Experimental and computational investigations of the potential improvement in helmet blast-protection through the use of a polyurea-based external coating

2016 ◽  
Vol 12 (1) ◽  
pp. 33-72 ◽  
Author(s):  
M. Grujicic ◽  
S. Ramaswami ◽  
J. S. Snipes ◽  
R. Yavari ◽  
P. Dudt
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Computational Study ◽  
Element Analysis ◽  
Content Type ◽  
Ballistic Impacts ◽  
Blast Protection ◽  
Protection Efficacy ◽  
Potential Improvement ◽  
External Coating

Purpose – The design of the Advanced Combat Helmet (ACH) currently in use was optimized by its designers in order to attain maximum protection against ballistic impacts (fragments, shrapnel, etc.) and hard-surface/head collisions. Since traumatic brain injury experienced by a significant fraction of the soldiers returning from the recent conflicts is associated with their exposure to blast, the ACH should be redesigned in order to provide the necessary level of protection against blast loads. The paper aims to discuss this issue. Design/methodology/approach – In the present work, an augmentation of the ACH for improved blast protection is considered. This augmentation includes the use of a polyurea (a nano-segregated elastomeric copolymer) based ACH external coating. To demonstrate the efficacy of this approach, blast experiments are carried out on instrumented head-mannequins (without protection, protected using a standard ACH, and protected using an ACH augmented by a polyurea explosive-resistant coating (ERC)). These experimental efforts are complemented with the appropriate combined Eulerian/Lagrangian transient non-linear dynamics computational fluid/solid interaction finite-element analysis. Findings – The results obtained clearly demonstrated that the use of an ERC on an ACH affects (generally in a beneficial way) head-mannequin dynamic loading and kinematic response as quantified by the intracranial pressure, impulse, acceleration and jolt. Originality/value – To the authors’ knowledge, the present work is the first reported combined experimental/computational study of the blast-protection efficacy and the mild traumatic brain-injury mitigation potential of polyurea when used as an external coating on a helmet.

Improvement in head blast-protection via the use of polyurea-augmented advanced combat helmet

2016 ◽  
Vol 7 (4) ◽  
pp. 516-552 ◽  
Author(s):  
Mica Grujicic ◽  
S Ramaswami ◽  
Jennifer Snipes ◽  
Ramin Yavari ◽  
Philip Dudt
Keyword(s):  
Interaction Analysis ◽  
Computational Study ◽  
Specific Impulse ◽  
Blast Mitigation ◽  
Content Type ◽  
Ballistic Impacts ◽  
Internal Lining ◽  
Maximum Protection ◽  
Fluid Solid Interaction ◽  
External Coating

Purpose – The purpose of this paper is to optimize the design of the advanced combat helmet (ACH) currently in use, by its designers in order to attain maximum protection against ballistic impacts (fragments, shrapnel, etc.) and hard-surface/head collisions. Since traumatic brain injury experienced by a significant fraction of the soldiers returning from the recent conflicts is associated with their exposure to blast, the ACH should be redesigned in order to provide the necessary level of protection against blast loads. In the present work, augmentations of the ACH for improved blast protections are considered. These augmentations include the use of a polyurea (a nano-segregated elastomeric copolymer)-based ACH external coating/internal lining. Design/methodology/approach – To demonstrate the efficacy of this approach, instrumented (unprotected, standard-ACH-protected, and augmented-ACH-protected) head-mannequin blast experiments are carried out. These experimental efforts are complemented with the appropriate combined Eulerian/Lagrangian transient non-linear dynamics computational fluid/solid interaction analysis. Findings – The results obtained indicated that: when the extent of peak over-pressure reduction is used as a measure of the blast-mitigation effectiveness, polyurea-based augmentations do not noticeably improve, and sometimes slightly worsen, the performance of the standard ACH; when the extent of specific impulse reduction is used as a measure of the blast-mitigation effectiveness, application of the polyurea external coating to the standard ACH improves the blast-mitigation effectiveness of the helmet, particularly at shorter values of the charge-detonation standoff distance (SOD). At longer SODs, the effects of the polyurea-based ACH augmentations on the blast-mitigation efficacy of the standard ACH are inconclusive; and the use of the standard ACH significantly lowers the accelerations experienced by the skull and the intracranial matter. As far as the polyurea-based augmentations are concerned, only the internal lining at shorter SODs appears to yield additional reductions in the head accelerations. Originality/value – To the authors’ knowledge, the present work contains the first report of a combined experimental/computational study addressing the problem of blast-mitigation by polyurea-based augmentation of ACH.

Flushing in relation to a possible rise in intracranial pressure: documentation of an unusual clinical sign

2000 ◽  
Vol 92 (6) ◽  
pp. 1040-1044 ◽  
Author(s):  
Gregory W. Hornig
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Intracranial Pressure ◽  
Intraventricular Hemorrhage ◽  
Pneumococcal Meningitis ◽  
Clinical Importance ◽  
Neurological Deterioration ◽  
Content Type ◽  
Transient Nature ◽  
Fine Print

✓ This report documents clinical features in five children who developed transient reddening of the skin (epidermal flushing) in association with acute elevations in intracranial pressure (ICP). Four boys and one girl (ages 9–15 years) deteriorated acutely secondary to intracranial hypertension ranging from 30 to 80 mm Hg in the four documented cases. Two patients suffered from ventriculoperitoneal shunt malfunctions, one had diffuse cerebral edema secondary to traumatic brain injury, one was found to have pneumococcal meningitis and hydrocephalus, and one suffered an intraventricular hemorrhage and hydrocephalus intraoperatively. All patients were noted to have developed epidermal flushing involving either the upper chest, face, or arms during their period of neurological deterioration. The response was transient, typically lasting 5 to 15 minutes, and dissipated quickly. The flushing reaction is postulated to be a centrally mediated response to sudden elevations in ICP. Several potential mechanisms are discussed. Flushing has clinical importance because it may indicate significant elevations in ICP when it is associated with neurological deterioration. Because of its transient nature, the importance of epidermal flushing is often unrecognized; its presence confirms the need for urgent treatment.

Intracranial bone marrow transplantation after traumatic brain injury improving functional outcome in adult rats

2001 ◽  
Vol 94 (4) ◽  
pp. 589-595 ◽  
Author(s):  
Asim Mahmood ◽  
Dunyue Lu ◽  
Yi Li ◽  
Jae Li Chen ◽  
Michael Chopp
Keyword(s):  
Traumatic Brain Injury ◽  
Bone Marrow ◽  
Brain Injury ◽  
Motor Function ◽  
Glial Fibrillary Acid Protein ◽  
Protein Markers ◽  
Adult Rats ◽  
Content Type ◽  
The Impact ◽  
Fine Print

Object. The authors tested the hypothesis that intracranial bone marrow (BM) transplantation after traumatic brain injury (TBI) in rats provides therapeutic benefit. Methods. Sixty-six adult Wistar rats, weighing 275 to 350 g each, were used for the experiment. Bone marrow prelabeled with bromodeoxyuridine (BrdU) was harvested from tibias and femurs of healthy adult rats. Other animals were subjected to controlled cortical impact, and BM was injected adjacent to the contusion 24 hours after the impact. The animals were killed at 4, 7, 14, or 28 days after transplantation. Motor function was evaluated both before and after the injury by using the rotarod test. After the animals had been killed, brain sections were examined using hemotoxylin and eosin and immunohistochemical staining methods. Histological examination revealed that, after transplantation, BM cells survived, proliferated, and migrated toward the injury site. Some of the BrdU-labeled BM cells were reactive, with astrocytic (glial fibrillary acid protein) and neuronal (NeuN and microtubule-associated protein) markers. Transplanted BM expressed proteins phenotypical of intrinsic brain cells, that is, neurons and astrocytes. A statistically significant improvement in motor function in rats that underwent BM transplantation, compared with control rats, was detected at 14 and 28 days posttransplantation. Conclusions. On the basis of their findings, the authors assert that BM transplantation improves neurological outcome and that BM cells survive and express nerve cell proteins after TBI.

Cerebral tissue PO2 and SjvO2 changes during moderate hyperventilation in patients with severe traumatic brain injury

2002 ◽  
Vol 96 (1) ◽  
pp. 97-102 ◽  
Author(s):  
Roberto Imberti ◽  
Guido Bellinzona ◽  
Martin Langer
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Brain Tissue ◽  
Severe Traumatic Brain Injury ◽  
Cerebral Perfusion ◽  
Content Type ◽  
Secondary Damage ◽  
Tissue Po2 ◽  
Two Parameters ◽  
Fine Print

Object. The aim of this study was to investigate the effects of moderate hyperventilation on intracranial pressure (ICP), jugular venous oxygen saturation ([SjvO2], an index of global cerebral perfusion), and brain tissue PO2 (an index of local cerebral perfusion). Methods. Ninety-four tests consisting of 20-minute periods of moderate hyperventilation (27–32 mm Hg) were performed on different days in 36 patients with severe traumatic brain injury (Glasgow Coma Scale score ≤ 8). Moderate hyperventilation resulted in a significant reduction in average ICP, but in seven tests performed in five patients it was ineffective. The response of SjvO2 and brain tissue PO2 to CO2 changes was widely variable and unpredictable. After 20 minutes of moderate hyperventilation in most tests (79.8%), both SjvO2 and brain tissue PO2 values remained above the lower limits of normality (50% and 10 mm Hg, respectively). In contrast, in 15 tests performed in six patients (16.6% of the studied population) brain tissue PO2 decreased below 10 mm Hg although the corresponding SjvO2 values were greater than 50%. The reduction of brain tissue PO2 below 10 mm Hg was favored by the low prehyperventilation values (10 tests), higher CO2 reactivity, and, possibly, by lower prehyperventilation values of cerebral perfusion pressure. In five of those 15 tests, the prehyperventilation values of SjvO2 were greater than 70%, a condition of relative hyperemia. The SjvO2 decreased below 50% in four tests; the corresponding brain tissue PO2 values were less than 10 mm Hg in three of those tests, whereas in the fourth, the jugular venous O2 desaturation was not detected by brain tissue PO2. The analysis of the simultaneous relative changes (prehyperventilation — posthyperventilation) of SjvO2 and brain tissue PO2 showed that in most tests (75.5%) there was a reduction of both SjvO2 and brain tissue PO2. In two tests moderate hyperventilation resulted in an increase of both SjvO2 and brain tissue PO2. In the remaining 17 tests a redistribution of the cerebral blood flow was observed, leading to changes in SjvO2 and brain tissue PO2 in opposite directions. Conclusions. Hyperventilation, even if moderate, can frequently result in harmful local reductions of cerebral perfusion that cannot be detected by assessing SjvO2. Therefore, hyperventilation should be used with caution and should not be considered safe. This study confirms that SjvO2 and brain tissue PO2 are two parameters that provide complementary information on brain oxygenation that is useful to reduce the risk of secondary damage. Changes in SjvO2 and brain tissue PO2 in opposite directions indicate that data obtained from brain tissue PO2 monitoring cannot be extrapolated to evaluate the global cerebral perfusion.

Early and persistent impaired percent alpha variability on continuous electroencephalography monitoring as predictive of poor outcome after traumatic brain injury

2002 ◽  
Vol 97 (1) ◽  
pp. 84-92 ◽  
Author(s):  
Paul M. Vespa ◽  
W. John Boscardin ◽  
David A. Hovda ◽  
David L. McArthur ◽  
Marc R. Nuwer ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Eeg Monitoring ◽  
Content Type ◽  
Poor Outcome ◽  
Continuous Electroencephalography ◽  
Continuous Eeg ◽  
Continuous Eeg Monitoring ◽  
Severe Tbi ◽  
Fine Print

Object. Early prediction of outcomes in patients after they suffer traumatic brain injury (TBI) is often nonspecific and based on initial imaging and clinical findings alone, without direct physiological testing. Improved outcome prediction is desirable for ethical, social, and financial reasons. The goal of this study was to determine the usefulness of continuous electroencephalography (EEG) monitoring in determining prognosis early after TBI, while the patient is in the intensive care unit. Methods. The authors hypothesized that the reduced percentage of alpha variability (PAV) in continuous EEG tracings indicates a poor prognosis. Prospective continuous EEG monitoring was performed in 89 consecutive patients with moderate to severe TBI (Glasgow Coma Scale [GCS] Scores 3–12) from 0 to 10 days after injury. The PAV was calculated daily, and the time course and trends of the PAV were analyzed in comparison with the patient's Glasgow Outcome Scale (GOS) score at the time of discharge. In patients with GCS scores of 8 or lower, a PAV value of 0.1 or lower is highly predictive of a poor outcome or death (positive predictive value 86%). The determinant PAV value was obtained by Day 3 after injury. Persistent PAV values of 0.1 or lower over several days or worsening of the PAV to a value of 0.1 or lower indicated a high likelihood of poor outcome (GOS Scores 1 and 2). In comparison with the combination of traditional initial clinical indicators of outcome (GCS score, pupillary response to light, patient age, results of computerized tomography scanning, and early hypotension or hypoxemia), the early PAV value during the initial 3 days after injury independently improved prognostic ability (p < 0.01). Conclusions. Continuous EEG monitoring performed with particular attention paid to the PAV is a sensitive and specific method of prognosis that can indicate outcomes in patients with moderate to severe TBI within 3 days postinjury.

Association between elevated brain tissue glycerol levels and poor outcome following severe traumatic brain injury

2005 ◽  
Vol 103 (2) ◽  
pp. 233-238 ◽  
Author(s):  
Tobias Clausen ◽  
Oscar Luis Alves ◽  
Michael Reinert ◽  
Egon Doppenberg ◽  
Alois Zauner ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Brain Tissue ◽  
Severe Traumatic Brain Injury ◽  
Time Course ◽  
Glycerol Concentration ◽  
Significant Information ◽  
Content Type ◽  
Significant Difference ◽  
Fine Print

Object. Glycerol is considered to be a marker of cell membrane degradation and thus cellular lysis. Recently, it has become feasible to measure via microdialysis cerebral extracellular fluid (ECF) glycerol concentrations at the patient's bedside. Therefore the aim of this study was to investigate the ECF concentration and time course of glycerol after severe traumatic brain injury (TBI) and its relationship to patient outcome and other monitoring parameters. Methods. As soon as possible after injury for up to 4 days, 76 severely head-injured patients were monitored using a microdialysis probe (cerebral glycerol) and a Neurotrend sensor (brain tissue PO2) in uninjured brain tissue confirmed by computerized tomography scanning. The mean brain tissue glycerol concentration in all monitored patients decreased significantly from 206 ± 31 µmol/L on Day 1 to 9 ± 3 µmol/L on Day 4 after injury (p < 0.0001). Note, however, that there was no significant difference in the time course between patients with a favorable outcome (Glasgow Outcome Scale [GOS] Scores 4 and 5) and those with an unfavorable outcome (GOS Scores 1–3). Significantly increased glycerol concentrations were observed when brain tissue PO2 was less than 10 mm Hg or when cerebral perfusion pressure was less than 70 mm Hg. Conclusions. Based on results in the present study one can infer that microdialysate glycerol is a marker of severe tissue damage, as seen immediately after brain injury or during profound tissue hypoxia. Given that brain tissue glycerol levels do not yet add new clinically significant information, however, routine monitoring of this parameter following traumatic brain injury needs further validation.

Blast Response Characteristics for an Instrumented Helmet on a Skull-Brain Surrogate

2011 ◽  
Author(s):  
Matthew Ford ◽  
Kirth Simmonds ◽  
David Horner ◽  
John Gauvin ◽  
Amit Bagchi
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
High Velocity ◽  
Selection Process ◽  
Impact Response ◽  
Military Operations ◽  
Ballistic Impacts ◽  
Response Characteristics ◽  
Us Military ◽  
Blast Response

In current US Military operations, warfighters are frequently subjected to blast events, which can lead to traumatic brain injury (TBI). In response to this recent and increasingly prevalent threat, helmet systems must protect the head against high velocity, short duration overpressures in addition to blunt and ballistic impacts. Understanding the blast impact response characteristics of helmet systems may improve the design and selection process for headborne equipment and contribute to reducing blast-related brain injury.

scholarly journals Increased incidence and impact of nonconvulsive and convulsive seizures after traumatic brain injury as detected by continuous electroencephalographic monitoring

1999 ◽  
Vol 91 (5) ◽  
pp. 750-760 ◽  
Author(s):  
Paul M. Vespa ◽  
Marc R. Nuwer ◽  
Valeriy Nenov ◽  
Elisabeth Ronne-Engstrom ◽  
David A. Hovda ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Status Epilepticus ◽  
Brain Injury ◽  
Scale Score ◽  
Eeg Monitoring ◽  
Content Type ◽  
Continuous Eeg ◽  
Nonconvulsive Seizures ◽  
Continuous Eeg Monitoring ◽  
Fine Print

Object. The early pathophysiological features of traumatic brain injury observed in the intensive care unit (ICU) have been described in terms of altered cerebral blood flow, altered brain metabolism, and neurochemical excitotoxicity. Seizures occur in animal models of brain injury and in human brain injury. Previous studies of posttraumatic seizures in humans have been based principally on clinical observations without a systematic approach to electroencephalographic (EEG) recording of seizures. The purpose of this study was to determine prospectively the incidence of convulsive and nonconvulsive seizures by using continuous EEG monitoring in patients in the ICU during the initial 14 days postinjury.Methods. Ninety-four patients with moderate-to-severe brain injuries underwent continuous EEG monitoring beginning at admission to the ICU (mean delay 9.6 ± 5.4 hours) and extending up to 14 days postinjury. Convulsive and nonconvulsive seizures occurred in 21 (22%) of the 94 patients, with six of them displaying status epilepticus. In more than half of the patients (52%) the seizures were nonconvulsive and were diagnosed on the basis of EEG studies alone. All six patients with status epilepticus died, compared with a mortality rate of 24% (18 of 73) in the nonseizure group (p < 0.001). The patients with status epilepticus had a shorter mean length of stay (9.14 ± 5.9 days compared with 14 ± 9 days [t-test, p < 0.03]). Seizures occurred despite initiation of prophylactic phenytoin on admission to the emergency room, with maintenance at mean levels of 16.6 ± 2.8 mg/dl. No differences in key prognostic factors (such as the Glasgow Coma Scale score, early hypoxemia, early hypotension, or 1-month Glasgow Outcome Scale score) were found between the patients with seizures and those without.Conclusions. Seizures occur in more than one in five patients during the 1st week after moderate-to-severe brain injury and may play a role in the pathobiological conditions associated with brain injury.

Investigation of Cross-Species Scaling Methods for Traumatic Brain Injury Using Finite Element Analysis

2020 ◽  
Vol 37 (2) ◽  
pp. 410-422 ◽  
Author(s):  
Taotao Wu ◽  
Jacobo Antona-Makoshi ◽  
Ahmed Alshareef ◽  
J. Sebastian Giudice ◽  
Matthew B. Panzer
Keyword(s):  
Traumatic Brain Injury ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Brain Injury ◽  
Element Analysis ◽  
Scaling Methods
Sign in / Sign up

Export Citation Format

Share Document