scholarly journals Defining blast loading ‘zones of relevance’ for primary blast injury research: A consensus of injury criteria for idealised explosive scenarios

2021 ◽  
Author(s):  
Jack Denny ◽  
Alexander Dickinson ◽  
Genevieve Langdon
Keyword(s):  
Blast Wave ◽  
Blast Loading ◽  
Wave Interaction ◽  
Blast Injury ◽  
Blast Injuries ◽  
Loading Conditions ◽  
Primary Blast ◽  
Injury Criteria ◽  
The 1960S ◽  
Injury Research

Blast injuries remain a serious threat to defence and civilian populations around the world. ‘Primary’ blast injuries (PBIs) are caused by direct blast wave interaction with the human body, particularly affecting air-containing organs. Despite development of blast injury criteria since the 1960s, work to define blast loading conditions for safety limits, protective design and injury research has received relatively little attention. With a continued experimental focus on PBI mechanisms and idealised blast assumptions, meaningful test outcomes rely on appropriate simulated conditions. This paper critically evaluates existing predictive criteria for PBIs (grouped into those affecting the auditory system, pulmonary injuries and brain trauma) as a function of incident blast wave parameters, assuming idealised air blast scenarios. Analysis of the multi-injury criteria reveals new insights and understanding. It showed that blast conditions of relevance to realistic explosive threats are limited and they should be an important consideration in the design of clinical trials simulating blast injury. Zones of relevance for PBI research are proposed to guide experimental designs and compare future data. This work will prove valuable to blast protection engineers and clinical researchers seeking to determine blast loading conditions for safety limits, protective design requirements and injury investigations.

scholarly journals Guidelines to inform the generation of clinically relevant and realistic blast loading conditions for primary blast injury research

2021 ◽  
pp. bmjmilitary-2021-001796
Author(s):  
J W Denny ◽  
A S Dickinson ◽  
G S Langdon
Keyword(s):  
Blast Wave ◽  
Blast Loading ◽  
Wave Interaction ◽  
Blast Waves ◽  
Experimental Investigations ◽  
Loading Conditions ◽  
Primary Blast ◽  
Blast Overpressure ◽  
Engineering Theory ◽  
Blast Traumatic Brain Injury

‘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<Z<6.0 to generate loading conditions found outside the fireball and of clinical relevance to a range of PBIs. 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.

Pathophysiology of primary blast injury

2018 ◽  
Vol 165 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Jason E Smith ◽  
J Garner
Keyword(s):  
Blast Injury ◽  
Blast Injuries ◽  
Primary Blast ◽  
Front Door

The majority of patients injured in the recent conflicts in Iraq and Afghanistan were as a result of explosion, and terrorist incidents have brought blast injuries to the front door of many civilian hospitals that had not previously encountered such devastation. This article reviews the physics and pathophysiology of blast injury with particular relevance to the presentation and management of primary blast injury, which is the mechanism least familiar to most clinicians and which may cause devastating injury without externals signs.

scholarly journals Blast injury research models

2011 ◽  
Vol 366 (1562) ◽  
pp. 144-159 ◽  
Author(s):  
E. Kirkman ◽  
S. Watts ◽  
G. Cooper
Keyword(s):  
Significant Proportion ◽  
Surgical Care ◽  
Pressure Profile ◽  
Blast Injury ◽  
Supplemental Oxygen ◽  
Blast Injuries ◽  
Confined Spaces ◽  
Clinically Significant ◽  
Injury Research ◽  
New Strategies

Blast injuries are an increasing problem in both military and civilian practice. Primary blast injury to the lungs (blast lung) is found in a clinically significant proportion of casualties from explosions even in an open environment, and in a high proportion of severely injured casualties following explosions in confined spaces. Blast casualties also commonly suffer secondary and tertiary blast injuries resulting in significant blood loss. The presence of hypoxaemia owing to blast lung complicates the process of fluid resuscitation. Consequently, prolonged hypotensive resuscitation was found to be incompatible with survival after combined blast lung and haemorrhage. This article describes studies addressing new forward resuscitation strategies involving a hybrid blood pressure profile (initially hypotensive followed later by normotensive resuscitation) and the use of supplemental oxygen to increase survival and reduce physiological deterioration during prolonged resuscitation. Surprisingly, hypertonic saline dextran was found to be inferior to normal saline after combined blast injury and haemorrhage. New strategies have therefore been developed to address the needs of blast-injured casualties and are likely to be particularly useful under circumstances of enforced delayed evacuation to surgical care.

Primary Blast Brain Injury Mechanisms: Current Knowledge, Limitations, and Future Directions

2018 ◽  
Vol 140 (2) ◽  
Author(s):  
Elizabeth Fievisohn ◽  
Zachary Bailey ◽  
Allison Guettler ◽  
Pamela VandeVord
Keyword(s):  
Brain Injury ◽  
Current Knowledge ◽  
Future Research ◽  
Primary Blast ◽  
Injury Criteria ◽  
Blast Traumatic Brain Injury ◽  
Injury Mechanisms ◽  
Combination Of Theories ◽  
Injury Research

Mild blast traumatic brain injury (bTBI) accounts for the majority of brain injury in United States service members and other military personnel worldwide. The mechanisms of primary blast brain injury continue to be disputed with little evidence to support one or a combination of theories. The main hypotheses addressed in this review are blast wave transmission through the skull orifices, direct cranial transmission, skull flexure dynamics, thoracic surge, acceleration, and cavitation. Each possible mechanism is discussed using available literature with the goal of focusing research efforts to address the limitations and challenges that exist in blast injury research. Multiple mechanisms may contribute to the pathology of bTBI and could be dependent on magnitudes and orientation to blast exposure. Further focused biomechanical investigation with cadaver, in vivo, and finite element models would advance our knowledge of bTBI mechanisms. In addition, this understanding could guide future research and contribute to the greater goal of developing relevant injury criteria and mandates to protect our soldiers on the battlefield.

Guidelines for using animal models in blast injury research

2018 ◽  
Vol 165 (1) ◽  
pp. 38-40 ◽  
Author(s):  
Sarah Watts ◽  
E Kirkman ◽  
D Bieler ◽  
S Bjarnason ◽  
A Franke ◽  
...  
Keyword(s):  
Animal Models ◽  
Blast Injury ◽  
Research Community ◽  
Living Systems ◽  
Blast Injuries ◽  
Complex Phenomenon ◽  
Injury Mechanisms ◽  
Health Factors ◽  
Research Task ◽  
Injury Research

Blast injury is a very complex phenomenon and frequently results in multiple injuries. One method to investigate the consequences of blast injuries is with the use of living systems (animal models). The use of animals allows the examination and evaluation of injury mechanisms in a more controlled manner, allowing variables such as primary or secondary blast injury for example, to be isolated and manipulated as required. To ensure a degree of standardisation across the blast research community a set of guidelines which helps researchers navigate challenges of modelling blast injuries in animals is required. This paper describes the guidelines for Using Animal Models in Blast Injury Research developed by the NATO Health Factors and Medicine (HFM) Research Task Group 234.

Response of Post-Mortem Human Head Under Primary Blast Loading Conditions: Effect of Blast Overpressures

2013 ◽  
Author(s):  
Shailesh Ganpule ◽  
Robert Salzar ◽  
Namas Chandra
Keyword(s):  
Brain Injury ◽  
Blast Loading ◽  
Human Head ◽  
Severe Injury ◽  
Post Mortem ◽  
Loading Conditions ◽  
Primary Blast ◽  
Blast Overpressure ◽  
Moderate Traumatic Brain Injury ◽  
The Brain

Blast induced neurotrauma (BINT), and posttraumatic stress disorder (PTSD) are identified as the “signature injuries” of recent conflicts in Iraq and Afghanistan. The occurrence of mild to moderate traumatic brain injury (TBI) in blasts is controversial in the medical and scientific communities because the manifesting symptoms occur without visible injuries. Whether the primary blast waves alone can cause TBI is still an open question, and this work is aimed to address this issue. We hypothesize that if a significant level of intracranial pressure (ICP) pulse occurs within the brain parenchyma when the head is subjected to pure primary blast, then blast induced TBI is likely to occur. In order to test this hypothesis, three post mortem human heads are subjected to simulated primary blast loading conditions of varying intensities (70 kPa, 140 kPa and 200 kPa) at the Trauma Mechanics Research Facility (TMRF), University of Nebraska-Lincoln. The specimens are placed inside the 711 mm × 711 mm square shock tube at a section where known profiles of incident primary blast (Friedlander waveform in this case) are obtained. These profiles correspond to specific field conditions (explosive strength and stand-off distance). The specimen is filled with a brain simulant prior to experiments. ICPs, surface pressures, and surface strains are measured at 11 different locations on each post mortem human head. A total of 27 experiments are included in the analysis. Experimental results show that significant levels of ICP occur throughout the brain simulant. The maximum peak ICP is measured at the coup site (nearest to the blast) and gradually decreases towards the countercoup site. When the incident blast intensity is increased, there is a statistically significant increase in the peak ICP and total impulse (p<0.05). Even after five decades of research, the brain injury threshold values for blunt impact cases are based on limited experiments and extensive numerical simulations; these are still evolving for sports-related concussion injuries. Ward in 1980 suggested that no brain injury will occur when the ICP<173 kPa, moderate to severe injury will occur when 173 kPa<ICP<235 kPa and severe injury will occur when ICP>235 kPa for blunt impacts. Based on these criteria, no injury will occur at incident blast overpressure level of 70 kPa, moderate to severe injuries will occur at 140 kPa and severe head injury will occur at the incident blast overpressure intensity of 200 kPa. However, more work is needed to confirm this finding since peak ICP alone may not be sufficient to predict the injury outcome.

Primary Blast Injury

2018 ◽  
pp. 313-317
Author(s):  
Leslie V. Simon
Keyword(s):  
Brain Injury ◽  
Soft Tissue ◽  
Soft Tissue Injuries ◽  
Blast Injury ◽  
Injury Pattern ◽  
Blast Injuries ◽  
Pulmonary Injury ◽  
Primary Blast ◽  
Gastrointestinal Injury ◽  
Air Interface

This case illustrates the classic injury pattern seen in primary blast injury. Primary blast injury, caused only by high-order explosives, is the result of the blast wave’s compressive effect on tissue. Effects are greatest at the tissue-air interface. Ear damage is the most common and pulmonary injury is the most lethal. Gastrointestinal injury and brain injury are also common. Traumatic amputations due to primary blast injury were extremely rare in survivors prior to Operations Iraqi and Enduring Freedom. Primary blast injury is usually associated with secondary, tertiary, and quaternary blast injuries. Blast victims require a meticulous approach because the dramatic nature of the obvious soft tissue injuries may distract even experienced trauma providers from focusing on more lethal occult injuries.

Blast-Induced Neurotrauma: Characterizing the Blast Wave Impact and Tissue Deformation

2010 ◽  
Author(s):  
Jian Gao ◽  
Sean Connell ◽  
Riyi Shi ◽  
Jun Chen
Keyword(s):  
Blast Wave ◽  
High Speed ◽  
Surface Deformation ◽  
Tissue Sample ◽  
Blast Injury ◽  
Spinal Cord Tissue ◽  
Temporal Development ◽  
Wave Impact ◽  
Primary Blast ◽  
Blast Induced Neurotrauma

Primary blast injury, caused by exposure to the primary pressure wave emitted from explosive ordnance, is a common trauma associated with modern warfare activities. The central nervous system is particularly vulnerable to primary blast injury, which is responsible for many of the war related casualties and mortalities. An ex vivo model system is developed to introduce a blast wave, generated from a shock tube, directly to spinal cord tissue sample. A high-speed shadowgraphy is utilized to visualize the development of the blast wave and its interaction with the tissue samples. The surface deformation of the tissues is also measured for the analysis of internal stress and possible damage occurred in the tissue sample. Understanding the temporal development of the blast-tissue interaction provides valuable input for characterizing and modeling blast-induced neurotrauma. Particularly, tracking the sample surface deformation over time provides realistic boundary conditions for numerically simulating the injury and understanding the temporal development of stress.

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