Comment on the "fatal accident due to anti-personnel ARGES EM01 rifle grenade explosion".

Explosion has become one of the most common causes of death of the combat casualties. I made a comment on one case of autopsy whose cause of death was the accidental denotation of a 355 g rifle grenade and reviewed the clinical approaches and strategies of the blast injury.

Explosion has become one of the most common causes of death of the combat casualties. Due to the rising of terrorism attacks worldwide, the explosion also challenges the civilian health care system more heavily than ever before. The essential mechanism of blast injuries by the denotation will ensure the efficiency and the quality of acute response and medical care.

This article reported the case of autopsy whose cause of death was the accidental denotation of a 355 g rifle grenade. As well, this article reviewed the mechanism of blast injury, medical response and the assessment of injury severity to further understand the mechanism involved in blast injury, based on which the acute care and first response in increased global terrorism events would be reinforced.

In recent decades, the explosion has become the top killer of modern combat casualties rather than firearms. The combat casualties in the United States caused by explosion in Iraq and Afghanistan wars accounted for around 80% of the toll, whereas those casualties caused by firearms dropped to only 20% or so. The situation was contrary to that in the Civil War. Unfortunately, due to the emerging terrorism, the civilian injuries caused by explosion have become more common than ever before. Therefore, this study aimed to review the primary principles for the early medical care of blast injury.

According to the recent more than 10-year experiences of combat casualty care in the US army, 90% of Kill-in-War (KIW) occurred before arrival at the medical services. After arrival, the mortality was about 12%. Based on the cause of death, it could be defined as non-survival and potentially survival death. More than 50% of non-survival death was brain injury.2, 3 the most common cause of potentially survival death was the trunk extinguishing hemorrhage that was failed to be controlled by the compression, followed by tourniquet applicable hemorrhage and the bleeding that could not be stopped by tourniquet but compression. Next were the airway obstruction, tension pneumothorax and sepsis. Based on the result of autopsy, the injuries of femoral vessels in the left conjunction region might be the primary cause of death in this case. However, there were no detailed medical records concerning the basic physical examination, injury severity assessment (including the vital signs) and the level of consciousness. Although the autopsy documented the soft tissue injuries in the whole body, most of them were in the face, right upper and left lower quadrant abdomen and left leg. The lacerated lesions were found in the lung, heart and upper abdominal organs and the intracranial hematoma was also identified. However, the amount of the bleeding or clot in the cavities, the actual position of intracranial hematoma and its features were not described. No specific detailed evidence referred to the epidural hematoma or subdural hematoma. Regarding to the evidences above, the death could not be simply attributed to hemorrhage shock. From this perspective, the primary assessment of blast injury is essential to give efficient acute care.

In general, the casualty would be suspected of severe blast injury if he or she presents: (1) >10% total body surface area (TBSA) of burn injury; (2) maxillofacial fracture; (3) penetrating wound in the torso indicating high energy released by the denotation. Giving that the target organs of blast injury would be particularly air-filled (such as lung), the acute care for blast injury should follow the ‘ABC’ rule (airway-breath-circulation) rather than the ‘CAB’ scenario (circulation-airway-breath) that has been recently advocated by ATLS (advanced trauma life support).

“A” refers to the airway. After blast injury, the clearing of the airway includes the removal of broken teeth, bone fragments and foreign bodies, control of bleeding and airway management. If the patients present respiratory dysfunction, nasotracheal intubation should be performed, if it fails, the oral-tracheal intubation should be achieved.

“B” refers to the breath. Lung is the target organ of primary blast injury and acute lung injury is also the most fatal cause of shock wave. In the acute phase after injury, the “butterfly sign” would be identified on the chest X-ray. Apnea, bradycardia and hypotension are the common clinical triad which characterizes primary blast injury of the lung. However, severe blast lung injury rarely exists in the survivors, while air embolism is common, especially coronary air embolism which is far more fatal. The preventive strategy is to promptly place the patient in Trendelenburg position (head down) and on the left side (left lateral decubitus position) in order to trap air bubbles in the non-dependent segment of the right ventricle so that distal arteries could not be occluded by embolism. Respiration should be monitored in any suspected lung injury. The doctor should keep in mind that artificial ventilation may not be as efficient in blast lung injury as in other trauma-related cardiopulmonary resuscitation (CPR) procedure.

“C” refers to the circulation. As noted before, exsanguinating hemorrhage is the most common cause of potentially survival death after trauma. Stabilized hemostasis is also the first priority of trauma care. On-the-scene first aid includes prompt application of tourniquet or compression to stop bleeding as much as possible. It is the most effective approach to control the life-threatening hemorrhage, which helps to deliver the patient to medical services capable of surgical intervention. Penetrating wound is the indication of emergent thoracotomy and laparotomy. The severity assessment should be obtained to determine the priority cavity that should be taken care of, in addition, the surgical position, the region of disinfection and sterilization as well as the surgical drapes should be considered beforehand, which need to satisfy both procedures. Focused abdominal stenography for trauma (FAST) is expected to be helpful before surgery for the surgery planning strategies. Evidences of GCS and brain CT scan are the basis of severity assessment of brain injury, if possible, general CT scan should be ordered. Re-checking the vital signs including blood pressure should be contemporary to the damage-control resuscitation and damage-control surgery. The predominant principles of damage-control resuscitation are as follow: 1:1:1 ratio of fresh frozen plasma (FFP) to packed red blood cell (pRBC) to platelet; permissive hypotension; restrained crystalloids. The hemodynamics and the fluid amount and infusion speed should be adjusted more precisely. Appropriate antibiotics could be prescribed at this stage.

Although blast injury has become the most common death cause of combat casualties, the majority of primary blast injuries are accompanied by blunt injury or penetrating injury with different severities. The high-velocity projectile is commonly involved in secondary blast injury; tertiary blast injury is caused by the shockwave that throws victims against solid objects; quaternary injury refers to all other injuries not included in the above-mentioned three classifications, including flash burns, crush injury, toxication, etc. The majority of casualties caused by blast injury are the multiple trauma, even polytrauma. The severity of blast injury depends on the released energy of detonation, the characteristics of the explosion, the surrounding environment and the toxic gas. If the patient is buried, it would retard the rescue, so the severity should be upgraded. To minimize the mortality of blast injury patients, the prompt and efficient treatment is critical.

In general, compared with the civilian settings, blast injury is dominant in combat casualties during recent years. However, due to the emerging attacks of global terrorism, the threat of explosion caused by improvised explosion devices or homemade bombs becomes more and more popular, co-existing with other major industrial accidents and civilian casualty incidents. The understanding of blast injury mechanism and its subtypes, and the practice of acute care protocols will promote medical response to the explosion events.