BLUNT

OverviewChest trauma is a significant source of morbidity and mortality in the United States. This article focuses on chest trauma caused by blunt mechanisms. Penetrating thoracic injuries are addressed in Penetrating Chest Trauma.

Blunt injury to the chest can affect any one or all components of the chest wall and thoracic cavity. These components include the bony skeleton (ribs, clavicles, scapulae, and sternum), the lungs and pleurae, the tracheobronchial tree, the esophagus, the heart, the great vessels of the chest, and the diaphragm. In the subsequent sections, each particular injury and injury pattern resulting from blunt mechanisms is discussed. The pathophysiology of these injuries is elucidated, and diagnostic and treatment measures are outlined.

Morbidity and mortality

Trauma is the leading cause of death, morbidity, hospitalization, and disability in Americans aged 1 year to the middle of the fifth decade of life. As such, it constitutes a major health care problem. According to the Centers for Disease Control and Prevention, 126,438 deaths occurred from unintentional injury in 2011.[1]

Frequency

Trauma is responsible for more than 100,000 deaths annually in the United States.[1] Estimates of thoracic trauma frequency indicate that injuries occur in 12 persons per 1 million population per day. Approximately 33% of these injuries necessitate hospital admission. Overall, blunt thoracic injuries are directly responsible for 20-25% of all deaths, and chest trauma is a major contributor in another 50% of deaths.

Etiology

By far the most important cause of significant blunt chest trauma is motor vehicle accidents (MVAs). MVAs account for 70-80% of such injuries. As a result, preventive strategies to reduce MVAs have been instituted in the form of speed limit restriction and the use of restraints. Pedestrians struck by vehicles, falls, and acts of violence are other causative mechanisms. Blast injuries can also result in significant blunt thoracic trauma.

Pathophysiology

The major pathophysiologies encountered in blunt chest trauma involve derangements in the flow of air, blood, or both in combination. Sepsis due to leakage of alimentary tract contents, as in esophageal perforations, also must be considered.

Blunt trauma commonly results in chest wall injuries (eg, rib fractures). The pain associated with these injuries can make breathing difficult, and this may compromise ventilation. Direct lung injuries, such as pulmonary contusions (see the image below), are frequently associated with major chest trauma and may impair ventilation by a similar mechanism. Shunting and dead space ventilation produced by these injuries can also impair oxygenation.

Left pulmonary contusion following a motor vehicle accident involving a pedestrian.Space-occupying lesions (eg, pneumothorax, hemothorax, and hemopneumothorax) interfere with oxygenation and ventilation by compressing otherwise healthy lung parenchyma. A special concern is tension pneumothorax in which pressure continues to build in the affected hemithorax as air leaks from the pulmonary

parenchyma into the pleural space. This can push mediastinal contents toward the opposite hemithorax. Distortion of the superior vena cava by this mediastinal shift can result in decreased blood return to the heart, circulatory compromise, and shock.

At the molecular level, animal experimentation supports a mediator-driven inflammatory process further leading to respiratory insult after chest trauma. After blunt chest trauma, several blood-borne mediators are released, including interleukin-6, tumor necrosis factor, and prostanoids. These mediators are thought to induce secondary cardiopulmonary changes.

Blunt trauma that causes significant cardiac injuries (eg, chamber rupture) or severe great vessel injuries (eg, thoracic aortic disruption) frequently results in death before adequate treatment can be instituted. This is due to immediate and devastating exsanguination or loss of cardiac pump function. This causes hypovolemic or cardiogenic shock and death.

Sternal fractures are rarely of any consequence, except when they result in blunt cardiac injuries.

Clinical

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

Obtaining as detailed a clinical history as possible is extremely important in the assessment of a patient who has sustained blunt thoracic trauma. The time of injury, mechanism of injury, estimates of MVA velocity and deceleration, and evidence of associated injury to other systems (eg, loss of consciousness) are all salient features of an adequate clinical history. Information should be obtained directly from the patient whenever possible and from other witnesses to the accident if available.

For the purposes of this discussion, blunt thoracic injuries may be divided into the following three broad categories:

Chest wall fractures, dislocations, and barotrauma (including diaphragmatic injuries) Blunt injuries of the pleurae, lungs, and aerodigestive tracts Blunt injuries of the heart, great arteries, veins, and lymphatics

A concise exegesis of the clinical features of each condition in these categories is presented. This classification is used in subsequent sections to outline indications for medical and surgical therapy for each condition.

Relevant AnatomyThe thorax is bordered superiorly by the thoracic inlet, just cephalad to the clavicles. The major arterial blood supply to and venous drainage from the head and neck pass through the thoracic inlet.

The thoracic outlets form the superolateral borders of the thorax and transmit branches of the thoracic great vessels that supply blood to the upper extremities. The nerves that make up the brachial plexus also access the upper extremities via the thoracic outlet. The veins that drain the arm (of which the most important is the axillary vein) empty into the subclavian vein, which returns to the chest via the thoracic outlet.

Inferiorly, the pleural cavities are separated from the peritoneal cavity by the hemidiaphragms. Communication routes between the thorax and abdomen are supplied by the diaphragmatic hiatuses, which allow egress of the aorta, esophagus, and vagal nerves into the abdomen and ingress of the vena cava and thoracic duct into the chest.

The chest wall is composed of layers of muscle, bony ribs, costal cartilages, sternum, clavicles, and scapulae. In addition, important neurovascular bundles course along each rib, containing an intercostal nerve, artery, and vein. The inner lining of the chest wall is the parietal pleura. The visceral pleura invests the lungs. Between the visceral and parietal pleurae is a potential space, which, under normal conditions, contains a small amount of fluid that serves mainly as a lubricant.

The lungs occupy most of the volume of each hemithorax. Each is divided into lobes. The right lung has three lobes, and the left lung has two lobes. Each lobe is further divided into segments.

The trachea enters through the thoracic inlet and descends to the carina at thoracic vertebral level 4, where it divides into the right and left mainstem bronchi. Each mainstem bronchus divides into lobar bronchi. The bronchi continue to arborize to supply the pulmonary segments and subsegments.

The heart is a mediastinal structure contained within the pericardium. The right atrium receives blood from the superior vena cava and the inferior vena cava. Right atrial blood passes through the tricuspid valve into the right ventricle. Right ventricular contraction forces blood through the pulmonary valve and into the pulmonary arteries. Blood circulates through the lungs, where it acquires oxygen and releases carbon dioxide.

Oxygenated blood courses through the pulmonary veins to the left atrium. The left heart receives small amounts of nonoxygenated blood via the thebesian veins, which drain the heart, and the bronchial veins. Left atrial blood proceeds through the mitral valve into the left ventricle.

Left ventricular contraction propels blood through the aortic valve into the coronary circulation and the thoracic aorta, which exits the chest through the diaphragmatic hiatus into the abdomen. A ligamentous attachment (a remnant of the ductus arteriosus) exists between the descending thoracic aorta and pulmonary artery just beyond the takeoff of the left subclavian artery.

The esophagus exits the neck to enter the posterior mediastinum. Through much of its course, it lies posterior to the trachea. In the upper thorax, it lies slightly to the right with the aortic arch and descending thoracic aorta to its left. Inferiorly, the esophagus turns leftward and enters the abdomen through the esophageal diaphragmatic hiatus.

The thoracic duct arises primarily from the cisterna chyli in the abdomen. It traverses the diaphragm and runs cephalad through the posterior mediastinum in proximity to the spinal column. It enters the neck and veers to the left to empty into the left subclavian vein.

WorkupInitial emergency workup of a patient with multiple injuries should begin with the ABCs (airway, breathing, and circulation), with appropriate intervention taken for each step.

Laboratory studies

A complete blood count (CBC) is a routine laboratory test for most trauma patients. The CBC helps gauge blood loss, though the accuracy of findings to help determine acute blood loss is not entirely reliable. Other important information provided includes platelet and white blood cell counts, with or without differential.

Arterial blood gas (ABG) analysis, though not as important in the initial assessment of trauma victims, is important in their subsequent management. ABG determinations are an objective measure of ventilation, oxygenation, and acid-base status, and their results help guide therapeutic decisions such as the need for endotracheal intubation and subsequent extubation.

Patients who are seriously injured and require fluid resuscitation should have periodic monitoring of their electrolyte status. This can help to avoid problems such as hyponatremia or hypernatremia. The etiology of certain acid-base abnormalities can also be identified, eg, a chloride-responsive metabolic alkalosis or hyperchloremic metabolic acidosis.

The coagulation profile, including prothrombin time (PT)/activated partial thromboplastin time (aPTT), fibrinogen, fibrin degradation product, and D-dimer analyses, can be helpful in the management of patients who receive massive transfusions (eg, >10 units of packed red blood cells [RBCs]). Patients who manifest hemorrhage that cannot be explained by surgical causes should also have their profile monitored.

Whereas elevated serum troponin I levels correlate with the presence of echocardiographic or electrocardiographic abnormalities in patients with significant blunt cardiac injuries, these levels have low sensitivity and predictive values in diagnosing myocardial contusion in those without. Accordingly, troponin I level determination does not, by itself, help predict the occurrence of complications that may require admission to the hospital. Accordingly, its routine use in this clinical situation is not well supported.[2, 3]

Measurement of serum myocardial muscle creatine kinase isoenzyme (creatine kinase-MB) levels is frequently performed in patients with possible blunt myocardial injuries. The test is rapid and inexpensive. This diagnostic

modality has been criticized because of poor sensitivity, specificity, and positive predictive value in relation to clinically significant blunt myocardial injuries.

Lactate is an end product of anaerobic glycolysis and, as such, can be used as a measure of tissue perfusion. Well-perfused tissues mainly use aerobic glycolytic pathways. Persistently elevated lactate levels have been associated with poorer outcomes. Patients whose initial lactate levels are high but are rapidly cleared to normal have been resuscitated well and have better outcomes.

Type and crossmatch are among the most important blood tests in the evaluation and management of a seriously injured trauma patient, especially one who is predicted to require major operative intervention.

Chest radiography

The chest x-ray (CXR) is the initial radiographic study of choice in patients with thoracic blunt trauma. A chest radiograph is an important adjunct in the diagnosis of many conditions, including chest wall fractures, pneumothorax, hemothorax, and injuries to the heart and great vessels (eg, enlarged cardiac silhouette, widened mediastinum).

In contrast, certain cases arise in which physicians should not wait for a chest radiograph to confirm clinical suspicion. The classic example is a patient presenting with decreased breath sounds, hyperresonant hemithorax, and signs of hemodynamic compromise (ie, tension pneumothorax). This scenario warrants immediate decompression before a chest radiograph is obtained.[4]

A 2012 study by Paydar et al indicated that routine chest radiography in stable blunt trauma patients may be of low clinical value. The authors propose that careful physical examination and history taking can accurately identify those patients at low risk for chest injury, thus making routine radiographs unnecessary.[5]

Computed tomography

Because of the lack of sensitivity of chest radiography in identifying significant injuries, computed tomography (CT) of the chest is frequently performed in the trauma bay in the hemodynamically stable patient. In one study, 50% of patients with normal chest radiographs were found to have multiple injuries on chest CT. As a result, obtaining a chest CT scan in a supposedly stable patient with significant mechanism of injury is becoming routine practice.

Helical CT and CT angiography (CTA) are being used more commonly in the diagnosis of patients with possible blunt aortic injuries. Most authors advocate that positive findings or findings suggestive of an aortic injury (eg, mediastinal hematoma) be augmented by aortography to more precisely define the location and extent of the injury.[6, 7, 8]

Abdominal CT alone or combined with cervical spinal CT detected almost all occult small pneumothoraces in one study of patients with blunt trauma, whereas cervical spinal CT alone detected only one third of cases. [9]

Aortography

Aortography has been the criterion standard for diagnosing traumatic thoracic aortic injuries. However, its limited availability and the logistics of moving a relatively critical patient to a remote location make it less desirable. In addition, the introduction of spiral CT scanners, which have 100% sensitivity and greater than 99% specificity, has caused the role of aortography in the evaluation of trauma patients to decline.

However, where spiral CT is equivocal, aortography can provide a more exact delineation of the location and extent of aortic injuries. Aortography is much better at demonstrating injuries of the ascending aorta. In addition, it is superior at imaging injuries of the thoracic great vessels.[10, 11]

Thoracic ultrasonography

Ultrasound examinations of the pericardium, heart, and thoracic cavities can be expeditiously performed by surgeons and emergency department (ED) physicians within the ED. Pericardial effusions or tamponade can be reliably recognized, as can hemothoraces associated with trauma. The sensitivity, specificity, and overall accuracy of ultrasonography in these settings are all greater than 90%.

Contrast esophagography

Contrast esophagograms are indicated for patients with possible esophageal injuries in whom esophagoscopy results are negative. The esophagogram is first performed with water-soluble contrast media. If this provides a negative result, a barium esophagogram is completed. If these results are also negative, esophageal injury is reliably excluded.

Esophagoscopy and esophagography are each approximately 80-90% sensitive for esophageal injuries. These studies are complementary and, when performed in sequence, identify nearly 100% of esophageal injuries.

Focused assessment for sonographic examination of trauma patient

The focused assessment for the sonographic examination of the trauma patient (FAST) is routinely conducted in many trauma centers. Although mainly dealing with abdominal trauma, the first step in the examination is to obtain an image of the heart and pericardium to assess for evidence of intrapericardial bleeding.

Electrocardiography

The 12-lead electrocardiogram (ECG) is a standard test performed on all thoracic trauma victims. ECG findings can help identify new cardiac abnormalities and help discover underlying problems that may impact treatment decisions. Furthermore, it is the most important discriminator to help identify patients with clinically significant blunt cardiac injuries.

Patients with possible blunt cardiac injuries and normal ECG findings require no further treatment or investigation for this injury. The most common ECG abnormalities found in patients with blunt cardiac injuries are tachyarrhythmias and conduction disturbances, such as first-degree heart block and bundle-branch blocks.

However, according to a 2012 practice management guideline from the Eastern Association for the Surgery of Trauma, ECG alone should not be considered sufficient for ruling out blunt cardiac injury. The guideline recommends obtaining an admission ECG and troponin I from all patients in whom blunt cardiac injury is suspected and states that such injury can be ruled out only if both the ECG and the troponin I level are normal.[12]

Echocardiography

Transesophageal echocardiography (TEE) has been extensively studied for use in the workup of possible blunt rupture of the thoracic aorta. Its sensitivity, specificity, and accuracy in the diagnosis of this injury are each approximately 93-96%.

The advantages of TEE include the easy portability, no requisite contrast, minimal invasiveness, and short time required to perform. TEE can also be used intraoperatively to help identify cardiac abnormalities and monitor cardiac function.[13, 14, 15] The disadvantages include operator expertise, long learning curve, and the fact that it is relatively weak at helping identify injuries of the descending aorta.

Transthoracic echocardiography (TTE) can help identify pericardial effusions and tamponade, valvular abnormalities, and disturbances in cardiac wall motion. TTEs are also performed in cases of patients with possible blunt myocardial injuries and abnormal ECG findings.

Esophagoscopy

Esophagoscopy is the initial diagnostic procedure of choice in patients with possible esophageal injuries. Either flexible or rigid esophagoscopy is appropriate, and the choice depends on the experience of the clinician. Some authors prefer rigid esophagoscopy to evaluate the cervical esophagus and flexible esophagoscopy for possible injuries of the thoracic and abdominal esophagus. If esophagoscopy findings are negative, esophagography should be performed as outlined above.

Bronchoscopy

Fiberoptic or rigid bronchoscopy is performed in patients with possible tracheobronchial injuries. Both techniques are extremely sensitive for the diagnosis of these injuries. Fiberoptic bronchoscopy offers the advantage of allowing an endotracheal tube to be loaded onto the scope and the endotracheal intubation to be performed under direct visualization if necessary.

Indications and Contraindications

Indications

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

The following section reviews indications for surgical intervention in blunt traumatic injuries according to the previously presented classification system. Surgical indications are further stratified into conditions necessitating an immediate operation and those in which surgery is needed for delayed manifestations or complications of trauma.

Chest wall fractures, dislocations, and barotrauma (including diaphragmatic injuries)

Indications for immediate surgery include (1) traumatic disruption with loss of chest wall integrity and (2) blunt diaphragmatic injuries.

Relatively immediate and long-term indications for surgery include (1) delayed recognition of blunt diaphragmatic injury and (2) the development of a traumatic diaphragmatic hernia.

Blunt injuries of pleurae, lungs, and aerodigestive tracts

Indications for immediate surgery include (1) a massive air leak following chest tube insertion; (2) a massive hemothorax or continued high rate of blood loss via the chest tube (ie, 1500 mL of blood upon chest tube insertion or continued loss of 250 mL/hr for 3 consecutive hours); (3) radiographically or endoscopically confirmed tracheal, major bronchial, or esophageal injury; and (3) the recovery of gastrointestinal tract contents via the chest tube.

Relatively immediate and long-term indications for surgery include (1) a chronic clotted hemothorax or fibrothorax, especially when associated with a trapped or nonexpanding lung; (2) empyema; (3) traumatic lung abscess; (4) delayed recognition of tracheobronchial or esophageal injury; (5) tracheoesophageal fistula; and (6) a persistent thoracic duct fistula/chylothorax.

Blunt injuries of heart, great arteries, veins, and lymphatics

Indications for immediate surgery include (1) cardiac tamponade, (2) radiographic confirmation of a great vessel injury, and (3) an embolism into the pulmonary artery or heart.

Relatively immediate and long-term indications for surgery include the late recognition of a great vessel injury (eg, development of traumatic pseudoaneurysm).

Contraindications

No distinct, absolute contraindications exist for surgery in blunt thoracic trauma. Rather, guidelines have been instituted to define which patients have clear indications for surgery (eg, massive hemothorax, continued high rates of blood loss via chest tube).

A controversial area has been the use of ED thoracotomy in patients with blunt trauma presenting without vital signs. The results of this approach in this particular patient population have been dismal and have led many authors to condemn it.

Treatment & ManagementChest wall fractures, dislocations, and barotrauma (including diaphragmatic injuries)

Rib fractures

Rib fractures are the most common blunt thoracic injuries. Ribs 4-10 are the ones most frequently involved. Patients usually report inspiratory chest pain and discomfort over the fractured rib or ribs. Physical findings include local tenderness and crepitus over the site of the fracture. If a pneumothorax is present, breath sounds may be decreased and resonance to percussion may be increased.

Rib fractures may also be a marker for other associated significant injury, both intrathoracic and extrathoracic. In one report, 50% of patients with blunt cardiac injury have rib fractures. Fractures of ribs 8-12 should raise the

suggestion of associated abdominal injuries. Lee and colleagues reported a 1.4- and 1.7-fold increase in the incidence of splenic and hepatic injury, respectively, in those with rib fractures.

Elderly patients with three or more rib fractures have been shown to have a fivefold increase in mortality and a fourfold increase in the incidence of pneumonia.

Effective pain control is the cornerstone of medical therapy for patients with rib fractures. For most patients, this consists of oral or parenteral analgesic agents. Intercostal nerve blocks may be feasible for those with severe pain who do not have numerous rib fractures. A local anesthetic with a relatively long duration of action (eg, bupivacaine) can be used. Patients with multiple rib fractures whose pain is difficult to control can be treated with epidural analgesia.

Adjunctive measures in the care of these patients include early mobilization and aggressive pulmonary toilet. Rib fractures do not require surgery. Pain relief and the establishment of adequate ventilation are the therapeutic goals for this injury. Rarely, a fractured rib lacerates an intercostal artery or other vessel, resulting in the need for surgical control to achieve hemostasis acutely. In the chronic phase, nonunion and persistent pain may also necessitate an operation.

Flail chest

A flail chest, by definition, involves three or more consecutive rib fractures in two or more places, which produce a free-floating, unstable segment of chest wall. Separation of the bony ribs from their cartilaginous attachments, termed costochondral separation, can also cause flail chest.

Patients report pain at the fracture sites, pain upon inspiration, and, frequently, dyspnea. Physical examination reveals paradoxical motion of the flail segment. The chest wall moves inward with inspiration and outward with expiration. Tenderness at the fracture sites is the rule. Dyspnea, tachypnea, and tachycardia may be present. The patient may overtly exhibit labored respiration due to the increased work of breathing induced by the paradoxical motion of the flail segment.

A significant amount of force is required to produce a flail segment. Therefore, associated injuries are common and should be aggressively sought. The clinician should specifically be aware of the high incidence of associated thoracic injuries such as pulmonary contusions and closed head injuries, which, in combination, significantly increase the mortality associated with flail chest.

All of the treatments mentioned above for rib fractures are suitable for flail chest. Respiratory distress or insufficiency can ensue in some patients with flail chest because of severe pain secondary to the multiple rib fractures, the increased work of breathing, and the associated pulmonary contusion. This may necessitate endotracheal intubation and positive-pressure mechanical ventilation. Intravenous fluids are administered judiciously; fluid overloading can precipitate respiratory failure, especially in those with significant pulmonary contusions.

To stabilize the chest wall and avoid endotracheal intubation and mechanical ventilation, various operations have been devised for correcting flail chest (eg, pericostal sutures, application of external fixation devices, and placement of plates or pins for internal fixation). With improved understanding of pulmonary mechanics and better mechanical ventilatory support, surgical therapy has not proved superior to supportive and medical measures. Most authors, however, would agree that stabilization is warranted if thoracotomy is indicated for another reason.

First and second rib fractures

First and second rib fractures are considered a separate entity from other rib fractures because of the excessive energy transfer required to injure these sturdy and well-protected structures. First and second rib fractures are harbingers of associated cranial, major vascular, thoracic, and abdominal injuries. The clinician should aggressively seek to exclude the presence of these other injuries.

Pain control and pulmonary toilet are the specific treatment measures for rib fractures. First and second rib fractures do not require surgical therapy. An exception to this would be the need to excise a greatly displaced bone fragment.

Clavicular fractures

Clavicular fractures are among the most common injuries to the shoulder girdle area. Common mechanisms include a direct blow to the shaft of the bone, a fall on an outstretched hand, and a direct lateral fall against the shoulder. Approximately 75-80% of clavicular fractures occur in the middle third of the bone. Patients report tenderness over the fracture site and pain with movement of the ipsilateral shoulder or arm.

Physical findings include anteroinferior positioning of the ipsilateral arm as compared with the contralateral arm. The proximal segment of the clavicle is displaced superiorly because of the action of the sternocleidomastoid.

Nearly all clavicular fractures can be managed without surgery. Primary treatment consists of immobilization with a figure-eight dressing, clavicle strap, or similar dressing or sling. Oral analgesics can be used to control pain. Surgery is rarely indicated. Surgical intervention is occasionally indicated for the reduction of a badly displaced fracture.

Sternoclavicular joint dislocations

Strong lateral compressive forces against the shoulder can cause sternoclavicular joint dislocation. Anterior dislocation is more common than posterior dislocation. Patients report pain with arm motion or when a compressive force is applied against the affected shoulder. The ipsilateral arm and shoulder may be anteroinferiorly displaced. With anterior dislocations, the medial end of the clavicle can become more prominent. With posterior dislocations, a depression may be discernible adjacent to the sternum. Associated injuries to the trachea, subclavian vessels, or brachial plexus can occur with posterior dislocations.

Closed or open reduction is generally advised. Treatment strategies depend on whether the patient has an anterior or posterior dislocation.

For anterior dislocations, local anesthesia and sedative medications are administered, and lateral traction is applied to the affected arm that is placed in abduction and extension. This maneuver, combined with direct pressure over the medial clavicle, can occasionally reduce an anterior dislocation. For posterior dislocations, a penetrating towel clip can be used to grasp the medial clavicle to provide the necessary purchase for anterior manual traction to reduce the joint. Proper levels of pain control, up to and including general anesthesia, are provided. If closed reduction fails, open reduction is performed.

Sternal fractures

Most sternal fractures are caused by MVAs. The upper and middle thirds of the bone are most commonly affected in a transverse fashion. Patients report pain around the injured area. Inspiratory pain or a sense of dyspnea may be present. Physical examination reveals local tenderness and swelling. Ecchymosis is noted in the area around the fracture. A palpable defect or fracture-related crepitus may be present.

Associated injuries occur in 55-70% of patients with sternal fractures. The most common associated injuries are rib fractures, long bone fractures, and closed head injuries. The association of blunt cardiac injuries with sternal fractures has been a source of great debate. Blunt cardiac injuries are diagnosed in fewer than 20% of patients with sternal fractures. Caution should be exercised before myocardial injury is completely excluded. The workup should begin with electrocardiography (ECG).

Most sternal fractures require no therapy specifically directed at correcting the injury. Patients are treated with analgesics and are advised to minimize activities that involve the use of pectoral and shoulder girdle muscles. The most important aspect of the care for these patients is to exclude blunt myocardial and other associated injuries.

Patients who are experiencing severe pain related to the fracture and those with a badly displaced fracture are candidates for open reduction and internal fixation. Various techniques have been described, including wire suturing and the placement of plates and screws. The latter technique is associated with better outcomes.

Scapular fractures

Scapular fractures are uncommon. Their main clinical importance is the high-energy forces required to produce them and the attendant high incidence of associated injuries. The rate of associated injuries is 75-100%, most commonly involving the head, chest, or abdomen.

Patients with scapular fractures report pain around the scapula. Tenderness, swelling, ecchymosis, and fracture-related crepitus can all be present. The fracture is most frequently located in the body or neck of the scapula. More than 30% of scapular fractures are missed during the initial patient evaluation. The discovery of a scapular fracture should prompt a concerted effort to exclude major vascular injuries and injuries of the thorax, abdomen, and neurovascular bundle of the ipsilateral arm.

Shoulder immobilization is the standard initial treatment. This can be accomplished by placing the arm in a sling or shoulder harness. Range-of-motion exercises are started as soon as possible to help prevent loss of shoulder mobility. Surgery is infrequently indicated. Involvement of the glenoid, acromion, or coracoid may require open reduction and internal fixation with the goal of maintaining proper shoulder mobility.

Scapulothoracic dissociation

Sometimes called flail shoulder, this rare injury occurs when very strong traction forces pull the scapula and other elements of the shoulder girdle away from the thorax. The muscular, vascular, and nervous components of the shoulder and arm are severely compromised. Physical findings include significant hematoma formation and edema in the shoulder area. Neurologic deficits include loss of sensation and motor function distal to the shoulder. Pulses in the arm are typically decreased or lost due to axillary artery thrombosis.

No specific medical therapy has been developed for this devastating injury. Surgery is rarely indicated early in the course of this injury. If the affected limb retains sufficient neurovascular integrity and function, operative fixation may be indicated to restore shoulder stability. Many scapulothoracic dissociations result in a flail limb that is insensate or is associated with severe pain due to proximal brachial plexus injury. An above-the-elbow amputation may be the best approach for these patients.

Chest wall defects

The management of large, open chest wall defects initially requires irrigation and debridement of devitalized tissue to avoid progression into a necrotizing wound infection. Once the infection is under control, subsequent treatment depends on the severity and level of defect. Reconstructive options range from skin grafting to well vascularized flaps to a variety of meshes with or without methylmethacrylate. The choice of reconstruction depends upon the depth of the defect.

Traumatic asphyxia

The curious clinical constellation known as traumatic asphyxia is the result of thoracic injury due to a strong crushing mechanism, such as might occur when an individual is pinned under a very heavy object. Some effects of the injury are compounded if the glottis is closed during application of the crushing force.

Patients present with cyanosis of the head and neck, subconjunctival hemorrhage, periorbital ecchymosis, and petechiae of the head and neck. The face frequently appears very edematous or moonlike. Epistaxis and hemotympanum may be present. A history of loss of consciousness, seizures, or blindness may be elicited. Neurologic sequelae are usually transient. Recognition of this syndrome should prompt a search for associated thoracic and abdominal injuries.

The head of the patient's bed should be elevated to approximately 30° to decrease transmission of pressure to the head. Adequate airway and ventilatory status must be assured, and the patient is given supplemental oxygen. Serial neurologic examinations are performed while the patient is monitored in an intensive care setting. No specific surgical therapy is indicated for traumatic asphyxia. Associated injuries to the torso and head frequently require surgical intervention.

Blunt diaphragmatic injuries

Diaphragmatic injuries are relatively uncommon. Blunt mechanisms, usually a result of high-speed MVAs, cause approximately 33% of diaphragmatic injuries. Most diaphragmatic injuries recognized clinically involve the left side, though autopsy and computed tomography (CT)-based investigations suggest a roughly equal incidence for both sides.

This injury should be considered in patients who sustain a blow to the abdomen and present with dyspnea or respiratory distress. Because of the very high incidence of associated injuries, eg, major splenic or hepatic trauma, it is not unusual for these patients to present with hypovolemic shock.

Most diaphragmatic injuries are diagnosed incidentally at the time of laparotomy or thoracotomy for associated intra-abdominal or intrathoracic injuries. Initial chest radiographs are normal. Findings suggestive of diaphragmatic disruption on chest radiographs may include abnormal location of the nasogastric tube in the chest, ipsilateral hemidiaphragm elevation, or abdominal visceral herniation into the chest.

In a patient with multiple injuries, CT is not very accurate, and magnetic resonance imaging (MRI) is not very realistic. Bedside emergency ultrasonography is gaining popularity, and case reports in the literature have supported its use in the evaluation of diaphragm. Diagnostic laparoscopy and thoracoscopy have also been reported to be successful in the identification of diaphragmatic injury.

A confirmed diagnosis or the suggestion of blunt diaphragmatic injury is an indication for surgery. Blunt diaphragmatic injuries typically produce large tears measuring 5-10 cm or longer. Most injuries are best approached via laparotomy. An abdominal approach facilitates exposure of the injury and allows exploration for associated abdominal organ injuries. The exception to this rule is a posterolateral injury of the right hemidiaphragm. This injury is best approached through the chest because the liver obscures the abdominal approach.

Most injuries can be repaired primarily with a continuous or interrupted braided suture (1-0 or larger). Centrally located injuries are most easily repaired. Lateral injuries near the chest wall may require reattachment of the diaphragm to the chest wall by encirclement of the ribs with suture during the repair. Synthetic mesh made of polypropylene or Dacron is occasionally needed to repair large defects.[16, 17]

Blunt injuries of pleurae, lungs, and aerodigestive tracts

Pneumothorax

Pneumothoraces in blunt thoracic trauma are most frequently caused when a fractured rib penetrates the lung parenchyma. However, this is not an absolute rule. Pneumothoraces can result from deceleration or barotrauma to the lung without associated rib fractures.

Patients report inspiratory pain or dyspnea and pain at the sites of the rib fractures. Physical examination demonstrates decreased breath sounds and hyperresonance to percussion over the affected hemithorax. In practice, many patients with traumatic pneumothoraces also have some element of hemorrhage, producing a hemopneumothorax.

Patients with pneumothoraces require pain control and pulmonary toilet. All patients with pneumothoraces due to trauma need a tube thoracostomy. The chest tube is connected to a collection system (eg, Pleur-evac) that is entrained to suction at a pressure of approximately – 20 cm H 2 O. Suction continues until no air leak is detected. The tube is then disconnected from suction and placed to water seal. If the lung remains fully expanded, the tube may be removed and another chest radiograph obtained to ensure continued complete lung expansion.

A prospective, observational, multicenter study sought to determine which factors predicted failed observation in blunt trauma patients.[18] Using data from 569 blunt trauma patients, the study identified 588 with an occult pneumothorax (OPTX); one group underwent immediate tube thoracostomy and the second group was observed.

Patients in whom observation failed spent more days on ventilators and had longer hospital and intensive care unit lengths of stay; 15% developed complications.[18]No patient in this group developed a tension pneumothorax or experienced adverse events by delaying tube thoracostomy. The investigators concluded that whereas most blunt trauma patients with OPTX can be carefully monitored without tube thoracostomy, OPTX progression and respiratory distress were significant predictors of failed observation.

Hemothorax

Accumulation of blood within the pleural space can be due to bleeding from the chest wall (eg, lacerations of the intercostal or internal mammary vessels attributable to fractures of chest wall elements) or to hemorrhage from the lung parenchyma or major thoracic vessels.

Patients report pain and dyspnea. Physical examination findings vary with the extent of the hemothorax. Most hemothoraces are associated with a decrease in breath sounds and dullness to percussion over the affected

area. Massive hemothoraces due to major vascular injuries manifest with the aforementioned physical findings and varying degrees of hemodynamic instability.

Hemothoraces are evacuated by means of tube thoracostomy. Multiple chest tubes may be required. Pain control and aggressive pulmonary toilet are provided. Tube output is monitored closely. Indications for surgery can be based on the initial and cumulative hourly chest tube drainage, in that massive initial output and continued high hourly output are frequently associated with thoracic vascular injuries that require surgical intervention. Guidelines are provided elsewhere (see Indications).

Large, clotted hemothoraces may necessitate an operation for evacuation to allow full expansion of the lung and to avoid the development of other complications such as fibrothorax and empyema. Thoracoscopic approaches have been used successfully in the management of this problem.[19]

Open pneumothorax

Open pneumothorax is more commonly caused by penetrating mechanisms but may rarely occur with blunt thoracic trauma.

Patients are typically in respiratory distress due to collapse of the lung on the affected side. Physical examination should reveal a chest wall defect that is larger than the cross-sectional area of the larynx. The affected hemithorax demonstrates a significant-to-complete loss of breath sounds. The increased intrathoracic pressure can shift the contents of the mediastinum to the opposite side, decreasing the return of blood to the heart, potentially leading to hemodynamic instability.

Treatment for an open pneumothorax consists of placing a three-way occlusive dressing over the wound to preclude the continued ingress of air into the hemithorax and to allow egress of air from the chest cavity. A tube thoracostomy is then performed. Pain control and pulmonary toilet measures are applied.

After initial stabilization, most patients with open pneumothoraces and loss of chest wall integrity undergo operative wound debridement and closure. Those with loss of large chest wall segments may need reconstruction and closure with prosthetic devices (eg, polytetrafluoroethylene patches). Patch placement can serve as definitive therapy or as a bridge to formal closure with rotational or free tissue flaps.

With low chest wall injuries, some authors describe detaching the diaphragm, with operative reattachment at a higher intrathoracic level. This converts the open chest wound into an open abdominal wound, which is easier to manage.

Traumatic pulmonary herniation through the ribs, though uncommon, may occur following chest trauma. Unless incarceration or infarction is evident, immediate repair is not indicated.

Tension pneumothorax

The mechanisms that produce tension pneumothoraces are the same as those that produce simple pneumothoraces. However, with a tension pneumothorax, air continues to leak from an underlying pulmonary parenchymal injury, increasing pressure within the affected hemithorax.

Patients are typically in respiratory distress. Breath sounds are severely diminished to absent, and the hemithorax is hyperresonant to percussion. The trachea is deviated away from the side of the injury. The mediastinal contents are shifted away from the affected side. This results in decreased venous return of blood to the heart. The patient exhibits signs of hemodynamic instability, such as hypotension, which can rapidly progress to complete cardiovascular collapse.

Immediate therapy for this life-threatening condition includes decompression of the affected hemithorax by needle thoracostomy. A large-bore (ie, 14- to 16-gauge) needle is inserted through the second intercostal space in the midclavicular line. A tube thoracostomy is then performed. Pain control and pulmonary toilet are instituted.

Pulmonary contusion and other parenchymal injuries

The forces associated with blunt thoracic trauma can be transmitted to the lung parenchyma. This results in pulmonary contusion, characterized by development of pulmonary infiltrates with hemorrhage into the lung tissue.

Clinical findings in pulmonary contusion depend on the extent of the injury. Patients present with varying degrees of respiratory difficulty. Physical examination demonstrates decreased breath sounds over the affected area. Other parenchymal injuries (eg, lacerations) can be produced by fractured ribs and, rarely, by deceleration mechanisms.

Pain control, pulmonary toilet, and supplemental oxygen are the primary therapies for pulmonary contusions and other parenchymal injuries. If the injury involves a large amount of parenchyma, significant pulmonary shunting and dead space ventilation may develop, necessitating endotracheal intubation and mechanical ventilation.

Laceration or avulsion injuries that cause massive hemothoraces or prolonged high rates of bloody chest tube output may require thoracotomy for surgical control of bleeding vessels. If central bleeding is identified during thoracotomy, hilar control is gained first. Once the extent of injury is confirmed, it may become necessary to perform a pneumonectomy, keeping in mind that trauma pneumonectomy is generally associated with a high mortality rate (>50%).[20]

In 2012, the Eastern Association for the Surgery of Trauma released an updated practice management guideline on the management of pulmonary contusion and flail chest.[21]

Blunt tracheal injuries

Although the incidence of blunt tracheobronchial injuries is low (1-3%), most patients with such injuries die before reaching the hospital. These injuries include fractures, lacerations, and disruptions. Blunt trauma most often produces fractures. These injuries are devastating and are frequently caused by severe rapid deceleration or compressive forces applied directly to the trachea between the sternum and vertebrae.

Patients are in respiratory distress. They typically cannot phonate and frequently present with stridor. Other physical signs include an associated pneumothorax and massive subcutaneous emphysema.

Blunt tracheal injuries are immediately life-threatening and require surgical repair. Bronchoscopy is required to make the definitive diagnosis. The first therapeutic maneuver is the establishment of an adequate airway. If airway compromise is present or probable, a definitive airway is established.

Endotracheal intubation remains the preferred route if feasible. This can be facilitated by arming a flexible bronchoscope with an endotracheal tube and performing the intubation under direct bronchoscopic guidance. The tube must be placed distal to the site of injury. Always be prepared to perform an emergency tracheotomy or cricothyroidotomy to establish an airway if this fails. These maneuvers are best performed in the controlled environment of an operating room.

The operative approach to repair of a blunt tracheal injury includes debridement of the fracture site and restoration of airway continuity with a primary end-to-end anastomosis. Defects of 3 cm or larger frequently require proximal and distal mobilization of the trachea to reduce tension on the anastomosis. The type of incision made for repairing the tracheal injury is determined by the level and extent of injury and the involvement of other thoracic organs.

Blunt bronchial injuries

Rapid deceleration is the most common mechanism causing major blunt bronchial injuries. Many of these patients die of inadequate ventilation or severe associated injuries before definitive therapy can be provided.

Patients are in respiratory distress and present with physical signs consistent with a massive pneumothorax. Ipsilateral breath sounds are severely diminished to absent, and the hemithorax is hyperresonant to percussion. Subcutaneous emphysema may be present and may be massive. Hemodynamic instability may be present and is caused by tension pneumothorax or massive blood loss from associated injuries.

Laceration, tear, or disruption of a major bronchus is life-threatening. These injuries require surgical repair. As with tracheal injuries, establishment of a secure and adequate airway is of primary importance.

Patients with major bronchial lacerations or avulsions have massive air leaks. The approach to repair of these injuries is ipsilateral thoracotomy on the affected side after single-lung ventilation is established on the

uninjured side. Some patients cannot tolerate this and require jet-insufflation techniques. Operative repair consists of debridement of the injury and construction of a primary end-to-end anastomosis.

Blunt esophageal injuries

Because of the relatively protected location of the esophagus in the posterior mediastinum, blunt injuries of this organ are rare. Blunt esophageal injuries are usually caused by a sudden increase in esophageal luminal pressure resulting from a forceful blow. Injury occurs predominantly in the cervical region; rarely, intrathoracic and subdiaphragmatic ruptures are also encountered.

Associated injuries to other organs are common. Physical clues to the diagnosis may include subcutaneous emphysema, pneumomediastinum, pneumothorax, or intra-abdominal free air. Patients who present a significant time after the injury may manifest signs and symptoms of systemic sepsis.

General medical supportive measures are appropriate. Fluid resuscitation and broad-spectrum intravenous antibiotics with activity against gram-positive organisms and anaerobic oral flora are administered. Surgery is required.

Injuries identified within 24 hours of their occurrence are treated by debridement and primary closure. Some surgeons choose to reinforce these repairs with autologous tissue. Wide mediastinal drainage is established with multiple chest tubes.

If more than 24 hours has passed since injury, primary repair buttressed by well-vascularized autologous tissue is still the best option if technically feasible. Examples of tissues used to reinforce esophageal repairs include parietal pleura and intercostal muscle. Very distal esophageal injuries can be covered with a tongue of gastric fundus. This is called a Thal patch.

For patients in poor general condition and those with advanced mediastinitis or severe associated injuries, esophageal exclusion and diversion is the most prudent choice. A cervical esophagostomy is made, the distal esophagus is stapled, the stomach is decompressed via gastrostomy, and a feeding jejunostomy tube is placed. Wide mediastinal drainage is established with multiple chest tubes.

Blunt injuries of heart, great arteries, veins, and lymphatics

Blunt pericardial injuries

Isolated blunt pericardial injuries are rare. Blunt mechanisms produce pericardial tears that can result in herniation of the heart and associated decrements in cardiac output. Physical examination may elicit a pericardial rub.

Most blunt pericardial injuries can be closed by simple pericardiorrhaphy. Large defects that cannot be closed primarily without tension can usually be left open or be patch-repaired.

Blunt cardiac injuries

MVAs are the most common cause of blunt cardiac injuries. Falls, crush injuries, acts of violence, and sporting injuries are other causes. Blunt cardiac injuries range from mild trauma associated only with transient arrhythmias to rupture of the valve mechanisms, interventricular septum, or myocardium (cardiac chamber rupture).

Therefore, patients can be asymptomatic or can manifest signs and symptoms ranging from chest pain to cardiac tamponade (eg, muffled heart tones, jugular venous distension, hypotension) to complete cardiovascular collapse and shock due to rapid exsanguination.

Many patients with blunt cardiac injuries do not require specific therapy. Those who develop an arrhythmia are treated with the appropriate antiarrhythmic drug. Elaboration on these drugs and their administration is beyond the scope of this article.

Patients with severe blunt cardiac injuries who survive to reach the hospital require surgery. Most patients in this group have cardiac chamber rupture due to a high-speed MVA. The right side involvement is most common, involving the right atrium and right ventricle. They present with signs and symptoms of cardiac tamponade or exsanguinating hemorrhage. A few may be stable initially, resulting in delayed diagnosis.

Those with tamponade benefit from rapid pericardiocentesis or surgical creation of a subxiphoid window. The next step is to repair the cardiac chamber by cardiorrhaphy. Cardiopulmonary bypass techniques can facilitate this procedure. Unstable patients may benefit from insertion of an intra-aortic counterpulsation balloon pump.

Commotio cordis or sudden cardiac death in an otherwise healthy individual generally results from participation in a sporting event or some form of recreational activity. It is a direct result of blow to the heart just before the T-wave, resulting in ventricular fibrillation. Survival is not unheard of, if resuscitation and defibrillation are started within minutes. Preventive strategies include chest protective gear during sporting activities.[22, 23, 24]

Blunt injuries of thoracic aorta and major thoracic arteries

High-speed MVAs are the most common cause of blunt injuries to the thoracic aortic injuries and the major thoracic arteries. Falls from heights and MVAs involving a pedestrian are other recognized causes. Injury mechanisms include rapid deceleration, production of shearing forces, and direct luminal compression against points of fixation (especially at the ligamentum arteriosum). Many of these patients die of vessel rupture and rapid exsanguination at the scene or before reaching definitive care. Blunt aortic injuries follow closely behind head injury as a cause of death after blunt trauma.

Important historical details include the exact mechanism of injury and estimates of the amount of energy transferred to the patient (eg, magnitude of deceleration). Other important details include whether the victim was ejected from a vehicle or thrown if struck by a vehicle, height of the fall, and whether other fatalities occurred at the scene.

Physical clues include signs of significant chest wall trauma (eg, scapular fractures, first or second rib fractures, sternal fractures, steering wheel imprint), hypotension, upper-extremity blood pressure differential, loss of upper or lower extremity pulses, and thoracic spine fractures. Signs of cardiac tamponade may be present. Decreased breath sounds and dullness to percussion due to massive hemothorax can also be found.

As many as 50% of patients with these devastating, life-threatening injuries have no overt external signs of injury. Therefore, a high index of suspicion is warranted for earlier intervention.

The management of these injuries, especially those of the thoracic aorta, is evolving. Many patients undergo delayed repair of contained descending thoracic aortic ruptures. This approach is most frequently used when severe associated injuries are present that require urgent correction.

Temporizing medical therapy includes the administration of short-acting beta-blockers (eg, labetalol, esmolol) to control the heart rate and to decrease the mean arterial pressure to approximately 60 mm Hg.

Because repair of thoracic aortic injuries using cardiopulmonary bypass is associated with fewer major neurologic complications, some authors advocate stabilization of the victim plus beta-blocker administration until transfer is feasible to a facility where the injury can be repaired using cardiopulmonary bypass or centrifugal pump techniques. These techniques maintain distal aortic perfusion. Results have been excellent, and postoperative paraplegia rates have been significantly reduced.[25]

Endovascular stent grafts are being developed to repair thoracic aortic injuries. Although several authors have reported success in treating such injuries with endovascular stents, the long-term durability of the stents is yet unknown. Further experience with this technique will allow more victims with concomitant severe injuries to become operative candidates.

Techniques for repair of the innominate artery and subclavian vessels vary, depending on the type of injury. Many require only lateral arteriorrhaphy. Large injuries of the innominate artery are managed first by placement of a bypass graft from the ascending aorta to the distal innominate artery. The injury is then approached directly and is oversewn or patched.[26, 27, 28]

Proximal pulmonary arterial injuries are relatively easy to repair when in an anterior location. Posterior injuries frequently require cardiopulmonary bypass. Pulmonary hilar injuries present the possibility of rapid exsanguination and are best treated with pneumonectomy. Peripheral pulmonary arterial injuries are approached easily by thoracotomy on the affected side. They may be repaired or the corresponding pulmonary lobe or segment may be resected.

Blunt injuries of the superior vena cava and major thoracic veins

Injuries limited to the major veins of the thorax are rare. These patients usually present with associated injuries to other major thoracic vascular structures. The clinical history, including mechanisms of injury, and physical examination are similar to those described for blunt injuries of the thoracic aorta and major thoracic arteries.

Major thoracic venous injuries are amenable to lateral venorrhaphy. If repair proves to be difficult or impossible, injured subclavian or azygous veins can be ligated. Injuries of the thoracic inferior or superior vena cava may require shunt placement or cardiopulmonary bypass to facilitate repair.

Blunt injuries of thoracic duct

Thoracic ductal injuries due to blunt mechanisms are rare. They are sometimes found in association with thoracic vertebral trauma. No signs or symptoms are specific for this injury at presentation. The diagnosis is usually delayed and is confirmed when a chest tube is inserted for a pleural effusion and returns chyle. This is termed a chylothorax.

Conservative management with chest tube drainage is successful in most cases, effecting closure of the ductal injury without surgery. Chyle production can be decreased by maintaining the patient on total parenteral nutrition or by providing enteral nutrition with medium-chain triglycerides as the fat source.

If a fistula persists after an attempt at nonoperative management, thoracotomy is performed to identify and ligate the fistula. This is usually advisable after 2-3 weeks of persistent drainage or if the total lymphocyte count dwindles. Provision of a meal high in fat content (or ice cream) the night before the operation increases the volume of chyle and facilitates identification of the fistula.

General surgical approach

Preoperative

Patients with immediately life-threatening injuries that necessitate surgery cannot afford a protracted workup. At minimum, the ABCs must be established. Frequently, resuscitation efforts in these patients must continue in transit to and in the operating room.

Those with indications for surgery but who are not in extremis should also have their ABCs established. On the basis of the mechanism of injury, clinical history, and physical findings, a search is conducted to exclude associated injuries. Diagnostic procedures are completed if time and the patient's condition permit (eg, cervical spine radiography, head CT, chest and abdominal CT, FAST examination). Blood is drawn and sent for typing, crossmatching, and other tests (eg, complete blood count and arterial blood gas analysis).

Intraoperative

An adequate, secured airway is necessary, as is intravenous access. Monitoring devices such as a Foley urinary catheter, central venous pressure monitor, or pulmonary artery catheter should be considered based on the severity of injury, preoperative functional status, and anticipated length of the operation. Some injuries may require the use of single-lung ventilation techniques. This should be discussed with the anesthesiologist as early as possible.

Cardiopulmonary bypass or a centrifugal pump is used when necessary. Patient positioning and choice of incision are very important. Median sternotomy is used to access the heart, intrapericardial portion of the pulmonary vessels, ascending aorta and aortic arch, venae cavae, and the innominate artery. Branches of the innominate artery are exposed by extending the median sternotomy into the neck.

A posterolateral left thoracotomy in the fourth intercostal space is used to approach the descending thoracic aorta. The right subclavian artery is exposed via a median sternotomy that is extended into the neck. Proximal control for the left subclavian artery is achieved through an anterolateral left thoracotomy in the third intercostal space. Distal control for this vessel is obtained through a supraclavicular incision.

The distal esophagus can be approached via a left posterolateral thoracotomy; more proximal injuries require a right thoracotomy. The thoracic duct is approached through a right thoracotomy.

Injuries to the lung or more peripheral pulmonary vessels are accessed through a posterolateral thoracotomy. Injuries to the proximal two thirds of the trachea are best approached through a collar incision and extension via a T-incision through the manubrium, which allows exposure to the middle and distal trachea. Injuries of the

distal trachea, carina, or right main stem bronchus are best approached through right fourth intercostals posterolateral thoracotomy. Injuries of the left mainstem bronchus are best approached through a left posterolateral thoracotomy.

Postoperative

Patients are extubated as soon as feasible in the postoperative period. Monitoring devices are kept in place while needed but are removed as soon as possible.

Intravenous fluids are provided until the patient has had a return of gastrointestinal function, at which time the patient can be fed. Patients with severe associated injuries, especially those in a coma, may require prolonged enteral tube feedings.

Pain control is important in these patients because it facilitates breathing and helps to prevent pulmonary complications such as atelectasis and pneumonia. Chest physiotherapy and nebulizer treatments are used as necessary, and the use of an incentive spirometer is encouraged.

Chest tubes are placed for suction until fluid drainage has fallen sufficiently and the lung is completely expanded without evidence of air leak. Tubes may then be placed to water seal and may be removed if a chest radiograph demonstrates continued lung expansion.

Follow-up

After discharge, patients are monitored to ensure that adequate wound healing has occurred and to assess for the development of complications. Patients with vascular injuries and grafts may be monitored to ensure that complications such as pseudoaneurysms do not develop.

For patient education resources, see the Skin Conditions and Beauty Center, as well as Bruises and Bronchoscopy.

ComplicationsPatients with blunt thoracic trauma are subject to myriad complications during the course of their care.

Wound complications include the following:

Wound infection Wound dehiscence (particularly problematic in sternal wounds)

Cardiac complications include the following:

Myocardial infarction Arrhythmias Pericarditis Ventricular aneurysm  formation Septal defects Valvular insufficiency

Pulmonary and bronchial complications include the following:

Atelectasis Pneumonia Pulmonary abscess Empyema Pneumatocele , lung cyst Clotted hemothorax Fibrothorax Bronchial repair disruption Bronchopleural fistula

Vascular complications include the following:

Graft infection Pseudoaneurysm

Graft thrombosis Deep venous thrombosis Pulmonary embolism

Neurologic complications include the following:

Causalgia (injuries that involve the brachial plexus) Paraplegia (the spinal cord is at risk during repair of a ruptured thoracic aorta) Stroke

Esophageal complications include the following:

Leakage of repair Mediastinitis Esophageal fistula Esophageal stricture , late (click here to complete a Medscape CME activity on treating esophageal strictures)

Complications involving the bony skeleton include the following:

Skeletal deformity Chronic pain Impaired pulmonary mechanics

Outcome and PrognosisFor the great majority of patients with blunt chest trauma, outcome and prognosis are excellent. Most (>80%) require either no invasive therapy or, at most, a tube thoracostomy to effect resolution of their injuries. The most important determinant of outcome is the presence or absence of significant associated injuries of the central nervous system, abdomen, and pelvis.

Some injuries, such as cardiac chamber rupture, thoracic aortic rupture, injuries of the intrathoracic inferior and superior vena cava, and delayed recognition of esophageal rupture, are associated with high morbidity and mortality.

Future and ControversiesFuture directions for improving the diagnosis and management of blunt thoracic trauma involve diagnostic testing, endovascular techniques, and patient selection.

The use of thoracoscopy for the diagnosis and management of thoracic injuries will increase. Also, the use of ultrasonography for the diagnosis of conditions such as hemothorax and cardiac tamponade will become more widespread. Finally, spiral CT scanning techniques will be used more frequently for definitive diagnosis of major vascular lesions (eg, injuries to the thoracic aorta and its branches).

Endovascular techniques for the repair of great vessel injuries will be developed further and applied more frequently. Also, patient selection and nonsurgical therapies for delayed operative management of thoracic aortic rupture will be refined.

PENETRATING

BackgroundThoracic injuries account for 20-25% of deaths due to trauma and contribute to 25-50% of the remaining deaths. Approximately 16,000 deaths per year in the United States alone are attributable to chest trauma.[1] Therefore, thoracic injuries are a contributing factor in up to 75% of all trauma-related deaths. The increased

prevalence of penetrating chest injury (associated with the "drug war" in the United States) and improved prehospital and perioperative care have resulted in an increasing number of critically injured but potentially salvageable patients presenting to trauma centers. Recently, the classic "trimodal" temporal distribution of trauma deaths has been questioned, even though it has been widely taught in the design of trauma systems. [2]

For more information, visit Medscape’s Trauma Resource Center.

History of the ProcedureOne of the earliest writings of thoracic injury was noted in the Edwin Smith Surgical Papyrus, written in 3000 BCE. Galen reported attempts to treat gladiators with chest injuries with open packing. In 1635, Labeza de Vaca first described operative removal of an arrowhead from the chest wall of a Native American. In 1814, Larrey (Napoleon's military surgeon) reported various injuries to the subclavian vessels. Rehn performed the first successful human cardiorrhaphy in Germany in 1896. Hill performed the first cardiorrhaphy in the United States in 1902 and initiated the modern treatment of the wounded heart.

Penetrating trauma to the thoracic vessels was not extensively reported until the 20th century because of the absence of survivors. In 1934, Alfred Blalock was the first American surgeon to successfully repair an aortic injury. Guidelines for treating thoracic trauma were not established until World War II.

Additional experience in the treatment of penetrating trauma to the thorax was gained in later military experiences, including the conflicts in Korea and Vietnam, and, to a lesser degree, in US actions in Grenada, Panama, the Balkans, Somalia, and the Persian Gulf. Other large international experiences have derived from the Falkland Island conflict, various Middle Eastern engagements, and multiple conflicts in the African states.

Significant experience has also been gained from large US metropolitan areas as a result of assaults involving firearms and handheld weapons and impalements resulting from falls or leaps from elevations. Researchers from Houston, Tex; Los Angeles, Calif; Atlanta, Ga; Detroit, Mich; and Denver, Colo, have been particularly productive in their treatments of thoracic penetrating trauma. The number of trauma patients in these large metropolitan areas rose so rapidly in the 1970s and 1980s that the military sent its medical personnel to train caregivers at these centers.[3, 4]

With the advancement of wartime medical care and access to The Joint Theater Trauma Registry (JTTR), thoracic injury patterns have changed dramatically. As a result of advances in body armor and the establishment of excellent medical care at the battlefield, mortal thoracic wounds seem to have decreased, allowing patients who would have previously died to live long enough to receive treatment.[5]

ProblemAny entry wound below the nipples (front) and the inferior scapular angles (dorsum) should be considered an entry point for a course that may have carried the missile into the abdominal cavity. Missiles from gunshot wounds (GSWs) can penetrate all body regions regardless of the point of entry. Any patient with a gunshot entry wound for which a corresponding exit wound cannot be identified should be considered to have a retained projectile, which could embolize to the central or distal vasculature. A patient with combined intrathoracic and intra-abdominal wounds has a markedly greater chance of dying.

For information on treating penetrating abdominal wounds, see the articleAbdominal Stab Wound Exploration.

EtiologyMechanism of injury

The mechanism of injury may be categorized as low, medium, or high velocity. Low-velocity injuries include impalement (eg, knife wounds), which disrupts only the structures penetrated. Medium-velocity injuries include bullet wounds from most types of handguns and air-powered pellet guns and are characterized by much less primary tissue destruction than wounds caused by high-velocity forces. High-velocity injuries include bullet wounds caused by rifles and wounds resulting from military weapons.

Shotgun injuries, despite being caused by medium-velocity projectiles, are sometimes included within management discussions for high-velocity projectile injuries. This inclusion is reasonable because of the kinetic energy transmitted to the surrounding tissue and subsequent cavitation, as described by the following equation in which KE is kinetic energy, M is mass, and V is velocity:

KE = ½ MV2

The 3 major subcategories of ballistics are internal, external, and terminal. Internal ballistics describe the characteristics of the projectile within the gun barrel. External ballistics examines the factors that affect the projectile during its path to the target, including wind resistance and gravity. Terminal ballistics evaluates the projectile as it strikes its target.

The amount of tissue damage is directly related to the amount of energy exchange between the penetrating object and the body part. The density of the tissue involved and the frontal area of the penetrating object are the important factors determining the rate of energy loss.

The energy exchange produces a permanent cavity inside the tissue. Part of this cavity is a result of the crushing of the tissue as the projectile passes through. The expansion of the tissue particles away from the pathway of the bullet creates a temporary cavity. Because this cavity is temporary, one must realize that it was once present in order to understand the full extent of injury.

Penetrations from blast fragments or from fragmentation weapons can be particularly destructive because of their extremely high velocities. Weapons designed specifically for antipersonnel effects (eg, mines, grenades) can generate fragments with initial velocities of 4500 ft/s, a far greater speed than even most rifle bullets. The tremendous energy imparted to tissue from fragments with such velocity causes extensive disruptive and thermal tissue damage. Weaponry of the 21st century consists mostly of improvised explosive devices (IEDs). These devices are homemade bombs and they create a deadly triad of penetrating, blast, and burn wounds. Of the thoracic trauma that is seen in the current Global War on Terror, 40% is penetrating chest trauma.

PathophysiologyAs noted by Inci and colleagues in a 1998 study of 755 patients with thoracic injuries, penetrating chest trauma (PCT) comprises a broad spectrum of injuries and severity.[6] The injuries and number of patients (some with >1 injury) is listed as follows:[6]

Hemothorax  - 190 Hemopneumothorax - 184 Pneumothorax  - 144 Diaphragmatic rupture  - 121 Open hemopneumothorax - 95 Pulmonary contusion - 50 Open pneumothorax - 24 Rib fracture o Fewer than 2 fractures - 16o More than 2 fractures - 13

Subcutaneous emphysema - 14 Bilateral pneumothorax - 9 Open bilateral hemopneumothorax - 13 Pneumomediastinum - 6 Thoracic wall lacerations - 4 Bilateral hemopneumothorax - 3 Open bilateral pneumothorax - 3 Sternal fracture - 3 Bilateral diaphragmatic rupture - 2

The clinical consequences depend on the mechanism of the injury, the location of the injury, associated injuries, and underlying illnesses. Organs at risk, in addition to the intrathoracic contents, include the intraperitoneal viscera, the retroperitoneal space, and the neck.

PresentationInitial management

As always in trauma, management begins with establishing ABCs. Indications for emergency endotracheal intubation include apnea, profound shock, and inadequate ventilation. Chest radiography is not indicated in patients with clinical signs of a tension pneumothorax, and immediate chest decompression is accomplished with either a large-bore needle at the second intercostal space or, more definitively, with a tube thoracostomy.

A sucking chest wound must be appropriately covered to permit adequate ventilation and to prevent the iatrogenic development of a tension pneumothorax.

Damage control operation appears to be the new mantra in the advanced care of penetrating thoracic trauma. Damage control requires modification of the ABCs of trauma, in that resuscitative and diagnostic techniques are used simultaneously in the immediate time after the unstable patient's presentation. Quickly and solely controlling hemorrhage and contamination to expedite reestablishing a survivable physiology is the essence of thoracic damage control. Additionally, aggressive correction of the acidosis, coagulopathy, and hypothermia occurs in the ICU.[7]

Volume replenishment is the cornerstone of treating hemorrhagic shock but can also cause significant compromise of other organ systems. Continuous infusions of even blood or normotonic fluids cause significant peripheral tissue edema, frank acute respiratory distress syndrome (ARDS) or a tremendous increase in lung water ("soggy lungs"), and cardiac compromise. Newer approaches, described in both military and civilian literature, are emphasizing the use of hypertonic solutions in an effort to minimize these complications.

Alternatively, several groups have championed the concept of "scoop and run" when treating injuries in the field.[8] With the development of modern (civilian) emergency medical services, the field care of injured patients has improved. Rapid assessment to identify life-threatening injuries along with key interventions, namely management of the airway and control of hemorrhage, and avoidance of massive volume increases before rapid transport to the closest appropriate facility is the current standard of care. This is in contrast to the concept of "stay and play," during which trained personnel make major triage and treatment decisions in the field.

If the patient has persistently low systemic pressure, a source of ongoing blood loss or some other mechanisms to explain the hypotension (eg, cardiac tamponade, tension pneumothorax) should be preferentially sought. Additionally, some data suggest that continued volume resuscitation before surgical control of bleeding may worsen both the bleeding process and final outcome.

Fluid collections in either hemothorax should be treated with percutaneous thoracostomy tubes. See the image below and the article Hemothorax.

Upright posteroanterior chest rediograph of patient with right-sided hemothorax.

IndicationsThoracotomy

Thoracotomy may be indicated for acute or chronic conditions. Acute indications include the following:

Cardiac tamponade Acute hemodynamic deterioration/cardiac arrest in the trauma center Penetrating truncal trauma (resuscitative thoracotomy) Vascular injury at the thoracic outlet Loss of chest wall substance (traumatic thoracotomy) Massive air leak Endoscopic or radiographic evidence of significant tracheal or bronchial injury Endoscopic or radiographic evidence of esophageal injury Radiographic evidence of great vessel injury Mediastinal passage of a penetrating object Significant missile embolism to the heart or pulmonary artery

Transcardiac placement of an inferior vena caval shunt for hepatic vascular woundsPatients who arrive in cardiac arrest or who arrest shortly after arrival may be candidates for emergency resuscitative thoracotomy. A right chest tube must be placed simultaneously. The use of emergency resuscitative thoracotomy has been reported to result in survival rates of 9-57% for patients with penetrating cardiac injuries and survival rates of 0-66% for patients with noncardiac thoracic injuries, but overall survival rates are approximately 8%.[9]

The proportion of patients with PCT who can be treated without operation has been reported to vary from 29-94%.[9]

Chronic indications for thoracotomy include the following:

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

Another indication for acute thoracostomy is often based on chest tube output. Immediate evacuation of 1500 mL of blood is a sufficient indication; however, the trend in output is more important. If bleeding persists with a steady trend of more than 250 mL/h, thoracotomy is probably indicated.

Thoracoscopy

The role of video-assisted thoracoscopic surgery in the management of penetrating chest trauma is expanding rapidly. Initially promoted for the management of retained hemothoraces and the diagnosis of diaphragmatic injury, trauma and thoracic surgeons are now using thoracoscopy for treatment of chest wall bleeding, diagnosis of transmediastinal injuries, pericardial window, and persistent pneumothoraces.[10] The major contraindication to video-assisted thoracoscopic surgery is hemodynamic instability.

Relevant AnatomyThe anatomy of the thoracic cage is well-known and encompasses the area beneath the clavicles and superior to the diaphragm, bound laterally by the rib cage, anteriorly by the sternum and ribs, and posteriorly by the rib and vertebral bodies. Entry into the thorax may be made by sternotomy; thoracotomy (incising between selected ribs, most commonly the fourth and fifth) on either the right or left side; or a clamshell incision, consisting of left and right thoracotomy incisions traversing the sternum to join the two. Additional modifications of each of these approaches are not discussed in detail here.

Particular care must be exercised laterally near the sternum, where the internal thoracic (mammary) artery lies 2-4 cm on either side. Similarly, remember that immediately inferior to each rib body are the intercostal artery, vein, and nerve, from which voluminous bleeding can occur. Patients have required reexploration for injuries to these various vessels and have exsanguinated as a result of missed injuries to these vessels.

Anteriorly, injuries to the heart should be presumed to have occurred if entry points are present anywhere between the 2 midclavicular lines. On occasion, significant injury to the heart has occurred from entry points lateral to these margins, as in gunshot or missile injuries.

Exceptionally long penetrating instruments and weapons (eg, arrows, swords, lances) can also directly penetrate the heart from a distant entry point. Similarly, injuries to any of the intrathoracic structures can be effected with long penetrating devices; consider the possibility of injuries to the diaphragm, great vessels, or posterior mediastinal structures in these cases.

The right atrium and right ventricle are the anterior portions of the heart; these areas are the primary sites involved in penetrating injuries of the heart.

ContraindicationsContraindications to various explorations and techniques are discussed in their respective sections.

Laboratory Studies Laboratory examinations are rarely required in the acute treatment of patients with penetrating chest injuries.

Hemoglobin or hematocrit values and arterial blood gas determinations offer the most useful information for treating these patients; however, tests may be temporarily delayed until patients are stabilized. Blood chemistry results, serum electrolyte values, and WBC and platelet counts add little information for initial treatment but can establish a baseline by which to follow the course of the patient through his or her therapy. Underlying medical conditions (eg, diabetes, chronic renal insufficiency), either known or discovered via the laboratory examinations, should be noted and treated when appropriate.

Imaging Studies With improvements in modern imaging, a number of different diagnostic modalities are available to aid in

precisely defining the extent of trauma. Various groups have championed their own protocols as preeminent. In reality, any number of acceptable algorithms can help in the treatment of a patient with PCT.

Admission history and physical examination are usually brief and are oriented to the injury. Evaluations of vital signs, consciousness, airway competency, vascular integrity, and pump (cardiac) function are rapidly performed before devoting attention to the point of injury.

If the patient is stable and no significant injury is found that requires immediate surgery, a full diagnostic evaluation can be performed.

Chest radiography remains the basis for initiating other investigations. CT scanning is rapidly evolving into a primary diagnostic tool because of its ability to image various

intrathoracic structures and to differentiate substances of different densities (eg, solid vs air-containing fluid collections). With the advent of multidetector CT in clinical practice, the speed of data acquisition and image reconstruction has improved dramatically, and many reports emphasizing this change in imaging approach have been published.[11] Delayed radiographs have been the standard of care for stable patients with penetrating chest trauma. Initial chest CT scan obviates the need for repeat chest radiograph after penetrating thoracic trauma.[12]

Aortography, once considered the criterion standard for determining vascular injuries, has gradually fallen out of favor for faster, less invasive, and better-tolerated imaging techniques. The revival of aortography with endovascular intervention for trauma to the thoracic aorta or branches of the aortic arch (innominate, carotid, and subclavian arteries) is largely a product of modern technology. Endovascular stent graft arterial repair has altered the approach to vascular trauma.[13]

Penetrating injuries traversing the mediastinum or in proximity to posterior mediastinal structures dictate esophageal and tracheal evaluation, preferably by direct visualization (eg, esophagoscopy, bronchoscopy).

Specialized windows for ultrasonography have been developed to allow imaging of some intrathoracic structures despite the presence of lung air. Using the Focused Assessment with Sonography for Trauma protocols, evaluation of the thorax and the abdomen can be completed within minutes.

Readily available in most centers, echocardiography has been developed to a point at which it is now indispensable in helping evaluate injuries to the heart and the ascending and descending aortas. More recent work has demonstrated that ultrasonography can also be used to detect hemothoraces and pneumothoraces with accuracy.[14]

In appropriate settings, close observation (without thoracotomy) may be considered. However, the limitations of each of the above-noted diagnostic modalities must be remembered, and these modalities must not be extended beyond their functional limits, especially if patient safety is compromised.

Other Tests Because most trauma patients are young, extensive cardiac evaluations are often unnecessary. Admission

ECGs can be deferred until the patient is stable unless cardiac injury is considered likely. Frequently, however, immediacy of resuscitation and definitive treatment preclude obtaining ECGs. In elderly patients, ECG evidence of prior myocardial infarctions may assist in the management of dysrhythmias or potential cardiac failure.

Diagnostic Procedures See Imaging Studies.

Surgical TherapyAny organ within the chest is potentially susceptible to penetrating trauma, and each should be considered when evaluating a patient with thoracic injury. These organs include the chest wall; the lung and pleura; the tracheobronchial system, including the esophagus, diaphragm, thoracic blood vessels, and thoracic duct; and the heart and mediastinal structures.

There has been an incremental increase in the utilization of cardiothoracic surgeons over the last 10 years for thoracic trauma operative intervention and with little data available, it does appear to have resulted in improved patient outcomes. This was recently reported in the Annals of Thoracic Surgery.[15]

Chest wall injury

The chest serves the important functions of respiration and of protection of the vital intrathoracic and upper abdominal organs from externally applied force and is composed of the rigid structure of the rib cage, clavicles, sternum, scapulae, and heavy overlying musculature. Most wounds to these structures can be managed nonoperatively or by simple techniques such as tube thoracostomy. The treatment of a stable patient with a normal initial chest radiograph remains controversial.

Ammons and coworkers further defined the role of outpatient observation of selected patients with nonpenetrating thoracic GSWs and stab wounds. In their study, observation for 6 hours with subsequent repeat chest radiography revealed a 7% rate of delayed pneumothorax, and hospitalization was avoided in 86% of patients treated according to this protocol.

Large, open, chest wall defect closure can be a formidable task. When techniques involving closure with autogenous tissue of myocutaneous flaps based on the trapezius, rectus abdominus, pectoral, or latissimus dorsi muscles fail, prosthetic material (eg, polypropylene mesh, expanded polytetrafluoroethylene, cyanoacrylate) may be used.

Rarely, chest wall hemorrhage from the muscular, intercostal, and internal mammary arteries can result in exsanguination and may require operative control.

First and second rib fractures are often accompanied by serious associated injuries, particularly if multiple rib fractures are evident. Treatment of any associated injuries must be expeditious.

Severe thoracic injury that causes paradoxical motion of segments of the chest wall has been termed flail chest, which may be categorized by size or location. In adults, pulmonary contusion accompanies flail chest injuries in approximately half the patients.

The primary treatment of chest wall injuries is a combination of pain control, aggressive pulmonary and physical therapy, selective use of intubation and ventilation, and close observation for respiratory decompensation. Sufficient evidence now supports the notion that the pathophysiologic findings associated with severe chest wall trauma are related to the underlying injuries, chiefly pulmonary contusion and parenchymal injuries, and have little to do with the movement of the chest wall.

Indications for operative fixation of the chest wall or sternum include the following:

Need for thoracotomy for other reasons Large flail segments in patients with borderline premorbid pulmonary status Severe instability and pain and failure to wean from the ventilator after an adequate trial Secondary infections

Lung injuries

Injuries related to the pleural space can generally be divided into pneumothorax or hemothorax. Most patients with such injuries can be cared for with a simple tube thoracostomy. A massive hemothorax is defined as more than 1500 mL of blood in the pleural space. Usually, 200-300 mL of blood must collect in the pleural space before a hemothorax can be detected on a chest radiograph.

Although tube thoracostomy is often a lifesaving procedure and is relatively straightforward, it should not be taken too lightly. A review of almost 600 tube thoracostomies revealed a complication rate of 21%.[16]

Pulmonary parenchymal lacerations result in bleeding and air leaks, and the vast majority of these lacerations can be treated with tube thoracostomy. These lacerations extend from the surface of the lung toward the hilum or the trajectory of the penetrating object. They can vary from minor lacerations to lobar bisection. Of penetrating injuries that require thoracostomy, 80-90% can be managed using simple measures (eg, stapling, tractotomy, oversewing).

Less than 3% of all patients who require thoracotomy require a pneumonectomy, and this procedure is reserved for patients with severe hilar vascular injuries. Postoperatively, aggressive diuresis and selective lung ventilation may reduce the prevalence of pulmonary edema and stump dehiscence.

Tracheobronchial injuries

Up to 75-80% of penetrating injuries involve the cervical trachea, while 75-80% of blunt injuries occur within 2.5 cm of the carina. These injuries always occur with other injuries, especially to the great vessels; without early recognition and prompt intervention, they frequently are fatal.

Respiratory distress, subcutaneous emphysema, pneumothorax, hemoptysis, and mediastinal emphysema are the most common manifestations. Occasionally, complete or near-complete transection results in the "fallen lung" sign on chest radiographs. If possible, perform bronchoscopy on any patient in whom tracheobronchial injury is suggested. Patients with small injuries without appreciable leaks who do not require positive-pressure ventilation can be treated nonoperatively; however, most patients require urgent repair. The principles of operative repair include debridement with tension-free, end-to-end anastomosis while preserving the blood supply. The preferred suture technique is debatable but usually requires a monofilament suture with knots tied on the outside.

Delay or lack of recognition is common, and subsequent complications of stenosis and obstruction are the rule in missed tracheobronchial injuries.

Esophageal injuries

The exact prevalence of injury to the esophagus due to external trauma is unknown but is less than 1% of patients with injuries admitted to hospitals. The majority of esophageal injuries are due to penetrating trauma from a variety of instruments (ie, iatrogenic trauma).

Recognizing injury to the esophagus following trauma is difficult because of the rarity of injuries to this organ, the paucity of clinical signs in the initial 24 hours, and/or the presence of multiple other injuries. Delayed treatment results in the rapid development of sepsis and an associated high risk of death; therefore, any possibility of injury must prompt aggressive investigation, including radiography, endoscopy, and thoracoscopy (when warranted). The combined use of these techniques has a sensitivity of almost 100%.

Operative management is dictated by the site of primary injury, associated injuries, condition of the patient, degree of local suppuration, condition of the esophageal tissues, and delay since injury.

Primary repair with adequate tissue buttressing and drainage is the preferred method. Exclusion-diversion procedures have been advocated when primary repair is thought to be contraindicated. Esophageal replacement, when required, is, at best, a poor substitute for the original organ.

Complications after esophageal repair include esophageal leaks and fistulae, wound infections, mediastinitis, empyema, sepsis, and pneumonia. Long-term complications, such as esophageal stricture, are also possible.

Diaphragmatic injury

The diaphragm is frequently injured in penetrating thoracoabdominal trauma. Such injury occurs in 15% of stab wounds and in 46% of GSWs. Only 15% of the injuries are more than 2 cm long; therefore, herniation of abdominal contents is rarely immediate. Blunt injuries tend to result in larger lacerations.

Importantly, no distinctive signs and symptoms are associated with penetrating diaphragmatic injuries. A high index of suspicion is usually required for diagnosis.

Penetrating diaphragmatic injuries are frequently difficult to diagnose without laparoscopy or laparotomy. Diagnostic peritoneal lavage appears to be the best-studied procedure, although no consensus has been reached regarding the best RBC count to use. Newer diagnostic modalities, such as laparoscopy and thoracoscopy, can be useful in both diagnosing and treating penetrating diaphragmatic injuries.

In general, acute injuries are approached with laparoscopy or laparotomy because of associated injuries and chronic injuries are approached with thoracoscopy because of dense adhesions that arise between the abdominal contents and the lung. Most injuries require repair with heavy, nonabsorbable sutures; some large tears may require mesh closure. Lateral tears may require resuspension from the chest wall.

Up to 13% of injuries are missed in emergent settings, and the patient may present years later when visceral herniation occurs (85% within 3 y), manifesting as decreased cardiopulmonary reserve, obstruction, or frank sepsis. Bowel strangulation and gangrene are associated with a high mortality rate.

Thoracic great vessel injury

The great vessels of the chest include the aorta, its major branches at the arch (eg, innominate, carotid, subclavian), and the major pulmonary arteries. The primary venous conduits include the superior and inferior vena cavae and their main tributaries, as well as the pulmonary veins. Damage to vascular structures depends on the specific location and degree of vessel disruption; arterial injuries are more rapidly fatal. The prevalence of great vessel injuries ranges from 0.3-10%.

More than 90% of thoracic great vessel injuries are caused by penetrating trauma (ie, gunshot, shrapnel, stab wounds, therapeutic misadventures). Historically, thoracic injuries are associated with a high morbidity rate; however, Pate and coworkers reported a 71% survival rate in patients who reach the hospital alive after penetrating chest injuries. The trauma surgeon must resuscitate, diagnose, and treat the patient within minutes following admission to the trauma emergency unit.

A patient's hemodynamic stability dictates the next phase of managing a penetrating great vessel injury. Patients who are stable after initial resuscitation are best served by a further diagnostic workup. Helical CT scanning, CT angiography, and transesophageal echocardiography offer several advantages over other diagnostic studies.

Helical CT scanning is a noninvasive, sensitive test to assess mediastinal hematomas and to assess aortic wall and intraluminal abnormalities. The development of multidetector-row CT scanning allows for significantly shorter acquisition times (< 2 min for whole body CT scan), the ability to retrospectively reconstruct thinner sections, and improvements in 3-dimensional reconstructions. CT angiography is rapidly developing into a primary method of determining vascular injuries, obviating the much more invasive and operator-dependent conventional angiographic techniques, long held to be the criterion standard for assessment of vascular trauma. The role of transesophageal echocardiography is evolving.

While the usefulness of transesophageal echocardiography to characterize and confirm traumatic aortic dissections is undisputed, it has only recently begun to be used directly in trauma evaluation. The lack of experienced operators in the emergency department setting is apparently being overcome, and continued exposure of the technique will undoubtedly increase its use in the evaluation of trauma patients. If required, conventional angiography or digital subtraction techniques are performed with a surgeon in attendance. The role of intravascular ultrasound in the evaluation of the trauma patient has yet to be clarified.

Patients who remain in extremis or show continued rapid hemodynamic deterioration are best served by an emergency thoracotomy for rapid descending aortic cross-clamping and manual control of bleeding. Patients who are successfully resuscitated but remain hemodynamically unstable or who demonstrate continued massive blood loss are unable to undergo a further diagnostic workup and are immediately taken to the operating room.

A choice of proper incision in order to gain adequate exposure for control and repair of the injury is of prime importance. The median sternotomy with supraclavicular extensions for access to the subclavian vessels is the most useful incision. The posterolateral thoracotomy is the incision of choice for access to the descending thoracic aorta. The trapdoor, or book, incision has historic significance only.

Operative repair of thoracic aortic injuries is virtually always possible by lateral aortorrhaphy with extremely short cross-clamp times. Rarely, if ever, is an interposition graft required. Adjunctive measures of

cardiopulmonary bypass, temporary bypass shunts, or active aortic shunts (eg, a centrifugal pump) are usually not described for use in patients with penetrating trauma but are almost exclusively used for blunt injury. Paraplegia has only rarely been reported following successful repair of penetrating thoracic aortic injury, even after prolonged aortic cross-clamping following emergency thoracotomy.

Because of the proximity of other organs to the thoracic great vessels, an additional diagnostic workup including bronchoscopy, esophagoscopy, and echocardiography may be necessary. The timing of these interventions continues to be debated. Patients with great vessel injuries have a higher prevalence of associated venous, esophageal, and bronchial plexus injuries compared with patients without great vessel injuries. Trauma patients with severe concomitant injuries who are unlikely to tolerate operative repair may be treated more frequently with endovascular stenting in the future. Mitchell's series of stent graft repair of thoracic aortic lesions includes 7 posttraumatic cases.

The Society for Vascular Surgery published data regarding the use of endovascular grafts in the treatment of acute aortic transections; 97% were due to a motor vehicle accident. Sixty symptomatic patients were treated with an aortic endograft, with a mean operative time of 125 minutes and an all-cause mortality rate of 9.1% at 30 days.[17]

Nonoperative treatment predominantly applies to patients with blunt aortic injuries who are unlikely to benefit from immediate repair (eg, minor intimal defects, small pseudoaneurysms). The long-term natural history of these minor vascular injuries remains uncertain; therefore, careful follow-up monitoring, including serial imaging studies, is a critical component of nonoperative treatment.

Cardiac injuries

Traumatic cardiac penetration is highly lethal, with case fatality rates of 70-80%. The degree of anatomic injury and occurrence of cardiac standstill, both related to the mechanism of injury, determine survival probability. Patients who reach the hospital before cardiac arrest occurs usually survive. Those patients surviving penetrating injury to the heart without coronary or valvular injury can be expected to regain normal cardiac function on long-term follow up.[18]

Ventricular injuries are more common than atrial injuries, and the right side is involved more often than the left side. In 1997, Brown and Grover noted the following distribution of penetrating cardiac injuries:[19]

Right ventricle - 43% Left ventricle - 34% Right atrium - 16% Left atrium - 7%

The Beck triad (ie, high venous pressure, low arterial pressure, muffled heart sounds) is documented in only 10-30% of patients who have proven tamponade.[20]

Pericardiocentesis can be both diagnostic and therapeutic, although some centers report a false-negative rate of 80% and a false-positive rate of 33%. This procedure is reserved for patients with significant hemodynamic compromise without another likely etiology.

Echocardiography is a rapid, noninvasive, and accurate test for pericardial fluid. It has a sensitivity of at least 95% and is now incorporated into the Focused Assessment with Sonography for Trauma protocol. Once again, the management algorithm is based on the patient's hemodynamic status, with patients who are in extremis or who are profoundly unstable benefiting from emergency thoracotomy with ongoing aggressive resuscitation. In patients with GSWs from high-caliber missiles, the absence of an organized cardiac rhythm portends a grave prognosis. For patients with stab wounds or GSWs from low-caliber missiles who are apparently lifeless upon arrival, resuscitative thoracotomy is justified.

Stable patients with cardiac wounds may be diagnosed using a subxiphoid pericardial window. Bleeding must be rapidly controlled using finger occlusion, sutures, or staples. Inflow occlusion and cardiopulmonary bypass are rarely necessary. Distal coronary injuries are usually ligated, whereas proximal injuries may require bypass grafts. Intracardiac shunts or valvular injuries in patients who survive are usually minor and do not require emergent repair. Foreign bodies in the left cardiac chambers must be removed.

Postoperative deterioration may be due to bleeding or postischemic cardiac myocardial dysfunction. Residual and delayed sequelae include postpericardiotomy syndrome, intracardiac shunts, valvular dysfunction,

ventricular aneurysms, and pseudoaneurysms. Wall et al, in a classic 1997 paper, described in detail the management of 60 complex cardiac injuries.[21]

Follow-upFor patient education resources, see the Procedures Center and Skin, Hair, and Nails Center, as well as Bronchoscopy and Puncture Wound.

ComplicationsRetained pulmonary parenchymal foreign bodies

The decision to remove a retained foreign body depends on its size, its location, and any specific problems associated with it. Objects larger than 1.5 cm in diameter, centrally located missiles, irregularly shaped objects, and missiles associated with evidence of contamination may be prophylactically removed. Typically, such removal is best performed 2-3 weeks following the acute injury.

Chest wall hernia

A chest wall hernia is usually a complication of thoracotomy. A patient with a chest wall hernia presents with pain and an obvious defect, but occasionally a lung may be entrapped and become necrotic. Management includes resection of nonviable tissue and closure with tissue flaps or artificial material

Posttraumatic lung cyst

Pseudocyst of the lung is a rare development and usually manifests as a well-circumscribed, rounded, central air cavity identified on chest radiographs or CT scans. Most do not require specific treatment and resolve spontaneously within a few weeks. Patients with secondary infection present with a lung abscess and should be treated using standard therapy, including antibiotics and drainage.

Pulmonary hematoma

Hematomas form in 4-11% of patients with pulmonary contusions and are observed more frequently in patients with blunt trauma. Symptoms of fever and hemoptysis usually abate in 1 week, although chest radiograph findings usually demonstrate resolution within 4 weeks. Hematomas are associated with an increased prevalence of abscess formation.

Systemic air embolism

Systemic air embolism is usually described following central penetrating lung injury and is a special risk following primary blast injuries to the lungs. Air can enter the left side of the heart through bronchial and pulmonary venous fistulae and embolize to the coronary and systemic circulations. A precipitating factor is often the institution of positive-pressure ventilation with resulting air being forced into the low-pressure pulmonary venules. Embolism can also occur with any thoracic great vessel injury. Manifestations include seizures, arrhythmias, and cardiac arrest. Resuscitation requires thoracotomy, clamping of the pulmonary hilum, and aspiration of air from the left ventricle and ascending aorta. Experience with hyperbaric oxygen therapy has generally been good but is usually reserved for those centers with access to larger chambers (ie, to support associated medical personnel).

Bronchial stricture

Missed tracheobronchial laceration may result in significant strictures. Patients present with variable degrees of dyspnea. Evaluation with bronchoscopy and CT scanning is followed by treatment with open operative repair or stenting.

Tracheoesophageal fistula

Delayed tracheoesophageal fistula is rare, generally manifesting approximately 10 days following injury, possibly from delayed necrosis following a blast injury. Usually, the airway at or just above the carina is involved. The timing of surgery or intervention is unclear and depends on the degree of ventilatory leak and the overall condition of the patient.

Persistent air leak and bronchopleural fistula

Traumatic air leaks that last longer than 7 days are unlikely to resolve spontaneously, and judicious manipulation of the chest tube to increase or decrease the suction may be appropriate in order to facilitate healing. Bronchopleural fistulae imply a direct communication between the major airways and the pleural space and usually require some form of intervention for closure.

Empyema

Empyema occurs in 2-6% of patients with PCT. Traumatic empyema differs from nontraumatic forms because it is more often loculated and requires operative debridement. Initial treatment is tube drainage. Thoracoscopy, particularly if performed within 7-10 days, is effective for draining the infection.

Ventilator-associated pneumonia

Ventilator-associated pneumonia occurs in 9-44% of ventilated patients. It increases the mortality rate in patients who do not have ARDS from 26% to 48% and in patients with ARDS from 28% to 67%. Management consists of ventilator support and appropriate systemic antibiotic therapy.

Missile embolization

Embolization to the pulmonary arteries is usually treated with surgical removal or interventional techniques. A chest radiograph taken immediately preceding incision or intraoperative fluoroscopy is mandatory in order to detect more distal embolization that may occur during positioning. Asymptomatic patients with small distal fragments may be treated expectantly. Occasionally, missile emboli may migrate through a patent foramen ovale or from central parenchymal or vascular injuries to gain access to the left side of the heart and then to the systemic circulation.

Cardiovascular fistulae

Most cardiovascular arterial-to-venous fistulae occur following stab wounds. Virtually all manifest as a machinery murmur after approximately 1 week. Innominate artery-to-vein fistulae are the most common. Patients with coronary artery fistulae, usually to the right ventricle, present with ischemia, cardiomyopathy, pulmonary hypertension, or bacterial endocarditis. Aortocardiac, aortopulmonary, and aortoesophageal fistula are quite rare because the probability of survival from the acute injury is slim. While requiring open repair in the past, interventional techniques may be used in a large number of these patients.

Thoracic duct injury and chylothorax

Injuries to the thoracic great vessels may be complicated by concomitant thoracic duct injury, which, if unrecognized, may produce devastating morbidity due to severe nutritional depletion. Initial management of a delayed chylothorax is always aggressive but nonoperative. Hyperalimentation with total enteral foodstuff restriction (ie, parenteral hyperalimentation) may result in a significant number of spontaneously sealing thoracic duct injuries. Failure to spontaneously seal after 5-7 days indicates the need for surgical intervention, which should be individualized because the optimal approach is controversial. The number of proponents for direct suture control is equal to the number of those preferring a right thoracotomy to ligate the vessel as it traverses the diaphragm. Experienced personnel can approach the duct thoracoscopically or with video assistance, thus minimizing additional discomfort to the patient.

Outcome and PrognosisThe outcomes of treating patients with PCT are directly related to the extents of patients' injuries and the timeliness of initiation of treatments. Patients arriving in a stable condition may expect full recovery, but patients presenting with lesser levels of stability have diminishing probabilities of survival. Do not attempt to resuscitate, let alone definitively treat, patients presenting with no vital signs or with obviously nonsurvivable injuries (eg, massive cardiac destruction).

Guidelines for initiation of emergency department thoracotomy were published in 2003.[22]

Reporting from a single center in 2010, patients who died had a significantly lower systolic blood pressure (42 +/- 36 mmHg) compared with those who survived (83 +/- 27 mmHg, p< 0.001).[23]

Future and Controversies

The current management of penetrating thoracic injury is a hurried, brute-force approach necessitated by the life-threatening nature of many of these injuries. As surgical experience with less invasive techniques and minimal incision approaches increases, these methods will likely find their appropriate places in the treatment of these patients. Already, interventional radiologic techniques can safely treat many patients with intrathoracic vascular injuries and have been successfully used to retrieve intracardiac missiles. Traumatically disrupted aortae have been treated with stenting; in stable patients with penetrating injuries to the thoracic vessels, use of this modality should be considered. Currently, however, traditional approaches and techniques have little competition in the treatment of critically injured and frequently unstable patients.

The mechanism of thoracic injury in modern battles is shifting more from penetrating wounds to combination blast injuries. The mortality of those injured has increased (12% vs 3% in Vietnam) and may represent the devastation caused by IEDs and the subsequent multisystem injuries they cause. The overall killed-in-action rate has decreased, whereas the died-of-wounds rate has increased. Half of all thoracic injuries reported from the battle front on the Global War on Terror occurred in the civilian population.[5]