Thorax trauma

Frequency Trauma is responsible for more than 100,000 deaths annually in the United States. 1 Estimates of thoracic trauma frequency indicate that injuries occur in 12 persons per million population per day. Approximately 33% of these injuries require hospital admission. Overall, blunt thoracic injuries are directly responsible for % of all deaths, and chest trauma is a major contributor in another 50% of deaths.

Etiology By far, the most important cause of significant blunt chest trauma is motor vehicle accidents (MVAs). MVAs account for 70-80% of such injuries.

Pathophysiology The major pathophysiologies encountered in blunt chest trauma involve derangements in the flow of air, blood, or both in combination. Sepsis due to leakage of alimentary tract contents, as in esophageal perforations, also must be considered. Blunt trauma commonly results in chest wall injuries (eg, rib fractures). The pain associated with these injuries can make breathing difficult, and this may compromise ventilation. Direct lung injuries, such as pulmonary contusions, are frequently associated with major chest trauma and may impair ventilation by a similar mechanism.

Clinical The clinical presentation of patients with blunt chest trauma varies widely and ranges from minor reports of pain to florid shock. The presentation depends on the mechanism of injury and the organ systems injured.

Workup Approach Considerations Initial emergency workup of a patient with multiple injuries should begin with the ABCs of trauma, with appropriate intervention taken for each step. Laboratory Studies CBC count Arterial blood gas Serum chemistry profile Coagulation profile Serum troponin levels Serum myocardial muscle creatine kinase isoenzyme levels Serum lactate levels Blood type and crossmatch Imaging Studies Chest radiographs Chest CT scan Aortogram Thoracic ultrasound Contrast esophagogram Focused Assessment for the Sonographic Examination of the Trauma Patient

Workup Diagnostic Tests and Procedures Twelve-lead electrocardiogram Transesophageal echocardiography Transthoracic echocardiography Flexible or rigid esophagoscopy Fiberoptic or rigid bronchoscopy

Indications Operative intervention is rarely necessary in blunt thoracic injuries. In one report, only 8% of cases with blunt thoracic injuries required an operation. Most can be treated with supportive measures and simple interventional procedures such as tube thoracostomy.

Chest wall fractures, dislocations, and barotrauma (including diaphragmatic injuries) Indications for immediate surgery include (1) traumatic disruption with loss of chest wall integrity and (2) blunt diaphragmatic injuries. Relatively immediate and long-term indications for surgery include (1) delayed recognition of blunt diaphragmatic injury and (2) the development of a traumatic diaphragmatic hernia.

Blunt injuries of the pleurae, lungs, and aerodigestive tracts Indications for immediate surgery include (1) a massive air leak following chest tube insertion; (2) a massive hemothorax or continued high rate of blood loss via the chest tube (ie, 1500 mL of blood upon chest tube insertion or continued loss of 250 mL/h for 3 consecutive hours); (3) radiographically or endoscopically confirmed tracheal, major bronchial, or esophageal injury; and (3) the recovery of gastrointestinal tract contents via the chest tube. Relatively immediate and long-term indications for surgery include (1) a chronic clotted hemothorax or fibrothorax, especially when associated with a trapped or nonexpanding lung; (2) empyema; (3) traumatic lung abscess; (4) delayed recognition of tracheobronchial or esophageal injury; (5) tracheoesophageal fistula; and (6) a persistent thoracic duct fistula/chylothorax.

Blunt injuries of the heart, great arteries, veins, and lymphatics Indications for immediate surgery include (1) cardiac tamponade, (2) radiographic confirmation of a great vessel injury, and (3) an embolism into the pulmonary artery or heart. Relatively immediate and long-term indications for surgery include the late recognition of a great vessel injury (eg, development of traumatic pseudoaneurysm).

Contraindications No distinct, absolute contraindications exist for surgery in blunt thoracic trauma.

Rib fractures Rib fractures are the most common blunt thoracic injuries. Ribs 4-10 are most frequently involved. Patients usually report inspiratory chest pain and discomfort over the fractured rib or ribs. Physical findings include local tenderness and crepitus over the site of the fracture. If a pneumothorax is present, breath sounds may be decreased and resonance to percussion may be increased. Rib fractures may also be a marker for other associated significant injury, both intrathoracic and extrathoracic. Effective pain control is the cornerstone of medical therapy for patients with rib fractures. For most patients, this consists of oral or parenteral analgesic agents. Intercostal nerve blocks may be feasible for those with severe pain who do not have numerous rib fractures. A local anesthetic with a relatively long duration of action (eg, bupivacaine) can be used. Patients with multiple rib fractures whose pain is difficult to control can be treated with epidural analgesia. Adjunctive measures in the care of these patients include early mobilization and aggressive pulmonary toilet. Rib fractures do not require surgery. Pain relief and the establishment of adequate ventilation are the therapeutic goals for this injury.

Flail chest A flail chest, by definition, involves 3 or more consecutive rib fractures in 2 or more places, which produces a free-floating, unstable segment of chest wall. Separation of the bony ribs from their cartilaginous attachments, termed costochondral separation, can also cause flail chest. Patients report pain at the fracture sites, pain upon inspiration, and, frequently, dyspnea. Physical examination reveals paradoxical motion of the flail segment. The chest wall moves inward with inspiration and outward with expiration. Tenderness at the fracture sites is the rule. Dyspnea, tachypnea, and tachycardia may be present. The clinician should specifically be aware of the high incidence of associated thoracic injuries such as pulmonary contusions and closed head injuries, which, in combination, significantly increase the mortality associated with flail chest. In an attempt to stabilize the chest wall and to avoid endotracheal intubation and mechanical ventilation, various operations have been devised for correcting flail chest. These include pericostal sutures, the application of external fixation devices, or the placement of plates or pins for internal fixation.

Blunt diaphragmatic injuries Diaphragmatic injuries are relatively uncommon. Blunt mechanisms, usually a result of high-speed MVAs, cause approximately 33% of diaphragmatic injuries. Most diaphragmatic injuries are diagnosed incidentally at the time of laparotomy or thoracotomy for associated intra-abdominal or intrathoracic injuries. Initial chest radiographs are normal. Findings suggestive of diaphragmatic disruption on chest radiographs may include abnormal location of the nasogastric tube in the chest, ipsilateral hemidiaphragm elevation, or abdominal visceral herniation into the chest. A confirmed diagnosis or the suggestion of blunt diaphragmatic injury is an indication for surgery. Blunt diaphragmatic injuries typically produce large tears measuring 5-10 cm or longer. Most injuries are best approached via laparotomy. Most injuries can be repaired primarily with a continuous or interrupted braided suture (1- 0 or larger). Synthetic mesh made of polypropylene or Dacron is occasionally needed to repair large defects.

Blunt Injuries of the Pleurae, Lungs, and Aerodigestive Tracts Pneumothorax Pneumothoraces in blunt thoracic trauma are most frequently caused when a fractured rib penetrates the lung parenchyma. Patients report inspiratory pain or dyspnea and pain at the sites of the rib fractures. Physical examination demonstrates decreased breath sounds and hyperresonance to percussion over the affected hemithorax. In practice, many patients with traumatic pneumothoraces also have some element of hemorrhage, producing a hemopneumothorax. Patients with pneumothoraces require pain control and pulmonary toilet. All patients with pneumothoraces due to trauma need a tube thoracostomy. The chest tube is connected to a collection system that is entrained to suction at a pressure of approximately -20 cm water. The tube continues suctioning until no air leak is detected. The tube is then disconnected from suction and placed to water seal. If the lung remains fully expanded, the chest tube may be removed and another chest radiograph obtained to ensure continued complete lung expansion.

Hemothorax The accumulation of blood within the pleural space can be due to bleeding from the chest wall (eg, lacerations of the intercostal or internal mammary vessels attributable to fractures of chest wall elements) or to hemorrhage from the lung parenchyma or major thoracic vessels. Patients report pain and dyspnea. Physical examination findings vary with the extent of the hemothorax. Most hemothoraces are associated with a decrease in breath sounds and dullness to percussion over the affected area. Massive hemothoraces due to major vascular injuries manifest with the aforementioned physical findings and varying degrees of hemodynamic instability. Hemothoraces are evacuated using tube thoracostomy. Multiple chest tubes may be required. Pain control and aggressive pulmonary toilet are provided. The chest tube output is monitored closely because indications for surgery can be based on the initial and cumulative hourly chest tube drainage. Large, clotted hemothoraces may require an operation for evacuation to allow full expansion of the lung and to avoid the development of other complications such as fibrothorax and empyema. Thoracoscopic approaches have been used successfully in the management of this problem. 15

Frontal chest radiograph shows pleural effusion (asterisk) opacifying entire left hemithorax (opacified hemithorax) with contralateral mediastinal shift (arrows).

42-year-old man with chronic empyema and opening in right chest wall. Frontal chest radiograph shows right-sided pleural effusion (asterisk) and chest wall defect (arrow)

15-year-old girl with blunt injury to lower thorax. Frontal chest radiograph shows pleural effusion (asterisk) opacifying entire right hemithorax.

Open pneumothorax This injury is more commonly caused by penetrating mechanisms but may rarely occur with blunt thoracic trauma. Patients are typically in respiratory distress due to collapse of the lung on the affected side. Physical examination should reveal a chest wall defect that is larger than the cross- sectional area of the larynx. The affected hemithorax demonstrates a significant-to-complete loss of breath sounds. The increased intrathoracic pressure can shift the contents of the mediastinum to the opposite side, decreasing the return of blood to the heart, potentially leading to hemodynamic instability. Treatment for an open pneumothorax consists of placing a 3-way occlusive dressing over the wound to preclude the continued ingress of air into the hemithorax and to allow egress of air from the chest cavity. A tube thoracostomy is then performed. Pain control and pulmonary toilet measures are applied. Traumatic pulmonary herniation through the ribs, though uncommon, may occur following chest trauma. Unless incarceration or infarction is evident, immediate repair is not indicated.

Pneumothorax

Erect frontal chest radiograph shows left-sided pneumothorax ("visceral pleural line" sign)

Tension pneumothorax The mechanisms that produce tension pneumothoraces are the same as those that produce simple pneumothoraces. However, with a tension pneumothorax, air continues to leak from an underlying pulmonary parenchymal injury, increasing pressure within the affected hemithorax. Patients are typically in respiratory distress. Breath sounds are severely diminished to absent, and the hemithorax is hyperresonant to percussion. The trachea is deviated away from the side of the injury. The mediastinal contents are shifted away from the affected side. This results in decreased venous return of blood to the heart. The patient exhibits signs of hemodynamic instability, such as hypotension, which can rapidly progress to complete cardiovascular collapse. Immediate therapy for this life-threatening condition includes decompression of the affected hemithorax by needle thoracostomy. A large-bore needle (ie, 14- to 16-gauge) is inserted through the second intercostal space in the midclavicular line. A tube thoracostomy is then performed. Pain control and pulmonary toilet are instituted.

Frontal chest radiograph shows complete right lung collapse (unilateral hyperlucent lung) (asterisk) with ipsilateral hemidiaphragmatic depression, widened intercostal spaces, and contralateral mediastinal shift (arrows) indicative of tension pneumothorax.

Pulmonary contusion and other parenchymal injuries The forces associated with blunt thoracic trauma can be transmitted to the lung parenchyma. This results in pulmonary contusion, as characterized by development of pulmonary infiltrates with hemorrhage into the lung tissue. Clinical findings in pulmonary contusion depend on the extent of the injury. Patients present with varying degrees of respiratory difficulty. Physical examination demonstrates decreased breath sounds over the affected area. Pain control, pulmonary toilet, and supplemental oxygen are the primary therapies for pulmonary contusions and other parenchymal injuries. If the injury involves a large amount of parenchyma, significant pulmonary shunting and dead space ventilation may develop, necessitating endotracheal intubation and mechanical ventilation. Laceration or avulsion injuries that cause massive hemothoraces or prolonged high rates of bloody chest tube output may require thoracotomy for surgical control of bleeding vessels. If central bleeding is identified during thoracotomy, hilar control is gained first. Once the extent of injury is confirmed, it may become necessary to perform a pneumonectomy, keeping in mind that trauma pneumonectomy is generally associated with a high mortality rate (>50%).

Left pulmonary contusion following a motor vehicle accident involving a pedestrian.

Acute lung injury

35-year-old woman 24 hours after motor vehicle collision. Frontal chest radiograph shows diffuse patchy lung opacities, suggesting acute respiratory distress syndrome.

Pulmonary parenchymal injuries. 48-year-old woman 1 hour after motor vehicle collision. Frontal chest radiograph shows diffuse bilateral opacities, suggestive of pulmonary contusions.

Pulmonary parenchymal injuries. 37-year-old man 1 week after blunt chest trauma. Frontal chest radiograph shows diffuse bilateral opacities and right-sided cavitary lung lesion (asterisk), reflecting sequela of prior lung laceration.

64-year-old man injured in motor vehicle collision. Frontal chest radiograph shows left-sided lung herniation (asterisk).

Blunt bronchial injuries Rapid deceleration is the most common mechanism causing major blunt bronchial injuries. Many of these patients die of inadequate ventilation or severe associated injuries before definitive therapy can be provided. Patients are in respiratory distress and present with physical signs consistent with a massive pneumothorax. Ipsilateral breath sounds are severely diminished to absent, and the hemithorax is hyperresonant to percussion. Subcutaneous emphysema may be present and may be massive. Hemodynamic instability may be present and is caused by tension pneumothorax or massive blood loss from associated injuries. Laceration, tear, or disruption of a major bronchus is life threatening. These injuries require surgical repair. As with tracheal injuries, establishment of a secure and adequate airway is of primary importance. Patients with major bronchial lacerations or avulsions have massive air leaks. The approach to repair of these injuries is ipsilateral thoracotomy on the affected side after single-lung ventilation is established on the uninjured side. Operative repair consists of debridement of the injury and construction of a primary end-to- end anastomosis.

Blunt esophageal injuries Because of the relatively protected location of the esophagus in the posterior mediastinum, blunt injuries of this organ are rare. Blunt esophageal injuries are usually caused by a sudden increase in esophageal luminal pressure resulting from a forceful blow. Injury occurs predominantly in the cervical region; rarely, intrathoracic and subdiaphragmatic ruptures are also encountered. Associated injuries to other organs are common. Physical clues to the diagnosis may include subcutaneous emphysema, pneumomediastinum, pneumothorax, or intra-abdominal free air. Patients who present a significant time after the injury may manifest signs and symptoms of systemic sepsis. General medical supportive measures are appropriate. Fluid resuscitation and broad-spectrum intravenous antibiotics with activity against gram-positive organisms and anaerobic oral flora are administered. Surgery is required. Injuries identified within 24 hours of their occurrence are treated by debridement and primary closure. Some surgeons choose to reinforce these repairs with autologous tissue. Wide mediastinal drainage is established with multiple chest tubes. If more than 24 hours have passed since injury, primary repair buttressed by well-vascularized autologous tissue is still the best option if technically feasible. Examples of tissues used to reinforce esophageal repairs include parietal pleura and intercostal muscle. Very distal esophageal injuries can be covered with a tongue of gastric fundus. This is called a Thal patch. For patients in poor general condition and those with advanced mediastinitis or severe associated injuries, esophageal exclusion and diversion is the most prudent choice. A cervical esophagostomy is made, the distal esophagus is stapled, the stomach is decompressed via gastrostomy, and a feeding jejunostomy tube is placed. Wide mediastinal drainage is established with multiple chest tubes.

Pneumomediastinum. 32-year-old woman with esophageal rupture after blunt trauma. Frontal chest radiograph shows triangular radiolucency in left cardiophrenic angle ("Naclerio's V" sign) (asterisk).

Mediastinal bleeding and infection. 43-year-old man with penetrating injury to chest. Frontal chest radiograph identifies mediastinal widening (double-headed arrow), suggestive of vascular injury.

Tracheobronchial injuries. 39-year-old man injured in motor vehicle crash. Frontal chest radiograph shows irregularity of left main bronchus (arrow) and mediastinal widening (double-headed arrow), indicative of paratracheal hematoma.

Esophageal injuries. 31-year-old man with Boerhaave's syndrome. Frontal chest radiograph shows bilateral pneumomediastinum (arrows).

Esophageal injuries. 34-year-old woman with hiatal hernia. Frontal chest radiograph shows large retrocardiac opacity (arrows).

Blunt cardiac injuries MVAs are the most common cause of blunt cardiac injuries. Falls, crush injuries, acts of violence, and sporting injuries are other causes. Blunt cardiac injuries range from mild trauma associated only with transient arrhythmias to rupture of the valve mechanisms, interventricular septum, or myocardium (cardiac chamber rupture). Therefore, patients can be asymptomatic or can manifest signs and symptoms ranging from chest pain to cardiac tamponade (eg, muffled heart tones, jugular venous distension, hypotension) to complete cardiovascular collapse and shock due to rapid exsanguination. Many patients with blunt cardiac injuries do not require specific therapy. Those who develop an arrhythmia are treated with the appropriate antiarrhythmic drug. Elaboration on these drugs and their administration is beyond the scope of this article. Patients with severe blunt cardiac injuries who survive to reach the hospital require surgery. Most patients in this group have cardiac chamber rupture due to a high-speed MVA. The right side involvement is most common, involving the right atrium and right ventricle. They present with signs and symptoms of cardiac tamponade or exsanguinating hemorrhage. A few may be stable initially, resulting in delayed diagnosis. Those with tamponade benefit from rapid pericardiocentesis or surgical creation of a subxiphoid window. The next step is to repair the cardiac chamber by cardiorrhaphy. Cardiopulmonary bypass techniques can facilitate this procedure. Unstable patients may benefit from insertion of an intra-aortic counterpulsation balloon pump. Commotio cordis or sudden cardiac death in an otherwise healthy individual generally results from participation in a sporting event or some form of recreational activity. It is a direct result of blow to the heart just before the T-wave, resulting in ventricular fibrillation. Survival is not unheard of, if resuscitation and defibrillation are started within minutes. Preventive strategies include chest protective gear during sporting activities

Pericardial tears and ruptures. 24-year-old man injured in motor vehicle crash. Frontal chest radiograph shows leftward shift of heart silhouette (asterisk).

Pericardial tears and ruptures. 36-year-old man injured in motor vehicle crash. Frontal chest radiograph shows complete rotation of heart silhouette (asterisk) with apex pointing toward right.

Pericardial effusion. 33-year-old woman with pericardial effusion. Frontal chest radiograph shows globular bilateral enlargement of cardiac silhouette ("water- bottle" sign) (asterisks).

Pericardial effusion. 27-year-old man with pericardial effusion. Lateral chest radiograph shows separation of retrosternal and epicardial fat ("epicardial fat-pad," "Oreo cookie," sandwich, or stripe sign) (arrows).

Pneumopericardium. 43-year-old woman with pneumopericardium. Frontal chest radiograph shows band of air outlining heart (halo sign) inferiorly (arrows).

Pneumopericardium. 34-year-old man with gunshot wound to chest. Frontal chest radiograph shows left-sided pneumothorax (asterisk) and bilateral pneumopericardium compressing heart ("small heart" sign) (arrows).

Blunt injuries of the thoracic aorta and major thoracic arteries High-speed MVAs are the most common cause of blunt thoracic aortic injuries and blunt injuries of the major thoracic arteries. The mechanisms of injury are rapid deceleration, production of shearing forces, and direct luminal compression against points of fixation (especially at the ligamentum arteriosum). Many of these patients die from vessel rupture and rapid exsanguination at the scene of the injury or before reaching definitive care. Blunt aortic injuries follow closely behind head injury as a cause of death after blunt trauma. Physical clues include signs of significant chest wall trauma (eg, scapular fractures, first or second rib fractures, sternal fractures, steering wheel imprint), hypotension, upper extremity blood pressure differential, loss of upper or lower extremity pulses, and thoracic spine fractures. Signs of cardiac tamponade may be present. Decreased breath sounds and dullness to percussion due to massive hemothorax can also be found. Up to 50% of patients with these devastating, life- threatening injuries have no overt external signs of injury. Therefore, a high index of suspicion is warranted for earlier intervention. Endovascular stent grafts are being developed to repair thoracic aortic injuries. While several authors have reported success in treating such injuries with endo stents, the long-term durability of the stents is yet unknown. Further experience with this technique will allow more victims with concomitant severe injuries to become operative candidates. Techniques for repair of the innominate artery and subclavian vessels vary depending on the type of injury. Many require only lateral arteriorrhaphy. Large injuries of the innominate artery are managed first by placement of a bypass graft from the ascending aorta to the distal innominate artery. The injury is then approached directly and is oversewn or patched. 21,22,23 Proximal pulmonary arterial injuries are relatively easy to repair when in an anterior location. Posterior injuries frequently require cardiopulmonary bypass. Pulmonary hilar injuries present the possibility of rapid exsanguination and are best treated with pneumonectomy. Peripheral pulmonary arterial injuries are approached easily by thoracotomy on the affected side. They may be repaired or the corresponding pulmonary lobe or segment may be resected.

Traumatic rupture of the aortic arch

Blunt aortic injury typically occurs in the proximal segment of the descending thoracic aorta, due in part to the sudden disruption of the aortic isthmus. (B) Successful repair of a blunt aortic injury can be accomplished using an endoluminal approach.

A wide aortic arch curvature is seen in a 65-year-old patient who sustained a blunt aortic transaction injury. (B) Angiogram of a 17-year-old traffic accident victim showing injury to the descending thoracic aorta. Note the acute sharp curvature of the aortic arch.

(A) Aortogram revealing a blunt aortic injury in a 16-year-old male (short arrow). (B) Placement of an oversized GORE TAG endoprosthesis resulted in poor device apposition to the aorta in the proximal landing zone (long arrow).

(A) Successful deployment of a GORE TAG thoracic device can be achieved when appropriate device selection is made, as evidenced by the full apposition of the stent-graft in the aortic lumen. (B) When the device is inappropriately oversized relative to the aortic diameter, it can lead to device collapse in its leading segment (arrow). Image courtesy of Dr Michael Dake and WL Gore Associates.

Gore TAG thoracic

Chest CT scan shows isthmic aortic rupture (asterisk) with massive left hemothorax and contrast media extravasation (arrows).

Ruptureof thoracic aorta

Penetrating Chest Trauma Thoracic injuries account for 20-25% of deaths due to trauma and contribute to 25-50% of the remaining deaths. Approximately 16,000 deaths per year in the United States alone are attributable to chest trauma.

Thoracotomy Thoracotomy may be indicated for acute or chronic conditions. Acute indications include the following: Cardiac tamponade Acute hemodynamic deterioration/cardiac arrest in the trauma center Penetrating truncal trauma (resuscitative thoracotomy) Vascular injury at the thoracic outlet Loss of chest wall substance (traumatic thoracotomy) Massive air leak Endoscopic or radiographic evidence of significant tracheal or bronchial injury Endoscopic or radiographic evidence of esophageal injury Radiographic evidence of great vessel injury Mediastinal passage of a penetrating object Significant missile embolism to the heart or pulmonary artery Transcardiac placement of an inferior vena caval shunt for hepatic vascular wounds

Chronic indications for thoracotomy include the following: Nonevacuated clotted hemothorax Chronic traumatic diaphragmatic hernia Traumatic cardiac septal or valvular lesion Chronic traumatic thoracic aortic pseudoaneurysm Nonclosing thoracic duct fistula Chronic (or neglected) posttraumatic empyema Infected intrapulmonary hematoma (eg, traumatic lung abscess) Missed tracheal or bronchial injury Tracheoesophageal fistula Innominate artery/tracheal fistula Traumatic arterial/venous fistula

Thoracoscopy The role of video-assisted thoracoscopic surgery in the management of penetrating chest trauma is expanding rapidly. Initially promoted for the management of retained hemothoraces and the diagnosis of diaphragmatic injury, trauma and thoracic surgeons are now using thoracoscopy for treatment of chest wall bleeding, diagnosis of transmediastinal injuries, pericardial window, and persistent pneumothoraces.