Blast injuries: biophysics, pathophysiology and management principles

Characteristics of injuries during the 2006 Lebanon conflict: a three-center retrospective study of survivors, 16 years after the conflict

Background

Armed conflict injury is a growing public health concern, particularly in regions like the Middle East and North Africa (MENA). The protracted conflicts and political unrest in this region have led to a substantial number of injuries. Despite this, there is still limited understanding of the specific injury patterns stemming from conflicts, such as the 2006 Lebanon conflict. This study aimed to assess the characteristics and burdens of injuries resulting from this conflict, which occurred 16 years prior to this research.

Methods

This retrospective study analyzed data of individuals affected by the 2006 Lebanon conflict, across three tertiary care centers. Demographics, injuries, complications, injury management, and hospitalization expenses were extracted from medical records and analyzed using SPSS version 29.0. Categorical variables were presented as counts and proportions, and continuous variables as mean ± standard deviation (SD). Hospital comparisons utilized chi-square or Fisher's exact tests for categorical variables, and one-way ANOVAs for continuous variables. Analysis was conducted from September to November 2023.

Results

Across three hospitals, 341 patients were studied, comprising 73.6% males and 26.4% females. Among them, a notable proportion (57.3% males and 34.1% females) fell within the 18-39 age range. Children and adolescents under 18 years accounted for 15.9% of males and 25.9% of females. Blast-related injuries predominated, with 24.5% resulting from direct damage caused by explosive parts and 33.3% from blast wave forces. Extremity trauma occurred in 49.0% of patients, and head/neck trauma in 24.9%. Common injuries, including penetrating, musculoskeletal, and traumatic brain injuries affected 34.9%, 31.1, and 10.0% of patients, respectively. Wound repair, fracture treatment, and debridement were the most performed procedures on 15.5, 13.5 and 9.7% of the patients, respectively. The total cost of care was USD 692,711, largely covered by the Ministry of Public Health (95.9%).

Conclusion

Conflict-related injuries significantly contribute to the global burden of disease. Therefore, there is a pressing need to improve national guidelines to prioritize life-threatening cases and potential long-term disabilities. Furthermore, enhancing electronic registry systems to collect clinical data on injured patients is essential for conducting research and better understanding the needs of conflict casualties.

High risk and low prevalence diseases: Blast injuries

INTRODUCTION

Blast injury is a unique condition that carries a high rate of morbidity and mortality, often with mixed penetrating and blunt injuries.

OBJECTIVE

This review highlights the pearls and pitfalls of blast injuries, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence.

DISCUSSION

Explosions may impact multiple organ systems through several mechanisms. Patients with suspected blast injury and multisystem trauma require a systematic evaluation and resuscitation, as well as investigation for injuries specific to blast injuries. Blast injuries most commonly affect air-filled organs but can also result in severe cardiac and brain injury. Understanding blast injury patterns and presentations is essential to avoid misdiagnosis and balance treatment of competing interests of patients with polytrauma. Management of blast victims can also be further complicated by burns, crush injury, resource limitation, and wound infection. Given the significant morbidity and mortality associated with blast injury, identification of various injury patterns and appropriate management are essential.

CONCLUSIONS

An understanding of blast injuries can assist emergency clinicians in diagnosing and managing this potentially deadly disease.

Beirut massive blast explosion: A unique injury pattern of the wounded population

INTRODUCTION

On August 4, 2020, a massive explosion of a warehouse holding 2,700 metric tons of ammonium nitrate took place in the port of Beirut, Lebanon. This incident, which is considered as one of the largest industrial disasters lead to the death of at least 220 people and more than 6000 injuries. Hospitals near the blast were damaged significantly which made it difficult to treat injured patients. The objective of this study is to report the epidemiology and characteristics of the injuries and their initial management that could be useful for healthcare workers and policymakers in case of a similar massive accident in the future.

MATERIALS AND METHODS

A retrospective study was conducted. All charts of patients admitted to the emergency room and outpatient clinics on the day of the blast and during the following 2 weeks were thoroughly reviewed. Due to initial chaos during triage, direct phone contact with patients was utilized in certain situations to confirm their identity or for further information. All acute injuries were recorded based on the region, severity, degree of emergency, initial and later management, type of injured organs, and surgical procedures.

RESULTS

A total of 159 patients presented to our facility. 153 patients presented to the ER on the same day of the blast. The mean age was 47.07 years and around 60% of the patients were males (n = 93). Most of the patients presented either from zone 1 (n = 67, 42%) or zone 3 (n = 68, 43%). The majority of injuries were secondary injuries due to glass (n = 131, 82.3%), with the head (34%) and upper extremities (31.2%) being most commonly affected. A total of 94 patients (62.6%) underwent a type of imaging and 64 patients (40.2%) had at least one surgery performed during their hospitalization in which 71% of the surgeries being related to the limbs.

CONCLUSION

This study demonstrated a unique injury pattern due to this type of blast. Injuries were mostly due to glass shrapnel. Contrary to bomb blasts, most injuries were located in the head and upper extremities rather than on the lower extremities.

Injury scoring systems for blast injuries: a narrative review

Injury scoring systems can be used for triaging, predicting morbidity and mortality, and prognosis in mass casualty incidents. Recent conflicts and civilian incidents have highlighted the unique nature of blast injuries, exposing deficiencies in current scoring systems. Here, we classify and describe deficiencies with current systems used for blast injury. Although current scoring systems highlight survival trends for populations, there are several major limitations. The reliable prediction of mortality on an individual basis is inaccurate. Other limitations include the saturation effect (where scoring systems are unable to discriminate between high injury score individuals), the effect of the overall injury burden, lack of precision in discriminating between mechanisms of injury, and a lack of data underpinning scoring system coefficients. Other factors influence outcomes, including the level of healthcare and the delay between injury and presentation. We recommend that a new score incorporates the severity of injuries with the mechanism of blast injury. This may include refined or additional codes, severity scores, or both, being added to the Abbreviated Injury Scale for high-frequency, blast-specific injuries; weighting for body regions associated with a higher risk for death; and blast-specific trauma coefficients. Finally, the saturation effect (maximum value) should be removed, which would enable the classification of more severe constellations of injury. An early accurate assessment of blast injury may improve management of mass casualty incidents.

Biomechanical Analysis of Head Subjected to Blast Waves and the Role of Combat Protective Headgear Under Blast Loading: A Review

Blast-induced traumatic brain injury (bTBI) is a rising health concern of soldiers deployed in modern-day military conflicts. For bTBI, blast wave loading is a cause, and damage incurred to brain tissue is the effect. There are several proposed mechanisms for the bTBI, such as direct cranial entry, skull flexure, thoracic compression, blast-induced acceleration, and cavitation that are not mutually exclusive. So the cause-effect relationship is not straightforward. The efficiency of protective headgears against blast waves is relatively unknown as compared with other threats. Proper knowledge about standard problem space, underlying mechanisms, blast reconstruction techniques, and biomechanical models are essential for protective headgear design and evaluation. Various researchers from cross disciplines analyze bTBI from different perspectives. From the biomedical perspective, the physiological response, neuropathology, injury scales, and even the molecular level and cellular level changes incurred during injury are essential. From a combat protective gear designer perspective, the spatial and temporal variation of mechanical correlates of brain injury such as surface overpressure, acceleration, tissue-level stresses, and strains are essential. This paper outlines the key inferences from bTBI studies that are essential in the protective headgear design context.

Terrorist attacks: common injuries and initial surgical management

Terrorism-related incidents and shootings that involve the use of war weapons and explosives are associated with gunshot and blast injuries. Despite the perceived threat of terrorism, these incidents and injuries are rare in Germany. For this reason, healthcare providers are unlikely to have a full understanding of the special aspects of managing these types of injuries. Until a clear and complete picture of the situation is available after a terrorist or shooter incident, tactical and strategic approaches to the clinical management of the injured must be tailored to circumstances that have the potential to overwhelm resources temporarily. Hospitals providing initial care must be aware that the first patients who are taken to medical facilities will present with uncontrollable bleeding from injuries to the trunk and body cavities. To improve the outcome of these patients in extremis, the aim of the index surgery is to stop the bleeding and control the contamination. Unlike damage control surgery, which is tailored to the patient's condition, tactical abbreviated surgical care (TASC) is first and foremost adapted to the overall situation. Once the patients are stabilised and all information on the situation is available, the surgical management and reconstruction of gunshot and blast injuries can follow the principles of damage control (DC) and definitive early total care (ETC). The purpose of this article is to provide an overview of the pathophysiology of gunshot and blast injuries, wound ballistics, and the approach and procedures of successful surgical management.

Blast injury of the hand related to warfare explosive devices: experience from the French Military Health Service

INTRODUCTION

The objective was to report on the experience of the French Army Health Service in the management of blast injury of the hands related to warfare explosive devices.

METHODS

A retrospective study was conducted in the Percy Military Hospital (role 4 medical treatment facility) among French soldiers who presented with a combat-related blast injury of the hand between 2002 and 2018. The functional result was assessed by the disabilities of the arm, shoulder and hand (DASH) and the Orthotics and Prosthetics User Survey (OPUS, upper extremity functional status) scores. Proximal amputations (PAs) and distal amputations (DAs) were distinguished for the analysis.

RESULTS

Fifteen patients with a mean age of 31±8 years were included. They totalised 20 blasted hands. There were 16 traumatic amputations: 8 in each of the PA and DA groups. Twelve patients had additional injuries, four of which were polytraumatic. Skin closure time and flap use were higher in the DA group. Only one thumb reconstruction was performed. At a mean follow-up of 6.5±4 years, the number of amputees wearing a prosthesis was higher in the PA group. The mean DASH and OPUS scores were 35.5%±24.0% and 64.0%±19.0%, respectively, with no difference between the two groups.

CONCLUSION

The severity of hand blasts related to warfare explosive devices requires the systematic application of damage control surgery. PAs are frequent and secondary reconstruction options are limited. The functional result is poor and similar between proximal and distal amputees.

In Situ Crosslinking Bionanocomposite Hydrogels with Potential for Wound Healing Applications

In situ forming hydrogels are a class of biomaterials that can fulfil a variety of important biomedically relevant functions and hold promise for the emerging field of patient-specific treatments (e.g., cell therapy, drug delivery). Here we report the results of our investigations on the generation of in situ forming hydrogels with potential for wound healing applications (e.g., complex blast injuries). The combination of polysaccharides that were oxidized to display aldehydes, amine displaying chitosan and nanostructured ZnO yields in situ forming bionanocomposite hydrogels. The physicochemical properties of the components, their cytotoxicity towards HaCat cells and the in vitro release of zinc ions on synthetic skin were studied. The in situ gel formation process was complete within minutes, the components were non-toxic towards HaCat cells at functional levels, Zn²⁺ was released from the gels, and such materials may facilitate wound healing.

Blast-Induced Cholesteatomas After Spontaneous Tympanic Membrane Healing

OBJECTIVES

To characterize blast-induced cholesteatomas (BIC) in terms of symptoms, presentation, and location within the middle ear cleft (MEC).

DESIGN

A search for all English language articles in "MEDLINE" via "PubMed" and "Google Scholar" was conducted.

RESULTS

A total of 67 ears with BIC were included. Fifty-eight ears in which the traumatic perforation failed to spontaneously close were excluded, leaving seven case reports (eight patients, nine ears) for statistical analysis. Time between blast exposure to spontaneous tympanic membrane (TM) closure was 16 days to 10 months. Time between blast exposure and cholesteatoma diagnosis was 5 months to 4 years. The cholesteatomas were diagnosed due to symptoms in two ears, as asymptomatic finding on physical examination in one ear and as asymptomatic finding in axial imaging in three ears.

CONCLUSIONS

BICs can develop behind intact tympanic membrane or along with TM perforation. Based on the current review, when a TM perforation and spontaneous healing were documented, after blast exposure, MRI scan is an integral component of the follow-up. The optimal timing for MRI performance after blast exposure, is yet to be identified.

Simulation of blast lung injury induced by shock waves of five distances based on finite element modeling of a three-dimensional rat

Blast lung injury (BLI) caused by both military and civilian explosions has become the main cause of death for blast injury patients. By building three-dimensional (3D) models of rat explosion regions, we simulated the surface pressure of the skin and lung. The pressure distributions were performed at 5 distances from the detonation center to the center of the rat. When the distances were 40 cm, 50 cm, 60 cm, 70 cm and 80 cm, the maximum pressure of the body surface were 634.77kPa, 362.46kPa, 248.11kPa, 182.13kPa and 109.29kPa and the surfaces lung pressure ranges were 928–2916 Pa, 733–2254 Pa, 488–1236 Pa, 357–1189 Pa and 314–992 Pa. After setting 6 virtual points placed on the surface of each lung lobe model, simulated pressure measurement and corresponding pathological autopsies were then conducted to validate the accuracy of the modeling. For the both sides of the lung, when the distance were 40 cm, 50 cm and 60 cm, the Pearson’s values showed strong correlations. When the distances were 70 cm and 80 cm, the Pearson’s values showed weak linear correlations. This computational simulation provided dynamic anatomy as well as functional and biomechanical information.

Blast injures to the thorax

One out of 10 of military casualties and 6-9 out of 10 civilian victims of terror incidents suffer pulmonary blast injuries when the attackers use explosives as weapon. No specific therapy exists for the primary, shock-wave injury to the lung. The treatment protocols are based on mechanical ventilation, intensive therapy and supportive care. Secondary and tertiary blast structural injuries to the thorax require damage control surgery, dominated by pleural space management (drainage) and haemorrhage control (thoracotomy if needed). Parenchyma resection of irreversibly destroyed lung is rarely needed, and non-anatomical resections are to be preferred. Delayed chest wall reconstruction follows haemodynamic stabilisation and completion of demarcation process. Blast injury to the chest requires a multidisciplinary approach, where the outcome is strongly influenced by the concomitant injuries.

The First Aid and Hospital Treatment of Gunshot and Blast Injuries

BACKGROUND

When gunshot and blast injuries affect only a single person, first aid can always be delivered in conformity with the relevant guidelines. In contrast, when there is a dynamic casualty situation affecting many persons, such as after a terrorist attack, treatment may need to be focused on immediately life-threatening complications.

METHODS

This review is based on pertinent publications retrieved by a selective search in Medline and on the authors' clinical experience.

RESULTS

In a mass-casualty event, all initial measures are directed toward the survival of the greatest possible number of patients, in accordance with the concept of "tactical abbreviated surgical care." Typical complications such as airway obstruction, tension pneumothorax, and hemorrhage must be treated within the first 10 minutes. Patients with bleeding into body cavities or from the trunk must be given priority in transport; hemorrhage from the limbs can be adequately stabilized with a tourniquet. In-hospital care must often be oriented to the principles of "damage control surgery," with the highest priority assigned to the treatment of life-threatening conditions such as hemodynamic instability, penetrating wounds, or overt coagulopathy. The main considerations in initial surgical stabilization are control of bleeding, control of contamination and lavage, avoidance of further consequences of injury, and prevention of ischemia. Depending on the resources available, a transition can be made afterward to individualized treatment.

CONCLUSION

In mass-casualty events and special casualty situations, mortality can be lowered by treating immediately life-threatening complications as rapidly as possible. This includes the early identification of patients with lifethreatening hemorrhage. Advance preparation for the management of a masscasualty event is advisable so that the outcome can be as favorable as possible for all of the injured in special or tactical casualty situations.

Vestibular Injury After Low-Intensity Blast Exposure

The increased use of close range explosives has led to a higher incidence of exposure to blast-related head trauma. Exposure to primary blast waves is a significant cause of morbidity and mortality. Active service members and civilians who have experienced blast waves report high rates of vestibular dysfunction, such as vertigo, oscillopsia, imbalance, and dizziness. Accumulating evidence suggests that exposure to blast-wave trauma produces damage to both the peripheral and central vestibular system; similar to previous findings that blast exposure results in damage to auditory receptors. In this study, mice were exposed to a 63 kPa peak blast-wave over pressure and were examined for vestibular receptor damage as well as behavioral assays to identify vestibular dysfunction. We observed perforations to the tympanic membrane in all blast animals. We also observed significant loss of stereocilia on hair cells in the cristae and macule up to 1 month after blast-wave exposure; damage that is likely permanent. Significant reductions in the ability to perform the righting reflex and balance on a rotating rod that lasted several weeks after blast exposure were prominent behavioral effects. We also observed a significant reduction in horizontal vestibuloocular reflex gain and phase lags in the eye movement responses that lasted many weeks following a single blast exposure event. OKN responses were absent immediately following blast exposure, but began to return after several weeks’ recovery. These results show that blast-wave exposure can lead to peripheral vestibular damage (possibly central deficits as well) and provides some insight into causes of vestibular dysfunction in blast-trauma victims.

Surgical Management of the Recent Orbital War Injury

Maxillofacial trauma affects sensitive and essential functions for the human being such as smell, breathing, talking, and the most importantly the sight. Trauma to the orbit may cause a vision loss especially if this trauma yields a high kinetic energy like that encountered during wars. The purpose of the study was to evaluate the surgical outcomes of the orbital war trauma, enriching the literature with the experience of the authors in this field. A total of 16 patients were injured, evacuated, and managed, between June 2014 and June 2017, from the fight between the Iraqi army and the Islamic State of Iraq and Syria (ISIS) in different areas of Iraq. Two-stage protocol was adopted, that is debridement and reconstruction. There were 14 military patients and 2 civilians. The cause of trauma was either bullet or shrapnel from an explosion. In the battlefield, delayed evacuation of the casualties led to increase the morbidity and mortality. Wearing a protective shield over the eye during the war along with fast evacuation highly improved the survival rates.

Blast injury prevalence in skeletal remains: Are there differences between Bosnian war samples and documented combat-related deaths?

Court cases at the International Criminal Tribunal for the Former Yugoslavia (ICTY) have seen questions raised about the recognition and causes of blast-related trauma and the relationship to human rights abuses or combat. During trials, defence teams argued that trauma was combat related and prosecutors argued that trauma was related to executions. We compared a sample of 81 cases (males between 18 and 75) from a Bosnian mass grave investigation linked to the Kravica warehouse killings to published combat-related blast injury data from World War One, Vietnam, Northern Ireland, the first Gulf War, Operation Iraqi Freedom and Afghanistan. We also compared blast fracture injuries from Bosnia to blast fracture injuries sustained in bombings of buildings in two non-combat 'civilian' examples; the Oklahoma City and Birmingham pub bombings. A Chi-squared statistic with a Holm-Bonferroni correction assessed differences between prevalence of blast-related fractures in various body regions, where data were comparable. We found statistically significant differences between the Bosnian and combat contexts. We noted differences in the prevalence of head, torso, vertebral area, and limbs trauma, with a general trend for higher levels of more widespread trauma in the Bosnian sample. We noted that the pattern of trauma in the Bosnian cases resembled the pattern from the bombing in buildings civilian contexts. Variation in trauma patterns can be attributed to the influence of protective armour; the context of the environment; and the type of munition and its injuring mechanism. Blast fracture injuries sustained in the Bosnian sample showed patterns consistent with a lack of body armour, blast effects on people standing in enclosed buildings and the use of explosive munitions.

Identification and management of inverted or everted edges of traumatic tympanic membrane perforations

Introduction

Most of traumatic tympanic membrane perforations have inverted or everted edges, however, the effects of inverted and everted edges on the spontaneous healing of the eardrum remain controversial.

Objective

We investigated the influence of inverted or everted edges on the spontaneous healing of traumatic tympanic membrane perforations.

Methods

The clinical records of patients with a traumatic tympanic membrane perforations who met the study criteria were retrieved and categorized into two groups, based on whether the eardrum was inverted or everted. The features along the edge of each inverted or everted eardrum were described using 30° and 70° endoscopes.

Results

In total, 196 patients (196 ears) met the inclusion criteria; of these, 148 had inverted or everted eardrums while 48 did not. Of the 148 patients with inverted or everted eardrums, the perforation edges were everted in 77 patients, inverted in 44 patients, drooping in 17 patients, and both inverted and everted in 10 patients. The perforation shape was triangular in 18.9% of patients, sector-shaped in 11.5%, kidney-shaped in 14.2%, ovoid in 20.3%, and irregularly shaped in 35.1% of patients. The difference was not significant between the with and without inverted/everted eardrum edges groups in terms of the closure rate or closure time. Similarly, the difference was not significant between the with and without edge approximation groups in terms of the closure rate or closure time at the end of the 12-month follow-up period.

Conclusion

This study suggests that endoscopic inspection can clearly identify inverted/everted eardrum edges using 30° and 70° endoscopes. The edge is glossy in inverted/everted eardrums, whereas the edge is rough and irregular in non-inverted/everted cases. The inverted/everted eardrums gradually became necrotic, but this did not affect the healing process. Additionally, edge approximation did not improve the healing outcome of traumatic tympanic membrane perforations.

[Approach to liver, spleen and pancreatic injuries including damage control surgery of terrorist attacks]

BACKGROUND

Terrorist attacks have outreached to Europe with more and more attacks on civilians. Derived from war surgery experience and from lessons learned from major incidents, it seems mandatory for every surgeon to improve understanding of the special circumstances of trauma following a terrorist attack and its' management.

METHOD

A short literature review is followed by outlining the damage control surgery (DCS) principle for each organ system with practical comments from the perspective of a specialized hepatobiliary (HPB) surgery unit.

CONCLUSION

Every surgeon has to become familiar with the new entities of blast injuries and terrorist attack trauma. This concerns not only the medical treatment but also tailoring surgical treatment with a view to a lack of critical resources under these circumstances. For liver and pancreatic trauma, simple treatment strategies are a key to success.

Assessing the Collective Dynamics of Motile Cilia in Cultures of Human Airway Cells by Multiscale DDM

The technique of differential dynamic microscopy is extended here, showing that it can provide a powerful and objective method of video analysis for optical microscopy videos of in vitro samples of live human bronchial epithelial ciliated cells. These cells are multiciliated, with motile cilia that play key physiological roles. It is shown that the ciliary beat frequency can be recovered to match conventional analysis, but in a fully automated fashion. Furthermore, it is shown that the properties of spatial and temporal coherence of cilia beat can be recovered and distinguished, and that if a collective traveling wave (the metachronal wave) is present, this has a distinct signature and its wavelength and direction can be measured.

[Civilian blast injuries: an underestimated problem? : Results of a retrospective analysis of the TraumaRegister DGU®]

BACKGROUND

Blast injuries are a rare cause of potentially life-threatening injuries in Germany. During the past 30 years such injuries were seldom the cause of mass casualties, therefore, knowledge and skills in dealing with this type of injury are not very extensive.

MATERIAL AND METHODS

A retrospective identification of all patients in the TraumaRegister DGU® of the German Trauma Society (TR-DGU) who sustained blast injuries between January 1993 and November 2012 was carried out. The study involved a descriptive characterization of the collective as well as three additional collectives. The arithmetic mean, standard deviation and 95 % confidence interval of the arithmetic mean for different demographic parameters and figures for prehospital and in-hospital settings were calculated. A computation of prognostic scores, such as the Revised Injury Severity Classification (RISC) and the updated version RISC II (TR-DGU-Project-ID 2012-035) was performed.

RESULTS

A total of 137 patients with blast injuries could be identified in the dataset of the TR-DGU. Of the patients 90 % were male and 43 % were transported by the helicopter emergency service (HEMS) to the various trauma centres. The severely injured collective with a mean injury severity scale (ISS) of 18.0 (ISS ≥ 16 = 52 %) had stable vital signs. In none of the cases was it necessary to perform on-site emergency surgery but a very high proportion of patients (59 %) had to be surgically treated before admittance to the intensive care unit (ICU). Of the patients 27 % had severe soft tissue injuries with an Abbreviated Injury Scale (AIS) ≥ 3 and 90 % of these injuries were burns. The 24 h in-hospital fatality was very low (3 %) but the stay in the ICU tended to be longer than for other types of injury (mean 5.5 ventilation days and 10.7 days in the intensive care unit). Organ failure occurred in 36 % of the cases, multiorgan failure in 29 % and septic events in 14 %. Of the patients 16 % were transferred to another hospital during the first 48 h. The RISC and the updated RISC II tended to underestimate the severity of injuries and mortality (10.2 % vs. 6.8 % and 10.7 % vs. 7.5 %, respectively) and the trauma associated severe hemorrhage (TASH) score underestimated the probability for transfusion of more than 10 units of packed red blood cells (5.0 % vs. 12.5 %).

CONCLUSION

This article generates several hypotheses, which should be confirmed with additional investigations. Until then it has to be concluded that patients who suffer from accidental blast injuries in the civilian setting (excluding military operations and terrorist attacks) show a combination of classical severe trauma with blunt and penetrating injuries and additionally a high proportion of severe burns (combined thermomechanical injury). They stay longer in the ICU than other trauma patients and suffer more complications, such as sepsis and multiorgan failure. Established scores, such as RISC, RISC II and TASH tend to underestimate the severity of the underlying trauma.

Shock tubes and blast injury modeling

Explosive blast injury has become the most prevalent injury in recent military conflicts and terrorist attacks. The magnitude of this kind of polytrauma is complex due to the basic physics of blast and the surrounding environments. Therefore, development of stable, reproducible and controllable animal model using an ideal blast simulation device is the key of blast injury research. The present review addresses the modeling of blast injury and applications of shock tubes.

Blast Injuries: From Improvised Explosive Device Blasts to the Boston Marathon Bombing

Although most trauma centers have experience with the imaging and management of gunshot wounds, in most regions blast wounds such as the ones encountered in terrorist attacks with the use of improvised explosive devices (IEDs) are infrequently encountered outside the battlefield. As global terrorism becomes a greater concern, it is important that radiologists, particularly those working in urban trauma centers, be aware of the mechanisms of injury and the spectrum of primary, secondary, tertiary, and quaternary blast injury patterns. Primary blast injuries are caused by barotrauma from the initial increased pressure of the explosive detonation and the rarefaction of the atmosphere immediately afterward. Secondary blast injuries are caused by debris carried by the blast wind and most often result in penetrating trauma from small shrapnel. Tertiary blast injuries are caused by the physical displacement of the victim and the wide variety of blunt or penetrating trauma sustained as a result of the patient impacting immovable objects such as surrounding cars, walls, or fences. Quaternary blast injuries include all other injuries, such as burns, crush injuries, and inhalational injuries. Radiography is considered the initial imaging modality for assessment of shrapnel and fractures. Computed tomography is the optimal test to assess penetrating chest, abdominal, and head trauma. The mechanism of blast injuries and the imaging experience of the victims of the Boston Marathon bombing are detailed, as well as musculoskeletal, neurologic, gastrointestinal, and pulmonary injury patterns from blast injuries.

Negative Pressure Wound Therapy in the Management of Combat Wounds: A Critical Review

Significance: Wounds sustained in a combat trauma often result in a composite tissue loss. Combat injuries, due to high energy transfer to tissues, lead to trauma at multiple anatomical sites. An early wound cover is associated with lower rate of infections and a faster wound healing. The concept of negative pressure wound therapy (NPWT) in the management of combat-related wounds has evolved from the civilian trauma and the wounds from nontraumatic etiologies. Recent Advances: Encouraged by the results of NPWT in noncombat-related wounds, the military surgeons during Operation Iraqi Freedom and Operation Enduring Freedom used this novel method in a large percentage of combat wounds, with gratifying results. The mechanism of NPWT in wound healing is multifactorial and often complex reconstructive procedure can be avoided in a combat trauma setting. Critical Issues: Wounds sustained in military trauma are heavily contaminated with dirt, patient clothing, and frequently associated with extensive soft tissue loss and osseous destruction. Delay in evacuation during an ongoing conflict carries the risk of systemic infection. Early debridement is indicated followed by delayed closure of wounds. NPWT helps to provide temporary wound cover during the interim period of debridement and wound closure. Future Directions: Future area of research in combat wounds is related to abdominal trauma with loss of abdominal wall. The concept of negative pressure incisional management system in patients with a high risk of wound breakdown following surgery is under review, and may be of relevance in combat wounds.

Noradrenalin effectively rescues mice from blast lung injury caused by laser-induced shock waves

Background

Blast lung injuries (BLI) caused by blast waves are extremely critical in the prehospital setting, and hypotension is thought to be the main cause of death in such cases. The present study aimed to elucidate the pathophysiology of severe BLI using laser-induced shock wave (LISW) and identify the initial treatment.

Methods

The current investigation comprised two parts. For the validation study, mice were randomly allocated to groups that received a single shot of 1.2, 1.3, or 1.4 J/cm² LISW to both lungs. The survival rates, systolic blood pressure (sBP), heart rate (HR), peripheral oxyhemoglobin saturation (SpO₂), and shock index were monitored for 60 min, and lung tissues were analyzed histopathologically. The study evaluated the effects of catecholamines as follows. Randomly assigned mice received 1.4 J/cm² LISW followed by the immediate intraperitoneal administration of dobutamine, noradrenalin, or normal saline. The primary outcome was the survival rate. Additionally, sBP, HR, SpO₂, and the shock index were measured before and 5 and 10 min after LISW, and the cardiac output, left ventricular ejection fraction, and systemic vascular resistance (SVR) were determined before and 1 min after LISW.

Results

The triad of BLI (hypotension, bradycardia, and hypoxemia) was evident immediately after LISW. The survival rates worsened with increasing doses of LISW (100 % in 1.2 J/cm² vs. 60 % in 1.3 J/cm², 10 % in 1.4 J/cm²). The histopathological findings were compatible with those of human BLI. The survival rate in LISW high group (1.4 J/cm²) was highest in the group that received noradrenalin (100 %), with significantly elevated SVR values (from 565 to 1451 dyn s/min⁵). In contrast, the survival rates in the dobutamine and normal saline groups were 40 and 10 %, respectively, and the SVR values did not change significantly after LISW in either group.

Conclusions

The main cause of death during the initial phase of severe BLI is hypotension due to the absence of peripheral vasoconstriction. Therefore, the immediate administration of noradrenalin may be an effective treatment during the initial phase of severe BLI.

Utility of basic fibroblast growth factor in the repair of blast-induced total or near-total tympanic membrane perforations: A pilot study

OBJECTIVE

A pilot study was performed to investigate the utility of basic fibroblast growth factor (bFGF) in the repair of blast-induced total or near-total tympanic membrane perforations (TMPs).

STUDY DESIGN

Prospective clinical study.

SETTING

Tertiary university hospital.

SUBJECTS AND METHODS

Patients who fulfilled the inclusion criteria were treated with 0.10-0.15 mL of bFGF solution applied directly to total or near-total TMPs once daily until the perforations closed or for a maximum of 6 months. The treatment response was monitored via serial otoendoscopy, and audiometric outcomes were evaluated.

RESULTS

Complete TMP closure was achieved in 16 of 17 patients with a blast-induced total or near-total TMP. The mean closure time was 28.4 ± 10.9 days. The improvement in hearing from pre- to post-treatment was statistically significant. There were no complications or adverse outcomes.

CONCLUSIONS

The direct application of bFGF to blast-induced total or near-total TMPs is a promising, minimally invasive alternative to conventional tympanoplasty, with a comparable success rate. As reported in the literature, the closure rate was higher than achieved with spontaneous healing. There was no effect of the inverted edge on healing outcome. The use of bFGF in this setting has immediate therapeutic applications for military personnel with blast-induced TMPs who are stationed in isolated, remote environments.

Extensively remodeled, fractured cetacean tympanic bullae show that whales can survive traumatic injury to the ears

Underwater human activities and anthropogenic noise in our oceans may be a major source of habitat degradation for marine life. This issue was highlighted by the opening of the United States Eastern Seaboard for seismic oil and gas exploration in 2014, which generated massive media coverage and widespread concern that seismic surveys could kill or deafen whales. We discovered 11 new specimens of fractured and healed cetacean ear bones, out of a survey of 2127 specimens housed in museum collections. This rare condition has been previously reported only in two specimens of blue whales (Balaenoptera musculus) from the early 1900s, summarized by Fraser & Purves (1953). All of our new specimens are represented by species for which this condition had never been reported previously, including both baleen and toothed whales. The baleen whale specimens (Balaenoptera physalus, Balaenoptera borealis, Balaenoptera acutorostrata) were collected during Canadian commercial whaling operations in the Atlantic Ocean in the 1970s; the specimens include ear bones with well-healed fractures, demonstrating that baleen whales are capable of overcoming traumatic injury to the ears. The toothed whale specimens (Delphinus sp., Berardius bairdii) were found dead on beaches in 1972 and 2001, respectively, with less remodeled fractures. Thus, ear injuries may be more lethal to the echolocating toothed whales, which rely on hearing for navigation and foraging. We explore several hypotheses regarding how these injuries could have occurred, and conclude that the most parsimonious explanations appear to be both direct and indirect effects of lytic processes from disease or calcium depletion, or damage from external pressure waves. Although further research is required to confirm whether the fractures resulted from natural or human-induced events, this study underscores the importance of museum collections and the work of stranding networks in understanding the potential effects of modern human activities on marine mammal health.

Blast Injuries

BACKGROUND

Blast injuries in the United States and worldwide are not uncommon. Partially due to the increasing frequency of both domestic and international terrorist bombing attacks, it is prudent for all emergency physicians to be knowledgeable about blasts and the spectrum of associated injuries.

OBJECTIVE

Our aim was to describe blast physiology, types of blast injuries associated with each body system, and manifestations and management of each injury.

DISCUSSION

Blast injuries are generally categorized as primary to quaternary injuries. Primary injuries result from the effect of transmitted blast waves on gas-containing structures, secondary injuries result from the impact of airborne debris, tertiary injury results from transposition of the entire body due to blast wind or structural collapse, and quaternary injuries include almost everything else. Different body systems are affected and managed differently. Despite previous dogma, multiple studies now show that tympanic membrane perforation is a poor predictor of other blast injury.

CONCLUSIONS

Blast events can produce a myriad of injuries affecting any and every body system. All emergency physicians should be familiar with the presentation and management of these injuries. This knowledge may also be incorporated into triage and discharge protocols guiding management of mass casualty events.

Intra-abdominal injury from extra-peritoneal ballistic trauma

Over the last century sporadic reports have described intra-abdominal injury without penetration of the abdominal cavity but the underlying mechanism of energy transfer appears variable. This article reviews the 19 documented cases of this phenomenon and discusses the mechanism of energy transfer in both primary blast injury and ballistic injury that may be responsible.

Primary blast lung injury prevalence and fatal injuries from explosions: insights from postmortem computed tomographic analysis of 121 improvised explosive device fatalities

BACKGROUND

Primary blast lung injury (PBLI) is an acknowledged cause of death in explosive blast casualties. In contrast to vehicle occupants following an in-vehicle explosion, the injury profile, including PBLI incidence, for mounted personnel following an external explosion has yet to be as well defined.

METHODS

This retrospective study identified 146 cases of UK military personnel killed by improvised explosive devices (IEDs) between November 2007 and July 2010. With the permission of Her Majesty's Coroners, relevant postmortem computed tomography imaging was analyzed. PBLI was diagnosed by postmortem computed tomography. Injury, demographic, and relevant incident data were collected via the UK Joint Theatre Trauma Registry.

RESULTS

Autopsy results were not available for 1 of 146 cases. Of the remaining 145 IED fatalities, 24 had catastrophic injuries (disruptions), making further study impossible, leaving 121 cases; 79 were dismounted (DM), and 42 were mounted (M). PBLI was noted in 58 cases, 33 (79%) of 42 M fatalities and 25 (32%) of 79 DM fatalities (p < 0.0001). Rates of associated thoracic trauma were also significantly greater in the M group (p < 0.006 for all). Fatal head (53% vs. 23%) and thoracic trauma (23% vs. 8%) were both more common in the M group, while fatal lower extremity trauma (7% vs. 48%) was more commonly seen in DM casualties (p < 0.0001 for all).

CONCLUSION

Following IED strikes, mounted fatalities are primarily caused by head and chest injuries. Lower extremity trauma is the leading cause of death in dismounted fatalities. Mounted fatalities have a high incidence of PBLI, suggesting significant exposure to primary blast. This has not been reported previously. Further work is required to determine the incidence and clinical significance of this severe lung injury in explosive blast survivors. In addition, specific characteristics of the vehicles should be considered.

Mechanisms of hearing loss after blast injury to the ear

Given the frequent use of improvised explosive devices (IEDs) around the world, the study of traumatic blast injuries is of increasing interest. The ear is the most common organ affected by blast injury because it is the body's most sensitive pressure transducer. We fabricated a blast chamber to re-create blast profiles similar to that of IEDs and used it to develop a reproducible mouse model to study blast-induced hearing loss. The tympanic membrane was perforated in all mice after blast exposure and found to heal spontaneously. Micro-computed tomography demonstrated no evidence for middle ear or otic capsule injuries; however, the healed tympanic membrane was thickened. Auditory brainstem response and distortion product otoacoustic emission threshold shifts were found to be correlated with blast intensity. As well, these threshold shifts were larger than those found in control mice that underwent surgical perforation of their tympanic membranes, indicating cochlear trauma. Histological studies one week and three months after the blast demonstrated no disruption or damage to the intra-cochlear membranes. However, there was loss of outer hair cells (OHCs) within the basal turn of the cochlea and decreased spiral ganglion neurons (SGNs) and afferent nerve synapses. Using our mouse model that recapitulates human IED exposure, our results identify that the mechanisms underlying blast-induced hearing loss does not include gross membranous rupture as is commonly believed. Instead, there is both OHC and SGN loss that produce auditory dysfunction.

The effects of explosion on the musculoskeletal system

Explosions remain the leading cause of death and injury to combatants in conflict. The current ‘Global War on Terror’ has resulted in a shift of explosive-related injuries from the battlefield into civilian centres. Despite musculoskeletal injuries being the most common injury witnessed in blast, there remains little research into the effects of blast on this system. In order to develop new treatment regimens and mitigation systems, there is a requirement to have a better understanding of skeletal trauma in this unique environment. The aim of this review article is to deconstruct the complex injury mechanisms witnessed in blast and relate them to its effects on the musculoskeletal system.

Rectal trauma in adults

Rectal trauma is associated with high rates of morbidity and mortality and generally affects young males due to its aetiology of violent crime and vehicular collision. Historically, management has followed principles derived from military practice, with faecal diversion, pre-sacral drainage and distal washout being mandatory. Civilian trauma studies examining management of colon and rectum injuries from the early 1950s identified major differences in the level of energy transfer between civilian and military wounds, given that the vast majority are penetrating in nature. This led to a re-evaluation of the necessity for these interventions for all rectal injuries. Current management depends on whether the injury is intra- or extraperitoneal, with those above the peritoneal reflection being readily accessible and amenable to treatment as for colon injury. Extraperitoneal injuries remain difficult to access and direct repair is usually impossible; the mainstay of treatment in most instances remains faecal diversion. The role of pre-sacral drainage and distal washout remains contentious in the realms of civilian rectal injury but retains a place in battlefield or other high-energy transfer rectal injuries where aggressive early management reduces septic complications. This article reviews the historical and current evidence for the management of both civilian and military extraperitoneal rectal injuries.

Effect of treatment at different time intervals for traumatic tympanic membrane perforation on the closure

CONCLUSION

Treatment of traumatic tympanic membrane (TM) perforation with everted or involute edge flaps at different time intervals within 1 week after the injury did not affect the perforation closure rate and mean closure time.

OBJECTIVE

To retrospectively analyze the effect of treatment at different time intervals for traumatic tympanic membrane perforation with gelatin sponge patch and edge approximation plus gelfoam patching.

METHODS

Patients with traumatic TM perforation visited at different days since the injury for medical treatment (1, 2, 3, 4, and 5-7 days post trauma). These patients were treated with the following prominent methods of treatment: gelatin sponge patch treatment and edge approximation plus gelfoam patching. Measurement indicators were perforation closure rate and mean closure time at 3 months.

RESULTS

In the group treated with the gelatin sponge patch technique, the patients sought medical treatment at different time intervals since the injury. Accordingly, the outcome of the treatment varied in terms of the perforation closure rates achieved in different patients in this group. The respective perforation closure rates were 100%, 100%, 96%, 94%, and 89% in accordance with the time interval at which the patients were treated since the injury. The results were not significantly different when compared by statistical analysis (p > 0.05); the mean closure times in each of the different sets of cases in this group were calculated and the following values were reported: 7.1 ± 2.3, 8.2 ± 1.6, 8.7 ± 1.2, 9.2 ± 3.1, and 10.7 ± 3.9 days. On the other hand, in the edge approximation plus gelfoam patching group, the perforation closure rates were 100%, 97%, 96%, 97%, and 94%, respectively. This was in accordance with the time elapsed since the injury for the patients who visited the hospital on different days. Statistical analysis confirmed that the perforation closure rates for the different cases of this group did not have any significant difference (p > 0.05); the mean closure times were 7.6 ± 1.9, 7.9 ± 2.2, 9.2 ± 2.8, 8.5 ± 3.6, and 11.2 ± 4.1 days, respectively, indicating that differences were not significant even in terms of mean closure rates for the different cases of this group (p > 0.05).

Outcome of children with edge-everted traumatic tympanic membrane perforations following spontaneous healing versus fibroblast growth factor-containing gelfoam patching with or without edge repair

OBJECTIVES

To retrospectively analyze the outcome of children with edge-everted tympanic membrane (TM) perforations following spontaneous healing and fibroblast growth factor-containing gelfoam patching with or without repair of the edge flaps.

METHODS

Medical records of children with TM perforations who underwent spontaneous healing (n = 69) or received fibroblast growth factor (FGF)-containing gelfoam patching treatment (n = 67) were retrieved from the Records Department of the Wenzhou Medical College-Affiliated Yiwu Hospital in China. The demographic data and outcome measures were analyzed and compared between these two groups of patients.

RESULTS

Patching with FGF-containing gelfoams significantly improved the healing rate (P < 0.01) and the average perforation closure time (P<0.01), as compared with spontaneous healing. Repair of the perforation edge flaps did not significantly affect the outcome of gelfoam patching (P>0.05), despite a slightly reduced healing rate (96.4% versus 100%) and a slightly shorter closure time (10.2 ± 2.6 d versus 10.9 ± 3.3 d) observed as compared with no edge repair. The everted perforation edge flaps formed scabs during the process of spontaneous healing whereas they underwent retraction and eventually dissolved during the process of gelfoam patching-facilitated healing.

CONCLUSIONS

As compared with spontaneous healing, FGF-containing gelfoam patching had an improved outcome in children with edge-everted traumatic eardrum perforation. Repair of everted edge flaps did not affect the healing outcome. Our results suggest that growth factor-containing gelfoam patching without eardrum flap repair would offer a feasible option to manage traumatic tympanic membrane perforations in children.

Abdominal trauma in primary blast injury

BACKGROUND

Blast injury is uncommon, and remains poorly understood by most clinicians outside regions of active warfare. Primary blast injury (PBI) results from the interaction of the blast wave with the body, and typically affects gas-containing organs such as the ear, lungs and gastrointestinal tract. This review investigates the mechanisms and injuries sustained to the abdomen following blast exposure.

METHODS

MEDLINE was searched using the keywords 'primary blast injury', 'abdominal blast' and 'abdominal blast injury' to identify English language reports of abdominal PBI. Clinical reports providing sufficient data were used to calculate the incidence of abdominal PBI in hospitalized survivors of air blast, and in open- and enclosed-space detonations.

RESULTS

Sixty-one articles were identified that primarily reported clinical or experimental abdominal PBI. Nine clinical reports provided sufficient data to calculate an incidence of abdominal PBI; 31 (3·0 per cent) of 1040 hospitalized survivors of air blast suffered abdominal PBI, the incidence ranging from 1·3 to 33 per cent. The incidence for open- and enclosed-space detonations was 5·6 and 6·7 per cent respectively. The terminal ileum and caecum were the most commonly affected organs. Surgical management of abdominal PBI is similar to that of abdominal trauma of other causes.

CONCLUSION

Abdominal PBI is uncommon but has the potential for significant mortality and morbidity, which may present many days after blast exposure. It is commoner after blast in enclosed spaces and under water.

Blast-related fracture patterns: a forensic biomechanical approach

Improved protective measures and medical care has increased the survivability from battlefield injuries. In an attempt to reduce the debilitating consequences of blast injury, understanding and mitigating the effects of explosion on the extremities is key. In this study, forensic biomechanical analyses have been applied to determine mechanisms of injury after the traumatic event. The aims of this study were (i) to determine which effects of the explosion are responsible for combat casualty extremity bone injury in two distinct environments, namely open, free-field (open group), and in vehicle or in cover (enclosed group), and (ii) to determine whether patterns of combat casualty bone injury differed between environments. Medical records of casualties admitted to a military hospital in Afghanistan were reviewed over a six-month period. Explosive injuries have been sub-divided traditionally into primary, secondary and tertiary effects. All radiographs were independently reviewed by a military radiologist, a team of military orthopaedic surgeons and a team of academic biomechanists, in order to determine 'zones of injury' (ZoIs), and their related mechanisms. Sixty-two combat casualties with 115 ZoIs were identified. Thirty-four casualties in the open group sustained 56 ZoIs; 28 casualties in the enclosed group sustained 59 ZoIs. There was no statistical difference in mean ZoIs per casualty between groups (p = 0.54). There was a higher proportion of lower limb injuries in the enclosed group compared with the open group (p < 0.05). Of the casualties in the open group, 1 ZoI was owing to the primary effects of blast, 10 owing to a combination of primary and secondary blast effects, 23 owing to secondary blast effects and 24 owing to tertiary blast effects. In contrast, tertiary blast effects predominated in the enclosed group, accounting for 96 per cent of ZoIs. These data clearly demonstrate two distinct injury groups based upon the casualties' environment. The enclosed environment appears to attenuate the primary and secondary effects of the explosion. However, tertiary blast effects were the predominant mechanism of injury, with severe axial loading to the lower extremity being a characteristic of the fractures seen. The development of future mitigation strategies must focus on reducing all explosion-related injury mechanisms. Integral to this process is an urgent requirement to better understand the behaviour of bone in this unique environment.

Ear injuries sustained by British service personnel subjected to blast trauma

Objectives:

To describe the pattern of ear injuries sustained by all British servicemen serving in Iraq and Afghanistan between 2006 and 2009; to identify all servicemen evacuated to the Royal Centre for Defence Medicine following blast injury; to ascertain how many underwent otological assessment; and to calculate the incidence of hearing loss.

Design and setting:

A retrospective analysis of data obtained from the Joint Theatre Trauma Registry and the Defence Analytical and Statistics Agency, together with audiometry records from the University Hospitals Birmingham National Health Service Trust.

Results:

Ear damage was present in 5 per cent of all British servicemen sustaining battle injuries. Tympanic membrane rupture occurred in 8 per cent of personnel evacuated with blast injuries. In 2006, 1 per cent of servicemen sustaining blast injury underwent audiography; this figure rose to 13 per cent in 2009. Fifty-three per cent of these audiograms were abnormal.

Conclusion:

The incidence of tympanic membrane rupture was higher than that found in previous conflicts. Otological assessment prior to and following military deployment is required to determine the incidence of ear injury amongst British servicemen following blast trauma.

Blast Injuries

Blasts injuries are responsible for about two-thirds of the conventional combat injuries during any military operation and account for a sizeable number during terrorist activities. The pathophysiology, clinical presentation and urgency of management vary significantly in primary blast injuries. These can lead to a wide range of overt and covert injuries, making diagnosis and management difficult. The clinical picture varies from acute respiratory distress to deafness with absence of any external injuries. Such patients are best identified and dealt with by a team of health care professionals well acquainted with battle field injuries.