Blunt Chest Trauma

Sef lucr. Dr. Cristina GrigorescuClinic of Thoracic Surgery

• Chest trauma is a significant source of morbidity and mortality in the United States.

• 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, sternum), lungs and pleurae, tracheobronchial tree, esophagus, heart, great vessels of the chest, and the diaphragm.

• Records describing chest trauma and its treatment date to antiquity. An ancient Egyptian treatise (the Edwin Smith Surgical Papyrus [circa 3000-1600 BC]) and Hippocrates' writings in the 5th century contain a series of trauma case reports, including thoracic injuries

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, approximately 118,000 accidental deaths occurred in the United States in 2005.

Frequency

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

Pathophisiology

• 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.

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• Space-occupying lesions, such as pneumothoraces, hemothoraces, and hemopneumothoraces, interfere with oxygenation and ventilation by compressing otherwise healthy lung parenchyma. A situation of 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. Following 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.

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 with a 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, the authors divide blunt thoracic injuries into 3 broad categories as follows: (1) chest wall fractures, dislocations, and barotrauma (including diaphragmatic injuries); (2) blunt injuries of the pleurae, lungs, and aerodigestive tracts; and (3) 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 Anatomy

• The 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 comprise the brachial plexus also access the upper extremities via the thoracic outlet. The veins that drain the arm, most importantly 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 3 lobes, and the left lung has 2 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 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 (remnant of ductus arteriosus) exists between the descending thoracic aorta and pulmonary artery just beyond the take-off 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.

Approach Considerations

• Initial emergency workup of a patient with multiple injuries should begin with the ABCs of trauma, with appropriate intervention taken for each step.

Laboratory studies

• CBC count• A CBC count is a routine laboratory test for

most trauma patients. The CBC count helps gauge blood loss, although 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• 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.

• Serum chemistry profile• 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.

• Coagulation profile• The coagulation profile, including prothrombin

time/activated partial thromboplastin time, fibrinogen, fibrin degradation product, and D-dimer analyses, can be helpful in the management of patients who receive massive transfusions (eg, >10 U packed RBCs). Patients who manifest hemorrhage that cannot be explained by surgical causes should also have their profile monitored.

• Serum troponin levels• The rate of cardiac injury in patients with blunt chest trauma

varies widely depending upon the diagnostic criteria. Troponin is a protein specific to cardiac cells. While 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. As such, troponin I level determination does not, by itself, help predict the occurrence of complications that may require admission to the hospital. Accordingly, their routine use in this clinical situation is not well supported.

• Serum myocardial muscle creatine kinase isoenzyme levels

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

• Serum lactate levels• 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.

• Blood type and crossmatch• Type and crossmatch are some of 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 radiographs• The chest radiograph (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 should be immediately decompressed before obtaining a chest radiograph.

• Chest CT scan• Due to lack of sensitivity of chest radiography to identify

significant injuries, computed tomography (CT) scan 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 scan. As a result, obtaining a chest CT scan in a supposedly stable patient with significant mechanism of injury is becoming routine practice.

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• Helical CT scanning 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.

• Aortogram• 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, with the new generation spiral CT scanners, which have 100% sensitivity and greater than 99% specificity, the role of aortography in the evaluation of trauma patients is declining. 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

• Thoracic ultrasound• 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 ultrasound in these settings are all more than 90%

• Contrast esophagogram• 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 the Sonographic Examination of the 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

• Twelve-lead electrocardiogram• 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.

• Transesophageal 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%. Its advantages 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.

• 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• 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.

• Flexible or rigid 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

• Fiberoptic or rigid 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 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 requiring 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 the pleurae, lungs, and aerodigestive tracts

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

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

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

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

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

Contraindications

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

Rib fractures

Rib fractures are the most common blunt thoracic injuries. Ribs 4-10 are most frequently involved. Patients usually report inspiratory chest pain and discomfort over the fractured rib or ribs. Physical findings include local tenderness and crepitus over the site of the fracture. If a pneumothorax is present, breath sounds may be decreased and resonance to percussion may be increased. Rib fractures may also be a marker for other associated significant injury, both intrathoracic and extrathoracic. 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 3 or more rib fractures have been shown to have a 5-fold increased mortality rate and a 4-fold increased 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, which requires surgical control to achieve hemostasis acutely. In the chronic phase, nonunion and persistent pain may also require an operation.

Flail chest

• A flail chest, by definition, involves 3 or more consecutive rib fractures in 2 or more places, which produces a free-floating, unstable segment of chest wall. Separation of the bony ribs from their cartilaginous attachments, termed costochondral separation, can also cause flail chest. Patients report pain at the fracture sites, pain upon inspiration, and, frequently, dyspnea. Physical examination reveals paradoxical motion of the flail segment. The chest wall moves inward with inspiration and outward with expiration. Tenderness at the fracture sites is the rule. Dyspnea, tachypnea, and tachycardia may be present. The 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 treatment modalities mentioned above for patients with rib fractures are appropriate for those with 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 because fluid overloading can precipitate respiratory failure, especially in patients with significant pulmonary contusions.

• In an attempt to stabilize the chest wall and to avoid endotracheal intubation and mechanical ventilation, various operations have been devised for correcting flail chest. These include pericostal sutures, the application of external fixation devices, or the placement of plates or pins for internal fixation. With improved understanding of pulmonary mechanics and better mechanical ventilatory support, surgical therapy has not been proven superior to the supportive and medical measures discussed. However, most authors would agree that stabilization is warranted if a 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 one of 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, or 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 compared to the contralateral arm. The proximal segment of the clavicle is displaced superiorly because of the action of the sternocleidomastoid muscle.

• Nearly all clavicular fractures can be managed without surgery. Primary treatment consists of immobilization with a figure-of-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.

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 used before completely excluding myocardial injury. The workup should begin with an 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.

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

• This curious clinical constellation is the result of thoracic injury due to a strong crushing mechanism, 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 neurological 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, although autopsy and CT scan–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 scan is not very accurate, and 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.

Pneumothorax

• Pneumothoraces in blunt thoracic trauma are most frequently caused when a fractured rib penetrates the lung parenchyma. This is not absolute. 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 water. The tube continues suctioning until no air leak is detected. The tube is then disconnected from suction and placed to water seal. If the lung remains fully expanded, the chest tube may be removed and another chest radiograph obtained to ensure continued complete lung expansion.

Hemothorax

• The accumulation of blood within the pleural space can be due to bleeding from the chest wall (eg, lacerations of the intercostal or internal mammary vessels attributable to fractures of chest wall elements) or to hemorrhage from the lung parenchyma or major thoracic vessels. Patients report pain and dyspnea. Physical examination findings vary with the extent of the hemothorax. Most hemothoraces are associated with a decrease in breath sounds and dullness to percussion over the affected area. Massive hemothoraces due to major vascular injuries manifest with the aforementioned physical findings and varying degrees of hemodynamic instability

• Hemothoraces are evacuated using tube thoracostomy. Multiple chest tubes may be required. Pain control and aggressive pulmonary toilet are provided. The chest tube output is monitored closely because indications for surgery can be based on the initial and cumulative hourly chest tube drainage. This is because massive initial output and continued high hourly output are frequently associated with thoracic vascular injuries that require surgical intervention

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

Open pneumothorax

• This injury is more commonly caused by penetrating mechanisms but may rarely occur with blunt thoracic trauma. Patients are typically in respiratory distress due to collapse of the lung on the affected side. Physical examination should reveal a chest wall defect that is larger than the cross-sectional area of the larynx. The affected hemithorax demonstrates a significant-to-complete loss of breath sounds. The increased intrathoracic pressure can shift the contents of the mediastinum to the opposite side, decreasing the return of blood to the heart, potentially leading to hemodynamic instability.

• Treatment for an open pneumothorax consists of placing a 3-way occlusive dressing over the wound to preclude the continued ingress of air into the hemithorax and to allow egress of air from the chest cavity. A tube thoracostomy is then performed. Pain control and pulmonary toilet measures are applied.

• 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 such as 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.

Tension pneumothorax

• The mechanisms that produce tension pneumothoraces are the same as those that produce simple pneumothoraces. However, with a tension pneumothorax, air continues to leak from an underlying pulmonary parenchymal injury, increasing pressure within the affected hemithorax. Patients are typically in respiratory distress. Breath sounds are severely diminished to absent, and the hemithorax is hyperresonant to percussion. The trachea is deviated away from the side of the injury. The mediastinal contents are shifted away from the affected side. This results in decreased venous return of blood to the heart. The patient exhibits signs of hemodynamic instability, such as hypotension, which can rapidly progress to complete cardiovascular collapse.

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

Pulmonary contusion

• The forces associated with blunt thoracic trauma can be transmitted to the lung parenchyma. This results in pulmonary contusion, as characterized by development of pulmonary infiltrates with hemorrhage into the lung tissue. Clinical findings in pulmonary contusion depend on the extent of the injury. Patients present with varying degrees of respiratory difficulty. Physical examination demonstrates decreased breath sounds over the affected area. 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%).

Blunt tracheal injuries

• While incidence of blunt tracheobronchial injuries is rare (1-3%), most patients with these 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 emergent 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 have passed since injury, primary repair buttressed by well-vascularized autologous tissue is still the best option if technically feasible. Examples of tissues used to reinforce esophageal repairs include parietal pleura and intercostal muscle. Very distal esophageal injuries can be covered with a tongue of gastric fundus. This is called a Thal patch.

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

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.

Blunt thoracic aortic injuries

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

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

• The management of these injuries, especially those of the thoracic aorta, is evolving. Many patients have 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-blocking agents (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.

• Endovascular stent grafts are being developed to repair thoracic aortic injuries. While several authors have reported success in treating such injuries with endo stents, the long-term durability of the stents is yet unknown. Further experience with this technique will allow more victims with concomitant severe injuries to become operative candidates. Techniques for repair of the innominate artery and subclavian vessels vary depending on the type of injury. Many require only lateral arteriorrhaphy. Large injuries of the innominate artery are managed first by placement of a bypass graft from the ascending aorta to the distal innominate artery. The injury is then approached directly and is oversewn or patched

• 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 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.

Complications

• Patients with blunt thoracic trauma are subject to myriad complications during the course of their care. This section outlines most major complications that may occur.

• Wound • Wound infection • Wound dehiscence - Particularly problematic

in sternal wounds.

• Cardiac

• Myocardial infarction• Arrhythmias • Pericarditis• Ventricular aneurysm formation • Septal defects • Valvular insufficiency

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

• Vascular

• Graft infection • Pseudoaneurysm • Graft thrombosis • Deep venous thrombosis • Pulmonary embolism

• Neurological

• Causalgia - Injuries that involve the brachial plexus • Paraplegia - Spinal cord at risk during repair of

ruptured thoracic aorta • Stroke

• Esophageal

• Leakage of repair • Mediastinitis • Esophageal fistula • Esophageal stricture .

• Bony skeleton

• Skeletal deformity • Chronic pain • Impaired pulmonary mechanics

Future and Controversies

• Future 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, ultrasound use 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.