Richard L. Byyny
Blunt chest trauma (BCT) is a common emergency department (ED) presentation. The trauma can range from the most minor chest wall contusion to catastrophic and fatal intrathoracic injury. BCT is involved in nearly one-third of admissions to trauma centers and accounts for about 25% of all trauma-related deaths in the United States (1). Most of these injuries are the result of motor vehicle collisions or pedestrians who are stuck by automobiles. Unlike penetrating injuries, BCT usually occurs when a large force is applied to a relatively larger area. Injury kinetics include acceleration and deceleration forces as well as transmission of blunt force to internal structures. BCT is often associated with multiple system trauma; including injury to the abdomen, head, spine, and extremities. Therefore, BCT must be evaluated in the context of these other injuries and, at times, more imminent life threats.
CLINICAL PRESENTATION
Chest Wall Injuries
Chest wall contusions and rib fractures account for the majority of blunt chest wall trauma (2). Rib fractures make breathing painful and can increase the patient’s morbidity and mortality by adversely affecting ventilation. Fractures typically occur at the site of the impact or the posterior angle where the rib is structurally the weakest. Fractures are more common in adults than children because of the relative inelasticity of the mature thorax. In fact the presence of rib fracture in children should raise the suspicion of child abuse and heighten the concern for coexisting intrathoracic injury (3). Elderly patients have a higher morbidity and mortality associated with rib fractures than younger patients with each additional fracture increasing the risk of death by 19% and increasing the risk of developing pneumonia by 27% (3). Although the fourth through the ninth ribs are most commonly involved, there is a fourfold increase in splenic injuries with left-sided rib fractures 9 to 11 and a threefold increase risk of liver injuries in right-sided rib fracture 9 to 11 (4). Multiple rib fractures or the presence of a flail chest wall segment may be associated with intrathoracic injury, usually a pulmonary contusion.
Clinical findings typically include pleuritic pain, tachypnea, splinting, and point tenderness intensified by deep breathing or coughing. Bony crepitus may be palpable. Anteroposterior compression of the thorax produces referred pain to the fracture site; if fracture is absent, there should not be referred pain to the localized area of tenderness.
Sternal Fractures
Sternal fractures usually result from high-energy forces to the midanterior chest wall. This force most commonly occurs from motor vehicle collisions in which the chest strikes the steering wheel, dashboard, or shoulder belt at high velocity. This force may result in a sternal fracture or costochondral separation and, in rare instances, an anterior flail chest when the sternum is disarticulated from the ribs. Patient may have point tenderness on their sternum, hematoma, or deformity.
Flail Chest
Flail chest occurs when three or more ribs are fractured in two or more places. In a patient who is breathing spontaneously, the negative intrathoracic pressure with inspiratory effort results in a paradoxical movement of the chest wall (the flail segment moves in during inspiration and out during expiration). There is usually no significant ventilatory compromise caused by the flail segment per se. In these patients, respiratory compromise is related to the degree of pulmonary contusion, which almost inevitably occurs when force is significant enough to cause a flail chest. However, in patients with large flail segments, the normal thoracic physiology is disrupted, causing respiratory failure requiring mechanical ventilation. All patients experience significant pain secondary to the respiratory movement of multiple rib fracture fragments and will often have tenderness, crepitus, and paradoxical movement of the chest wall. In some patients who are splinting or in those on positive-pressure ventilation, the flail segment may not be readily apparent. Palpation of the chest can help detect the injury. It is notable that in patients with flail segments the morbidity and mortality are increased when compared to patients with a similar numbers of fractures without a flail segment (5).
Pulmonary and Pleural Injuries
Blunt trauma may result in pneumothorax, hemothorax, or hemopneumothorax, usually secondary to a rib fracture penetrating the visceral pleura and lung parenchyma. Hemothorax usually results from disruption of an intercostal artery (see Chapter 32).
Pulmonary Contusion
The most common injury to the pulmonary parenchyma in BCT is pulmonary contusion. Among severely injured (ISS >15) blunt trauma patients approximately 27% had pulmonary contusion (6) and in children pulmonary contusion represents a large proportion of thoracic injuries (7). This injury results from transthoracic transmission of kinetic injury to the pulmonary parenchyma causing an alveolar–capillary membrane disruption and subsequent pulmonary edema. This injury results in areas of the lung that are perfused but not ventilated (i.e., a ventilation perfusion mismatch), resulting in hypoxia, hypercarbia, and acidosis.
Depending upon the extent, this injury results in minimal to life-threatening symptoms. A patient with a pulmonary contusion usually presents with dyspnea and tachypnea. There may be tenderness or obvious ecchymosis and deformity over the injured chest wall. Large pulmonary contusions are associated with tachycardia, hypotension, cyanosis, and low oxygen saturation. Patients with multiple rib fractures or flail segments of the chest wall are more likely to have associated pulmonary contusion.
Tracheal and Bronchial Injuries
Tracheal and bronchial injuries are rare accounting for only between 0.1% and 2% of patients who present to the ED (8). The majority of these injuries occur within 2 cm of the carina or at the origin of the lobar bronchi (9). Symptoms are usually related to the size of the defect in the airways and whether there is communication with the pleural space. Occasionally minimal symptoms may occur, even with severe tracheal or bronchial injury. Hemoptysis may occur in up to 25% of cases and subcutaneous emphysema or pneumomediastinum is present in 35% to 85% of cases (8). Patients can also present with dyspnea, hoarseness, or aphonia. This injury should be considered if there is a persistent air leak from a properly positioned chest tube and difficulty in fully reexpanding the lung.
Blunt Cardiac Injuries
By virtue of its location in the chest, the heart is susceptible to injury from compression of the chest wall and upper abdomen and from deceleration forces. It is the cause of death in up to 20% of automobile collisions. There is no gold standard to make the diagnosis of blunt cardiac injury; therefore, the true incidence is unknown and evaluating literature on the topic is difficult with different authors using different diagnostic standards. Therefore, there is a wide range of reported incidence from 20% to 76% of blunt thoracic trauma patients.
The right ventricle is the most commonly injured portion of the heart because of its relatively vulnerable position immediately behind the sternum; however, injuries to multiple chambers occur in 50% of cases (10). Blunt cardiac injury encompasses a spectrum of injuries including myocardial concussion, myocardial contusion, myocardial infarction, and myocardial rupture.
Myocardial concussion (commotio cordis) is a ventricular dysrhythmia or asystole secondary to a direct blow to the myocardium without pathologic evidence of cardiac injury. Myocardial concussion is the most common cause of sudden death in young athletes (11). Those patients who survive a myocardial concussion usually have little or no long-term sequelae from their blunt cardiac injury.
Myocardial contusion is characterized by localized edema and hemorrhage into cardiac muscle. This trauma may involve segments of the cardiac conduction system, most commonly the right bundle branches.
Traumatic myocardial infarction is rare but can occur from disruption of the coronary artery intima and subsequent thrombosis. The most severe form of blunt cardiac injury is cardiac rupture, which is a rare injury. These patients will present with hypotension or in extremis and usually have a right atrial or ventricular injury.
Physical findings in blunt cardiac injury may be nonspecific. Chest pain from either chest wall trauma or ischemia may be present. Seventy percent to 80% of patients with blunt cardiac injury have external signs of chest trauma including contusions, abrasions, palpable crepitus, and flail segments. The presence of a fractured sternum, once thought to be a marker for blunt cardiac injury, has not been shown to reliably correlate with the presence of a blunt cardiac injury (12). The most common vital sign abnormality is persistent sinus tachycardia after other causes have been treated. Hypotension is a serious sign and should raise the possibility of pericardial tamponade, myocardial rupture, or rupture of an internal cardiac structure such as a chordae tendineae or valve.
Great Vessel Injuries
Blunt aortic injury accounts for approximately 8,000 deaths per year in the United States, and up to 15% of automobile fatalities are caused by traumatic disruption of the aorta (13). Eighty percent of patients with aortic injuries die in the field. The tear of the aorta is usually a circumferential transverse laceration that disrupts the physical integrity of the intima and muscularis layers of the aorta. If the tear is complete, involving all three layers, this results in death caused by immediate exsanguination. In survivors, the adventitia remains intact, and blood is contained by a false aneurysm formed by the adventitia and surrounding mediastinal structures. If this injury is unrecognized, there is a significant risk of a free rupture and sudden death in the hours to days following this injury.
Disruption of the great vessels usually results from high-speed motor vehicle collisions, falls from a height, or ejection from motorcycles or other vehicles (13). The classic mechanism is a head-on motor vehicle collision, although the injury can occur after side or rear impacts. In seat-belted motor vehicle victims, descending thoracic tears are more common. Ascending aortic disruption is seen more often in unrestrained drivers or those who are ejected or fall from a height and experience vertical deceleration forces (14). Most often, these injuries involve the aorta but can involve the brachiocephalic artery and inferior vena cava. Patients with rupture of the vena cava have a poorer outcome because of continued, ongoing, significant blood loss and difficulty in controlling the bleeding and repairing the defect at surgery.
Several mechanisms have been postulated to explain aortic injuries. First, rapid horizontal deceleration produces shearing forces at the aortic isthmus just distal to the origin of the left subclavian artery. Ninety percent of traumatic aortic tears originate at this site. Anatomically, this frequency can be explained by the fact that the descending aorta is tethered by the ligamentum arteriosum and the intercostal arteries. The ascending aorta is relatively mobile and, during deceleration, continues to move forward while the descending aorta is held in place, resulting in shearing forces that cause a rent in the aorta (eFig. 31.1). The second proposed mechanism is that of the “water hammer” effect where a propagated wave of blood causes a surge in intraluminal pressure. Although the aorta may withstand intraluminal pressures of up to 350 mm Hg, this pressure may be surpassed leading to aortic injury (15). The final, and most likely, proposed mechanism is the “osseous pinch” model in which the aorta is pinched between the sternum and the vertebral column, resulting in shearing forces that cause injury to the aorta (16).
eFIGURE 31.1 Rapid deceleration injury causing a tear in the thoracic aorta. The ascending (anterior) aorta tends to continue moving forward, while the more fixed descending aorta is held stationary. The rupture occurs just distal to the ligamentum arteriosum at the level of the isthmus.
The symptoms and signs of traumatic great vessel disruption are often absent or missed because of coexisting, significant injuries to the head, spine, abdomen, pelvis, and extremities. The most frequently recorded complaints are chest pain, dyspnea, and back pain. However, it is of note that only 25% of patients present with retrosternal pain or pain radiating to the upper back which is considered typical of nontraumatic aortic dissection. Other symptoms include dysphagia, hoarseness, and ischemic pain of the extremities. Physical examination may reveal ecchymosis, abrasion, or tenderness of the anterior chest wall consistent with the impact of this area on a steering wheel. Thirty-one percent of patients with an aortic disruption present with the pseudocoarctation syndrome. In these cases, upper-extremity hypertension is present with decreased or absent femoral pulses because of compression of the aortic lumen by surrounding periaortic hematoma. Reflex stretching of the cardiac sympathetic fibers at the aortic isthmus may account for the observation that 72% of patients with aortic rupture manifest a relative hypertension (average blood pressure 152/98 mm Hg) (17). A harsh systolic murmur over the precordium or interscapular area (thought to be because of turbulent flow across the area of transection) has been reported to be present in 26% of cases (18). Unfortunately, the presence of great vessel injury cannot be confirmed or ruled out based on physical examination or history.
In confirmed cases of traumatic aortic injury, one-third to one-half of the patients have no external evidence of chest injury on initial presentation to the ED. Therefore, this injury should be suspected, even in the absence of these signs or symptoms, whenever there has been major acceleration–deceleration forces involving the chest (i.e., significant ejection mechanisms, falls from heights >10 ft, and motor vehicle collisions with speeds >30 mph, and a lack of proper vehicle restraints).
Diaphragmatic Injuries
Blunt traumatic diaphragmatic injury results from violent compression of the lower chest and upper abdomen and has an incidence between 0.5% and 8% of blunt trauma victims (15). Sixty percent to 90% of traumatic rupture of the diaphragm from blunt trauma occurs on the left side (19). Blunt trauma typically produces diaphragmatic defects of >10 cm on average and has a higher mortality rate than penetrating injury to the diaphragm because of the higher incidence of serious associated injuries to abdominal and chest structures.
Signs and symptoms of diaphragmatic rupture are highly variable depending upon the size of the defect, the mechanism, the abdominal viscus that herniates through the defect, and the degree of cardiopulmonary compromise. Common symptoms include cough, dyspnea, nonspecific chest or abdominal pain radiating to the shoulder, and the perception of peristalsis in the chest. Signs include an immobile left hemithorax, decreased breath sounds, and tympany or borborygmi in the left chest. Significant herniation of abdominal viscera into the thoracic cavity usually results in severe respiratory distress and may be clinically confused with a tension pneumothorax. A tension viscerothorax (gastrothorax) occurs when the resulting increase in intrapleural pressure causes shift of the mediastinum and hemodynamic collapse. Therefore, great care should be taken when performing a thoracostomy to verify a free pleural space before inserting the chest tube.
Esophageal Injuries
Esophageal injuries secondary to blunt trauma are rare occurrences yet critical to diagnose secondary to the high morbidity and mortality when treatment is delayed. They have been reported from sharp blows or when force is applied to the upper abdomen in which air and gastric contents are violently forced into the esophagus causing a perforation in the distal esophagus similar to those that results from retching and vomiting (i.e., Boerhaave syndrome). Injuries to the esophagus can also occur with compression of the esophagus against the spine, producing longitudinal tears in the upper thoracic esophagus and can be associated with laceration in the membranous (i.e., posterior) portion of the trachea, resulting in traumatic tracheoesophageal fistulas. Injuries to the esophagus can also occur from barotrauma, because the esophagus is a hollow, air-containing organ. An example of this is forceful insufflation of the esophagus from inhalation of aerosol cans, air compressors, or inflation devices or in children from the biting of inner tubes, and eruption of bottled carbonated beverages into the esophagus. Perforations of the esophagus can result from alkali ingestion, button batteries, foreign bodies, and iatrogenic misplaced tubes or endoscopes.
Signs and symptoms of esophageal injury are subcutaneous emphysema (especially in the neck or supraclavicular fossa), unexplained tachycardia, dyspnea, dysphagia, odynophagia, cyanosis, pneumomediastinum, pneumothorax, pleural effusion (particularly on the left), and hematemesis.
Traumatic Asphyxia
Traumatic asphyxia occurs when the thorax is squeezed between two objects for a prolonged period of time. This results in compression of the vena cava with resultant prolonged increased venous pressure to the neck and head. This prolonged squeeze and compromised venous return results in intense cyanosis of the upper chest, neck, and face as well as petechiae and subconjunctional hemorrhage. Some patients may have retinal hemorrhage and loss of consciousness because of cerebral hypoxia. Sometimes there are associated chest wall and pulmonary parenchymal injuries such as pulmonary contusion and hemopneumothorax.
DIFFERENTIAL DIAGNOSIS
The differential diagnosis of chest wall injuries includes rib fractures, flail chest, sternal fracture, costochondral separation, and chest wall contusion.
After blunt trauma, the differential diagnosis for pulmonary and pleural injuries includes pulmonary contusion, pneumothorax, hemothorax, hemopneumothorax, pulmonary contusion, tension pneumothorax, and acute pericardial tamponade. Tension pneumothorax must be differentiated from acute pericardial tamponade because both cause tachycardia, hypotension, and an elevated central venous pressure (CVP). In patients with tension pneumothorax breath sounds are absent or markedly diminished and pericardial ultrasound is normal.
The differential diagnosis of tracheal and bronchial injuries includes other traumatic causes of pneumomediastinum, such as a ruptured esophagus or an iatrogenic perforation of the esophagus, posterior pharynx, or pyriform sinus during attempts at endotracheal intubation.
In patients with blunt cardiac injury, rupture of the valves or chordae tendineae may result in acute cardiac failure. In rare instances, blunt cardiac injury may cause acute pericardial tamponade. This injury can be differentiated from tension pneumothorax by the presence of a pericardial effusion on ultrasound, as well as by bilaterally equal breath sounds on physical examination.
The majority of patients who suffer from blunt thoracic aortic injury have coexisting serious injuries. These include fractures of the sternum and ribs, hemothorax, pneumothorax, hemopneumothorax, tracheobronchial disruption, diaphragmatic rupture, esophageal perforation, acute pericardial tamponade, and blunt trauma to the myocardium.
Traumatic rupture of the diaphragm can be confused with a pneumothorax or a tension pneumothorax when abdominal viscera have herniated into the thoracic cavity resulting in respiratory distress and diminished or absent breath sounds, usually on the left side.
ED EVALUATION
Chest Wall Injuries
After a history and physical examination including pulse oximetry, chest wall trauma can be evaluated with chest radiography. However, chest radiographs may not be necessary in isolated, localized chest wall trauma when there are no physical findings and no respiratory distress manifested by tachypnea or decreased oxygen saturations. Up to 50% of rib fractures are missed on the initial chest radiographs; 10% do not visualize radiographically for 1 to 2 weeks after the injury regardless of the views taken. Specific rib views are unnecessary and much of the time the presumptive diagnosis can be made without radiography. A chest radiograph is valuable when looking for complications of rib fractures such as hemothorax, pneumothorax, pulmonary contusion, atelectasis, and pneumonia. Because elderly patients have a greater morbidity and mortality from complications of rib fractures, there should be a lower threshold for evaluating these patients with a chest x-ray and rib films (15).
Consideration should be given to observation, performance of the focused assessment with sonography in trauma (FAST) examination, or abdominal computed tomography (CT) in the presence of 9th through 11th rib fractures given the heightened risk for spleen or liver injury. Pain referred to either shoulder may indicate the presence of either hemothorax or pneumothorax or subdiaphragmatic hemorrhage from injury to the spleen or liver. Patients who present several days after their initial trauma with increasing pain, dyspnea, or fever following chest wall trauma should have a chest x-ray to ascertain if there are any late complications such as atelectasis or pneumonia.
Flail Chest
Patients with evidence of a flail chest on physical examination should be evaluated with oxygen saturation monitoring and a radiograph of the chest to detect the presence of underlying pulmonary contusion, pneumothorax, or hemothorax. Parenteral analgesics or regional nerve blocks are necessary for adequate analgesia.
Pulmonary and Pleural Injuries
Clinical signs of tension pneumothorax or massive hemothorax (decreased breath sounds or subcutaneous emphysema in association with hypotension, tachycardia, and respiratory distress) mandate initial placement of a needle or tube thoracostomy prior to obtaining chest radiography. Tension pneumothorax should be a clinical diagnosis and should not be captured on a chest x-ray. The extended focused abdominal ultrasound in trauma (E-FAST) has been more widely utilized to assist in the diagnosis of pneumothorax. In addition to usual components of the FAST examination (evaluation of the right upper quadrant, left upper quadrant, pericardium, and retrovesicular space) the E-FAST also includes ultrasonography of the pleural surface using the high-frequency linear probe. It has been shown to have superior sensitivity to the supine chest x-ray and can expedite the diagnosis of pneumothorax (20). If the patient is hemodynamically stable, a portable chest radiograph is the initial study of choice; this will demonstrate hemothorax, pneumothorax, and pneumomediastinum.
Pulmonary Contusion
Radiographic evidence of pulmonary contusion may not be evident initially on the chest x-ray because these injuries tend to get worse over the ensuing hours following injury with the peak not being present until 72 hours after injury (6). Radiographic findings usually lag behind the clinical findings. A contrast-enhanced helical CT scan of the chest will detect the presence of pulmonary contusions before they become visible on standard chest radiographs. CT scans may be used to measure the extent of the pulmonary contusion and to determine the prognosis (6). All patients should be placed on oxygen and have continuous oxygen saturation monitoring. If the oxygen saturation is low, an arterial blood gas can be obtained to calculate an alveolar–arterial gradient and followed serially to determine subsequent therapy.
Tracheal and Bronchial Injuries
These injuries should be suspected when there is a persistent air leak despite the proper placement of a tube thoracostomy on the involved side. All patients should have a chest x-ray to rule out associated pneumothorax and to confirm that all the holes on the chest tube are within the thoracic cavity. Consideration should also be given to diagnostic studies that rule out the presence of an esophageal disruption (discussed later in this chapter). Surgical consultation should be obtained so that bronchoscopy can be performed for definitive diagnosis.
Blunt Cardiac Injuries
All patients in whom this injury is suspected should have cardiac rhythm and oxygen saturation continuously monitored. An electrocardiogram (ECG) should be obtained to ascertain the presence of any dysrhythmia, bundle-branch block, or new changes on the ECG (15). An initial ED ultrasound of the pericardium to detect the presence of pericardial effusion and to determine, if possible, the quality of cardiac wall motion should be performed. New murmurs or acute congestive failure after chest trauma should raise the suspicion of a ruptured interventricular septum, valve leaflet, or chordae tendineae. Traumatic ventricular septal rupture presents with a pansystolic murmur heard throughout the entire precordium, especially at the left sternal border. This murmur may not be appreciated until the patient has been resuscitated to a euvolemic state. In patients exhibiting hemodynamic instability and clinical signs of cardiac failure, a formal echocardiogram should be obtained to look for the presence of pericardial tamponade, valvular or chordae tendineae disruption, and to determine cardiac output.
Chest radiographs are not helpful in diagnosing cardiac trauma per se but may be helpful in identifying other thoracic injuries. Although nondiagnostic, multiple ECG abnormalities have been described that range from persistent sinus tachycardia to ST- and T-wave changes and bundle-branch blocks (the most common being right bundle-branch block). If ECG abnormalities are present, the patient should be admitted for 24 to 48 hours of continuous cardiac monitoring. The presence of a normal ECG confers a negative predictive value of 95% in ruling out myocardial contusion (12). Troponin I is helpful in making the diagnosis and in the stratification of those at risk for life-threatening conditions. If the troponin is not elevated at 4 to 6 hours post injury and the ECG is normal, the patient may be discharged from the ED conferring a negative predictive value of 100% (12). Neither nuclear testing nor echocardiogram is useful in diagnosing myocardial contusion.
Great Vessel Injuries
In patients with a major traumatic mechanism, a chest x-ray is a helpful screening tool in detecting not only great vessel injuries but also other associated thoracic abnormalities. There are multiple radiographic features of great vessel injury (Fig. 31.1). The most sensitive finding in patients with aortic injury is a wide mediastinum (>6 cm upright and >8 cm supine anteroposterior view) (13). However, only 10% of patients with a wide mediastinum will end up having an aortic injury; other causes include sternal, rib, or spine fractures, and the supine radiography. Sitting the patient up after the cervical spine has been cleared will decrease the incidence of a wide mediastinum. Despite the many radiographic signs of traumatic aortic injury that have been described, in 7% to 28% of cases of aortic injury the chest radiograph is normal (eTable 31.1) (14). Therefore, it is prudent to consider further diagnostic studies, if there is a significant mechanism, even in the presence of a completely normal upright chest x-ray (13,21).
FIGURE 31.1 Upright posteroanterior chest radiographs of a 20-year-old man involved as a driver in a head-on motor vehicle collision (A) compared with that of a normal person (B). The first radiograph has several abnormalities suggestive of a great vessel disruption. A: Loss of detail of aortic knob with blurring of the aortic outline. B: Widened mediastinum (mediastinal width to chest width ratio >0.28). C: Opacification of the clear space between the aorta and pulmonary artery (aortopulmonary window). D: Obliteration of the medial aspect of the left upper field. The aortogram revealed rupture of the aortic arch. (Radiographs courtesy of the Department of Radiology, St. Luke’s Hospital, Milwaukee, WI.)
eTABLE 31.1
Radiographic Features of Great Vessel Injury
CT scanning of the chest with contrast has become the procedure of choice when the diagnosis of mediastinal great vessel injury is considered, with reported sensitivity and specificity of 96% to 100% and 98% to 100%, respectively (22,23). An added benefit to CT is the detection of other thoracic injuries. Furthermore, CT is noninvasive and can be completed in a short period of time. Contrast-enhanced CT of the chest should be performed in those patients who have any findings on chest x-ray associated with traumatic aortic injury, are hemodynamically stable, and have sustained significant acceleration–deceleration blunt-force chest trauma such as high-speed motor vehicle collisions or falls from a significant height. Positive criteria for the diagnosis of great vessel injury include periaortic hematoma, an irregular aortic contour, change in caliber of the aorta, and intraluminal irregularity (intimal flap).
Transesophageal echocardiography (TEE) is reported to have a sensitivity and specificity comparable to helical CT in the diagnosis of blunt aortic injury (23). In contrast to CT, TEE can be performed at the bedside in an unstable patient. However, in contrast to helical chest CT, its availability is limited in most EDs. TEE may be performed in an ICU setting or the operating room to diagnose aortic injury in unstable patients and those with other life-threatening injuries. This technique is contraindicated in patients with esophageal injury or unstable cervical spine injuries.
Aortography was once considered the gold standard for making the diagnosis of traumatic aortic injury, but it is now only used in a small number of cases with equivocal findings on helical CT, when planning the surgery in some selected cases, and interventional radiographic endovascular stenting is being increasingly used to treat patients with aortic injury (24).
Diaphragmatic Injuries
An immediate chest x-ray should be obtained when blunt traumatic rupture of the diaphragm is suspected by the clinical examination (i.e., decreased or absent breath sounds on the involved side, bowel sounds audible in the chest, severe respiratory distress), and the patient has sustained major blunt-force trauma to the lower chest or upper abdomen. In most instances of blunt traumatic rupture, the left hemidiaphragm is not visualized on the radiograph, and stomach or bowel is often visualized in the left hemithorax. Small diaphragmatic tears may not be obvious on initial chest x-ray but may be diagnosed with contrast-enhanced abdominal CT.
Esophageal Injuries
The presence of particulate matter in chest tube drainage as well as the presence of pneumomediastinum should lead the physician to consider esophageal perforation. This diagnosis has a very high morbidity and mortality if not recognized early and treated aggressively. When this diagnosis is suspected, it is imperative to move rapidly to a definitive diagnostic study to rule out this entity. The choice of the initial diagnostic procedure is somewhat controversial and is dependent upon the suspected injury. Some authors advocate esophagography, and others advocate esophagoscopy. Contrast esophagography has the disadvantage of potentially introducing contrast material into the mediastinum or peritoneum. Therefore, this study should first be performed with a water-soluble contrast material (i.e., Gastrografin), which has a much lower risk of mediastinitis or peritonitis than does barium. However, care should be taken in patients at risk for aspiration, as the entry of water-soluble contrast into the tracheobronchial tree can lead to pulmonary edema. If this study is negative, it can be followed by esophagoscopy, because Gastrografin will not obscure visualization of the lining of the esophagus. Ultimately, a barium esophagram may be needed to detect the presence of very small perforations.
Traumatic Asphyxia
Because these patients can sustain rib fractures and pulmonary contusions, one should consider chest CT to evaluate these injuries. Also, any patient with a neurologic deficit should have a CT of the head.
KEY TESTING
ED MANAGEMENT
Chest Wall Injuries
Chest wall contusions and rib fractures with no underlying pulmonary parenchymal injury should be managed with adequate analgesics as well as careful aftercare instructions encouraging the patient to cough and deep breathe every hour while awake to prevent the complications of atelectasis and subsequent pneumonia. Patients may be discharged with a spirometer to aid them in following these instructions. Consideration can be given to regional nerve blocks for multiple rib fractures, but these may only give significant pain relief for up to 12 hours. Admission, for pulmonary toilet and pain control, should be considered in the elderly especially those over 65 with rib fractures (3).
Flail Chest
Pain can be controlled with administration of narcotics, regional nerve blocks, or in severe cases, epidural anesthesia. Intubation should be considered if there is respiratory distress or ventilatory failure as manifested by a partial pressure of arterial oxygen (PaO2) of <60 mm Hg on a nonrebreather bag reservoir mask at sea level or low oxygen saturation. In elderly patients with flail chest, the physician should have a lower threshold for intubation, as the patients’ cardiac and pulmonary reserves are limited.
Sternal Fractures
Patients with suspected sternal fractures should have a standard posteroanterior (PA) and lateral chest x-ray. The lateral chest x-ray is the best view to determine if a fracture is present.
Pulmonary and Pleural Injuries
Tension pneumothorax, pneumothorax, and hemothorax should be treated emergently with tube thoracostomy (see Chapter 32). Patients with clinical evidence of tension pneumothorax should undergo immediate chest decompression prior to chest x-ray. Although this can be performed with a 14- or 16-gauge needle, in up to 30% of patients a standard needle will not reach the pleural space in the anterior second intercostal space and up to 18% of patient it will not reach the pleural space in the midaxillary line (25). Therefore, preference should be given to rapid decompression of the chest in the midaxillary line with eventual placement of a 28- to 36-French chest tube for adults or a 16- to 24-French chest tube for children. Alternatively clinicians can also place a pigtail catheter (26,27). Small (<15%), simple pneumothoraces or those visualized on CT only (occult pneumothorax) can often be observed and treated without thoracostomy (15). Patients with occult pneumothorax who will undergo transfer in an ambulance or helicopter are at risk for development of a larger pneumothorax (or tension pneumothorax), clinicians should consider tube thoracostomy. Although positive-pressure ventilation was once considered an absolute indication for tube thoracostomy, there exist more recent literature suggesting that it may be possible to observe patient with occult pneumothorax (28).
Patients with pulmonary contusions should be placed on continuous, high-flow oxygen via a nonrebreather bag reservoir mask, and their oxygen saturation should be continuously monitored. Patients with more severe injury can undergo a trial of noninvasive positive-pressure ventilation; however, those patients who exhibit falling oxygen saturations or hypercarbia should be considered for rapid sequence intubation (RSI) and positive-pressure ventilation (6). Independent lung ventilation with low tidal volume and positive end-expiratory pressure (PEEP) has been reported to be efficacious in the treatment of unilateral pulmonary contusions.
Patients with an initial thoracostomy tube output of >20 mL/kg or an ongoing blood loss of >7 mL/kg/h are candidates for operative thoracotomy.
Tracheal and Bronchial Injuries
In a patient who clinically has a major airway disruption or problems maintaining adequate oxygen saturation, endotracheal intubation should be performed. In some instances, selective intubation of the nontraumatized mainstem bronchus is indicated. All tracheobronchial lacerations and disruptions require a surgical consultation, further diagnostic studies (bronchoscopy), and definitive management.
Blunt Cardiac Injuries
All patients should be on oxygen and monitored for dysrhythmias. Any dysrhythmias should be treated per advanced cardiac life support (ACLS) guidelines. Care must be taken not to fluid overload patients with myocardial contusion as their compromised cardiac output may lead to pulmonary edema. Patients who remain hemodynamically compromised after adequate volume resuscitation may benefit from pressor support with dobutamine. Unstable patients with pericardial tamponade require pericardiocentesis or ED thoracotomy. Patients with abnormalities detected on echocardiography such as chordae tendineae or valvular disruption should be referred to a cardiac surgeon for definitive repair of these lesions. In those rare instances where blunt cardiac trauma results in myocardial infarction from intimal disruption and thrombosis of the coronary artery, patients should undergo emergency angioplasty because the use of thrombolytics is contraindicated. The last option for refractory cardiogenic shock is placement of an intra-aortic balloon pump. The prognosis for patients with blunt cardiac trauma is most closely correlated with the severity and number of other associated injuries, as most patients who have an isolated myocardial contusion do well.
Great Vessel Injuries
In patients in whom a traumatic aortic injury is strongly suspected or proven via CT scan of the chest, blood pressure should be controlled via the use of a β-blocker (usually intravenous [IV] esmolol) and an afterload-reducing agent (usually IV nitroprusside) (13). β-blocking agents are usually started first. The objective of lowering blood pressure is to decrease the shearing forces of the pulse pressure, thus decreasing the possibility of free rupture. Using nitroprusside without a β-blocking agent may result in a reflex tachycardia and increased intraluminal pressure. The systolic blood pressure should be maintained between 100 and 120 mm Hg with a heart rate of 55 to 65 beats/min. In patients with bleeding and associated hypotension, judicious resuscitation to a mean arterial pressure between 65 and 80 mm Hg is adequate. All patients must be emergently referred for definitive therapy. Although all of these patients have traditionally been treated surgically, endovascular stent placement using interventional radiographic techniques has been used successfully as well; it appears to have a lower risk of complications, and in some centers it has replaced open thoracotomy for the repair of aortic injuries. The decision on which therapy is best for the individual patient should be made in consultation with a surgeon and interventional radiologist. Many patients with aortic injury have associated life-threatening injuries that require management before repair of the aorta.
Diaphragmatic Injuries
A nasogastric tube should be placed and emergent surgical consultation for operative repair of the diaphragm should be obtained. Some of these patients may require RSI intubation, sedation, and mechanical ventilation if there is significant respiratory compromise. Unstable patients with tension viscerothorax should undergo careful tube thoracostomy placement. It is advisable to place the thoracostomy tube at a higher intercostal space to avoid injury to the bowel or introduction of the tube below the diaphragm.
Esophageal Injuries
Once the presence of an esophageal injury is confirmed by a contrast study of the esophagus or by esophagoscopy, surgical consultation for definitive surgical repair and drainage should be obtained to minimize the subsequent morbidity and mortality of this lesion. IV antibiotics should be administered preoperatively.
ED Thoracotomy
For patients with blunt trauma who sustain cardiac arrest prior to arrival in the ED, an ED thoracotomy is a futile procedure. Those patients who arrest after arrival in the ED and undergo ED thoracotomy have a 1.4% survival rate and thus are potential candidates for ED thoracotomy. Patients with isolated cardiac or pulmonary injuries have the best chance of survival after ED thoracotomy (29).
CRITICAL INTERVENTIONS
• Perform tube thoracostomy immediately for patients with clinical signs of tension pneumothorax or massive hemothorax (decreased breath sounds or subcutaneous emphysema in association with hypotension, tachycardia, and absent breath sounds).
• Obtain an ECG in patients with a mechanism consistent with potential myocardial contusion.
• Obtain an echocardiogram in unstable patients with clinical signs of cardiac failure to detect pericardial tamponade and valvular or chordae tendineae disruption.
• Administer esmolol, then nitroprusside, to control blood pressure in patients in whom a traumatic aortic injury is strongly suspected or proven by CT scan.
DISPOSITION
Patients with contused ribs and isolated rib fractures may be discharged from the ED. Patients should be instructed to return if they develop any increasing shortness of breath, fever, chills, cough, or other new symptoms. Patients with multiple rib fractures should be admitted for continued monitoring, observation, and, in some selected circumstances, consideration of epidural anesthesia for pain. In particular, elderly patients with rib fractures should be admitted for pain control and appropriate management to prevent pulmonary complications.
All patients with flail chest should be admitted to the hospital and carefully monitored via continuous oxygen saturation for an evolving pulmonary contusion, which almost always accompanies this injury. In addition, these patients have significant pain and usually require parenteral analgesics and consideration of regional or epidural nerve blocks.
Patients with fractures of the sternum sometimes need admission for analgesics because of associated injuries to the bony thorax and intrathoracic cavity. If the fracture is displaced, surgical reduction may be required. However, patients with isolated nondisplaced sternal fractures may be discharged after appropriate measures have been taken to rule out the presence of other thoracic injuries.
Patients with pneumothorax, hemothorax, hemopneumothorax, and tension pneumothorax should be admitted to the appropriate inpatient surgical service for continued observation and treatment. Most patients with a pneumothorax and hemothorax only require a tube thoracostomy and do not require subsequent thoracotomy. However, in those patients in whom active, continued bleeding occurs or a persistent air leak is present, additional studies and surgery may be necessary.
All patients with a suspected or proven pulmonary contusion should be admitted to the hospital for continued monitoring and treatment because most pulmonary contusions will gradually worsen over the first 24 hours.
Patients with tracheal and bronchial injuries must be admitted and often require surgical repair if the injuries do not spontaneously resolve.
Patients who have sustained blunt anterior chest trauma, who have no associated injury necessitating admission, and who have a normal ECG may be discharged from the ED. The prognosis of patients with blunt cardiac injury is related to the magnitude of the initial trauma, the preexisting condition of the heart, the size and location of the cardiac injury, and the patient’s other traumatic injuries; thus, those who are elderly or have coronary artery disease, significant dysrhythmias, a positive troponin, or any new abnormality on an ECG should be admitted for continuous monitoring for 12 to 24 hours. Patients with operable blunt trauma to the heart, such as myocardial and valve rupture or acute pericardial tamponade, need early and aggressive cardiac surgical treatment.
Traumatic disruption of the great vessels is potentially immediately life threatening; as soon as the diagnosis is suspected or confirmed, trauma or vascular surgery and interventional radiology should be consulted. After other more immediate life threats have been treated, these lesions should receive definitive surgical or interventional radiographic repair.
All patients with diaphragmatic injuries must be admitted to a trauma surgeon for definitive repair of the tear in the diaphragm as well as repair of associated intra-abdominal and intrathoracic injuries that often accompany these injuries.
Patients with confirmed esophageal perforation require antibiotics, admission, and immediate surgical consultation. Patients should be transferred to an appropriate surgeon and facility if resources for this definitive management are not available.
Those patients who have sustained traumatic asphyxia but have no evidence of significant chest wall, intrathoracic, or neurologic injury may be discharged home. Those patients with associated intrathoracic or neurologic injury should be admitted for continued observation and treatment.
Patients who must be transferred to another trauma facility for definitive treatment or critical care management should undergo a chest x-ray prior to transfer. Tube thoracostomy should be performed prior to transfer in patients with pneumothorax, hemothorax, or those with an occult pneumothorax detected only by CT. Patients with significant chest wall trauma or flail chest, especially the elderly, should be intubated prior to transfer. Any BCT patient with suspected aortic injury should be transferred to a trauma center.
Common Pitfalls
• Failure to appreciate a serious deceleration mechanism of injury.
• Failure to recognize the potential morbidity of rib fractures in the elderly.
• Delaying transfer of a patient to an appropriate level trauma center for definitive management of aortic injury.
• Failure to consider esophageal perforation in any patient with mediastinal emphysema.
• Insertion of a chest tube into an abdominal viscus in patients with a ruptured diaphragm.
• Overzealous fluid administration in patients with pulmonary or myocardial contusions.
• Failure to provide adequate analgesia and pulmonary care to patients with rib fractures, leading to the development of atelectasis and pneumonia.
REFERENCES
1. Khandhar SJ, Johnson SB, Calhoon JH. Overview of thoracic trauma in the United States. Thorac Surg Clin. 2007;17(1):1–9.
2. Sirmali M, Turut H, Topcu S, et al. A comprehensive analysis of traumatic rib fractures: Morbidity, mortality and management. Eur JCardiothorac Surg. 2003; 24(1):133–138.
3. Bulger EM, Arneson MA, Mock CN, et al. Rib fractures in the elderly. J Trauma. 2000;48(6):1040–1046; discussion 1046–1047.
4. Shweiki E, Klena J, Wood GC, et al. Assessing the true risk of abdominal solid organ injury in hospitalized rib fracture patients. J Trauma. 2001;50(4):684–688.
5. Velmahos GC, Vassiliu P, Chan LS, et al. Influence of flail chest on outcome among patients with severe thoracic cage trauma. Intl Surg. 2002;87(4):240–244.
6. Cohn SM, Dubose JJ. Pulmonary contusion: An update on recent advances in clinical management. World J Surg. 2010;34(8):1959–1970.
7. Balci AE, Kazez A, Eren S, et al. Blunt thoracic trauma in children: Review of 137 cases. Eur J Cardiothorac Surg. 2004;26(2):387–392.
8. Bernardin B, Troquet JM. Initial management and resuscitation of severe chest trauma. Emerg Med Clin North Am. 2012;30(2):377–400, viii–ix.
9. Kiser AC, O’Brien SM, Detterbeck FC. Blunt tracheobronchial injuries: Treatment and outcomes. Ann Thorac Surg. 2001;71(6):2059–2065.
10. Karalis DG, Victor MF, Davis GA, et al. The role of echocardiography in blunt chest trauma: A transthoracic and transesophageal echocardiographic study. J Trauma. 1994;36(1):53–58.
11. Lateef F. Commotio cordis: An underappreciated cause of sudden death in athletes. Sports Med. 2000;30(4):301–308.
12. Clancy K, Velopulos C, Bilaniuk JW, et al. Screening for blunt cardiac injury: An Eastern Association for the surgery of trauma practice management guideline. J Trauma Acute Care Surg. 2012;73(5 suppl 4):S301–S306.
13. Nagy K, Fabian T, Rodman G, et al. Guidelines for the diagnosis and management of blunt aortic injury: An EAST Practice Management Guidelines Work Group. J Trauma. 2000;48(6):1128–1143.
14. Frick EJ, Cipolle MD, Pasquale MD, et al. Outcome of blunt thoracic aortic injury in a level I trauma center: An 8-year review. J Trauma. 1997;43(5):844–851.
15. McGillicuddy D, Rosen P. Diagnostic dilemmas and current controversies in blunt chest trauma. Emerg Med Clin North Am. 2007;25(3):695–711, viii–ix.
16. Crass JR, Cohen AM, Motta AO, et al. A proposed new mechanism of traumatic aortic rupture: The osseous pinch. Radiology. 1990;176(3):645–649.
17. Fox S, Pierce WS, Waldhausen JA. Acute hypertension: Its significance in traumatic aortic rupture. J Thorac Cardiovasc Surg. 1979;77(4):622–625.
18. Symbas PN, Tyras DH, Ware RE, et al. Traumatic rupture of the aorta. Ann Surg. 1973;178(1):6–12.
19. Matsevych OY. Blunt diaphragmatic rupture: Four year’s experience. Hernia. 2008;12(1):73–78.
20. Dulchavsky SA, Schwarz KL, Kirkpatrick AW, et al. Prospective evaluation of thoracic ultrasound in the detection of pneumothorax. J Trauma. 2001;50(2):201–205.
21. Exadaktylos AK, Sclabas, G., Schmid SW, et al. Do we really need routine computed tomographic scanning in the primary evaluation of blunt chest trauma in patients with “normal” chest radiograph? J Trauma. 2001;51(6):1173–1176.
22. Parker MS, Matheson TL, Rao AV, et al. Making the transition: The role of helical CT in the evaluation of potentially acute thoracic aortic injuries. AJR Am J Roentgenol. 2001;176(5):1267–1272.
23. Vignon P, Boncoeur MP, Francois B, et al. Comparison of multiplane transesophageal echocardiography and contrast-enhanced helical CT in the diagnosis of blunt traumatic cardiovascular injuries. Anesthesiology. 2001;94(4):615–622; discussion 615 A.
24. Bent CL, Matson MB, Sobeh M, et al. Endovascular management of acute blunt traumatic thoracic aortic injury: A single center experience. J Vasc Surg. 2007;46(5):920–927.
25. Sanchez LD, Straszewski S, Saghir A, et al. Anterior versus lateral needle decompression of tension pneumothorax: Comparison by computed tomography chest wall measurement. Acad Emerg Med.2011;18(10):1022–1026.
26. Kulvatunyou N, Vijayasekaran A, Hansen A, et al. Two-year experience of using pigtail catheters to treat traumatic pneumothorax: A changing trend. J Trauma. 2011;71(5):1104–1107; discussion 1107.
27. Kulvatunyou N, Joseph B, Friese RS, et al. 14 French pigtail catheters placed by surgeons to drain blood on trauma patients: Is 14-Fr too small? J Trauma Acute Care Surg. 2012;73(6):1423–1427.
28. Mowery NT, Gunter OL, Collier BR, et al. Practice management guidelines for management of hemothorax and occult pneumothorax. J Trauma. 2011; 70(2):510–518.
29. Rhee PM, Acosta J, Bridgeman A, et al. Survival after emergency department thoracotomy: Review of published data from the past 25 years. J Am Coll Surg. 2000;190(3):288–298.