on the basis of the prophylaxis they had received. Patients were matched on the basis of demographics, injury characteristics, vital signs, and transfusion requirements using propensity score matching (PSM). The study endpoints were VTE, death, and craniotomy after initiation of prophylaxis. Univariate analysis was performed after PSM to compare outcomes.

RESULTS

A total of 2479 patients met the inclusion criteria (mean age 15.5 ± 3.7 years and 32.0% female), of which 1570 (63.3%) had received LMWH and 909 (36.7%) had received UH. Before PSM, patients receiving UH were younger, had a lower Glasgow Coma Scale score, and had a higher Injury Severity Score. Patients treated in pediatric hospitals were more likely to receive UH (12.9% vs 9.0%, p < 0.001) than patients treated in adult hospitals. Matched patients receiving UH had a higher incidence of VTE (5.1% vs 2.9%, p = 0.03).

CONCLUSIONS

LMWH prophylaxis in pediatric TBI appears to be more effective than UH in preventing VTE. Large, multicenter prospective studies are warranted to confirm the superiority of LMWH over UH in pediatric patients with TBI. Moreover, outcomes of VTE prophylaxis in the very young remain understudied; therefore, dedicated studies to evaluate this population are needed.

Timing and Type of Venous Thromboembolic Prophylaxis in Isolated Severe Liver Injury Managed Non-Operatively

BACKGROUND

The optimal timing and type of pharmacological venous thromboembolic prophylaxis (VTEp) after severe liver injury selected for nonoperative management (NOM) are controversial. The aim of this study was to assess the effect of timing and type of VTEp in severe liver injuries selected for NOM.

METHODS

ACS-TQIP database study (2013-17) including patients with blunt isolated severe liver injuries (AIS ≥ 3), selected for NOM, who received VTEp with either unfractionated heparin (UH) or low-molecular-weight heparin (LMWH). Patients who underwent laparotomy or angiointervention within 24 h or prior to the initiation of VTEp were excluded. The study population was stratified according to the timing of VTEp ≤ 48 h (EP) and > 48 h (LP) groups. Univariate and multivariate analyses were used to identify differences between the groups.

RESULTS

A total of 4074 patients was included in the study. 2004 (49.2%) received EP and 2070 (50.8%) LP. Patients with more severe injuries were more likely to receive LP than an EP [ISS 24 (19-29) vs 22 (17-27), p < 0.001]. On multivariate analysis (correcting for age, gender, comorbidities, blood pressure, GCS, ISS, type of VTEp), LP was identified as an independent risk factor for thromboembolic events (OR 1.52, p = 0.032) and mortality (OR 2.49, p = 0.031). LMWH was independently associated with lower mortality (OR 0.36, p = 0.007), compared to UH. EP did not increase the risk of laparotomy or angiointervention after starting VTEp, compared to LP (p = 0.992).

CONCLUSION

Early VTEp (≤ 48 h) is safe and independently associated with fewer thromboembolic events and a lower mortality after isolated severe liver injuries managed nonoperatively. LMWH was independently associated with improved outcomes when compared with UH.

The Safety of Early Thromboembolic Prophylaxis in Closed Traumatic Intracranial Hemorrhage

Background

Venous thromboembolism (VTE) is a major cause of morbidity and mortality in patients with traumatic brain injury (TBI); this study is testing the safety of enoxaparin use for the prevention of venous thromboembolism in this group of patients.

Patients and Methods

From January 2016 to May 2018, 46 patients (36 males, 10 females) with closed traumatic intracranial bleeding received early (ie, within 72 hours) venous thromboembolic prophylaxis with 40 mg of enoxaparin. Patients with traumatic intracranial hemorrhage were followed up both clinically and with repeated brain computed tomography to examine the safety of enoxaparin VTE prophylaxis.

Results

The age of the patients ranged from 16–91 years (43.9±25.8 years). Glasgow coma score ranged from 5–15 (9.9±4.7). Twenty patients had mild TBI (GCS 15–13), 17 patients had moderate TBI (GCS 12–9), and nine patients had severe TBI (GCS≤8). Brain computed tomography showed variable types of brain injuries. Non-surgical management was applied for 18 patients. Craniotomy and surgical evacuation of significant (≥1cm in maximum diameter) EDH and/or SDH was carried out in 26 patients. External ventricular drain was inserted in two patients with significant IVH. Thirty-eight patients had good overall outcome, eight patients showed poor outcome. None of the reviewed patients developed clinical deterioration and/or progression of the intracranial bleeding on follow-up brain CT scans.

Conclusion

Enoxaparin is a safe prophylaxis against venous thromboembolism in patients with traumatic closed intracranial bleeding.

Neural-respiratory inflammasome axis in traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality. Approximately 20-25% of TBI subjects develop Acute Lung Injury (ALI), but the pathomechanisms of TBI-induced ALI remain poorly defined. Currently, mechanical ventilation is the only therapeutic intervention for TBI-induced lung injury. Our recent studies have shown that the inflammasome plays an important role in the systemic inflammatory response leading to lung injury-post TBI. Here, we outline the role of the extracellular vesicle (EV)-mediated inflammasome signaling in the etiology of TBI-induced ALI. Furthermore, we evaluate the efficacy of a low molecular weight heparin (Enoxaparin, a blocker of EV uptake) and a monoclonal antibody against apoptosis speck-like staining protein containing a caspase recruitment domain (anti-ASC) as therapeutics for TBI-induced lung injury. We demonstate that activation of an EV-mediated Neural-Respiratory Inflammasome Axis plays an essential role in TBI-induced lung injury and disruption of this axis has therapeutic potential as a treatment strategy.

Early low-anticoagulant desulfated heparin after traumatic brain injury: Reduced brain edema and leukocyte mobilization is associated with improved watermaze learning ability weeks after injury

BACKGROUND

Unfractionated heparin administered immediately after traumatic brain injury (TBI) reduces brain leukocyte (LEU) accumulation, and enhances early cognitive recovery, but may increase bleeding after injury. It is unknown how non-anticoagulant heparins, such as 2,3-O desulfated heparin (ODSH), impact post-TBI cerebral inflammation and long-term recovery. We hypothesized that ODSH after TBI reduces LEU-mediated brain inflammation and improves long-term neurologic recovery.

METHODS

CD1 male mice (n = 66) underwent either TBI (controlled cortical impact [CCI]) or sham craniotomy. 2,3-O desulfated heparin (25 mg/kg [25ODSH] or 50 mg/kg [50ODSH]) or saline was administered for 48 hours after TBI in 46 animals. At 48 hours, intravital microscopy visualized rolling LEUs and fluorescent albumin leakage in the pial circulation, and the Garcia Neurologic Test assessed neurologic function. Brain edema (wet/dry ratio) was evaluated post mortem. In a separate group of animals (n = 20), learning/memory ability (% time swimming in the Probe platform quadrant) was assessed by the Morris Water Maze 17 days after TBI. Analysis of variance with Bonferroni correction determined significance (p < 0.05).

RESULTS

Compared with CCI (LEU rolling: 32.3 ± 13.7 LEUs/100 μm per minute, cerebrovascular albumin leakage: 57.4 ± 5.6%), both ODSH doses reduced post-TBI pial LEU rolling (25ODSH: 18.5 ± 9.2 LEUs/100 μm per minute, p = 0.036; 50ODSH: 7.8 ± 3.9 LEUs/100 μm per minute, p < 0.001) and cerebrovascular albumin leakage (25ODSH: 37.9 ± 11.7%, p = 0.001, 50ODSH: 32.3 ± 8.7%, p < 0.001). 50ODSH also reduced injured cerebral hemisphere edema (77.7 ± 0.4%) vs. CCI (78.7 ± 0.4 %, p = 0.003). Compared with CCI, both ODSH doses improved Garcia Neurologic Test at 48 hours. Learning/memory ability (% time swimming in target quadrant) was lowest in CCI (5.9 ± 6.4%) and significantly improved in the 25ODSH group (27.5 ± 8.2%, p = 0.025).

CONCLUSION

2,3-O desulfated heparin after TBI reduces cerebral LEU recruitment, microvascular permeability and edema. 2,3-O desulfated heparin may also improve acute neurologic recovery leading to improved learning/memory ability weeks after injury.

Timing of venous thromboprophylaxis in isolated severe pelvic fracture: Effect on mortality and outcomes

INTRODUCTION

Optimal timing of pharmacological thromboprophylaxis (VTEp) in patients with severe pelvic fractures remains unclear. The high risk of venous thromboembolic (VTE) complications after severe pelvic fractures supports early VTEp however concern for fracture-associated hemorrhage can delay initiation. Patients with pelvic fractures also frequently have additional injuries that complicate the interpretation of the VTEp safety profiles. To minimize this problem, the study included only patients with isolated severe pelvic fractures.

MATERIALS AND METHODS

The Trauma Quality Improvement Program was used to collect patients with blunt severe pelvic fractures (AIS > 3) who received VTEp with unfractionated heparin (UH) or low-molecular-weight heparin (LMWH). Patients with head, chest, spine, and abdominal injuries AIS > 3, or those with angio or operative intervention prior to VTEp were excluded. The study population was stratified according to timing of VTEp, early (<48 h) and late (>48 h). Outcomes included in-hospital mortality and VTE.

RESULTS

2752 patients were included in the study. Overall, 2007 patients (72.9%) received early VTEp, while 745 (27.1%) received late VTEp. LMWH was administered in 2349 (85.4%) and UH in 403 (14.6%). Late VTEp was associated with significantly higher incidence of VTE (4.3% vs. 2.2%, p = 0.004). Logistic regression identified late VTEp as an independent risk factor for VTE (OR 1.93, p = 0.009) and mortality (OR 4.03, p = 0.006). LMWH was an independent factor protective for both VTE and mortality (OR 0.373, p < 0.001, OR 0.266, p = 0.009, respectively).

CONCLUSION

In isolated severe pelvic fractures, early VTEp is independently associated with improved survival and fewer VTE. LMWH may be preferred over UH for this purpose.

Enoxaparin in the treatment of severe traumatic brain injury: A randomized clinical trial

Background:

Enoxaparin was shown to have a neuroprotective effect in animal models as well as a human study following traumatic brain injury. This study was conducted to assess the effect of enoxaparin on the clinical outcome of severe traumatic brain injury (TBI) and its safety.

Methods:

This study is a randomized double-blinded placebo-controlled trial. The inclusion criteria were age 16–70, a closed head injury, a postresuscitation Glasgow Coma Scale (GCS) between 5 and 8, and a latency time between the injury and entering the study of less than 5 h. The patients were randomized into enoxaparin and placebo groups. In the enoxaparin group, 0.5 mg/kg enoxaparin was injected subcutaneously every 6 h in six total doses. The two groups were compared for the occurrence of intracranial hematoma (ICH) and for clinical neurological outcome, assessed by the Glasgow Outcome Scale.

Results:

Twenty-seven patients were assigned to the placebo group and 26 to the enoxaparin group. The two groups were similar regarding baseline characteristics, including age, sex, postresuscitation GCS, and best motor response. The occurrence of new ICH or an ICH size increase was insignificantly more frequent in the enoxaparin group than the placebo group (26.9% vs. 7.4%, P = 0.076). The favorable outcome rate in the enoxaparin group was significantly higher than in the placebo group (57.7% vs. 25.9%, P = 0.019).

Conclusions:

This study showed that the early administration of enoxaparin could lead to favorable outcomes in severe TBI patients without significantly increasing cerebral hemorrhagic complications.

Heparin: The Silver Bullet of Aneurysmal Subarachnoid Hemorrhage?

Various neurological diseases have recently been associated with neuroinflammation and worsening outcomes. Subarachnoid hemorrhage has been shown to generate a potent neuroinflammatory response. Heparin is a potential effective anti-inflammatory agent to prevent initial injury as well as delayed neurological decline. Different mechanisms of action for heparin have been proposed including, but not limited to the binding and neutralization of oxyhemoglobin, decreased transcription and signal transduction of endothelin-1, inhibition of binding to vessel wall selectins and vascular leakage into the subarachnoid space as well as direct binding and neutralization of inflammatory molecules. With a reasonably safe side-effect profile, heparin has shown significant promise in small series in human studies of aneurysmal subarachnoid hemorrhage in decreasing both initial and delayed neurological injury. Further studies are needed to validate various neuroprotective features of heparin in subarachnoid hemorrhage as well as other disease states.

Early heparin administration after traumatic brain injury: Prolonged cognitive recovery associated with reduced cerebral edema and neutrophil sequestration

BACKGROUND

Early administration of unfractionated heparin (UFH) after traumatic brain injury (TBI) reduces early in vivo circulating leukocytes (LEUs) in peri-injury penumbral brain tissue, enhancing cognitive recovery 2 days after injury. It remains unclear how long this effect lasts and if this is related to persistently accumulating LEUs in penumbral brain tissue. We hypothesized that UFH reduces LEU brain tissue sequestration resulting in prolonged cognitive recovery.

METHODS

CD1 male mice underwent either TBI by controlled cortical impact (CCI) or sham craniotomy. Unfractionated heparin (75 or 225 U/kg) or vehicle was repeatedly administered after TBI. Neurologic function (Garcia Neurological Test [maximum score = 18]) and body weight loss ratios were evaluated at 24 hours to 96 hours after TBI. Brain and lung wet-to-dry ratios, hemoglobin levels, and brain LEU sequestration (Ly6G immunohistochemistry) were evaluated 96 hours postmortem. Analysis of variance with Bonferroni correction determined significance (p < 0.05).

RESULTS

Compared with untreated CCI animals (24 hours, 14.7 ± 1.0; 48 hours, 15.5 ± 0.7; 72 hours, 15.0 ± 0.8; 96 hours, 16.5 ± 0.9), UFH75 (24 hours, 16.0 ± 1.0, p < 0.01; 48 hours, 16.5 ± 0.7, p < 0.05; 72 hours, 17.1 ± 0.6, p < 0.01; 96 hours, 17.4 ± 0.7, p < 0.05) increased cognitive recovery throughout the entire observation period after TBI. At 48 hours, UFH225 significantly worsened body weight loss (10.2 ± 4.7%) as compared with uninjured animals (5.5 ± 2.9%, p < 0.05). Both UFH75 (60.8 ± 40.9 PMNs per high-power field [HPF], p < 0.05) and UFH225 (36.0 ± 17.6 PMNs/HPF, p < 0.01) significantly decreased brain neutrophil sequestration found in untreated CCI animals (124.2 ± 44.1 PMNs/HPF) 96 hours after TBI. Compared with untreated CCI animals (78.8 ± 0.8%), UFH75 (77.3 ± 0.6%, p = 0.04) reduced cerebral edema to uninjured levels (77.4 ± 0.6%, p = 0.04 vs. CCI). Only UFH225 (10.6 ± 1.2 g/dL) resulted in lower hemoglobin than in uninjured animals (13.0 ± 1.2 g/dL, p < 0.05).

CONCLUSIONS

Heparin after TBI reduces tissue LEU sequestration and edema in injured brain for up to 4 days. This is associated with persistent improved cognitive recovery, but only when low-dose UFH is given. Early administration of UFH following TBI may blunt LEU-related cerebral swelling and slow progression of secondary brain injury.

Unfractionated heparin versus low-molecular-weight heparin for venous thromboembolism prophylaxis in trauma

BACKGROUND

Venous thromboembolism (VTE) is a common complication in trauma patients. Pharmacologic prophylaxis is utilized in trauma patients to reduce their risk of a VTE event. The Eastern Association for the Surgery of Trauma guidelines recommend use of low-molecular-weight heparin (LMWH) as the preferred agent in these patients. However, there is literature suggesting that unfractionated heparin (UFH) is an acceptable, and less costly, alternative VTE prophylaxis agent with equivalent efficacy in trauma patients. We examined data from the Michigan Trauma Quality Improvement Program to perform a comparative effectiveness study of UFH versus LMWH on outcomes for trauma patients.

METHODS

We conducted an analysis of the Michigan Trauma Quality Improvement Program data from January 2012 to December 2014. The data set contains information on date, time, and drug type of the first dose of VTE prophylaxis. Thirty-seven thousand eight hundred sixty-eight patients from 23 hospitals were present with an Injury Severity Score of 5 or greater and hospitalization for more than 24 hours. Patients were excluded if they died within 24 hours or received no pharmacologic VTE prophylaxis or agents other than UFH or LMWH while admitted to the hospital. We compared patients receiving LMWH to those receiving UFH. Outcomes assessed were VTE event, pulmonary embolism, deep vein thrombosis, and mortality during hospitalization. We used a generalized estimating equation approach to fit population-averaged logistic regression models with the type of first dose of VTE prophylaxis as the independent variable. Unfractionated heparin was considered the reference value. Timing of the first dose of VTE prophylaxis was entered into the model in addition to standard covariates. Odds ratios were generated for each of the dependent variables of interest.

RESULTS

The analysis cohort consisted of 18,010 patients. Patients administered LMWH had a decreased risk of mortality (odds ratio, 0.64; confidence interval, 0.49-0.83), VTE (odds ratio, 0.67; confidence interval, 0.53-0.84), pulmonary embolism (odds ratio, 0.53; confidence interval, 0.35-0.79), and deep vein thrombosis (odds ratio, 0.73; confidence interval, 0.57-0.95) when compared with UFH following risk adjustment and accounting for hospital effect. The reduced risk of a VTE event for patients receiving LMWH was most pronounced for patients in the lower injury-severity categories.

CONCLUSIONS

In our examination of VTE prophylaxis drug effectiveness, LMWH was found to be superior to UFH in reducing the incidence of mortality and VTE events among trauma patients. Therefore, LMWH should be the preferred VTE prophylaxis agent for use in hospitalized trauma patients.

LEVEL OF EVIDENCE

Therapeutic, level III.

Unfractionated heparin after TBI reduces in vivo cerebrovascular inflammation, brain edema and accelerates cognitive recovery

BACKGROUND

Severe traumatic brain injury (TBI) may increase the risk of venous thromboembolic complications; however, early prevention with heparinoids is often withheld for its anticoagulant effect. New evidence suggests low molecular weight heparin reduces cerebral edema and improves neurological recovery after stroke and TBI, through blunting of cerebral leukocyte (LEU) recruitment. It remains unknown if unfractionated heparin (UFH) similarly affects brain inflammation and neurological recovery post-TBI. We hypothesized that UFH after TBI reduces cerebral edema by reducing LEU-mediated inflammation and improves neurological recovery.

METHODS

CD1 male mice underwent either TBI by controlled cortical impact (CCI) or sham craniotomy. UFH (75 U/kg or 225 U/kg) or vehicle (VEH, 0.9% saline) was administered 2, 11, 20, 27, and 34 hours after TBI. At 48 hours, pial intravital microscopy through a craniotomy was used to visualize live brain LEUs interacting with endothelium and microvascular fluorescein isothiocyanate-albumin leakage. Neurologic function (Garcia Neurological Test, GNT) and body weight loss ratios were evaluated 24 and 48 hours after TBI. Cerebral and lung wet-to-dry ratios were evaluated post mortem. ANOVA with Bonferroni correction was used to determine significance (p < 0.05).

RESULTS

Compared to positive controls (CCI), both UFH doses reduced post-TBI in vivo LEU rolling on endothelium, concurrent cerebrovascular albumin leakage, and ipsilateral cerebral water content after TBI. Additionally, only low dose UFH (75 U/kg) improved GNT at both 24 and 48 hours after TBI. High dose UFH (225 U/kg) significantly increased body weight loss above sham at 48 hours. Differences in lung water content and blood pressure between groups were not significant.

CONCLUSIONS

UFH after TBI reduces LEU recruitment, microvascular permeability, and brain edema to injured brain. Lower UFH doses concurrently improve neurological recovery whereas higher UFH may worsen functional recovery. Further study is needed to determine if this is caused by increased bleeding from injured brain with higher UFH doses.

Heparin and Heparin-Derivatives in Post-Subarachnoid Hemorrhage Brain Injury: A Multimodal Therapy for a Multimodal Disease

Pharmacologic efforts to improve outcomes following aneurysmal subarachnoid hemorrhage (aSAH) remain disappointing, likely owing to the complex nature of post-hemorrhage brain injury. Previous work suggests that heparin, due to the multimodal nature of its actions, reduces the incidence of clinical vasospasm and delayed cerebral ischemia that accompany the disease. This narrative review examines how heparin may mitigate the non-vasospastic pathological aspects of aSAH, particularly those related to neuroinflammation. Following a brief review of early brain injury in aSAH and heparin’s general pharmacology, we discuss potential mechanistic roles of heparin therapy in treating post-aSAH inflammatory injury. These roles include reducing ischemia-reperfusion injury, preventing leukocyte extravasation, modulating phagocyte activation, countering oxidative stress, and correcting blood-brain barrier dysfunction. Following a discussion of evidence to support these mechanistic roles, we provide a brief discussion of potential complications of heparin usage in aSAH. Our review suggests that heparin’s use in aSAH is not only safe, but effectively addresses a number of pathologies initiated by aSAH.

Dose-dependent neuroprotective effect of enoxaparin on cold-induced traumatic brain injury

Recent evidence exists that enoxaparin can reduce brain injury because of its anticoagulant activity. To investigate the potential therapeutic effect of enoxaparin on cold-induced traumatic brain injury, at 20 minutes after modeling, male BALB/c mouse models of cold-induced traumatic brain injury were intraperitoneally administered 3 and 10 mg/kg enoxaparin or isotonic saline solution. Twenty-four hours later, enoxaparin at 10 mg/kg greatly reduced infarct volume, decreased cell apoptosis in the cortex and obviously increased serum level of total antioxidant status. By contrast, administration of enoxaparin at 3 mg/kg did not lead to these changes. These findings suggest that enoxaparin exhibits neuroprotective effect on cold-induced traumatic brain injury in a dose-dependent manner.

Timing of Pharmacologic Venous Thromboembolism Prophylaxis in Severe Traumatic Brain Injury: A Propensity-Matched Cohort Study

BACKGROUND

Patients with severe traumatic brain injury (sTBI) are at high risk for developing venous thromboembolism (VTE). Nonetheless, pharmacologic VTE prophylaxis is often delayed out of concern for precipitating extension of intracranial hemorrhage (ICH). The purpose of this study was to compare the effectiveness of early vs late VTE prophylaxis in patients with sTBI, and to characterize the risk of subsequent ICH-related complication.

STUDY DESIGN

Adults with isolated sTBI (head Abbreviated Injury Scale score ≥3 and total Glasgow Coma Scale score ≤8) who received VTE prophylaxis with low-molecular-weight or unfractionated heparin were derived from the American College of Surgeons Trauma Quality Improvement Program (2012 to 2014). Patients were divided into EP (<72 hours) or LP (≥72 hours) groups. Propensity score matching was used to minimize selection bias. The primary end point was VTE (pulmonary embolism or deep vein thrombosis). Secondary outcomes were defined as late neurosurgical intervention (≥72 hours) or death.

RESULTS

We identified 3,634 patients with sTBI. Early prophylaxis was given in 43% of patients. Higher head injury severity, presence of ICH, and early neurosurgery were associated with late prophylaxis. Propensity score matching yielded a well-balanced cohort of 2,468 patients. Early prophylaxis was associated with lower rates of both pulmonary embolism (odds ratio = 0.48; 95% CI, 0.25-0.91) and deep vein thrombosis (odds ratio = 0.51; 95% CI, 0.36-0.72), but no increase in risk of late neurosurgical intervention or death.

CONCLUSIONS

In this observational study of patients with sTBI, early initiation of VTE prophylaxis was associated with decreased risk of pulmonary embolism and deep vein thrombosis, but no increase in risk of late neurosurgical intervention or death. Early prophylaxis may be safe and should be the goal for each patient in the context of appropriate risk stratification.