Epidemiology

Head and thoracic injuries from moving vehicle collisions (MVCs) and firearms account for the majority of the more than 160,000 injury-related deaths in the United States each year. Most fatalities occur immediately as a result of massive cardiac or vascular injury. Rib fractures are the most common thoracic cage injury following blunt thoracic trauma. Isolated first and second rib, sternum, and scapula fractures are no longer considered markers of traumatic aortic injury.¹ However, rib fractures must still be considered markers of significant injury. Most patients seen in trauma centers with rib fractures will have hemothorax, pneumothorax, or a pulmonary contusion. Three or more rib fractures at any anatomic site dramatically increases the risk for spleen and liver injury. Likewise, scapula fractures are uncommon yet signify a high-energy mechanism of injury, almost always with important associated injuries.

Seat belts have increased the incidence of sternum fractures while reducing the number of lives lost in MVCs. Isolated nondisplaced sternum fractures are no longer considered markers of blunt cardiac injury.² More complicated fracture patterns predict associated injuries. Fractures of the manubrium, manubrium-sternum synchondrosis, and proximal part of the sternum and severely displaced sternum fractures are associated with an increased incidence of spinal fractures. Displaced fractures of the body of the sternum are associated with a higher incidence of intrapulmonary and cardiac injuries.³

Pathophysiology

The most common mechanism of blunt thoracic trauma is an MVC, followed by falls, assaults, and crush injuries. Compressive forces directly injure the thoracic cage and underlying viscera and result in rib fractures and pulmonary contusion. Deceleration produces traction on fixed structures such as the isthmus of the aorta and the carina and results in traumatic aortic and tracheobronchial injuries. Blunt thoracic trauma causes penetrating thoracic trauma when rib or clavicle fractures impale thoracic or abdominal viscera.

Gunshot wounds and stab wounds are the most common mechanisms of penetrating thoracic trauma. Low-velocity stab wounds disrupt only the structures penetrated. Medium-velocity handguns and high-velocity military assault rifles produce temporary and permanent cavities of tissue damage. Missile injuries to the thorax often involve multiple anatomic regions, including the neck, diaphragm, abdomen, and retroperitoneum.

Presenting Signs and Symptoms

Classically, rib fractures are accompanied by localized tenderness and pleuritic chest pain, as well as splinting, crepitus, and ecchymosis. Patients with a classic sternum fracture have localized pain and tenderness along with ventral compression, ecchymosis, and deformity. Pain at the site of thoracic cage injuries increases with cough and deep inspiration. Patients with scapular fractures typically have rib and extremity fractures that often mask the diagnosis of scapula fracture.

Differential Diagnosis and Medical Decision Making

The initial portable anteroposterior (AP) chest radiograph should be inspected to confirm the diagnosis of rib fracture and underlying pleura or lung injury. Upright posteroanterior (PA) and lateral radiographs should be obtained if a high clinical index of suspicion remains for fracture or underlying injury. The presence of an occult “clinical rib fracture” with tenderness over the rib should be assumed even in the absence of radiographic findings. Rib radiographs seldom add to the clinical evaluation and are not routinely indicated.

Sternum fractures are best detected on the lateral chest radiograph. Associated rib fractures and mediastinal abnormalities may be evident on the PA view. In experienced hands, bedside ultrasound may be more sensitive than radiographs for detection of both rib and sternum fractures, as well as associated hemothorax or pneumothorax.^6,7 The electrocardiogram (ECG) should be examined for evidence of cardiac injury. Scapula fractures are often missed on the initial chest radiograph unless the scapular outline is specifically inspected. Shoulder radiographs can confirm suspected fractures (Fig. 78.1).

Fig. 78.1 A, Chest radiograph showing fractures of the clavicle (white arrow)) and scapula (black arrow). B, Lateral scapula fractures (arrows) visible on a computed tomography scan.

(From Westra SJ, Wallace EC. Imaging of pediatric chest trauma. Radiol Clin North Am 2005;43:267-81.)

Helical computed tomographic (CT) angiography should be performed on hemodynamically stable patients when clinically significant underlying injury is suspected. An abdominal CT scan can rule out intraabdominal injury in patients with tenderness or fracture of the sixth rib or below, three or more rib fractures, hypotension noted in the field or emergency department (ED), abdominal or flank tenderness, pelvic or femoral fractures, or gross hematuria.⁸

Treatment

Adequate pain control should be provided to prevent atelectasis in patients with simple acute rib fractures. Patients should be instructed to perform incentive spirometry or take 10 deep breaths every hour. Binders and belts are not recommended because such devices promote hypoventilation, which results in atelectasis and pneumonia. Shoulder slings and pendular exercise should be prescribed for most scapular fractures. Displaced fractures, especially those involving the scapular spine and neck, often require consultation with an orthopedic surgeon for repair.

Follow-up, Next Steps in Care, and Patient Education

Otherwise healthy patients with isolated rib fractures or sternum or scapula fractures may be discharged home. Elderly patients and those with multiple comorbid conditions may require admission for pain control and pulmonary therapy. An intercostal nerve block can be of marked benefit. Discharged patients should be informed that the pain will diminish after 2 weeks but may persist for up to 6 weeks. Follow-up with a trauma surgeon should be scheduled if pain persists beyond 4 weeks to detect delayed rib fracture complications.

Presenting Signs and Symptoms

Patients may have the classic signs and symptoms of respiratory distress, tenderness, crepitus, deformity, and paradoxic motion of the affected thoracic wall. Affected segments will move inward during inspiration and outward during expiration. More commonly, splinting secondary to severe pain or mechanical ventilation masks the diagnosis. Forced expiration and coughing accent the paradox.

Differential Diagnosis and Medical Decision Making

A chest radiograph can confirm the diagnosis and detect complications such as pneumothorax and hemothorax. A chest CT scan can further evaluate the underlying pulmonary contusion and assess for other underlying injuries such as traumatic aortic injury.

Treatment

Immediate chest tube placement is required for assessment and management of other injuries, including pneumothorax and hemothorax. Continuous positive airway pressure is the first-line treatment in awake and cooperative patients with worsening oxygenation or ventilation.¹⁰ Criteria for intubation include airway obstruction, respiratory distress, shock, closed head injury, and need for surgery. Endotracheal intubation should be performed only when necessary to avoid the increased mortality associated with nosocomial pneumonia.

Fluid replacement should be managed carefully to avoid overhydration and worsening of lung injury. Analgesia is titrated so that patients are more willing to make sufficient inspiratory effort, but excessive sedation should be avoided. Intercostal nerve blocks, epidural anesthesia, or even surgical fixation of the flail segment may be beneficial.¹¹ Stabilization of the flail segment in the ED or prehospital setting has not been shown to be helpful, and aggressive stabilizing efforts impede overall thoracic mechanics.

Follow-up, Next Steps in Care, and Patient Education

Consultation and admission for trauma or cardiothoracic surgery is advised when flail chest is suspected. Overall mortality from flail chest, though dependent on other injuries, ranges up to 35%. All patients with flail chest should be admitted to the intensive care unit, preferably at a level I trauma center for close observation of respiratory mechanics and worsening of pulmonary contusion.

Presenting Signs and Symptoms

Patients with a simple pneumothorax classically have chest pain, diminished breath sounds, crepitus, hyperresonance, and mild to moderate respiratory distress. Patients with tension pneumothorax are classically seen in extremis and exhibit jugular venous distention, tracheal deviation, unilaterally absent breath sounds, or tachycardia followed by hypotension immediately before death (or any combination thereof).¹² Patients with open pneumothorax have chest wall wounds that produce sonorous sounds and are in severe respiratory distress. Typical symptoms of hemothorax are respiratory distress, chest pain, and diminished breath sounds with dullness to percussion.

Atypical manifestations are more common than classic ones. Respiratory distress may occur as a result of multiple other causes. Patients can have severe pain from distracting injuries. Breath sounds may be difficult to hear in a noisy environment. Physical examination in patients with penetrating thoracic trauma is unreliable for the detection of pneumothorax or hemothorax.¹³ Patients with simple pneumothorax may be minimally symptomatic or may be cyanotic and in severe respiratory distress. Tension pneumothorax most commonly occurs in intubated patients as a result of positive pressure ventilation, sometimes after overzealous bagging.

Clinical reassessment of ventilated patients with decreasing oxygen saturation and hypotension may allow faster detection and treatment, even before chest radiographic diagnosis. Open pneumothorax may be missed if the patient is not completely exposed and rolled during the primary survey.

Differential Diagnosis and Medical Decision Making

The differential diagnosis for tension pneumothorax includes cardiac tamponade, massive hemothorax, and right mainstem intubation with left lung collapse. All will produce respiratory distress, hypotension, and tachycardia. Cardiac tamponade results in diminished heart sounds with normal breath sounds and a midline trachea. Massive hemothorax produces decreased or absent unilateral breath sounds and dullness to percussion. Chest tube insertion confirms the diagnosis. Right mainstem intubation results in jugular venous distention, tracheal deviation to the left, normal resonance, and diminished breath sounds on the left versus the right. In an intubated patient, the endotracheal tube should be checked and pulled back. In the field or resuscitation bay, bilateral needle thoracostomy should be performed when the patient is in distress, even if the diagnosis is uncertain. A rush of air confirms the diagnosis of tension pneumothorax. Chest tubes must be placed after needle decompression.

A chest radiograph can confirm the diagnosis of simple pneumothorax and hemothorax. A distance of 1 cm or one fingerbreadth between the chest wall and visceral pleural line correlates with a small, 10% to 15% pneumothorax. Anything larger requires immediate chest tube insertion. On a supine portable AP chest radiograph, a deep sulcus sign suggests pneumothorax. The affected costophrenic angle appears clearer and deep with depression of the hemidiaphragm as a result of localized air collection in a supine patient. In patients with a high index of clinical suspicion based on symptoms or penetrating injuries, some authorities advocate expiratory upright PA and lateral chest radiographs to make the lung volume smaller and the pneumothorax volume relatively larger and easier to visualize. Clinically significant pneumothorax should be evident on standard chest radiographs. The chest CT scan is more sensitive in visualizing pneumothorax; it often detects small occult pneumothoraces, which require close monitoring.

In an upright patient, a hemothorax appears as a fluid layer in the affected hemithorax. Early collections are noted to blunt the costophrenic angles on the AP and lateral radiographic views. Hemothorax often appears as only a diffuse hazy infiltrate in a supine trauma patient. Hemopneumothorax has a fluid layer with a flat superior border, in contrast to the round meniscus of an isolated hemothorax (Figs. 78.2 and 78.3). Decubitus views better demonstrate a small hemothorax.

Fig. 78.2 Chest radiograph showing obvious left-sided tension pneumothorax with mediastinal shift.

(From Ullman EA, Donley LP, Brady WJ. Pulmonary trauma emergency department evaluation and management. Emerg Med Clin North Am 2003;21:291-313.)

Fig. 78.3 Chest radiograph showing right hemopneumothorax along with a bullet.

(Image courtesy Dave Andreski, MD.)

An extended focused assessment with sonography for trauma (FAST) scan can diagnose pneumothorax and hemothorax with higher sensitivity than portable chest radiography can in experienced hands. An extended FAST scan is especially helpful when chest radiography is not immediately available and in mass casualty situations.¹⁴

Treatment

Tension pneumothorax and open pneumothorax are both clinical diagnoses that require immediate treatment with needle thoracostomy followed by tube thoracostomy, even when based on clinical evaluation, before radiographic confirmation. All suspicious open chest wounds should be covered with petrolatum gauze secured on three sides to prevent the entry of air during inspiration and allow the exit of air during expiration. Postprocedure radiographs should be obtained to confirm placement, drainage of air and blood, and reexpansion of lung. Prophylactic antibiotics with chest tube insertion do not reduce the risk for empyema or pneumonia.¹⁵

Operating room thoracotomy is indicated for patients with massive hemothorax (initial drainage of 1.5 to 2 L of blood), persistent bleeding of more than 200 mL/hr for 4 hours, and persistent hypotension or instability despite blood replacement. Autotransfusion should be performed in patients with massive hemothorax or persistent significant bleeding. It is prudent to prepare for autotransfusion early because most blood loss occurs at the time of initial chest tube insertion.

Follow-up, Next Steps in Care, and Patient Education

Traumatic pneumothorax and hemothorax generally require tube thoracostomy. The exception is a small stable pneumothorax in an otherwise healthy and symptom-free patient, which may be managed with observation.

Occult traumatic pneumothorax detected on a CT scan requires only close observation for respiratory distress, progression, and the development of complications. Tube thoracostomy must be immediately available but is not required even with positive pressure ventilation.¹⁶ Any prolonged surgery, diagnostic testing, or transport preventing immediate tube thoracostomy requires prophylactic placement.

In patients with penetrating injuries and a negative initial chest radiograph, upright PA and lateral chest radiographs should be repeated in 3 to 4 hours.¹⁷ Patients with normal findings on repeated radiographs and no significant associated injuries are discharged with wound care and follow-up instructions. Patients with asymptomatic blunt chest trauma and normal findings on the initial chest radiographs do not require repeated films before discharge. All patients with chest tubes are admitted to the trauma, cardiothoracic, or general surgery service in the care of personnel experienced in managing chest tube equipment.

Presenting Signs and Symptoms

Patients with pulmonary contusion typically have significant chest wall injury accompanied by dyspnea and tachypnea and progressing to hemoptysis, cyanosis, and hypotension. Inspection often reveals an obvious flail chest or ecchymosis overlying rib fractures. Auscultation reveals rhonchi, wheezes, rales, or minimal breath sounds. Blast injuries may result in significant pulmonary contusion with minimal chest wall injury. Delayed manifestations of pulmonary contusion can occur in initially well-appearing patients. Because the hemorrhage and edema will worsen, patients with even mild initial symptoms must be observed closely with continuous monitoring. The clinical findings usually progress over the initial hours through the first 2 days.

Differential Diagnosis and Medical Decision Making

The differential diagnosis in a trauma patient with respiratory distress and infiltrates on initial chest radiographs includes pulmonary contusion, congestive heart failure, aspiration pneumonia, and acute respiratory distress syndrome. Symptomatic congestive heart failure may predispose patients to blunt trauma, result from blunt myocardial injury, or develop during fluid resuscitation. Aspiration pneumonia leads to lobar opacification. Acute respiratory distress syndrome typically occurs 24 to 48 hours after the injury, often with diffuse bilateral infiltrates and a normal heart size.

The patchy or diffuse air space opacification above the site of injury with pulmonary contusion is often present on the initial chest radiograph and typically progresses over the first 6 hours (Fig. 78.4). Initial CT scanning is more sensitive than chest radiography but seldom changes the initial management of pulmonary contusion. Pulse oximetry is essential to detect early clinical deterioration.

Fig. 78.4 Chest radiograph showing right pulmonary contusion with pneumomediastinum and pneumopericardium.

(From Marx J, Hockberger R, Walls R, editors. Rosen’s emergency medicine: concepts and clinical practice. 6th ed. St. Louis: Mosby; 2006.)

Treatment

Prophylactic intubation is not recommended for patients with minimal symptoms. Indications for intubation in adult patients with pulmonary contusion include airway compromise, moderate to severe respiratory distress, hypoxia, hypercapnia, and the need for general anesthesia, as well as to facilitate the care of other injuries.

Follow-up, Next Steps in Care, and Patient Education

Patients with pulmonary contusion require admission to the intensive care unit for oxygen administration, chest physical therapy, incentive spirometry, suctioning, analgesia, and close monitoring. Overhydration must be avoided to prevent iatrogenic worsening of capillary leak and lung function. Prophylactic steroids and antibiotics are not recommended.¹⁸ Isolated pulmonary contusions typically resolve within 14 days without long-term complications. Disability and mortality rates are higher in patients with larger areas of contusion, flail chest, acute respiratory distress syndrome, and pneumonia.