INTRODUCTION — Blunt chest trauma puts multiple structures at risk of injury. In addition to direct trauma, rapid deceleration and other mechanisms can cause injury to thoracic structures. Major concerns include chest wall injury, such as rib fractures or flail chest; cardiovascular injury, such as blunt aortic injury (BAI) or cardiac contusion; and pulmonary injury, such as contusions or lacerations. BAI is the most lethal injury of the thorax if untreated.

This topic will review the epidemiology, diagnosis, and initial management of injuries sustained in adults from blunt thoracic trauma (BTT). Fundamentals of initial trauma management, thoracic trauma in children, and other injuries sustained from trauma are discussed separately. (See "Initial management of trauma in adults" and "Thoracic trauma in children: Initial stabilization and evaluation" and "Initial evaluation and management of rib fractures" and "Initial evaluation and management of chest wall trauma in adults" and "Initial evaluation and management of blunt cardiac injury" and "Initial evaluation and management of blunt abdominal trauma in adults".)

EPIDEMIOLOGY — Motor vehicle collisions (MVCs) represent the most common cause of major thoracic injury among emergency department (ED) patients [1,2]. Several factors are associated with a higher risk of thoracic injury:

●High speed

●Not wearing a seatbelt [3-5]

●Extensive vehicular damage

●Steering wheel deformity [6,7]

Increased mortality and morbidity is associated with multiple rib fractures, increased age, and higher injury severity scores (ISSs) [1,8-11]. (See "Initial evaluation and management of rib fractures".)

Studies of chest trauma are often based upon data from trauma registries that catalog admitted trauma patients. Patients with minor injuries or isolated rib fractures are often discharged and do not appear in such registries, leading to substantial bias in the trauma literature toward more seriously injured patients [10].

●Blunt aortic injury – The majority of blunt trauma patients who sustain a major aortic injury die immediately. Of those who reach the hospital alive, the majority either die during initial management or are unable to undergo aortic repair due to their injuries, both intra- and extrathoracic [12].

A number of occupant and collision characteristics are independently associated with blunt aortic injury (BAI), the most lethal of blunt thoracic injuries [3,13].

High-risk occupant characteristics include:

•Age ≥60 (relative risk [RR] 3.6; 95% CI 2.5-5.2)

•Front-seat occupancy (RR 3.1; 95% CI 1.5-6.3)

•Not wearing a seatbelt (RR 3.0; 95% CI 2.2-4.3)

High-risk collision characteristics include:

•Front- or near-side MVC (RR 3.1; 95% CI 1.9-5.1 and RR 4.3; 95% CI 2.6-7.2, respectively)

•Abrupt deceleration ≥40 km/hour (RR 3.8; 95% CI 2.6-5.6)

•Crushing of the vehicle (ie, ≥40 cm) (RR 4.1; 95% CI 2.7-6.3)

•Intrusion ≥15 cm (RR 5.0; 95% CI 3.5-7.3)

The risk of injury to the thoracic aorta is also greater among passengers traveling in a car struck by a sports utility vehicle (RR 1.7; 95% CI 1.2-2.3).

●Blunt cardiac and pulmonary injury – Up to 20 percent of deaths from MVCs are attributable to blunt cardiac injuries [14,15]. Most patients with such injuries die in the field. Pneumothorax is a common complication of thoracic trauma. The incidence of occult pneumothorax (ie, not diagnosed on chest radiograph [CXR]) among victims of blunt trauma is less clear, ranging from 2 to 55 percent in patients who undergo computed tomography (CT) of the chest or abdomen [16]. The risk of pulmonary contusion appears to correlate with crash severity and the proximity of the site of impact to the patient [17]. (See "Initial evaluation and management of blunt cardiac injury".)

●Rib fractures – Observational studies suggest that rib fractures occur in almost two-thirds patients with chest trauma due to MVCs. However, most of these studies evaluated patients involved in high-energy trauma admitted to trauma centers. In one study, researchers evaluated the chest radiographs of all alert patients presenting to their ED following blunt trauma [2]. They found that multiple rib fractures (>2) was the most common serious thoracic injury and occurred in approximately 5 percent of patients. The presence of multiple rib fractures, particularly ribs one through three, increases the risk of intrathoracic injury, especially in older adults. Even isolated, minor rib fracture may be associated with a small risk of pneumonia, especially in older adults and patients with pulmonary disease [18]. (See "Initial evaluation and management of rib fractures" and "Geriatric trauma: Initial evaluation and management".)

●Fractures of the sternum and scapula – The presence of a fracture of the sternum or scapula reflects trauma of significant force, which increases the risk for significant internal injury. Patients with such injuries warrant close evaluation. The epidemiology of these injuries is reviewed separately. (See "Initial evaluation and management of chest wall trauma in adults", section on 'Epidemiology'.)

ANATOMY AND MECHANISM

Anatomy and physiology — The rib cage, intercostal muscles, and costal cartilage form the basic structure of the chest wall (figure 1). In addition, neurovascular bundles comprised of an intercostal nerve, artery, and vein run along the inferior aspect of each rib. The inner lining of the chest wall is the parietal pleura. Visceral pleura covers the major thoracic organs. Between the two is a potential space normally containing a small amount of lubricating fluid, but blood or air can accumulate there following injury. The anterior chest wall also contains the sternum (figure 2) and pectoralis major and minor muscles, as well as the clavicle at its superior border. Posteriorly, the scapula provides added protection to the superior thorax. The scapula (figure 3) is a dense bone encased in muscle, and significant force is necessary to fracture it.

The chest wall has two important functions: to assist in the mechanics of respiration and to protect the intrathoracic organs. Adequate ventilation is accomplished by creating negative intrathoracic pressure during inspiration and positive pressure during expiration. During inspiration, a combination of diaphragmatic excursion and contraction of the intercostal muscles to raise the ribs in a "bucket-handle" fashion increases intrathoracic volume and decreases intrathoracic pressure, which then pulls air passively into the lungs. In expiration, this process is reversed: all the muscles relax and intrathoracic pressure passively increases and volume decreases, forcing air out of the lungs.

The chest wall protects against devastating injuries to the intrathoracic structures (figure 4 and figure 5 and figure 6). In fulfilling this role, the chest wall is commonly injured. While generally not life-threatening, chest wall injuries can be extremely painful and can lead to significant morbidity if not recognized and treated appropriately. (See "Initial evaluation and management of chest wall trauma in adults".)

The mediastinum is an anatomic division of the thorax extending from the diaphragm inferiorly to the thoracic inlet superiorly (figure 7 and figure 8 and figure 9). Its borders include the sternum anteriorly, the vertebral column posteriorly, and the parietal pleura laterally. Contained within the mediastinum are the heart, aorta, trachea, and esophagus. Injuries to any of these structures are potentially life threatening. One lung is located lateral to each side of the mediastinum.

With blunt trauma, the most common isolated mediastinal injury involves the aorta (figure 10). Hemorrhage from other nearby structures, such as venous lacerations or fractures of the ribs, sternum, or vertebra, can manifest as mediastinal blood, raising concern for aortic injury (algorithm 1). Aortic injuries are mainly transverse tears with relatively smooth margins. The underlying injury ranges from a simple subintimal hemorrhage, with or without intimal laceration, to complete aortic transection [19].

The diaphragm constitutes the floor of the thoracic cavity (figure 11). The diaphragm exhibits substantial movement with inspiration and expiration, and thus, posttraumatic pain in the lower thorax may reflect intraabdominal as well as intrathoracic injury.

Selected mechanisms — Blunt chest trauma occurs through a variety of mechanisms, including motor vehicle collisions (MVCs), assaults, and falls. Particularly in older adults, apparently minor trauma (eg, fall from standing) can cause serious injury. Any of the mechanisms listed can cause rib fractures, flail chest, or chest wall contusions.

Aortic tears usually occur from high-energy injuries to the thorax, often following rapid deceleration. Several theories for the mechanism of aortic disruptions have been proposed, and it is likely that a number of factors are involved. These theories are discussed separately. (See "Clinical features and diagnosis of blunt thoracic aortic injury", section on 'Pathophysiology of injury'.)

Pulmonary contusions most often result from high-energy MVCs. Mortality is difficult to quantify because pulmonary contusions often occur in tandem with other severe injuries. Damage leads to ventilation-perfusion inequalities and decreased lung compliance [20,21]. Researchers postulate several possible mechanisms for pulmonary contusion, including the implosion theory, where air expansion causes alveolar tearing; the "inertia effect," which occurs when lighter alveoli are stripped from the heavier bronchi; and the "spalling effect," which involves shearing at the gas-liquid interface.

PREHOSPITAL MANAGEMENT — Prehospital management depends on patient symptoms and severity of illness. Prehospital providers should treat patients with possible underlying pulmonary, cardiac, or major extrathoracic injuries according to the principles of Advanced Trauma Life Support (ATLS), paying special attention to the patient's airway, breathing, and circulation. Rapid transport to the closest trauma center is crucial; interventions causing unnecessary delay must be avoided. Basic interventions such as cervical spine immobilization are appropriate, as is the use of high-flow oxygen and monitoring. Transport should not be delayed to place intravenous (IV) lines or perform endotracheal intubation, unless the patient is in extremis and cannot be stabilized with bag mask ventilation. More extensive intervention may be needed if prolonged transport time is expected. A detailed discussion of prehospital trauma care is found elsewhere. (See "Prehospital care of the adult trauma patient".)

If the patient shows no evidence of respiratory difficulty or underlying injury, no intervention may be necessary. Before leaving the scene of a vehicular accident, prehospital caretakers should quickly make note of important features associated with increased risk of injury and convey these findings to clinicians at the trauma center upon arrival. Such findings include: significant intrusion into the passenger compartment, deformed steering wheel, ejection of the patient from the vehicle, and fatality at the scene. Prehospital hypotension is an important indication of significant injury, and this finding must be communicated to the clinicians assuming care of the patient.

PRIMARY EVALUATION AND MANAGEMENT

Primary survey and initial management — Initial resuscitation and management of the trauma patient is based upon protocols from Advanced Trauma Life Support (ATLS) and is reviewed separately; details pertaining to the initial assessment and management of BTT are discussed below. A basic algorithm for management of BTT is provided (algorithm 2). (See "Initial management of trauma in adults".)

Clinicians first assess and stabilize the patient's airway, breathing, and circulation, in that order (ABCs; ie, primary survey). The one caveat to this principle in patients with respiratory distress following chest trauma is that breathing may take priority over airway. If the patient is in respiratory distress due to a tension pneumothorax, the clinician should relieve the pneumothorax before performing endotracheal intubation, if needed. Positive-pressure ventilation following intubation will exacerbate a pneumothorax.

Tracheobronchial injury (TBI), a rare but life-threatening complication of severe chest trauma, may require that airway management be modified. Patients in extremis are intubated in standard fashion, but clinicians must take care to avoid exacerbating any injury during intubation and high airway pressures during mechanical ventilation. Bronchoscopy is the preferred approach to airway management because it allows for characterization of the lesion and safe placement of the tracheal tube, but it may not be practical in the acute setting with unstable patients. If TBI is suspected in a stable patient based on suggestive clinical or radiographic findings, immediate consultation for bronchoscopy should be obtained. (See 'Tracheobronchial injury' below.)

After addressing the patient's ABCs, the clinician continues the initial evaluation taking into account vital signs, the initial presentation, and the mechanism of injury. Mechanism is less predictive of injury severity and ultimate disposition than abnormal vital signs in the setting of blunt trauma [22]. Ultrasound examination (extended Focused Assessment with Sonography for Trauma [eFAST]), including assessment for pericardial effusion and pneumothorax, is performed as part of the examination. (See "Emergency ultrasound in adults with abdominal and thoracic trauma".)

For any patient with unstable vital signs, hypoxia, or obvious severe injury (eg, flail chest, multiple rib fractures, large open wounds), the clinician performs a rapid search with concurrent management of immediate life-threatening injuries of the head, cervical spine, abdomen, chest, and pelvis. Immediate surgical consultation should be obtained. (See "Initial management of trauma in adults", section on 'Primary evaluation and management'.)

Immediate life-threatening injuries from blunt chest trauma include:

●Tension pneumothorax

●Cardiac tamponade from myocardial injury (see "Cardiac tamponade")

●Aortic injury (see "Clinical features and diagnosis of blunt thoracic aortic injury")

●Hemothorax with severe, active bleeding (see 'Hemothorax' below)

●Tracheobronchial disruption (see "Identification and management of tracheobronchial injuries due to blunt or penetrating trauma")

Patients with respiratory distress, marked hemodynamic instability, or severe injury are intubated. Rapid sequence intubation is the preferred approach whenever possible, avoiding pretreatment and induction agents with the potential to cause hypotension. (See "Rapid sequence intubation for adults outside the operating room" and "Initial management of trauma in adults", section on 'Airway'.)

Patients with a tension pneumothorax may manifest tachypnea, chest pain, hypoxia, unilateral diminished or absent breath sounds, subcutaneous air, or unilateral hyperresonance to percussion, depending on the extent of the pneumothorax. Suspected tension pneumothorax is treated with immediate tube thoracostomy or needle decompression using a large angiocatheter (eg, 14 gauge) (image 1 and image 2 and image 3). (See 'Pulmonary injury' below.)

Needles as long as 7 to 8 cm may be necessary to decompress a pneumothorax, depending upon the size of the patient [23]. Acceptable sites for needle insertion include the second or third intercostal space in the midclavicular line or the fifth intercostal space in the anterior or mid-axillary line; however, success rates are likely higher when the anterior or mid-axillary line of the fifth intercostal space is used. If needle decompression is performed first, it is followed by tube thoracostomy soon afterwards. A size 28 to 32 French chest tube is used. Needle decompression is discussed in greater detail separately. (See "Prehospital care of the adult trauma patient", section on 'Needle chest decompression' and "Thoracostomy tubes and catheters: Indications and tube selection in adults and children".)

If an initially unstable patient stabilizes in the emergency department (ED) and does not require emergency surgery, chest computed tomography (CT) with contrast is performed to define the extent of any thoracic injury and exclude aortic rupture (image 4 and image 5). If the patient is unable to undergo CT due to the need for immediate operation, transesophageal echocardiography can be performed in the operating room to assess the aorta and heart. (See 'Aortic injury' below.)

Patients with cardiac tamponade may initially appear stable if the rate of bleeding is slow or the pericardium periodically decompresses by emptying blood into the pleural space. Some patients may complain of shortness of breath. Beck's triad (hypotension, jugular venous distension [JVD], muffled heart sounds) can be difficult to detect and may not be present. In hypovolemic patients, JVD may be absent. Ultimately, tamponade physiology causes diminished cardiac output, leading to a decrease in systolic blood pressure and narrowing of the pulse pressure. (See "Cardiac tamponade", section on 'Clinical presentation'.)

Following blunt trauma, cardiac tamponade is most often caused by myocardial injury and can be detected by ultrasound as part of the first study performed for the standard eFAST examination (movie 1). Pericardiocentesis is performed immediately in patients with a pericardial effusion and significant hypotension. In patients requiring transport to another hospital, a catheter should be placed when pericardiocentesis is performed. The catheter allows for drainage during transport should fluid reaccumulate and cause hypotension. (See "Emergency pericardiocentesis".)

If hemodynamic compromise is severe and tamponade cannot be relieved by percutaneous drainage, or if the patient develops cardiac arrest while being resuscitated, ED thoracotomy (EDT) may be necessary. (See "Initial evaluation and management of penetrating thoracic trauma in adults", section on 'Emergency department thoracotomy (EDT)' and "Resuscitative thoracotomy: Technique", section on 'Preparation'.)

Depending on the extent of bleeding, hemothorax causes diminished breath sounds and signs of shock and is apparent with bedside imaging. Hemothorax is treated with tube thoracostomy using a size 28 to 32 French chest tube. Immediate bloody drainage of ≥20 mL/kg is generally considered an indication for thoracotomy in the operating room. Vital signs, fluid resuscitation requirements, and concomitant injuries are also considered when determining the need for thoracotomy. (See 'Hemothorax' below.)

Severe injuries to the intrathoracic trachea, carina, or a mainstem bronchus due to blunt trauma generally present with varying degrees of dyspnea and subcutaneous emphysema. Emphysema may track into the mediastinum or neck, and emphysema, pneumothorax, or both may be apparent on a portable chest radiograph or ultrasound examination. Bilateral pneumothorax should raise suspicion for TBI. Airway management in patients with blunt TBI can be difficult due to anatomic distortion and, depending on the nature and extent of the wound, attempts at tracheal tube placement may exacerbate the injury. (See "Identification and management of tracheobronchial injuries due to blunt or penetrating trauma", section on 'Airway management'.)

The evaluation of hemodynamically stable patients without obvious signs of injury varies depending upon mechanism, age, and clinical suspicion. (See 'Subsequent management' below.)

Emergency thoracotomy — In the setting of blunt trauma, EDT rarely results in successful resuscitation [24-29]. Among blunt trauma patients, EDT enables neurologically intact survival in approximately less than 5 percent of those in shock, 1 percent of those without vital signs upon arrival to the ED, and none of those without signs of life in the field [28]. A more complete discussion of EDT, including epidemiology, indications, and practice guidelines, is found separately. (See "Initial evaluation and management of penetrating thoracic trauma in adults", section on 'Emergency department thoracotomy (EDT)'.)

Given the resources required and risks entailed in EDT, we recommend hospitals develop policies to determine the circumstances under which the procedure is to be performed. A trauma or thoracic surgeon should be readily available if EDT is performed: immediate surgical intervention may be necessary if the patient is to survive. The subset of blunt trauma patients most likely to survive an EDT neurologically intact includes the following:

●Patients who lose vital signs in the ED and appear to have no obvious nonsurvivable injury (eg, massive head trauma, multiple severe injuries)

●Patients with cardiac tamponade rapidly diagnosed by ultrasound, with no obvious nonsurvivable injury

EDT in blunt trauma patients appears to be futile in any one or more of the following circumstances:

●Patient required over 15 minutes of prehospital cardiopulmonary resuscitation (CPR)

●Patient is apneic, pulseless, and has no rhythm on cardiac monitor in the field

●Patient has massive, nonsurvivable injuries

Some observational data suggest that no blunt trauma patient who requires more than five minutes of CPR survives neurologically intact [27]. A systematic review of 27 observational studies involving 1369 blunt trauma patients reported an overall survival rate with good neurologic outcome of only 1.5 percent [30]. All surviving patients (n = 21) had either measurable vital signs at the scene or in the ED and a maximum duration of cardiopulmonary resuscitation of 11 to 15 minutes.

History, examination, and monitoring — Acute evaluation of BTT consists of rapidly assessing whether injury has occurred to cardiopulmonary and mediastinal structures. Depending on the presentation, this may be as simple as a thorough history and physical examination or may require multiple tests, including radiographs, CT scans, and echocardiography.

The clinician first determines whether the patient is at low or high risk for significant injury. This determination is based on the vital signs, the mechanism and potential for injury, and the patient's complaints and general clinical appearance [1,2,8-10]. Of note, according to a systematic review of studies of aortic injury from blunt trauma, many patients present with normal vital signs, and thus, hemodynamic stability does not rule out aortic injury [31].

The limited utility of mechanism should be emphasized: a young, healthy patient involved in a severe, rollover motor vehicle collision (MVC) may sustain no injuries, while a frail older adult patient who trips and falls may incur multiple rib fractures accompanied by a pulmonary contusion. (See 'Anatomy and mechanism' above.)

Studies suggest the history and physical examination are insensitive for detecting intrathoracic injury. This insensitivity stems in part from the nature of the studies, which often include a heterogeneous mix of patients and injuries, a low number of positive findings, and a lack of follow-up.

The risk of serious injury is low among alert patients without discomfort, dyspnea, or tenderness [32-35]. Hypoxia and abnormal lung sounds are the most specific signs for pneumothorax or hemothorax, while chest pain and tenderness are most sensitive, albeit nonspecific [36]. Normal lung sounds showed a high negative predictive value (NPV) for pneumothorax in one prospective, observational study, but the number of patients with abnormal findings was too low to draw definitive conclusions [34]. Important examination findings associated with life-threatening intrathoracic injuries that should be noted during the primary survey are described above. (See 'Primary survey and initial management' above.)

Chest radiograph — The chest radiograph (CXR) is the initial test for all patients with BTT who warrant imaging [37]. The CXR is inexpensive, noninvasive, and easy to obtain, and in many instances, it reveals useful information. For these reasons, we suggest a CXR be obtained in all patients who have sustained BTT of any significance, unless the patient requires immediate surgery or warrants immediate chest CT. Patients with minor trauma whose clinical evaluation reveals no signs of injury may not require a CXR; a decision instrument to help determine whether to forego a CXR is described at the end of this section.

The CXR is systematically reviewed for evidence of hemothorax (image 6), pneumothorax (image 1 and image 2 and image 3), pulmonary contusion (image 7), fractures (image 8), and aortic injury. Studies to determine CXR findings suggestive of blunt aortic injury (BAI) are limited by their observational design and the small number of injuries [38-40]. Nevertheless, although no single finding on CXR possesses high sensitivity or specificity for BAI, the following findings on a plain CXR increase the likelihood of BAI and indicate a need for further investigation:

●Wide mediastinum (supine CXR >8 cm; upright CXR >6 cm)

●Obscured aortic knob; abnormal aortic contour

●Left "apical cap" (ie, pleural blood above apex of left lung)

●Large left hemothorax

●Deviation of nasogastric tube rightward

●Deviation of trachea rightward and/or right mainstem bronchus downward

●Wide left paravertebral stripe

A widened mediastinum is a sensitive but nonspecific sign of aortic injury (image 4). Overall, the correlation between mediastinal widening and aortic injury is poor, except for aortic rupture with bleeding into the mediastinum. Aortic injuries account for about 20 percent of abnormal mediastinal widening on CXR after blunt trauma [41]. Further study, usually CT of the chest, is performed if CXR abnormalities consistent with aortic injury are identified or there is clinical concern for significant injury. (See 'Chest computed tomography' below.)

Initial evaluation with a portable, anterior-posterior (AP) CXR is performed in patients at greater risk of significant injury who must remain in the ED for closer monitoring. Such patients include those with a more severe mechanism of injury, hemodynamic instability, significant tenderness, a seatbelt sign across the abdomen (picture 1 and picture 2), hypoxia, or clinical signs of multiple rib fractures. The plain CXR may not have sufficient sensitivity to detect injury in these patients, and minor abnormalities on CXR or clinical concern are sufficient to justify more detailed imaging with chest CT or other modalities.

The stable patient with minimal findings (eg, minor abrasion, mild tenderness, and normal vital signs) can be sent to radiology for standard posterior-anterior (PA) and lateral CXR, provided the physical examination is otherwise unremarkable and there is no suspicion of major injury. Patients with pain and tenderness of the lower ribs, especially with pleuritic complaints, or abdominal pain and tenderness are at higher risk for both intrathoracic and intraabdominal injuries [42].

Normal PA and lateral chest radiographs in a low-risk patient obviate the need for additional studies to rule out intrathoracic or chest wall injury. Rib films are rarely needed. They may provide more information about fractures but rarely change management. The clinician can treat patients likely to have sustained a rib fracture on the basis of symptoms and signs, despite the absence of radiographic evidence [43-45]. (See "Initial evaluation and management of rib fractures".)

The NEXUS Chest Decision Instrument studies evaluated the utility of chest imaging in the assessment of blunt trauma. In practice, the instrument is used most often to determine the need for chest CT, but it may also be used to help determine the need for CXR (algorithm 3). The NEXUS investigations include a prospective validation study involving 9905 patients that reported on the tool's effectiveness for identifying blunt trauma patients at low risk of intrathoracic injury [46]. The instrument uses seven simple criteria:

●Age >60 years

●Mechanism involving rapid deceleration

●Chest pain

●Intoxication

●Abnormal alertness/mental status

●Distracting painful injury

●Tenderness to chest wall palpitation

Clinically significant intrathoracic injury is highly unlikely in the absence of all criteria. Although the study found the rule to have high sensitivity (98.8 percent; 95% CI 98.1-99.3) and NPV (98.5 percent; 95% CI 97.6-99.1), specificity was low (13.3 percent; 95% CI 12.6-14.1). Determination of the need for chest CT following blunt trauma is discussed below. (See 'Chest computed tomography' below.)

Ultrasound — Ultrasound (ie, FAST exam) has become an integral part of trauma evaluation, primarily to assess for pericardial tamponade and intraabdominal injury. Ultrasound of the chest is also commonly performed in the ED to rule out or diagnose pneumothorax or hemothorax. However, the sensitivity of ultrasound for significant injuries sustained from BTT is limited. CT remains the preferred imaging tool for patients with significant BTT. The use of ultrasound in thoracic trauma and related evidence are discussed separately. (See "Emergency ultrasound in adults with abdominal and thoracic trauma" and 'Chest computed tomography' below.)

Chest computed tomography

Indications and accuracy — The diagnostic accuracy of CT is far greater than plain radiography for intrathoracic injury and allows for detailed evaluation of intrathoracic structures [47-50]. CT provides greater sensitivity for diagnosing small pneumothoraces, pneumomediastinum, and pulmonary contusions and lacerations. In addition, contemporary scanners allow for rapid three-dimensional imaging of the aorta and bony structures if there are any findings or concerns raised by the initial examination or preliminary imaging studies [16,47,51].

Pending further study, we believe the decision to obtain a chest CT for BTT should be based upon the clinical findings. In addition to the physical examination, these include a plain CXR when one is obtained, the patient's mental status and distracting injuries, the mechanism of injury and any other relevant history, available resources, clinician judgment, institutional tolerance for delayed diagnosis (eg, forgoing a CT in favor of serial examinations and close observation), and other relevant factors.

The NEXUS research group has developed and prospectively validated decision instruments to help determine which adults with BTT can safely forego CT imaging of the chest [46,52,53]. The criteria and use of the NEXUS instruments are summarized in the following graphic (algorithm 3). It bears emphasizing that the purpose of the NEXUS guidelines is to help determine which patients can safely forego imaging; clinical judgment retains an important role in determining which patients should be imaged. (See 'NEXUS decision rules' below.)

The use of chest CT for trauma evaluation has increased dramatically; in many centers, patients involved in high-energy trauma are sent almost immediately for CT before a CXR can be performed. Patients with a low-risk mechanism, minor injuries by examination, and a normal CXR generally do not require CT imaging, which may be overused in these circumstances [47,54-57]. However, findings from some observational studies suggest that a substantial number of patients sustain clinically significant intrathoracic injuries that are identified by CT but do not manifest abnormal findings on plain CXR [49,58]. Conversely, abnormalities apparent on a plain radiograph strongly suggest the presence of a clinically significant injury [59]. We believe that it is reasonable to obtain a chest CT in patients with concerning clinical findings (eg, severe pain or marked chest tenderness, hypoxia, dyspnea, tachypnea) despite an unremarkable plain CXR or ultrasound, and in patients with an abnormal plain CXR despite the absence of obvious clinical signs of injury. This approach is consistent with the NEXUS guidelines.

Whether to obtain a CT purely on the basis of a high-risk mechanism remains controversial. Results of studies have been mixed but tend to favor performing a chest CT in patients with significant mechanisms of injury or severe concomitant injuries. As examples, one prospective study of consecutive trauma patients with a significant mechanism of injury found that 19.6 percent of chest CT scans revealed clinically important abnormalities despite the absence of external signs of thoracic injury in the 592 hemodynamically stable patients included [60]. A prospective study of 609 blunt trauma patients imaged with CT noted that 11 percent of chest CT scans deemed unnecessary by emergency clinicians prior to their being obtained were reported to have clinically meaningful findings, including two that resulted in critical actions (spinal surgery for a T8 burst fracture and chest tube insertion for a lung laceration) [61].

NEXUS decision rules — We believe the NEXUS instruments can provide useful guidance to clinicians and help to decrease the number of unnecessary CT scans obtained [46,52,53]. These instruments are highly sensitive and useful tools when applied appropriately. The criteria for all three NEXUS instruments are included with the following algorithm for imaging blunt chest trauma (algorithm 3).

While the absence of all criteria indicates low risk, the presence of any one criterion does not necessarily indicate high risk and the need for CT. In general, the clinician should have decided that imaging may be appropriate and useful, and then should apply the NEXUS criteria to determine whether imaging can be foregone safely without missing injury.

The first iteration of the NEXUS decision instrument (NEXUS Chest) includes the following criteria [46]:

●Age >60 years

●Chest pain

●Intoxication

●Abnormal alertness or mental status

●Chest wall tenderness

●Distracting painful injury

●Rapid deceleration mechanism (ie, fall >20 feet [>6 m], or MVC >40 mph [>65 km/hour])

If all criteria are absent, the patient has a very low risk for intrathoracic injury, and chest imaging of any kind is not indicated. The first validation study of this instrument included 9905 patients over the age of 14, evaluated at nine trauma centers, whose initial workup for blunt chest trauma included a plain CXR, chest CT, or both, which revealed 363 major injuries [46]. In this study, NEXUS Chest demonstrated a sensitivity of 98.8 percent and specificity of 13.3 percent for any thoracic injury seen on chest imaging.

In a subsequent iteration of the NEXUS decision instrument (Chest CT-All), age >60, chest pain, intoxication, and abnormal mental function were removed, while the following criteria were added [52]:

●Abnormal plain chest radiograph

●Sternal tenderness

●Thoracic spine tenderness

●Scapular tenderness

In a subsequent iteration created explicitly to detect major thoracic injury (Chest CT-Major), rapid deceleration mechanism was removed. Injuries considered major include aortic or great vessel injury, diaphragm rupture, pneumothorax or hemothorax requiring thoracostomy, spine or other major fracture requiring surgical repair, esophageal, tracheal, or bronchial injury requiring surgical intervention, pulmonary contusion requiring ventilatory support, and several others.

While all the NEXUS decision rules have demonstrated high sensitivity for major injury (approximately 99 percent), Chest CT-All had a specificity of 20.8 percent (95% CI 19.2-22.4) and an NPV of 99.8 percent (95% CI 98.9-100) for major injury, while for either major or minor injury, the rule demonstrated a specificity of 25.5 percent (95% CI 23.5-27.5%) and an NPV of 93.9 percent (95% CI 91.5-95.8). Chest CT-Major had a specificity of 31.7 percent (95% CI 29.9-33.5) and an NPV of 99.9 percent (95% CI 99.3-100) for major injury.

In a follow-up study of the 269 BTT patients who sustained major injuries, researchers noted that except for an abnormal plain CXR, the risk for major injury remained low in the presence of any one criterion [59]. By contrast, the sensitivity and specificity of an abnormal plain radiograph for major injury were relatively high (73.7 [95% CI 68.1-78.6] and 83.9 [95% CI 83.6-84.2], respectively), highlighting the importance of carefully assessing any plain CXR obtained. Clinicians should not hesitate to obtain imaging studies if they have concerns based upon their clinical assessment, regardless of the decision instrument used.

SUBSEQUENT MANAGEMENT

Unstable patient — Patients manifesting hemodynamic instability, hypoxia, or obvious severe injury require immediate assessment for life-threatening injuries with concurrent management, including surgical consultation. This is discussed above. (See 'Primary evaluation and management' above.)

Stable patient without apparent injury but with concerning mechanism — Patients who appear clinically stable without apparent injury but have sustained high-energy blunt trauma with rapid deceleration are at risk for severe injury. Their initial evaluation is performed in the trauma or critical care area within the emergency department (ED). A portable chest radiograph (CXR) is obtained as part of this immediate evaluation. If this study is normal and no severe extrathoracic injury is identified, a posterior-anterior (PA) and lateral CXR are subsequently obtained; however, if the patient meets appropriate criteria for computed tomography (CT) or there are findings on the anterior-posterior (AP) CXR that would warrant a CT scan, the patient should proceed directly to CT rather than imaging with additional plain radiographs. If the study is normal and no significant findings are seen, a PA and lateral CXR are the appropriate next step.

Stable patient without apparent injury or concerning mechanism — Patients who appear clinically stable, without apparent injury, without a concerning mechanism, and without abnormal findings on standard PA and lateral CXR require no further evaluation, with the possible exception of an electrocardiogram (ECG). An ECG is performed in all patients with anterior chest trauma, in older adults, and in patients with a history of coronary heart disease. (See "Initial evaluation and management of blunt cardiac injury".)

Patients without evidence of injury after appropriate evaluation may be discharged. Patients are informed of the possibility of delayed presentations of injury (eg, pneumothorax) and told to return to the ED immediately for such symptoms as severe pain, difficulty breathing, and lightheadedness. Of note, a small percentage of patients who sustain minor thoracic injury develop a delayed complication or longer-term disability of some type, according to prospective follow-up studies [62-64]. Given the potential for such problems, it is prudent to arrange for follow-up within approximately one week.

SPECIFIC INJURIES

Aortic injury

Evaluation — Patients involved in high-energy blunt trauma involving rapid deceleration (eg, fall over 3 m [10 feet], motor vehicle collision [MVC] at speeds >40 mph [>65 km/hour]) are at significant risk for blunt aortic injury (BAI). Almost 80 percent of BAIs cause immediate death from aortic transection. In a minority of patients, the adventitia and mediastinal structures contain the rupture, allowing the patient to survive transport to the hospital. If BAI goes undiagnosed, these patients generally sustain an aortic rupture within 24 hours [65]. Prompt emergency department (ED) diagnosis is crucial and may be lifesaving in some patients (algorithm 1). (See "Clinical features and diagnosis of blunt thoracic aortic injury" and "Management of blunt thoracic aortic injury".)

There are no clinical signs or examination findings with sufficient sensitivity or specificity to detect BAI, but the majority are associated with some other thoracic injury (eg, rib fracture, pneumothorax) [66]. Therefore, the clinician should use appropriate radiographic studies to assess every patient involved in high-energy trauma with rapid deceleration or who shows signs of severe chest injury. If the initial study is a chest radiograph (CXR), it should be closely scrutinized for any signs of aortic injury. (See 'Chest radiograph' above.)

Aortic injury is unlikely in patients with a truly normal CXR, no sign of significant injury on examination, and a mechanism that does not involve rapid deceleration [41,47,55,67]. No further testing is needed in such patients.

Any abnormality on CXR should be followed up with a computed tomography (CT) scan of the chest. A normal CT scan essentially rules out BAI [39,68,69]. Clinicians often have difficulty obtaining an upright, posterior-anterior (PA) CXR in a trauma patient and abnormalities may be missed on supine studies. A normal mediastinum can appear enlarged with ill-defined borders on a portable supine chest radiograph. In addition, a mediastinal hematoma does not necessarily reflect aortic injury. If the clinician has a strong suspicion for BAI, CT scan should be obtained regardless of CXR appearance. CT scan is extremely sensitive and specific for BAI, and surgeons can determine the need for operative intervention on the basis of CT findings [67,70]. Advances in multidetector CT (MDCT) have led to near 100 percent sensitivity and specificity of CT due to improved spatial resolution, better image quality, and capability for multiplanar reformations.

Other modalities used to diagnose BAI include angiography and transesophageal echocardiography (TEE). While angiography is the traditional gold standard and is theoretically more sensitive than CT, its use should be reserved for those patients with equivocal CT scans. Angiography is more time consuming and invasive and rarely improves upon CT.

Imaging — Clinicians should obtain CT of the chest to assess for BAI if mechanistic, clinical, or preliminary radiographic evidence suggests the possibility of intrathoracic injury (table 1 and algorithm 1). Such evidence includes the following:

●High-energy trauma involving rapid deceleration AND any of the following:

•Chest wall contusions or deformity

•Multiple rib fractures

•Pneumothorax or hemothorax

•Abnormal CXR (eg, wide mediastinum) (see 'Chest radiograph' above)

Chest CT has near 100 percent sensitivity and specificity for BAI and is used most often to make the diagnosis [71-74]. Aortic injuries can be categorized as minimal or significant on the basis of abnormalities of the external aortic wall seen on CT. While the exact definition is not well established, minimal aortic injury is defined as a subcentimeter intimal abnormality or localized intramural hematoma without external contour deformity [75,76]. Unlike significant aortic injuries (eg, active aortic bleeding, full thickness aortic rupture, pseudoaneurysm), minimal aortic injury does not require immediate surgical intervention. The incidence of minimal aortic injury is estimated to be 10 to 30 percent of all BAIs, an increase that may be attributable to the improved spatial resolution of CT scanners. (See "Clinical features and diagnosis of blunt thoracic aortic injury" and "Management of blunt thoracic aortic injury".)

CT enables detection of other intrathoracic injuries in addition to BAI. Among patients with abnormal CXR findings, chest CT identifies injuries that would not otherwise be found, resulting in significant changes in management between 20 and 30 percent of the time [47,77,78]. An equivocal CT scan should be followed by a repeat CT study in 24 hours or by angiography to exclude aortic injury [67,70].

Most studies that assess the use of CT in chest trauma involve critically ill or severely injured patients. Therefore, it is difficult to draw conclusions about the appropriate use of CT in patients without evidence of severe injury, based solely on mechanism. (See 'Chest computed tomography' above.)

TEE is an excellent modality to assess for BAI in patients too unstable for chest CT. TEE has high sensitivity and specificity for BAI, can be performed in the ED or the operating room, requires no contrast, and provides information about cardiac injury and function.

TEE is operator dependent and suffers in some studies from loss of sensitivity as the interposition of the air-filled trachea between the aorta and esophagus creates a blind spot, precluding adequate evaluation of the distal ascending aorta and proximal arch. It should not be performed in patients with unstable cervical spine injuries or esophageal injuries.

TEE compares favorably with angiography or CT scan in the majority of cases and diagnoses some intimal tears not seen on corresponding angiography, although the clinical significance of these tears is unclear [79-81]. It also has utility in diagnosing valvular injuries and pericardial effusions. Unlike transesophageal imaging, transthoracic echocardiography, while excellent for diagnosing significant pericardial effusions, cannot reliably diagnose BAI [79,80].

Management — Patients with BAI awaiting transport to the operating room or a monitored setting for medical management require careful control of their blood pressure and heart rate. The medical management of patients with blunt thoracic injury is discussed in detail separately. (See "Management of blunt thoracic aortic injury", section on 'Anti-impulse therapy'.)

Options for surgical treatment of aortic injury include open repair (via thoracotomy) or endovascular repair. These are reviewed separately. (See "Surgical and endovascular repair of blunt thoracic aortic injury".)

In some cases, emergency surgery is not feasible. The relative risks and benefits of immediate versus delayed repair are discussed separately. (See "Management of blunt thoracic aortic injury", section on 'Approach to management'.)

Cardiac injury

Cardiac contusion — Clinicians should obtain an electrocardiogram (ECG) on all blunt trauma patients with any of the following:

●Pain and tenderness directly over the mid-anterior chest

●Sternal fracture

●History suggestive of cardiac disease (eg, accident precipitated by syncope, severe chest pain, or shortness of breath)

●Active symptoms or signs suggestive of cardiac disease

●Major mechanism of injury (eg, rollover, high speed, fatality at scene)

Findings such as unexplained persistent tachycardia, new bundle branch block, or dysrhythmia raise concern for cardiac contusion, and patients with such findings should be admitted for cardiac monitoring and possibly echocardiography. Unexplained tachycardia should also prompt the clinician to look for other injuries or ongoing hemorrhage. Blunt cardiac injury, including the use of cardiac biomarkers, is discussed in greater detail separately. (See "Initial evaluation and management of blunt cardiac injury".)

Myocardial rupture — Most patients with severe blunt cardiac injury do not reach the ED alive [14,15]. Of those who do, hypotension may have reduced pressure on the injured myocardium, which may subsequently rupture as fluid resuscitation restores systemic pressure. Other injuries may lead to delayed rupture within several days of admission.

Nonspecific signs and concomitant injuries make clinical diagnosis of myocardial injury difficult [15]. Signs such as hypotension associated with distended neck veins and muffled heart sounds suggest tamponade, which often occurs with severe cardiac injury; however, these findings may be absent. Immediate bedside ultrasound by a skilled ultrasonographer can reveal the diagnosis rapidly (movie 1) [14,82,83]. The clinician should perform or obtain bedside echocardiography in any patient with unexplained shock out of proportion to apparent injuries or despite aggressive resuscitation. When immediate bedside ultrasound is unavailable and the clinician strongly suspects tamponade, pericardiocentesis should be performed.

ED thoracotomy (EDT) rather than pericardiocentesis may be the best treatment for tamponade from blunt myocardial injury if the patient is too unstable to be moved to the operating room [14]. For patients amenable to operative intervention, intubation should be delayed, if possible, until just before sternotomy because abundant anecdotal evidence suggests induction may precipitate hemodynamic collapse [82]. (See 'Emergency thoracotomy' above.)

Myocardial infarction — Myocardial infarction (MI) is a rare complication of blunt chest trauma [84,85]. Causes include coronary artery dissection and thrombosis [85-87]. The left anterior descending artery appears to be involved most often, but any coronary artery may be involved [85,88]. A rapid ECG is obtained in the BTT patient to screen for cardiac contusion and to rule out the rare MI. The management of MI in the setting of blunt thoracic injury is discussed separately. (See "Initial evaluation and management of blunt cardiac injury", section on 'Acute coronary syndrome'.)

Pulmonary injury — Major pulmonary injuries that require treatment and admission include pneumothorax, hemothorax, pulmonary contusion, pulmonary parenchymal injuries, and tracheobronchial injuries.

Pneumothorax — Pneumothorax is a common complication of blunt trauma, often sustained from a fractured rib [89]. Patients may manifest tachypnea, chest pain, hypoxia, unilateral diminished or absent breath sounds, or unilateral hyperresonance to percussion, depending on the extent of the pneumothorax. Crepitus is a less common finding but may be present. (See 'Primary survey and initial management' above.)

The supine chest radiograph has high specificity for diagnosing a pneumothorax from blunt injury, but its sensitivity is variable. Ultrasound is a more sensitive initial screening tool. (See 'Ultrasound' above and 'Chest radiograph' above.)

Patients with historical features (eg, pleuritic pain, dyspnea) or examination findings (eg, rib fracture) that place them at risk for pneumothorax should be evaluated with an upright PA CXR using inspiratory and expiratory views or a CT scan of the chest (image 1 and image 9 and image 10). Another approach in patients whose initial radiograph does not reveal a pneumothorax but who are at risk is to repeat the radiograph in six hours.

Antibiotics should be given to patients undergoing tube thoracostomy following chest trauma. (See "Thoracostomy tubes and catheters: Placement techniques and complications", section on 'Antibiotic prophylaxis'.)

Occult pneumothorax — With the increased use of helical CT to evaluate trauma patients, the question of how to manage an occult pneumothorax arises frequently [90]. Occult pneumothorax is one not visible on a plain CXR but seen on cervical, chest, or abdominal CT. In approximately 5 to 10 percent of patients, occult pneumothoraces expand and become clinically significant, in some cases developing into a tension pneumothorax. The potential risk of an expanding pneumothorax is greater in patients receiving positive-pressure ventilation either during surgery or for long-term pulmonary support [91].

Most studies support treating asymptomatic blunt trauma patients with occult pneumothoraces less than 8 mm in length (as determined by CT) with observation alone [16,92,93]; a chest tube is placed if the pneumothorax enlarges or the patient becomes symptomatic [93]. We believe this is a reasonable approach. In all cases of occult pneumothorax not managed with tube thoracostomy, close monitoring for signs of an expanding or tension pneumothorax is critical.

Debate continues about the need for tube thoracostomy in patients with occult pneumothorax who require positive-pressure ventilation, reflecting the conflicting data [94-97]. One randomized trial found that such patients are at significant risk of developing a life-threatening tension pneumothorax [94]; a subsequent randomized trial reported that observation of such patients, without chest tube placement, was not associated with an increased incidence of pneumothorax progression [97]. Both trials involved few patients; thus, it is difficult to draw meaningful conclusions.

Until results from well-performed randomized trials become available, we suggest placement of a chest tube for all patients with occult pneumothorax who will be mechanically ventilated. In addition, we believe that tube thoracostomy is an important intervention for patients with an occult pneumothorax who are at significant risk of hypotension from hemorrhage due to major or multiple injuries, and those who would not tolerate even a brief period of hypoxia or hypotension (eg, intracerebral injury). (See "Thoracostomy tubes and catheters: Indications and tube selection in adults and children".)

However, not all trauma surgeons advocate tube thoracostomy in such cases. Practice guidelines from the Eastern Association for the Surgery of Trauma state that observation is an acceptable option [90]. If tube thoracostomy is not performed in patients requiring mechanical ventilation, careful monitoring looking for signs that the pneumothorax may be expanding is critical.

Hemothorax — Injuries leading to massive hemothorax include aortic rupture, myocardial rupture, and injuries to hilar structures. Other causes include injuries to the lung parenchyma and intercostal or mammary blood vessels. A volume of 300 mL is needed for hemothorax to manifest on an upright CXR. In skilled hands, ultrasound can diagnose hemothorax accurately. (See 'Ultrasound' above.)

Hemothorax is treated with tube thoracostomy using a size 28 to 32 French chest tube [98,99]. Immediate bloody drainage of ≥20 mL/kg (approximately 1500 mL) is generally considered an indication for surgical thoracotomy. Shock and persistent, substantial bleeding (generally >3 mL/kg/hour) are additional indications. Vital signs, fluid resuscitation requirements, and concomitant injuries are considered when determining the need for thoracotomy.

In general, a pneumohemothorax is treated with drainage by tube thoracostomy. Small, clinically insignificant collections may be treated with needle aspiration or drainage at the discretion of the trauma surgeon [100].

Pulmonary contusion — Pulmonary contusion is another common consequence of blunt chest trauma [20,101]. Pulmonary contusions generally develop over the first 24 hours and resolve in about one week. Irregular, nonlobular opacification of the pulmonary parenchyma on CXR is the diagnostic hallmark (image 11 and image 7). About one-third of the time, the contusion is not evident on initial radiographs [101]. Chest CT provides better resolution but rarely alters management unless other injuries are found. Contusions evident on CT but not plain radiograph have better outcomes [102].

Pain control and pulmonary toilet are the mainstays of treatment. Prophylactic endotracheal intubation is unnecessary, but patients with hypoxia or difficulty ventilating require airway management. While opinions vary, fluid resuscitation with crystalloid to euvolemia appears appropriate. Common complications include pneumonia and acute respiratory distress syndrome (ARDS). (See "Acute respiratory distress syndrome: Clinical features, diagnosis, and complications in adults" and "Acute respiratory distress syndrome: Supportive care and oxygenation in adults".)

Tracheobronchial injury — Tracheobronchial injuries occur in less than 1 percent of patients with BTT, and few studies exist to guide diagnosis and management [103]. Most patients who sustain such injuries die at the scene [103,104]. The trachea is protected from injury by its position relative to the mandible, sternum, and vertebral column, and its relative elasticity. Injury of the cervical trachea is uncommon but can occur from a direct blow, which may be of low energy; injury of the intrathoracic trachea results from high-energy trauma, generally motor vehicle collisions (MVCs) and sometimes crush injuries. Most tracheal or bronchial injuries occur as part of multiple trauma and are accompanied by additional injuries to the lungs and chest wall. The right main bronchus is involved most often, generally within 1 to 2 cm of the carina, followed by the left main bronchus. (See "Identification and management of tracheobronchial injuries due to blunt or penetrating trauma", section on 'Incidence' and "Identification and management of tracheobronchial injuries due to blunt or penetrating trauma", section on 'Mechanism and location of injury'.)

Diagnosis of tracheobronchial injury (TBI) is often difficult [105]. Intrathoracic injury can be subtle and indolent, presenting with retained secretions, recurrent pneumothoraces, and airway obstruction. The sine qua non of intrathoracic TBI is a significant air leak and pneumothorax or pneumomediastinum that reaccumulates despite tube thoracostomy (image 12). A cervical injury may present without a significant air leak if the tear or rupture is contained by the adventitia. Signs of cervical tracheal injury include dyspnea, hoarseness, and subcutaneous emphysema.

Radiographs generally reveal marked air in local soft tissue (ie, subcutaneous emphysema). If tracheal disruption occurs, the larynx can rise, allowing the hyoid bone to ascend above the level of the third cervical vertebra, an unusual finding otherwise. Fractures of the first three ribs are associated with intrathoracic injury [105,106]. Other radiologic findings on plain film include persistent pneumothorax with a dependent lung (image 12), interstitial air in the wall of the trachea or mainstem bronchus, abnormal location of the endotracheal tube (ETT), and a distended ETT cuff due to protrusion of the trachea. Of note, an isolated finding on CXR of air outlining the trachea or mainstem bronchus due to pneumomediastinum or occult pneumomediastinum seen on CT does not correlate significantly with tracheobronchial rupture and does not require extensive evaluation [106,107].

Definitive diagnosis is made in the operating room or by bronchoscopy. CT enables diagnosis of some tracheal tears, but its sensitivity is unknown [106]. If TBI is suspected, obtain a CT and consult a thoracic surgeon for evaluation and possible bronchoscopy. The management of TBI is discussed separately. (See "Identification and management of tracheobronchial injuries due to blunt or penetrating trauma".)

Diaphragm rupture — Penetrating trauma accounts for most diaphragm ruptures. Nevertheless, diaphragm rupture is reported to occur in approximately 1 percent of BTT patients and has been reported in up to 8 percent of those requiring laparotomy. However, the reported incidence is increasing as the resolution and diagnostic accuracy of CT scanners improves. While case reports exist of diaphragm rupture following minor trauma, [108,109], the great majority of cases result from high-energy injuries, most often MVCs [110]. Data from studies of highway MVCs suggest that significant intrusion (≥30 cm) into the passenger compartment following head-on or near-side collisions and rapid deceleration (≥40 km/hour) increase the risk of sustaining a diaphragmatic rupture [111].

Left-sided rupture occurs approximately twice as often as right-sided rupture in blunt trauma patients [110,112,113]. Anatomic differences account for this discrepancy: the posterolateral aspect of the left hemidiaphragm is relatively weak, and the bowel and stomach provide less protection than the liver. Diagnosis is easiest in left-sided injuries when bowel enters the thoracic cavity. Small tears may require years before negative intrathoracic pressure and the positive intraabdominal pressure ultimately lead to herniation of viscera.

Severe concomitant injuries occur in many cases of diaphragm rupture. Injuries to the spleen and liver are relatively common, as are hemothorax and pneumothorax. Pelvic and long bone fractures, closed head injuries, and BAI can also occur. Diaphragm injuries are often diagnosed incidentally during laparotomy or thoracotomy to treat coexistent injuries. Symptoms vary and generally reflect the severity of both the diaphragm injury (eg, tear versus rupture with herniation) and associated injuries. (See "Recognition and management of diaphragmatic injury in adults", section on 'Associated injuries'.)

Diaphragm injury may be associated with epigastric and abdominal pain, referred shoulder pain, shortness of breath, vomiting, dysphagia, or shock. The initial CXR is normal or nondiagnostic in up to 50 percent of patients. Nevertheless, the CXR may reveal diagnostic findings, such as abdominal viscera in the hemithorax, a nasogastric tube in the thorax, or a focal constriction of herniated viscera at the site of the tear, producing circumferential compression (collar sign). CXR may also reveal nonspecific findings such as atelectasis, pleural effusion, loss of the usual hemidiaphragm contour, eventration of the diaphragm, and pneumothorax or hemothorax, although none of these are sensitive or specific for diaphragm injury. Serial CXRs may be useful, especially in patients in whom positive-pressure ventilation has prevented bowel herniation [106,114]. Because many studies do not differentiate between penetrating and blunt injuries, plain CXR may have greater accuracy in detecting injuries due to blunt trauma than has been thought.

The multidetector CT (MDCT) has improved our ability to diagnose diaphragmatic injury and is the test used most often for diagnosis in hemodynamically stable patients. (See "Recognition and management of diaphragmatic injury in adults", section on 'Computed tomography'.)

Esophageal rupture — Blunt trauma patients rarely sustain esophageal rupture. Esophageal injury lacks specific symptoms and generally occurs in multiple trauma, making it difficult to diagnose. Injuries may be seen in the cervical, thoracic, and distal esophagus [106,115-117]. Given the small number of reported cases, it is difficult to describe any specific patterns of injury. Potential mechanisms include compression, traction from cervical hyperextension, and direct penetration from thoracic fractures [106]. Signs of injury may include blood in the nasogastric aspirate, subcutaneous cervical air, and neck hematoma, but none are sensitive [118,119]. (See "Overview of esophageal injury due to blunt or penetrating trauma in adults".)

Plain radiograph may reveal pneumomediastinum, pleural effusion, mediastinal contour changes (which progress with inflammation), or a gas bubble in the nasogastric tube or esophagus, if a tracheoesophageal communication exists. Diagnosis is made by endoscopy or esophagography using water-soluble contrast. CT may show subtle air leaks beside the site of perforation, although the sensitivity or specificity of such findings is unclear [106]. Pneumomediastinum without a clear cause suggests the need for further evaluation. However, a CT with an isolated finding of pneumomediastinum does not mandate further evaluation [120,121]. Esophageal injuries are often associated with severe concomitant injuries that may mask findings, delaying diagnosis until mediastinitis or an empyema develops [106,115].

Chest wall injury

Sternal fracture — Sternal fractures usually result from a high-energy direct blow to the anterior chest wall. Typically, these fractures occur during an MVC when the driver's chest strikes the steering column or rapid deceleration causes an occupant's chest to slam against their cross-shoulder seatbelt [122-124].

The extent of sternal fracture displacement correlates with the risk for associated intrathoracic injury, although even nondisplaced fractures carry a substantial risk and significant extrathoracic injuries can also occur [122,125,126]. Common associated injuries include cranial injury (including intracranial hemorrhage), rib fracture, pulmonary contusion, spinal fracture, retrosternal hematoma, pneumothorax and hemothorax, and extremity trauma [124]. If a thoracic spine fracture occurs concomitantly, it may be an unstable burst fracture and should be investigated [127]. Other important albeit less common associated injuries include hemopericardium, cardiac contusion, and aortic tear. (See "Evaluation of thoracic and lumbar spinal column injury".)

We suggest a contrast-enhanced CT of the chest and an ECG be obtained to rule out associated injuries if a sternal fracture is diagnosed on plain film. Depending upon clinical circumstances, cardiac biomarkers may also be obtained. Imaging for the diagnosis of sternal fracture and the use of biomarkers for blunt cardiac injury are discussed separately. (See "Initial evaluation and management of chest wall trauma in adults", section on 'Sternal fracture' and "Initial evaluation and management of blunt cardiac injury", section on 'Cardiac biomarkers'.)

In a hemodynamically stable patient with an isolated, nondisplaced sternal fracture and no ECG abnormalities, cardiac monitoring is rarely warranted [122,124]. Many such patients may be safely discharged provided careful clinical evaluation raises no concerns about other injuries, a responsible adult will remain with the patient, and adequate follow-up is arranged. We suggest that patients with associated intrathoracic injuries, severe pain, or poor pulmonary reserve, particularly older adults, be admitted for observation. The management of isolated sternal fractures is reviewed separately. (See "Initial evaluation and management of chest wall trauma in adults", section on 'Sternal fracture'.)

Scapular fracture — Scapular fractures occur from trauma involving significant force and raise concern for further injury [128]. High-speed MVCs and falls from heights are common mechanisms. Associated injuries include intrathoracic injuries, clavicle fractures, rib fractures, spine fractures, spleen and liver injuries, and tibial fractures (usually in pedestrians struck by motor vehicles). The association between scapular fracture and BAI may be overestimated [129].

We obtain a contrast-enhanced chest CT in most patients with a scapular fracture following significant blunt chest trauma because of the forces involved and the risk of concomitant injury [130]. We further suggest clinicians obtain consultation with trauma and orthopedic surgery. If the chest CT and workup for extrathoracic trauma reveal no injuries, and no concerns exist about analgesia, comorbidities, or the patient's social circumstances, patients with scapular fractures may be discharged.

Rib fracture — Patients with three or more rib fractures, especially older adult patients, are at significant risk for complications such as pulmonary contusion and pneumonia, even in the absence of other injuries, and should be admitted for observation. Rarely, healthy, younger individuals with three rib fractures, having undergone a thorough clinical and radiographic evaluation by clinicians experienced in trauma management and an appropriate period of observation, may be discharged from the ED. The management and disposition of patients with rib fractures and no other injuries is discussed separately. (See "Initial evaluation and management of rib fractures", section on 'Disposition' and "Inpatient management of traumatic rib fractures".)

Flail chest — Flail chest occurs when three or more adjacent ribs are each fractured in two places, creating one floating segment comprised of several rib sections and the soft tissues between them (figure 12). This unstable section of chest wall exhibits paradoxical motion (ie, it moves in the opposite direction of the uninjured, normal-functioning chest wall) with breathing and is associated with significant morbidity from pulmonary contusion. Abnormal motion can be difficult to detect, making the diagnosis difficult.

Initial management of flail chest consists of oxygen and close monitoring for early signs of respiratory compromise, ideally using both pulse oximetry and capnography in addition to clinical observation. Stabilization of the segment with manual or object pressure restricts chest wall expansion, thereby interfering with proper respiratory mechanics, and is no longer used. Use of noninvasive positive airway pressure by mask may obviate the need for endotracheal intubation in alert patients. Patients with severe injuries, respiratory distress, or progressively worsening respiratory function require endotracheal intubation and mechanical ventilatory support. (See "Inpatient management of traumatic rib fractures", section on 'Flail chest'.)

Sternoclavicular dislocation — The sternoclavicular (SC) joint is a diarthrodial, saddle-type synovial joint that can sublux or dislocate anteriorly or posteriorly. The usual mechanism is a direct, high-velocity blow to the medial clavicle or medial compression of the shoulder girdle. If the shoulder and arm are posterior to the plane of the body during compression, an anterior dislocation results; if the shoulder and arm are anterior, a posterior dislocation results.

Although uncommon, posterior SC joint dislocations can cause significant internal injury [131,132]. Posterior displacement of the clavicle can cause breathing difficulty from tracheal compression, lacerate or occlude the subclavian or brachiocephalic vessels, damage the lung parenchyma causing a pneumothorax, or injure the laryngeal nerve (which may present as hoarseness). Therefore, a contrast-enhanced CT of the chest is performed to look for associated injuries.

Patients with a posterior SC dislocation commonly present with anterior chest and shoulder pain exacerbated by arm movement but may also complain of dyspnea, dysphagia, or upper extremity paresthesias depending upon the internal injury sustained. Examination may reveal a prominence at the SC joint with anterior dislocation, but a corresponding depression may be difficult to detect with a posterior dislocation. It is important to check pulses in the affected extremity.

Plain radiographs are not sensitive for detecting SC dislocation. While special views can be obtained to improve sensitivity (eg, "serendipity view" with beam angled approximately 45 degrees cephalad), it is best to obtain a contrast-enhanced CT of the chest if there is any suspicion for posterior dislocation or internal injury [132]. This study enables evaluation for both bony and vascular injury.

Initial treatment of SC dislocation depends upon the type of dislocation and the severity of associated symptoms:

●Anterior subluxations require no immediate treatment. However, a true anterior dislocation should be reduced within 12 to 24 hours. This can often be done as an outpatient by orthopedic surgery.

●Posterior SC dislocations become increasingly difficult to reduce after 24 hours, so timely diagnosis and treatment are important. Many can be reduced under procedural sedation in the ED. In general, reduction should be performed by an orthopedist, but airway compromise may mandate immediate reduction by the emergency clinician. Consultation with cardiovascular surgery is necessary, especially when underlying hematoma is seen on CT, as bleeding from a vascular injury may occur following reduction. Unless immediate reduction must be performed due to airway compromise, the cardiovascular surgeon should evaluate the patient and make needed preparations before the reduction is performed.

Several reduction techniques have been proposed. Most are variations of a traction-abduction method, where traction is applied to the affected arm, which is held in 10 to 15 degrees of extension and 90 degrees of abduction, while pressure is applied to the posterior aspect of the clavicle. Another option is to grasp the proximal clavicle using a sterile towel clip and sterile technique and pull it anteriorly, while traction is maintained on the arm.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: General issues of trauma management in adults" and "Society guideline links: Thoracic and lumbar spine injury in adults".)

SUMMARY AND RECOMMENDATIONS

●Initial management of the patient with blunt thoracic trauma (BTT) follows the basic principles of Advanced Trauma Life Support (ATLS). A basic algorithm for the management of BTT is provided (algorithm 2). (See 'Primary survey and initial management' above and "Initial management of trauma in adults".)

●Clinicians managing BTT first assess and stabilize the patient's airway, breathing, and circulation (ABCs). The one caveat to this principle is that breathing may take priority over airway if a tension pneumothorax is present. In this case, the clinician should relieve the pneumothorax before performing tracheal intubation, if needed. (See 'Primary survey and initial management' above.)

●When determining the likelihood of severe injury from BTT, abnormal vital signs are more important than mechanism of injury. Immediate life-threatening injuries from blunt chest trauma include:

•Aortic injury

•Tension pneumothorax

•Hemothorax with severe, active bleeding

•Pericardial tamponade from myocardial injury

•Tracheobronchial disruption

Emergency management of life-threatening injuries is discussed above (see 'Primary survey and initial management' above). Subsequent management of specific injuries is discussed separately. (See 'Aortic injury' above and 'Pulmonary injury' above and 'Cardiac injury' above.)

●In the setting of blunt trauma, emergency department thoracotomy (EDT) rarely results in successful resuscitation. The subset of blunt trauma patients most likely to survive an EDT neurologically intact include either of the following:

•Patients who lose vital signs in the emergency department (ED) and appear to have no obvious nonsurvivable injury (eg, massive head trauma, multiple severe injuries)

•Patients with cardiac tamponade rapidly diagnosed by ultrasound, with no obvious nonsurvivable injury (see 'Emergency thoracotomy' above)

●We suggest a chest radiograph (CXR) be obtained in all patients who have sustained BTT of any significance, unless the patient requires immediate surgery or warrants immediate chest computed tomography (CT). The CXR is systematically reviewed for evidence of hemothorax, pneumothorax, pulmonary contusion, fractures, and aortic injury. Hemodynamically stable patients with concerning abnormalities identified on CXR generally undergo chest CT. The NEXUS guide to imaging can help determine whether CT imaging is necessary in such patients (algorithm 3). (See 'Chest radiograph' above.)

●Patients involved in high-energy blunt trauma involving rapid deceleration are at significant risk for blunt aortic injury (BAI). Nearly 80 percent of BTT patients who sustain BAI die at the scene. No clinical signs or examination findings and no single finding on CXR possess adequate sensitivity or specificity for BAI. Most patients with BAI have sustained other thoracic injuries (eg, rib fracture, pneumothorax). The following CXR findings increase the likelihood of BAI and indicate a need for further investigation, usually chest CT:

•Wide mediastinum (supine CXR >8 cm; upright CXR >6 cm)

•Obscured aortic knob; abnormal aortic contour

•Left "apical cap" (ie, pleural blood above apex of left lung)

•Large left hemothorax

•Deviation of nasogastric tube rightward

•Deviation of trachea rightward and/or right mainstem bronchus downward

•Wide left paravertebral stripe

BAI is discussed in detail above. (See 'Aortic injury' above.)

●Bedside ultrasound is a critical tool for the diagnosis of traumatic pericardial tamponade. Ultrasound is more sensitive for diagnosing pneumothorax than CXR and is also useful for diagnosing hemothorax. We suggest a chest CT be obtained if any concerning findings are identified on CXR, if the patient has persistent chest pain or dyspnea, or if the patient is unable to undergo a thorough clinical examination because of an extrathoracic injury. NEXUS decision instruments can help to determine the need for CT. (See 'Ultrasound' above and 'Chest computed tomography' above.)

●BTT is capable of causing a wide range of injuries, some of which are difficult to detect by physical examination or with plain radiographs. Common and important injuries are discussed in the text. (See 'Specific injuries' above.)