Emergency War Surgery NATO Handbook: Part I: Types of Wounds and Injuries: Chapter V: Blast Injuries
United States Department of Defense
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The individual with primary blast injury usually presents with associated injuries. The basic principles of triage and trauma care management still pertain. Airway establishment, control of hemorrhage. and reversal of shock should proceed without consideration of the presence of blast injury. Since an overly generous administration of fluids during the resuscitation may complicate pulmonary injury, pulmonary artery catheterization and pressure monitoring may be necessary to guide fluid therapy in complex cases. When possible, blast victims should be kept sedentary, as exercise may increase mortality by increasing air emboli or by worsening lung hemorrhage.
Tympanic rupture is treated conservatively. After examination, any debris should be cleared from the external canal; however, no irrigation should be attempted. The majority of tympanic tears will heal spontaneously. About one fourth will require surgical closure which can be delayed for weeks.
Air emboli from a severe blast may be lethal within minutes. The incidence of severe air embolism can be lessened by placing the individual in the prone position with the left side down, the back at a 45° angle to the ground, and the head lower than the feet. This position is thought to distribute emboli to the lower extremities rather than to the head vessels, and is also thought to trap air in the right heart. If seen early enough, prompt use of a compression chamber may be lifesaving. Hyperbaric therapy works both by physically reducing the size of the bubbles and by speeding their absorption. The addition of oxygen to the hyperbaric environment probably adds little to the effect of the increased pressure. In the absence of hyperbaric capability, empiric therapy for CNS injury or cardiac ischemia should be instituted.
Respiratory distress should be Immediately treated with supplemental oxygen, and the individual should be evaluated to establish whether the etiology is pneumothorax or pulmonary parenchymal failure from blast or other causes (e.g., inhalation of toxic gases). Progressive respiratory failure poses a particular problem since positive pressure ventilation may increase the incidence and severity of both air emboli and pulmonary barotrauma. If oxygen delivery via conventional binasal prongs or a face mask is insufficient to produce adequate tissue oxygenation, constant positive airway pressure (CPAP), either by face mask or endotracheal tube, should be employed to keep small airways open and to improve oxygenation. Positive pressure ventilation assistance should not be withheld if the clinical situation deteriorates.
Inhalation anesthesia carries a very high morbidity in blast injury. This is probably due to the unmonitored use of positive pressure ventilation intraoperatively and to the difficulty of neurologically assessing the patient. Every effort should be made to perform surgical procedures under regional or spinal anesthesia. Airway pressures during inhalation anesthesia should be kept as low as possible since intraoperative pneumothorax can be produced. Consideration should be given to the prophylactic use of chest tubes. One should anticipate the very possible occurrence of pleural complications by performing frequent physical examinations and chest roentgenograms.
Blast injury of the gastrointestinal tract should be managed in the same way as blunt trauma. Hypovolemic shock in the absence of other obvious etiology should suggest visceral rupture, and warrants diagnostic peritoneal lavage and consideration of laparotomy. Decompression via a nasogastric tube should be undertaken with any peritoneal signs and whenever ventilatory assistance is instituted. The patient should be observed for several days because of the risk of delayed perforation. The role of antibiotics and anti-inflammatory medication is unclear, although both have their advocates.
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