Explosives And Blast Injuries

High-energy events in which a solid or a liquid can be quickly converted into a gas can occur in three grades: deflagration: Quick burning but minimal Explosion Explosion: subsonic ignition and blast (low grade explosive) Detonation: (überrschallschnelle ignition and blast highly explosive) would be an example of deflagration lightning fast (no bang) that results when an open pile is ignited black powder. The same black powder would sealed in a container cause a low-grade explosion. In high-grade explosive ignition wave goes through the material at supersonic velocity and causes a supersonic Burst (detonation) wave; Typical examples are nitroglycerin and trinitrotoluene (TNT see Table: Examples of low and high grade explosives). Examples of low and high grade explosives low grade explosives nitrocellulose “Smokeless” gunpowder black powder Most solid rocket propellants pipe bombs fireworks High explosives of ammonium nitrate (NH4NO3) Amatol 80/20 (NH4NO3 + TNT) Ammonal (NH4NO3 + TNT + aluminum) ANFO (NH4NO3 + oil) RDX (cyclotrimethylenetrinitramine), TNT (trinitrotoluene), nitroglycerin (The explosive component in dynamite) PETN (pentaerythritol tetranitrate) composition B (TNT + RDX) composition C-4 (RDX + plasticizer r) picric case of mass seizures of casualties with explosions, three concentric zones are identified: the epicenter of the blast Secondary perimeter periphery of the blast in the epicenter of the explosion (Dead Zone), all survivors injured probably fatal, technical rescue and recovery will be needed, and advanced first Help as well as a large number of volunteers who will take care of the victims be required for all survivors. Within the secondary perimeter (critical loss zone), are survivors have multiple injuries, and standard rescue and a moderate number of helpers who take care of the victims, will be needed. In the periphery of the explosion ( “walking-wounded zone”), most victims no life-threatening injuries and psychological trauma, a rescue is not needed and first aid and self-help are needed. Pathophysiology blast injuries include both physical and psychological trauma. Physical trauma includes fractures, impaired breathing, injury to the soft tissue and internal organs, internal and external blood loss with shock, burns and sensory impairments, especially of hearing and seeing. Five mechanisms of blast injuries have been described (see Table: Mechanisms of blast injuries): Mechanisms of blast injuries type mechanism Typical injuries primary impact of supersonic shock wave on the body Subject preferably hollow or gas-filled structures Pulmonary barotrauma ( “Explosion lung”) tympanic membrane and middle ear damage stomach bleeding and perforation Augapfelruptur Dim traumatic brain injury (concussion) Secondary impact of dirt of the explosion on the body Penetrating or blunt injury eyes penetration (apparent or occult) Tertiary impact of the body, which is cast by explosion to surrounding surfaces or debris fractures and traumatic amputations Closed and open brain injury Quaternary processes, irrespective of primary, secondary or tertiary explosion injury (eg. to result as burns, toxic inhalation, crush injuries by inclusions under rubble, worsening of disease) burns, crush injury with rhabdomyolysis and compartment syndrome airway injury by inhaled pollutants asthma, angina pectoris, or MI triggered by the event quinary seem of toxic materials from the body by absorbed the explosion. Affects the immune system and perhaps the autonomic nervous system and results in an immediate hyperinflammatory state fever sweating Low central venous pressure tissue edema, the supersonic shock wave at the primary blast injuries (PBI) compressed gas-filled spaces, which then re-expand quickly, resulting in shear and tensile forces that damage the fabric can perforate and organs. Blood is forced out of the vasculature in the air spaces and the surrounding tissue. Pulmonary involvement (pulmonary injury due to explosion pressure) can lung contusion, systemic air embolism (V A in the brain and spinal cord..) And cause injuries related to free radicals (thrombosis, Lipo-oxygenation and disseminated intravascular coagulation); this is a common cause of delayed mortality. PBI also include intestinal barotrauma (particularly in underwater explosions), acoustic barotrauma (including Trommelfellmembranruptur, Hämototympanum without breakage and fracture or dislocation of bones in the middle ear) and traumatic brain injury. Symptoms and signs Most injuries (z. B. fractures, lacerations, injuries to the brain) manifest themselves as well as with other types of trauma. Lung injury by explosion pressure may shortness of breath, causing hemoptysis, cough, chest pain, tachypnea, wheezing, decreased breath sounds, respiratory arrest, hypoxia, cyanosis and hemodynamic instability. Air embolism such as stroke, MI, acute abdomen, blindness, deafness, spinal cord injury or limp can manifest itself. Damage to the eardrum and inner ear can affect hearing, which should always be checked. Patients with abdominal injury from explosion may have abdominal pain, nausea, vomiting, blood vomiting, rectal pain, tenesmus, testicular pain and unexplained hypovolemia. Diagnosis Clinical examination Imaging tests such as by findings appear Patients are like most trauma victims studied (handling trauma patients: evaluation and treatment), except that special attention be focused on the detection of blast injuries, especially “explosion lung” (and thus air embolism), ear trauma, occult penetrating injuries and crush injuries. Apnea, bradycardia and hypotension are the clinical triad, traditionally associated with lung injury by explosion. A tympanic membrane was considered Indikatpr for a lung injury by explosion, but revenge petechiae may be a better predictor. A chest x-ray is performed and radiographs can show a characteristic butterfly pattern. Cardiac monitoring is performed in all patients. Patients with possible crush injury are tested for myoglobinuria, hyperkalemia and ECG changes. Triage With blast injuries often deal less severely injured patients preclinical triage and go directly to the hospitals, thereby previously established medical resources by the later arrival of more severely injured patients may be overwhelmed. The triage on site different from the standard trauma triage mainly in that blast injuries can be difficult to detect at first, so the initial triage should be focused on “Explosion lung” to recognize “explosion abdomen” and acute crush syndrome in addition to the more obvious injuries. Therapy attention should be paid (neurological status) and exposure of the patient to airway, breathing, circulation, disability (handling trauma patients: evaluation and treatment). O2 with high flow and hydration are priorities and early placement of a chest tube should be considered. Most injuries (z. B. lacerations, fractures, burns, internal injuries, head injuries) are treated as elsewhere in the Merck Manual described. Because air embolism may worsen after initiation of positive pressure ventilation, a positive pressure ventilation should be avoided if possible. If this is used, slower and lower inspiratory pressure settings should be selected. Patients with air embolism should be positioned in the coma position, between the left lateral decubitus position with the head and abdomen below or at the height of the heart. Hyperbaric O2 (HBO) therapy can be useful (Hyperbaric Oxygen Therapy (HBO)). If an acute crush syndrome is diagnosed or suspected, urinary catheterization is performed in order to allow continuous monitoring of urine. Forced diuresis by using an alkaline mannitol solution, to obtain a urinary excretion of up to 8 L / day, and a urine pH ? 5 can help. BGA, electrolytes and muscle enzymes should be monitored. Control hyperkalemia with calcium, insulin and glucose (hyperkalemia: Treatment). Hyperbaric oxygen therapy may be particularly useful in patients with deep tissue infections. carried monitoring of compartment syndrome clinically and by measuring the Kompartementdrucks. Patients may need a fasciotomy if the difference between the diastolic blood pressure and room pressure is <30 mm Hg. Hypovolemia and hypotension may initially not be apparent, but suddenly occur after Gewebsauflösung and reperfusion, so large quantities of intravenous fluid (e.g.., 1 to 2 liters of normal saline), both given before and after reperfusion. Liquid is further supplied in an amount sufficient to maintain a urinary excretion of 300 to 500 ml / h. Reproduced in this article is the opinion of the author and not the official policy of the Department of Army, Department of Defense or the US Government.

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