Intravascular coagulation: a major secondary insult in nonfatal traumatic brain injury

Treatment of severe coagulopathy after gunshot injury to the head using recombinant activated factor VII

PURPOSE

Patients with severe penetrating head injury often have a coagulopathy that is difficult to correct. In this report, we describe 3 such patients who were treated with activated factor VII (FVIIa) to stop ongoing hemorrhage that was refractory to conventional treatment.

SUBJECTS AND METHODS

We treated 3 patients with severe head injury secondary to gunshot wounds to the head. All 3 patients had ongoing bleeding secondary to a severe consumptive coagulopathy that was refractory to treatment with fresh frozen plasma, platelets, and cryoprecipitate. Recombinant FVIIa was then administered to achieve hemostasis.

RESULTS

Administration of FVIIa (90-120 microg/kg) was successful in rapidly achieving hemostasis and correcting abnormal laboratory parameters indicative of coagulopathy in all patients. Although all 3 patients died, control of bleeding made organ donation possible in 2 patients.

CONCLUSION

In patients with a severe head injury and coagulopathy, use of FVIIa may help in correction of coagulopathy and decrease transfusion requirements. In patients where ongoing bleeding precludes the declaration of brain death, the use of this agent might help in achieving hemodynamic stability and preserve the possibility of organ donation. The ethical implications of using FVIIa in this situation are discussed.

Apo E genotype not associated with intravascular coagulation in traumatic brain injury

There is considerable evidence linking both genotype and coagulopathy to vascular complications of traumatic brain injury (TBI) and other cerebral insults. The authors explored a possible connection between the apolipoprotein E (Apo E) genotype, coagulopathy and intravascular microthombosis (IMT) in TBI. The predicted association was not confirmed.

Acute Subdural Hematoma: New Model Delineation and Effects of Coagulation Inhibitors

OBJECTIVE

To develop a highly reproducible rat model and behavioral tests for acute subdural hematoma (ASDH) and to investigate the role of intravascular coagulation and thrombin in the pathogenesis of brain injury in this model.

METHODS

A new method was implemented to inject 200 microl of autologous blood subdurally in rats. Immunohistochemistry was used to investigate intravascular fibrin deposition and thrombin levels in the cortex underlying the ASDH. Effectiveness of systemic heparin, argatroban, or ginkgolide B treatment was determined by histological lesion volume, number of occluded microvessels, and neurological deficits. Neurological deficits were monitored for 7 days after ASDH by use of forelimb placing, forelimb use asymmetry, and corner turn tests.

RESULTS

Consistent brain damage and sensorimotor deficits were observed in all animals with ASDH. Histological analysis demonstrated occluded microvessels and enlarged perivascular spaces in the underlying cortex starting 1 hour after hematoma induction. Fibrin and thrombin immunoreactivity were increased in the lesioned cortical parenchyma at 4 and 24 hours. However, no intravascular fibrin deposition was detected. Heparin induced hemorrhagic transformation in the cortical lesion and did not attenuate microvessel occlusion. Argatroban and ginkgolide B did not induce hemorrhage but failed to improve microvessel occlusion, lesion volume, and neurological deficits.

CONCLUSION

Intravascular coagulation and thrombin are not the major mediators of brain damage after ASDH. The model and behavioral tests presented in this study can be used to investigate other putative mechanisms of injury and to test future therapeutic interventions in ASDH.

The influence of the peptide NAP on Mac-1-deficient mice following closed head injury

A single administration of the neuroprotective peptide NAP was previously shown to protect against death associated with closed head injury (CHI) and enhance recovery of the surviving mice. The protective effect was accompanied by down-regulation of the relative mRNA content of the complement receptor 3 (Mac-1, a marker for inflammation) as measured about a month after the injury. In contrast, the mRNA transcripts for activity-dependent neuroprotective protein (ADNP, the NAP containing protein) were shown to increase 29 days post CHI in the injured hemisphere of Mac-1 expressing mice. The present study was set out to investigate: (1) are Mac-1-deficient mice less susceptible to the adverse outcome of traumatic head injury; (2) does NAP treatment affect Mac-1-deficient mice subjected to head injury; and (3) is Mac-1 expression associated with ADNP expression. Results showed that (1) Mac-1-deficient mice were partially protected against death associated with severe head injury as compared to Mac-1 expressing mice. (2) Significant protection against death was observed in NAP-treated mice and an increase in recovery was observed in the NAP-treated Mac-1 mice 4 weeks after injury. (3) ADNP expression did not change in the Mac-1-deficient mice following head injury. Our working hypothesis is that a month following injury, gene expression in the injured brain is altered and competing proteins are expressed such as Mac-1 that is associated with inflammation and ADNP that is associated with neuroprotection. Obviously, this plasticity in gene expression is intimately interwoven with the genetic background of the animal. NAP treatment tilts the balance toward neuroprotection.

Multimodal early onset stimulation combined with enriched environment is associated with reduced CNS lesion volume and enhanced reversal of neuromotor dysfunction after traumatic brain injury in rats

This study was designed to determine whether exposure to multimodal early onset stimulation (MEOS) combined with environmental enrichment (EE) after traumatic brain injury (TBI) would improve neurological recovery and to elucidate its morphological correlates. Male Sprague-Dawley rats were subjected to lateral fluid percussion (LFP) brain injury or to sham operation. After LFP, one-third of the animals (injured and sham) were placed under conditions of standard housing (SH), one-third were kept in EE only, and one-third received EE + MEOS. Assessment of neuromotor function 24 h post-injury using a standardized composite neuroscore test revealed an identical pattern of neurological impairment in all animals subjected to LFP. Neuromotor dysfunction in SH animals remained on a similar level throughout the experiment, while improvements were noted in both other groups 7 days post-injury (dpi). On 15 dpi, reversal of neuromotor dysfunction was significantly better in EE + MEOS animals vs. SH- and EE-only groups. In parallel, the comparison of lesion volume in EE + MEOS- vs. EE-only vs. SH rats revealed that animals exposed to EE + MEOS had consistently the lowest values (mm3, mean +/- SD; n = 6 rats in each group) as measured in serial brain sections immunostained for neuron-specific enolase (5.2 +/- 3.4 < or = 5.5 +/- 4.1 < 9.5 +/- 1.9), caspase 3-active/C3A (5.9 +/- 4.0 < or = 6.4 +/- 3.9 < 10.3 +/- 1.8) and glial fibrillary acidic protein (6.0 +/- 3.4 < or = 6.5 +/- 4.3 < 10.7 +/- 1.2). This first report on the effect of EE + MEOS treatment strongly indicates that the combined exposure reduces CNS scar formation and reverses neuromotor deficits after TBI in rats.

Subsequent Development of Thrombocytopenia and Coagulopathy in Moderate and Severe Head Injury: Support for Serial Laboratory Examination

BACKGROUND

Patients with moderate and severe traumatic brain injury (TBI) are at risk for secondary brain insults such as thrombocytopenia and coagulopathy. This study assessed the development of thrombocytopenia and coagulopathy at admission and within the subsequent 72 hours after TBI.

METHODS

Blunt trauma patients with moderate or severe TBI and an extracranial Abbreviated Injury Scale score less than 3 were reviewed. Data collection included initial and subsequent prothrombin time, partial thromboplastin time, and platelet values.

RESULTS

On initial evaluation, thrombocytopenia was present in 14% and coagulopathy in 21% of patients. By the third day, thrombocytopenia and coagulopathy increased to 46% and 41%, respectively. Of patients who died, 67% had thrombocytopenia and 62% had coagulopathy.

CONCLUSION

Patients with moderate and severe TBI are at risk for thrombocytopenia and coagulopathy, not only at admission but also on subsequent laboratory examination. Repeat laboratory evaluation is warranted even if initial results are normal in this population.

Atorvastatin reduction of intravascular thrombosis, increase in cerebral microvascular patency and integrity, and enhancement of spatial learning in rats subjected to traumatic brain injury

OBJECT

Atorvastatin, a beta-hydroxy-beta-methylglutaryl coenzyme A reductase inhibitor, has pleiotropic effects, such as promoting angiogenesis, increasing fibrinolysis, and reducing inflammatory responses, and has shown promise in enhancing recovery in animals with traumatic brain injury (TBI) and stroke. The authors tested the effect of atorvastatin on vascular changes after TBI.

METHODS

Male Wistar rats subjected to controlled cortical impact injury were perfused at different time points with fluorescein isothiocyanate (FITC)--conjugated dextran 1 minute before being killed. Spatial memory function had been measured using a Morris Water Maze test at various points before and after TBI. The temporal profile of intravascular thrombosis and vascular changes was measured on brain tissue sections by using a microcomputer imaging device and a laser confocal microscopy. The study revealed the following results. 1) Vessels in the lesion boundary zone and hippocampal CA3 region showed a variety of damage, morphological alterations, reduced perfusion, and intraluminal microthrombin formation. 2) Atorvastatin enhanced FITC-dextran perfusion of vessels and reduced intravascular coagulation. 3) Atorvastatin promoted the restoration of spatial memory function.

CONCLUSIONS

These results indicated that atorvastatin warrants investigation as a potential therapeutic drug for TBI.

Delayed Thrombosis after Traumatic Brain Injury in Rats

Secondary thrombosis may contribute to cerebral ischemia caused by traumatic brain injury (TBI). In this study, we sought to investigate the temporal and spatial profiles of intravascular thrombosis and to evaluate the effect of atorvastatin, a beta-hydroxy-beta-methylglutaryl coenzyme-A (HMG-CoA) reductase inhibitor, on thrombosis after TBI. Young male Wistar rats weighing 350-400 g were subjected to controlled cortical impact injury, and were sacrificed at 1 and 4 h, and 1, 3, 8, and 15 days after TBI (5 rats/time point), respectively. For the evaluation of the effects of atorvastatin on intravascular thrombosis, rats were subjected to TBI, and subsequently atorvastatin (1 mg/kg) was orally administered starting 1 day after TBI and then daily until sacrifice at 3, 8, and 15 days after TBI (5 rats/time point). Before sacrifice of animals, blood was withdrawn and employed for the measurement of von Willibrand factor and platelet activity using enzyme-linked immunoabsorbant assay (ELISA). Brain tissues were prepared for histological analysis. The data show that (1) delayed thrombosis is present in the lesion boundary zone and in the hippocampal CA3 region, starting at 1-4 h, peaking at 1-3 days, and then declining at 8 and 15 days after TBI; (2) intravascular thrombosis also occurs in the other areas of cortex, striatum, and corpus callosum, but with a scattered distribution; (3) delayed thrombi are composed of platelets, fibrin, and vWF; and (4) reduction of the plasma vWF level and platelet activity by atorvastatin decreases delayed thrombosis after TBI. These data suggest that atorvastatin reduces intravascular thrombosis attributed to hemostatic disturbances caused by TBI.

Altered NO function contributes to impairment of uPA and tPA cerebrovasodilation after brain injury

Urokinase (uPA) and tissue plasminogen activator (tPA) are serine proteases implicated in fibrinolysis, but their role in the regulation of the cerebrovascular response to brain trauma has not been investigated. This study was designed to (1) characterize the cerebrovascular activity of uPA and tPA, (2) investigate the role of nitric oxide (NO) in uPA and tPA vascular activity, and (3) characterize the effect of fluid percussion brain injury (FPI) on vascular responses to uPA and tPA. The closed cranial window technique in chloralose anesthetized newborn pigs was used to measure pial artery diameter and collect CSF for radioimmunoassay (RIA) of cGMP concentration. Topical uPA (10(-9), 10(-7) M) elicited pial artery dilation that was blunted by the NO synthase inhibitor, L-NNA (10(-6) M) (8 +/- 1% and 13 +/- 1 vs. 3 +/- 1% and 7 +/- 2%, respectively). Vasodilation in response to uPA was associated with an increase in CSF cGMP concentration (645 +/- 20, 865 +/- 39 and 1088 +/- 33 fmol/mL cGMP for control, uPA 10(-9), 10(-7) M, respectively). Similar data were obtained for tPA. Pial artery dilation to uPA was blunted following FPI (7 +/- 1% and 12 +/- 1% vs. 3 +/- 1% and 6 +/- 1%, respectively), while uPA-associated release of cGMP was blocked (677 +/- 45, 909 +/- 53, and 1110 +/- 55 vs. 283 +/- 10, 316 +/- 18, and 333 +/- 26 fmol/mL for control, uPA 10(-9), 10(-7) M before and after FPI, respectively). Similar data were obtained for tPA. These data show that uPA and tPA produce pial artery dilation in an NO-dependent manner. FPI blunted uPA and tPA induced pial artery dilation as well as the associated release of cGMP. These data suggest therefore that altered NO function contributes to the impairment of uPA and tPA cerebrovasodilation after brain injury.

Factor VIIa for Correction of Traumatic Coagulopathy

INTRODUCTION

Activated factor VIIa (FVIIa) was developed to treat hemophiliacs with high-titer antibodies to factor VIII. FVIIa initiates thrombin formation by binding with exposed tissue factor. Anecdotal reports have described the utility of FVIIa in correcting coagulopathy from trauma, but no large series exists. We present our experience with 81 coagulopathic trauma patients treated using FVIIa in years 2001-2003, compared with "control" patients matched from the trauma registry from the same time period.

METHODS

Use of FVIIa was restricted to active hemorrhage with clinical coagulopathy. We recorded the cause of coagulopathy, dose of FVIIa administered, effect on clinical coagulation, pertinent laboratory values, length of stay, number and type of blood products administered, and patient outcome. For the same time period we also examined outcomes in coagulopathic patients who did not receive FVIIa.

RESULTS

Causes of coagulopathy were diverse, and included acute traumatic hemorrhage (46 patients), traumatic brain injury (20), warfarin use (9), congenital Factor VII deficiency (2), and other acquired hematologic defects (4). Coagulopathy was reversed in 61/81 cases (75%), with an associated reduction in PT from 19.6 to 10.8 (p=0.000018). 34 patients (42%) survived to hospital discharge (20/46 traumatic hemorrhage, 5/20 TBI, 4/9 on warfarin, 2/2 factor deficient, 3/4 other). Patients died from irreversible shock, multiple organ system failure, or traumatic brain injury. FVIIa patients had a higher mortality than coagulopathic controls matched by specific anatomic injuries, admission lactate value, and predicted probability of survival. Only a group identified by all three characteristics had a similar mortality to the FVIIa cohort, but the number of patients that could be matched this way was too small to be meaningful.

CONCLUSION

FVIIa therapy lead to an immediate reduction in coagulopathic hemorrhage in most cases, accompanied by a significant improvement in laboratory measures. Application of FVIIa as a therapy of last resort makes the identification of equivalent control patients difficult. Use of FVIIa should be considered for any patient with coagulopathic hemorrhage in which surgically-accessible bleeding has been controlled. Prospective trials of FVIIa in patients with traumatic coagulopathy are strongly indicated, and should focus on appropriate patient selection and the dose and timing of therapy.

Association between intravascular microthrombosis and cerebral ischemia in traumatic brain injury

OBJECTIVE

To determine the association between traumatic cerebral ischemia and intravascular thrombosis, a common finding after traumatic brain injury (TBI).

METHODS

We reviewed samples of the frontal cortex and hippocampus from individuals who had sustained a fatal TBI. Sections stained with hematoxylin and eosin were reviewed and rated for severity of selective neuronal necrosis (SNN). Because intravascular fibrin microthrombi may lyse within a few days of TBI, we restricted our analysis to patients who had died within 48 hours of injury. Medical records in all cases were reviewed to rule out severe or prolonged hypotension or hypoxemia. Eleven patients with severe or global SNN were compared with 11 patients in whom SNN was mild or absent. Slides adjacent to the hematoxylin and eosin sections were stained with an immunofluorescent antibody to antithrombin III and were reviewed for intravascular microthrombosis. The number of microthrombi on each slide was counted by an investigator blinded to the hematoxylin and eosin findings, and density of intravascular microthrombi was calculated.

RESULTS

Intravascular microthrombi were noted in every section, excluding control (non-TBI) brain tissue. However, the density of microthrombi varied with the degree of SNN. We found a highly significant difference in the mean density of microthrombi between patients with severe SNN (7.74 +/- 3.7/cm(2)) and those with little or no SNN (2.58 +/- 1.0/cm(2)). Furthermore, a good correlation was noted between the location of intravascular microthrombi and that of SNN.

CONCLUSION

These data support a strong link between intravascular microthrombosis and neuronal death after brain trauma in humans and may have important implications for new therapeutic approaches.

Traumatic brain injury

PURPOSE OF REVIEW

Management of the patient with traumatic brain injury is a rapidly advancing field, characterized in recent years by an improved understanding of intracranial pathophysiology and ways in which outcomes can be improved. Many traditional therapies, such as fluid restriction and hyperventilation, have been called into question and are no longer recommended. Other proposed therapies, such as deliberate hypothermia, remain controversial. This detailed review of the recent literature helps the reader come to an understanding of current scientific and evidence-based practices in this area, with emphasis on those therapies most likely to be of use to the practicing intensivist.

RECENT FINDINGS

High-quality care of the traumatic brain injury patient demands the integrated activities of a number of different medical and nursing specialties. The best outcomes today are achieved by those systems that are able to focus as a team on the collective goal of minimizing secondary brain injury, and the respiratory therapist adjusting the patient's mechanical ventilation may be just as important to this effort as the attending neurosurgeon. Although the search for new diagnostic, prognostic, and therapeutic modalities continues (many of the more promising of which are reviewed in this article), it is clear that there exists no "silver bullet" therapy that will help all patients. Instead, it is the systematic integration and application of many small advances that will ultimately lead to better outcomes.

SUMMARY

Some issues in traumatic brain injury have now been resolved, and specific recommendations can be made. Fluid therapy directed toward a euvolemic state is now universally recommended, for example, as is the role of intracranial pressure monitoring. Other areas, such as the use of hypertonic saline, remain controversial. In both cases the authors have made an effort to cite the most recent literature, so that readers can draw their own conclusions from the original source material.

Responses of posttraumatic pericontusional cerebral blood flow and blood volume to an increase in cerebral perfusion pressure

In and around traumatic contusions, cerebral blood flow (CBF) is often near or below the threshold for ischemia. Increasing cerebral perfusion pressure (CPP) in patients with head injuries may improve CBF in these regions. However, the pericontusional response to this intervention has not been studied. Using positron emission tomography (PET), we have quantified the response to an increase in CPP in and around contusions in 18 contusions in 18 patients. Regional CBF and cerebral blood volume (CBV) were measured with PET at CPPs of 70 and 90 mmHg using norepinephrine to control CPP. Based upon computed tomography, regions of interest (ROIs) were placed as two concentric ellipsoids, each of 1-cm width, around the core of the contusions. Measurements were compared with a control ROI in tissue with normal anatomic appearance. Baseline CBF and CBV increased significantly with increasing distance from the core of the lesion. The increase in CPP led to small increases in CBF in all ROIs except the core. The largest absolute CBF increase was found in the control ROI. Relative CBF increases did not differ between ROIs so that ischemic areas remained ischemic. Pericontusional oedema on computed tomography was associated with lower absolute values of CBF and CBV but did not differ from nonoedematous tissue in the relative response to CPP elevation.