Table of Contents
What Is a Penetrating Chest Injury?
The chest, also known as the thorax, is the region between the root of the neck (superiorly) and the abdomen (inferiorly). It is often referred to as the box because it contains organs and tissues of various organ systems; they are-
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Respiratory System- Lungs, bronchi, trachea, and pleura,
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Cardiovascular- Heart, pericardium, great vessels, and lymphatics.
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Nervous System- Vagus nerve, sympathetic nerve, phrenic nerve, and recurrent laryngeal nerve.
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Immune System- Thymus.
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Digestive System- Esophagus (food pipe).
Any injury that pierces into the chest's contents resulting in a deep entry wound is known as a penetrating chest injury. If the object that has pierced into the box passes all the way through the exit wound, then it is known as a perforating trauma.
Penetrating chest injury, also known as an open wound injury, based on the cause is of two types:
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High-Energy Injuries- Also known as ballistic-type injuries, are caused due to gunshot wounds, arrow wounds, and those resulting from explosions. They cause more tissue injury due to their greater kinetic energy.
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Low-Energy Injuries- These injuries result from stabbings and slashings.
Penetrating injuries can potentially disrupt two vital life-sustaining systems- the respiratory and the cardiovascular systems. These injuries have the potential to be fatal and thus, a rapid, organized, and logical approach to evaluating and resuscitating these patients is critical.
What Happens in Penetrating Chest Injuries?
The force and location of the injury play a predictive factor in penetrating chest trauma. For example, a simple stab wound can cause a greater injury than a peripheral gunshot wound if the former is deep enough to lacerate the trachea and the subclavian artery.
The mechanism of stab wounds and ballistic wounds is explained below for a better understanding-
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Stabbing Wounds: They produce localized tissue damage along the path of the weapon. The injury pattern is predicted by the location of the wound and by the size, shape, and length of the object that is used to stab. Other influential factors include the position of and the distance between the victim and the attacker.
- Ballistic Wounds: These injuries involve crushing and tearing of the tissue along the path of the projectile. The kinetic energy (a function of the mass and velocity) of the projectile (bullet) determines the extent of the damage.
Handgun and shotgun bullets produce tissue destruction along the path of the projectile, whereas wounds from high-powered rifles produce local tissue destruction and cavitation.
Cavitation is the result of a pressure wave that is created when a projectile passes through the tissue. This pressure wave is capable of causing stretching, deformation, and often tissue death.
Understanding the mechanism of different types of penetrating chest injuries helps to assess the damage.
How Are Penetrating Chest Injuries Assessed?
The extremely time-sensitive nature of penetrating injuries demands simultaneous assessment and approach, both of which will be covered in this section. As soon as the patient is bought to the emergency department, a trauma surgeon or a cardiothoracic surgeon will perform the following steps in the given order to maximize the chances of survival.
The ABCs (airway, breathing, and circulation) of the patient should be given the first priority; aberrations in them should be addressed immediately.
Any penetrating injury to the chest must be assumed to have caused internal organ damage, which may involve the heart, lungs, tracheobronchial tree, great vessels, and other contents of the box.
If the patient has suffered cardiac arrest and shows signs of life (like pulse), the surgeon will proceed directly to a left anterior thoracotomy (incision between the ribs to access the contents of the box) while the patient is being intubated.
If the patient is non-arrested (not in cardiac arrest), the next step is to determine if the patient is hemodynamically stable or unstable (hypotensive and tachycardic); the patient should also be checked for any respiratory distress. The patient is considered to be hemodynamically unstable and has respiratory distress if they have any of the following conditions-
1. Tension Pneumothorax-
- It occurs when the air becomes trapped in the pleural surface after damage to the lung parenchyma. Continuous accumulation of air in the pleural space will lead to hypotension (low blood pressure), hypoxia (insufficient oxygen supply), and cardiopulmonary collapse.
- Symptoms include dyspnea (difficulty in breathing), chest pain, tachypnea (rapid breathing), agitation, and restlessness.
- Signs include hypotension, decreased breath sounds, cyanosis (bluish discoloration of the skin and mucous membranes), hyper resonation on percussion of the injured side, tracheal deviation, and distinct heart sounds. Intubated patients will have increased airway resistance with gagging and decreased oxygen saturation.
- Treatment includes decompression and closed thoracostomy (inserting a thin plastic tube into the pleural space).
2. Massive Hemothorax-
- It affects both the respiratory and circulatory systems. It is defined as the accumulation of a significant amount of blood in the thorax leading to hemorrhagic shock and atelectasis (compression and collapse of the lungs), all of which can be confirmed with a computed tomographic (CT) scan.
- Dyspnea and decreased level of consciousness are the frequently observed symptoms; signs include hypotension, tachycardia (increased heartbeat), decreased breathing sounds, and dullness on percussion.
- Treatment includes closed chest thoracostomy (if the initial drainage is more than 1500 ml) or thoracotomy (if the initial drainage is more than 200 ml).
3. Cardiac Tamponade-
- It occurs as a result of hemorrhage into the pericardial sac (a fibrous sac that encloses the heart and its vessels). This accumulation of blood prevents venous return to the heart and reduces cardiac output.
- Symptoms include dyspnea, chest pain, and restlessness. The classic signs of cardiac tamponade constitute Beck’s triad- hypotension, distended neck veins, and muffled heart sounds.
- It can be diagnosed with the help of clinical observation and focussed transthoracic trauma ultrasonography.
- Depending on the severity, treatment can be pericardiocentesis (a surgical procedure to remove fluid from the pericardial sac), a pericardial window, or an emergency thoracotomy.
If the patient is stable and has very less respiratory distress, then it is advised to obtain an AP (anterioposterior) supine X-ray. The X-ray will show a pneumothorax or a hemothorax, which can be managed with chest tubes and thoracotomy, respectively.
If the injury is between the nipples and the clavicle and lower coastal margin, the result is a cardiac injury. Patients with cardiac injury present with the symptoms of massive hemothorax and cardiac tamponade and should be treated accordingly.
If the injury suggests a trajectory through the lung parenchyma alone, a computed tomographic (CT) scan with or without contrast will easily locate the path (of the bullet track or stab wound) and its relation to the pulmonary hilum and mediastinal structures. Treatment is the same as pneumothorax.
If all the X-rays are normal and there is no firm indication that the lungs and the heart were not penetrated, then it is advised to observe the patient for six hours and then repeat the investigations again. If there are signs of pneumothorax or hemothorax, treatment (as mentioned above) should be done accordingly. The patient can be discharged from the emergency department if the film is normal.
Conclusion
Penetrating chest injuries used to have one of the highest mortality rates due to their life-threatening and time-sensitive consequences. Advancements in interventional radiologic techniques have made the retrieval of intracardiac missiles and treatment of intrathoracic vascular injuries safe. This, when combined with efficient ongoing monitoring, has drastically increased the survival rate of affected patients.
