-
BMJ Military Health Aug 2023'Primary' blast injuries (PBIs) are caused by direct blast wave interaction with the human body, particularly affecting air-containing organs. With continued...
'Primary' blast injuries (PBIs) are caused by direct blast wave interaction with the human body, particularly affecting air-containing organs. With continued experimental focus on PBI mechanisms, recently on blast traumatic brain injury, meaningful test outcomes rely on appropriate simulated conditions. Selected PBI predictive criteria (grouped into those affecting the auditory system, pulmonary injuries and brain trauma) are combined and plotted to provide rationale for generating clinically relevant loading conditions. Using blast engineering theory, explosion characteristics including blast wave parameters and fireball dimensions were calculated for a range of charge masses assuming hemispherical surface detonations and compared with PBI criteria. While many experimental loading conditions are achievable, this analysis demonstrated limits that should be observed to ensure loading is clinically relevant, realistic and practical. For PBI outcomes sensitive only to blast overpressure, blast scaled distance was demonstrated to be a useful parameter for guiding experimental design as it permits flexibility for different experimental set-ups. This analysis revealed that blast waves should correspond to blast scaled distances of 1.75
Blast waves with positive phase durations (2-10 ms) are more practical to achieve through experimental approaches, while representing realistic threats such as improvised explosive devices (ie, 1-50 kg trinitrotoluene equivalent). These guidelines can be used by researchers to inform the design of appropriate blast loading conditions in PBI experimental investigations. Topics: Humans; Explosions; Blast Injuries; Brain Injuries, Traumatic
PubMed: 34035162
DOI: 10.1136/bmjmilitary-2021-001796 -
British Journal of Anaesthesia Aug 2014Trauma is the leading cause of death during the first four decades of life in the developed countries. Its haemodynamic response underpins the patient's initial ability... (Review)
Review
Trauma is the leading cause of death during the first four decades of life in the developed countries. Its haemodynamic response underpins the patient's initial ability to survive, and the response to treatment and subsequent morbidity and resolution. Trauma causes a number of insults including haemorrhage, tissue injury (nociception) and, predominantly, in military casualties, blast from explosions. This article discusses aspects of the haemodynamic responses to these insults and subsequent treatment. 'Simple' haemorrhage (blood loss without significant volume of tissue damage) causes a biphasic response: mean arterial blood pressure (MBP) is initially maintained by the baroreflex (tachycardia and increased vascular resistance, Phase 1), followed by a sudden decrease in MAP initiated by a second reflex (decrease in vascular resistance and bradycardia, Phase 2). Phase 2 may be protective. The response to tissue injury attenuates Phase 2 and may cause a deleterious haemodynamic redistribution that compromises blood flow to some vital organs. In contrast, thoracic blast exposure augments Phase 2 of the response to haemorrhage. However, hypoxaemia from lung injury limits the effectiveness of hypotensive resuscitation by augmenting the attendant shock state. An alternative strategy ('hybrid resuscitation') whereby tissue perfusion is increased after the first hour of hypotensive resuscitation by adopting a revised normotensive target may ameliorate these problems. Finally, morphine also attenuates Phase 2 of the response to haemorrhage in some, but not all, species and this is associated with poor outcome. The impact on human patients is currently unknown and is the subject of a current physiological investigation.
Topics: Analgesics, Opioid; Blast Injuries; Healthy Volunteers; Hemodynamics; Hemorrhage; Humans; Musculoskeletal System; Oxygen Consumption; Resuscitation; Wounds and Injuries
PubMed: 25038158
DOI: 10.1093/bja/aeu232 -
Journal of the Royal Army Medical Corps Feb 2019
Topics: Blast Injuries; Humans; Interdisciplinary Research; Military Medicine; Quality Improvement
PubMed: 29769370
DOI: 10.1136/jramc-2018-000968 -
Scientific Reports Oct 2020At present, there are no set guidelines establishing cumulative limits for blast exposure numbers and intensities in military personnel, in combat or training...
At present, there are no set guidelines establishing cumulative limits for blast exposure numbers and intensities in military personnel, in combat or training operations. The objective of the current study was to define lung injury, pathology, and associated behavioral changes from primary repeated blast lung injury under appropriate exposure conditions and combinations (i.e. blast overpressure (BOP) intensity and exposure frequency) using an advanced blast simulator. Male Sprague Dawley rats were exposed to BOP frontally and laterally at a pressure range of ~ 8.5-19 psi, for up to 30 daily exposures. The extent of lung injury was identified at 24 h following BOP by assessing the extent of surface hemorrhage/contusion, Hematoxylin and Eosin staining, and behavioral deficits with open field activity. Lung injury was mathematically modeled to define the military standard 1% lung injury threshold. Significant levels of histiocytosis and inflammation were observed in pressures ≥ 10 psi and orientation effects were observed at pressures ≥ 13 psi. Experimental data demonstrated ~ 8.5 psi is the threshold for hemorrhage/contusion, up to 30 exposures. Modeling the data predicted injury risk up to 50 exposures with intensity thresholds at 8 psi for front exposure and 6psi for side exposures, which needs to be validated further.
Topics: Animals; Blast Injuries; Disease Models, Animal; Explosions; Explosive Agents; Lung Injury; Male; Pressure; Rats, Sprague-Dawley; Risk; Time Factors
PubMed: 33024181
DOI: 10.1038/s41598-020-73643-7 -
Vision Research Sep 2021While chronic visual symptom complaints are common among Veterans with a history of mild traumatic brain injury (mTBI), research is still ongoing to characterize the...
While chronic visual symptom complaints are common among Veterans with a history of mild traumatic brain injury (mTBI), research is still ongoing to characterize the pattern of visual deficits that is most strongly associated with mTBI and specifically, the impact of blast-related mTBI on visual functioning. One area that has not been well explored is the potential impact of blast mTBI on refractive error. While myopic shifts have been documented following head injuries in civilian populations, posttraumatic myopic shifts have not been explored in participants with military mTBI. This study investigated the impact of blast mTBIs on a range of visual function measures including distance acuity and refractive error, in a well-characterized cohort of thirty-one Post-9/11 veterans for whom detailed clinical interviews regarding military and TBI history were available. Seventeen participants had a history of blast-related mTBI (blast mTBI + group) while 14 did not (blast mTBI- group). Results show an increased frequency of convergence insufficiency and myopia in the blast mTBI + group relative to the blast mTBI- group. Linear regression analyses further show that deficits in distance acuity and refractive error are associated with the number of blast mTBIs during military service but not the number of non-blast mTBIs or the number of lifetime non-blast TBIs and cannot be accounted for by PTSD. These results are consistent with long-lasting damage following blast mTBI to subcortical visual structures that support both vergence movements and the accommodative functions needed to see clearly objects at varying distances.
Topics: Afghan Campaign 2001-; Blast Injuries; Brain Concussion; Humans; Iraq War, 2003-2011; Myopia; Neuropsychological Tests; Ocular Motility Disorders; Stress Disorders, Post-Traumatic
PubMed: 34000559
DOI: 10.1016/j.visres.2021.04.004 -
The association between blast exposure and transdiagnostic health symptoms on systemic inflammation.Neuropsychopharmacology : Official... Aug 2022Chronic elevation of systemic inflammation is observed in a wide range of disorders including PTSD, depression, and traumatic brain injury. Although previous work has...
Chronic elevation of systemic inflammation is observed in a wide range of disorders including PTSD, depression, and traumatic brain injury. Although previous work has demonstrated a link between inflammation and various diagnoses separately, few studies have examined transdiagnostic symptoms and inflammation within the same model. The objective of this study was to examine relationships between psychiatric and health variables and systemic inflammation and to determine whether mild traumatic brain injury (mTBI) and/or exposure to blast munitions moderate these relationships. Confirmatory factor analysis in a large sample (N = 357) of post-9/11 Veterans demonstrated a good fit to a four-factor model reflecting traumatic stress, affective, somatic, and metabolic latent variables. Hierarchical regression models revealed that each of the latent variables were associated with higher levels of systemic inflammation. However, the strongest relationship with inflammation emerged among those who had both war-zone blast exposures and metabolic dysregulation, even after adjusting for mental health latent variables. Exploratory analyses showed that blast exposure was associated with metabolic dysregulation in a dose-response manner, with self-reported closer blast proximity associated with the greatest metabolic dysregulation. Together, these results provide a greater understanding of the types of symptoms most strongly associated with inflammation and underscore the importance of maintaining a healthy lifestyle to reduce the impact of obesity and other metabolic symptoms on future chronic disease in younger to middle-aged Veterans.
Topics: Afghan Campaign 2001-; Blast Injuries; Humans; Inflammation; Iraq War, 2003-2011; Middle Aged; Stress Disorders, Post-Traumatic; Veterans
PubMed: 34400776
DOI: 10.1038/s41386-021-01138-8 -
Biophysical Journal Oct 2019Toward the goal of understanding the pathophysiology of mild blast-induced traumatic brain injury and identifying the physical forces associated with the primary injury...
Toward the goal of understanding the pathophysiology of mild blast-induced traumatic brain injury and identifying the physical forces associated with the primary injury phase, we developed a system that couples a pneumatic blast to a microfluidic channel to precisely and reproducibly deliver shear transients to dissociated human central nervous system (CNS) cells, on a timescale comparable to an explosive blast but with minimal pressure transients. Using fluorescent beads, we have characterized the shear transients experienced by the cells and demonstrate that the system is capable of accurately and reproducibly delivering uniform shear transients with minimal pressure across the cell culture volume. This system is compatible with high-resolution, time-lapse optical microscopy. Using this system, we demonstrate that blast-like shear transients produced with minimal pressure transients and submillisecond rise times activate calcium responses in dissociated human CNS cultures. Cells respond with increased cytosolic free calcium to a threshold shear stress between 8 and 21 Pa; the propagation of this calcium response is a result of purinergic signaling. We propose that this system models, in vitro, the fundamental injury wave produced by shear forces consequent to blast shock waves passing through density inhomogeneity in human CNS cells.
Topics: Blast Injuries; Brain Injuries; Explosions; Humans; Lab-On-A-Chip Devices; Pressure; Shear Strength; Stress, Mechanical
PubMed: 31495447
DOI: 10.1016/j.bpj.2019.07.052 -
Acta Neuropathologica Communications Sep 2023Mild traumatic brain injury (mTBI) induced by low-intensity blast (LIB) is a serious health problem affecting military service members and veterans. Our previous reports...
Mild traumatic brain injury (mTBI) induced by low-intensity blast (LIB) is a serious health problem affecting military service members and veterans. Our previous reports using a single open-field LIB mouse model showed the absence of gross microscopic damage or necrosis in the brain, while transmission electron microscopy (TEM) identified ultrastructural abnormalities of myelin sheaths, mitochondria, and synapses. The neurovascular unit (NVU), an anatomical and functional system with multiple components, is vital for the regulation of cerebral blood flow and cellular interactions. In this study, we delineated ultrastructural abnormalities affecting the NVU in mice with LIB exposure quantitatively and qualitatively. Luminal constrictive irregularities were identified at 7 days post-injury (DPI) followed by dilation at 30 DPI along with degeneration of pericytes. Quantitative proteomic analysis identified significantly altered vasomotor-related proteins at 24 h post-injury. Endothelial cell, basement membrane and astrocyte end-foot swellings, as well as vacuole formations, occurred in LIB-exposed mice, indicating cellular edema. Structural abnormalities of tight junctions and astrocyte end-foot detachment from basement membranes were also noted. These ultrastructural findings demonstrate that LIB induces multiple-component NVU damage. Prevention of NVU damage may aid in identifying therapeutic targets to mitigate the effects of primary brain blast injury.
Topics: Animals; Mice; Proteomics; Blast Injuries; Brain Concussion; Arvicolinae; Basement Membrane; Brain Injuries
PubMed: 37674234
DOI: 10.1186/s40478-023-01636-4 -
The Journal of Surgical Research May 2023To establish a blast- and fragment-induced pelvic injury animal model in rabbits, observe its injury characteristics, and explore the effects of hemostatic resuscitation...
INTRODUCTION
To establish a blast- and fragment-induced pelvic injury animal model in rabbits, observe its injury characteristics, and explore the effects of hemostatic resuscitation combined with damage control surgery (DCS) with respect to this injury model.
METHODS
Forty-eight rabbits were randomly allocated to four groups: group A rabbits were subjected to pelvic injury, group B rabbits to pelvic injury + DCS, group C rabbits to pelvic injury + DCS + resuscitation with Hextend, and group D rabbits to pelvic injury + DCS + Hextend + hemostatic resuscitation with tranexamic acid, fibrinogen concentrate, and prothrombin complex concentrate. Simulated blast and fragment-induced pelvic injury was produced by a custom-made machine. We implemented CT scanning and necropsy to assess the injury state and calculated the coefficient of variation (CV) of the cumulative abbreviated injury scale (AIS) to assess the reproducibility of the animal model. Immediately after instrumentation (0 h), and 1 h, 2 h, 4 h, and 8 h after injury, blood samples were taken for laboratory tests.
RESULTS
We found that severe pelvic injury was produced with an AIS CV value of 10.32%, and the rabbits demonstrated severe physiologic impairment and coagulo-fibrinolytic derangements with high mortality. In rabbits of group D, however, physiologic and coagulo-fibrinolytic parameters were significantly enhanced with improved organ function and lowered mortality when compared with the other three groups.
CONCLUSIONS
We herein established in rabbits a blast- and fragment-induced pelvic injury animal model that exhibited high reproducibility, and we demonstrated that hemostatic resuscitation plus DCS was effective in improving the outcome.
Topics: Animals; Rabbits; Blast Injuries; Fibrinogen; Hemostasis; Hemostatics; Hydroxyethyl Starch Derivatives; Reproducibility of Results; Resuscitation
PubMed: 36680876
DOI: 10.1016/j.jss.2022.12.031 -
The Journal of Trauma and Acute Care... Aug 2022Improvised explosive devices have resulted in a unique polytrauma injury pattern termed dismounted complex blast injury (DCBI), which is frequent in the modern military...
BACKGROUND
Improvised explosive devices have resulted in a unique polytrauma injury pattern termed dismounted complex blast injury (DCBI), which is frequent in the modern military theater. Dismounted complex blast injury is characterized by extremity amputations, junctional vascular injury, and blast traumatic brain injury (bTBI). We developed a combat casualty relevant DCBI swine model, which combines hemorrhagic shock (HS) and tissue injury (TI) with a bTBI, to study interventions in this unique and devastating military injury pattern.
METHODS
A 50-kg male Yorkshire swine were randomized to the DCBI or SHAM group (instrumentation only). Those in the DCBI group were subjected to HS, TI, and bTBI. The blast injury was applied using a 55-psi shock tube wave. Tissue injury was created with bilateral open femur fractures. Hemorrhagic shock was induced by bleeding from femoral arteries to target pressure. A resuscitation protocol modified from the Tactical Combat Casualty Care guidelines simulated battlefield resuscitation for 240 minutes.
RESULTS
Eight swine underwent the DCBI model and five were allocated to the SHAM group. In the DCBI model the mean base excess achieved at the end of the HS shock was -8.57 ± 5.13 mmol·L -1 . A significant coagulopathy was detected in the DCBI model as measured by prothrombin time (15.8 seconds DCBI vs. 12.86 seconds SHAM; p = 0.02) and thromboelastography maximum amplitude (68.5 mm DCBI vs. 78.3 mm in SHAM; p = 0.0003). For the DCBI models, intracranial pressure (ICP) increased by a mean of 13 mm Hg, reaching a final ICP of 24 ± 7.7 mm Hg.
CONCLUSION
We created a reproducible large animal model to study the combined effects of severe HS, TI, and bTBI on coagulation and ICP in the setting of DCBI, with significant translational applications for the care of military warfighters. Within the 4-hour observational period, the swine developed a consistent coagulopathy with a concurrent brain injury evidenced by increasing ICP.
Topics: Animals; Blast Injuries; Blood Coagulation Disorders; Brain Injuries; Brain Injuries, Traumatic; Disease Models, Animal; Male; Resuscitation; Shock, Hemorrhagic; Swine
PubMed: 35545808
DOI: 10.1097/TA.0000000000003674