A traumatic pneumothorax is one of the most common injuries sustained following penetrating thoracic trauma. A pneumothorax is the presence of air between the parietal and visceral pleura. It occurs from injuries sustained either to the lung parenchyma or the tracheobronchial tree. Pneumothoraces result in ventilation-perfusion mismatches via shunting; blood continues to perfuse areas of the lung that are poorly oxygenated.
Air within the enclosed intrathoracic space, analogous to blood within the skull in traumatic intracranial hemorrhages, applies pressure to the lung, which ultimately can lead to its collapse. Pneumothoraces can be divided into several categories: simple pneumothorax, open pneumothorax, and tension pneumothorax. A simple pneumothorax is defined as one that is non-expanding. An open pneumothorax, often colloquially called a sucking chest wound, is seen commonly in penetrating traumas and is an unsealed opening in the chest wall. See Figure 3. This creates complications through its alteration of the vacuum normally present within the pleural cavity, which prevents the lungs from fully expanding.
This image shows an open chest and sucking open pneumothorax after impalement. A tension pneumothorax, the most life-threatening of the three, presents a true emergency. When the pressure in the thoracic cavity becomes high enough to shift the mediastinal contents and cause insufficient blood return to the heart, the patient is at high risk of rapid decompensation.
Diagnosing a pneumothorax often can be accomplished by physical exam alone.
In an unstable patient with unilateral absent breath sounds or a sucking chest wound, the physician should not wait for imaging before intervening. However, in unstable patients in whom the diagnosis is less clear, ultrasound has become the modality of choice. Although in the past a chest X-ray was considered the best tool for diagnosing pneumothorax in the trauma bay, a paradigm shift has taken place. In an evidence-based review, Wilkerson et al found thoracic ultrasound to be superior to chest X-ray for detecting pneumothorax. The bedside lung ultrasound in emergency BLUE protocol for assessing the patient in acute respiratory failure highlights the techniques for diagnosing a pneumothorax on ultrasound.
In a normal patient, lung sliding signifies the parietal and visceral pleura sliding past each other. On the other hand, the absence of lung sliding represents a pneumothorax. A very specific finding, one named the lung point, represents the point at which the inflated lung meets the pneumothorax. The definitive management for pneumothorax is a tube thoracostomy. The urgency with which it should be placed, and whether the pneumothorax will resorb without one, depends on the percent volume involved. In the prehospital setting, the management for a tension pneumothorax is still needle decompression.
However, multiple studies have highlighted the pitfalls of this procedure. For example, in the obese population, a conventional catheter often does not reach the thoracic cavity. Contrary to common practice, they found that the success rate was highest at the fifth intercostal space, not the second, with an equally low complication rate cardiac, lung, aorta, liver injury.
They found smaller catheters to have the same efficacy with reduced pain. A completely occlusive dressing risks an open pneumothorax becoming a tension pneumothorax. As in the other types, definitive treatment for an open pneumothorax is the placement of a tube thoracostomy. See Figure 4. The chest radiograph shows bilateral pneumothoraces with bilateral tube thoracostomies.
Note the subcutaneous emphysema seen bilaterally, worse on the left. A hemothorax is an accumulation of blood within the thoracic cavity. It is caused by injury to the intercostal vessels, the lung parenchyma, the internal mammary artery, or the great vessels. Because the hemithorax can hold up to four liters of volume, patients rapidly bleeding into this cavity can exsanguinate. As a result, patients who sustain penetrating injuries to the great vessels often succumb to their injuries in the field. On the other hand, injury to the smaller vessels causes blood to accumulate slowly within the thoracic cavity, leading to the typical symptoms of pain, dyspnea, and tachypnea.
See Figures 5 and 6. The chest radiograph above shows a male patient after a gunshot wound to the thorax with associated retained bullet fragments, right-sided hemothorax and pulmonary contusion, and subcutaneous emphysema. The above chest radiograph shows a deep sulcus sign with hemopneumothorax on the right after a gunshot wound to the chest.
The thoracic duct is another structure prone to injury in penetrating thoracic traumas. It is located within the left hemithorax and collects most of the lymph that circulates throughout the body. Injury to this structure leads to an entity called a chylothorax, which is the accumulation of this lymphatic fluid within the thorax.
The symptoms are indistinguishable from a hemothorax, and the diagnosis most often is made when the milky appearing chyle drains from the chest tube. The diagnosis of a hemothorax in penetrating chest trauma initially is based on the history and physical exam. The first diagnostic modality of choice remains a chest X-ray.
However, it must be noted that chest radiographs can miss up to 1, mL of blood in the supine patient. Although not as sensitive in diagnosing a hemothorax as a pneumothorax, studies have shown ultrasound to be more effective than chest X-ray in diagnosing small amounts of fluid within the thoracic cavity. The management of hemothorax after a penetrating wound involves a tube thoracostomy.
Inaba et al evaluated whether the size of the chest tube affects complication rates.
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When comparing 28F chest tubes to 40F tubes, they found a similar rate of complications, a similar efficacy of drainage, and a similar level of pain, leading them to conclude that size does not matter. Rapid exsanguination from the chest tube, defined as more than 1, mL immediately returned, is an indication to perform a thoracotomy in the ED. Pulmonary contusions can be seen in both penetrating and blunt trauma.
Unlike many of the other previously discussed pathologies, the sequelae of pulmonary contusions often develop over days rather than minutes. Pulmonary contusions occur from direct force to the chest wall. This results in damage to the lung parenchyma with associated hemorrhage and edema involving the alveoli. Pulmonary contusions see Figure 5 can lead to severe complications such as ARDS, respiratory failure, atelectasis, and pneumonia. The modalities for diagnosing a pulmonary contusion, like those of the other penetrating chest trauma injuries, are chest X-ray and CT scan.
It often takes 24 to 48 hours after the initial injury to show the full sequelae of the disease process. The management of pulmonary contusions depends on the severity, the presence of associated injuries, and the comorbid conditions of the patient. Again, because the full effect of pulmonary contusions does not develop until 24 to 48 hours after initial injury, it is important to monitor these patients closely.
The mainstays of treatment are preventing respiratory failure and ensuring adequate blood oxygenation. Large contusions are challenging to manage. However, patients with significant respiratory distress or those who are altered from other injuries require intubation.
Injured lungs are prone to becoming stiff; therefore, high pressure settings on the ventilator often are required. The ARDS protocol was created to manage patients such as these. It allows for appropriate oxygenation in stiff and injured lungs. The guidelines recommend resuscitating with isotonic crystalloid or colloid solution until there are signs of adequate tissue perfusion. Once the patient is properly resuscitated, however, the guidelines recommend against unnecessary fluid administration. As in patients with multiple rib fractures, the guidelines also emphasize the use of optimal analgesia and aggressive chest physiotherapy to decrease the likelihood of respiratory failure.
The mediastinum contains many vital structures.
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It can be divided into the superior and inferior mediastinum. The superior mediastinum contains the thymus, brachiocephalic veins, superior vena cava, azygous vein, aortic arch, pulmonary arteries, vagus nerve, and phrenic nerves.
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The inferior mediastinum is subdivided further into anterior, middle, and posterior. The anterior mediastinum contains the caudal thymus gland and sternopericardial ligaments. The middle mediastinum contains the heart and great vessels along with the phrenic nerves. The posterior mediastinum contains the descending aorta, esophagus, thoracic duct, sympathetic chains, vagus nerves, and hemiazygos vein. In penetrating chest trauma, great vessel injuries superior vena cava, inferior vena cava, pulmonary arteries, pulmonary veins, and the aorta often cause rapid hemorrhagic shock.
Penetrating Chest Injury
As mentioned previously, these injuries have a very high mortality, and patients often exsanguinate before arriving in the ED. The diagnostic approach to trans-mediastinal injuries has changed over the years. As always, unstable patients need definitive and rapid intervention with the trauma surgeon in the operating room.
The arresting patient often requires an ED thoracotomy. Traditionally, stable patients have received a very extensive evaluation, including an endoscopy, contrast swallow, angiography, and echocardiography. However, recent data have shown that a cardiac FAST exam and a CT angiogram are sufficient to rule out life-threatening injuries safely. If there is obvious injury, the patient will require an interventional radiologist or surgeon to correct it definitively. If the scan is equivocal, the provider should perform the traditional, more extensive method for evaluation, which includes a bronchoscopy, angiography, esophagogastroduodenoscopy EGD , and a swallow study.
The decision to perform an ED thoracotomy must be made within minutes. The goal, specifically in penetrating mediastinal injuries, is to locate and control great vessel or cardiac bleeding. In the ED setting, great vessel bleeds must be found and repaired using non-absorbable sutures. Although often difficult to identify, the aorta can be found lying anterior to the vertebral body and posterior to the esophagus. Once identified, a vascular clamp is used to occlude the descending aorta and obtain temporary hemostasis. In penetrating cardiac injuries, as opposed to blunt injuries, tamponade is less common because a laceration of the pericardium allows the blood to be released from the pericardial sac.
See Figure 7. It remains important, however, to keep this differential diagnosis in mind in any unstable trauma patient. This triad consists of hypotension, jugular venous distention, and muffled heart sounds. Ultrasound has become one of the most valuable tools in diagnosing cardiac injuries, particularly cardiac tamponade. The physician should keep in mind, however, that the absence of a pericardial effusion in patients with penetrating thoracic trauma does not rule out cardiac injuries, for the reasons stated above. Definitive treatment for the crashing or arresting patient in whom a cardiac injury is suspected is an ED thoracotomy.
Once the thoracic cavity is open and can be visualized, the area should be evaluated for injuries. If tamponade is present or suspected, a pericardiotomy should be performed to release fluid from the pericardial sac. When making the initial incision through the pericardium, care should be taken to avoid injury to the phrenic nerve. The phrenic nerve should be identified first and an incision should be made anterior and parallel to it. For penetrating wounds to the myocardium, a finger can be placed over the defect while awaiting definitive care.
Another temporary measure is placing a Foley catheter through the wound to control bleeding. See Figure 7B. The balloon is inflated and the defect is occluded by pulling pressure. Penetrating myocardial injuries are closed definitively with surgical staples or with non-absorbable sutures. Although less common in penetrating trauma than blunt trauma, patients in a lethal arrhythmia can be resuscitated via internal defibrillation while the thorax is open. Internal paddles are placed on the anterior and posterior aspects of the heart, and a shock is administered directly to the myocardium.
In an arresting patient, direct cardiac compressions can be performed in an open thorax as well. This image shows a ruptured myocardium after a stab wound to the anterior chest. Rapid repair of ruptured myocardium with staples and Foley catheter tamponade before definitive operating room repair. Tracheobronchial injuries include lacerations to the trachea or bronchi. Injuries to these structures allow air to accumulate within the pleural cavity, the mediastinum, and soft tissues. Although only seen in about 0.
Therefore, keeping a high suspicion for associated injuries is essential. Diagnosing tracheobronchial injuries can be difficult, and they often are missed initially if a high index of suspicion is not maintained. Although nonspecific, the first diagnostic modality of choice is a chest X-ray.
Pneumomediastinum, subcutaneous air, and a pneumothorax that persists despite tube thoracostomy should increase the suspicion for this injury. The initial goals in treating tracheobronchial injuries include stabilizing the airway and defining the extent of the injury. The presence of a persistent air leak is highly suggestive of tracheobronchial injury. Definitive surgical intervention includes performing a thoracotomy or median sternotomy to either suture or resect the injured structure. A delay in diagnosis and treatment has been shown to influence outcomes negatively.
Esophageal injuries often are difficult to diagnose because they are not associated with a specific clinical sequela. Although esophageal injury is rare, one should maintain a high clinical suspicion for it in patients with a penetrating trauma that traverses the mediastinum with a left hemothorax or pneumothorax without a rib fracture, the presence of particulate matter in chest tube drainage, or the presence of pneumomediastinum.
Definitive diagnosis can prove difficult because even with a high clinical suspicion, CT scan with IV contrast alone often can miss esophageal injuries.
As mentioned in the section above, if there is no evidence that a penetrating object traversed the mediastinum on CT scan, no further imaging is required. However, if the CT scan is equivocal, further imaging is necessary because a missed esophageal injury portends a poor prognosis. A flexible esophagogastroduodenoscopy is valuable because it directly visualizes the esophagus, but it should be used with caution in the acute setting because of the risk of additional injury.
Initial ED management, as in all trauma patients, should include airway protection and fluid resuscitation. Early initiation of broad-spectrum antibiotics should be implemented in the ED as well. In patients who require operative management, an open surgery is the most common approach. The mortality for these injuries remains high, so early recognition and consultation for definitive management leads to the best outcomes.
The diaphragm is a muscular structure essential mechanically for normal ventilation and anatomically for separating the negatively pressured thorax from the peritoneal cavity. Therefore, injuries to the diaphragm can lead to significant respiratory compromise or bowel injury. During normal respirations, the diaphragm spans T4 to T12; consequently, a high index of suspicion must be maintained with any injury for which the penetrating missile traverses this area. Diaphragmatic injuries are more common in isolation on the left because it is protected by the liver on the right.
The chest radiograph demonstrates herniation of the colon within the anterior mediastinum after a previous diaphragmatic injury. Diagnostic imaging of these injuries begins with a chest radiograph. Injuries that are large enough cause the bowel to herniate into the thorax, which can be seen on chest X-ray. Additionally, a coiled nasogastric tube in the thoracic cavity is diagnostic of a diaphragmatic injury. However, small injuries often are mistaken for other pathologies on chest X-ray. A thorascope is inserted through a small incision, allowing the surgeon to visualize the lungs, mediastinum, and diaphragm directly.
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Most diaphragmatic injuries require surgical management. The exception is small right-sided injuries that can be tamponaded by the liver. In stable patients, delayed surgical management may be preferred because it allows for more minimally invasive techniques. Although laparotomy always has been the treatment of choice for surgical repair of diaphragmatic defects, thoracolaparoscopic intervention is a newer, less invasive method of treatment.
Penetrating chest trauma can be life-threatening because vital structures are housed within the thoracic cavity. Although much of the management of trauma patients has not changed over the years, better imaging modalities have allowed less invasive and more portable options for diagnosing injuries. Also, advances in resuscitation strategies with massive transfusion protocol, permissive hypotension, and availability of hemoglobin oxygen-carrying products has led to a decrease in morbidity.
Regardless of the type of injury, an algorithmic approach to the trauma patient ensures a thorough evaluation and effective management strategy. Financial Disclosure: Dr. Reprints Share. Related Articles Penetrating Thoraco-abdominal Injury. Lund University Libraries M. Nucleus Medical Art, Inc. Bowker Readex Readex, Karger s. Sage Publications Sage Publications, Inc. Wharton School. William S. Hein William S.
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