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Overview of Thoracic Trauma

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Thoracic trauma causes about 25% of traumatic deaths in the US. Many chest injuries cause death during the first minutes or hours after trauma; they can frequently be treated at the bedside with definitive or temporizing measures that do not require advanced surgical training.

Etiology

Chest injuries can result from blunt or penetrating trauma. The most important chest injuries include the following:

Many patients have simultaneous hemothorax and pneumothorax (hemopneumothorax).

Bone injuries are common, typically involving the ribs (see Rib Fracture ) and clavicle (see Clavicle Fractures ), but fractures of the sternum and scapula may occur.  The esophagus and diaphragm (see Overview of Abdominal Trauma ) also can be damaged by chest trauma. Because the diaphragm can be as high as the nipple line during exhalation, penetrating trauma to the chest at or below nipple level can also cause intra-abdominal injuries.

Pathophysiology

Most morbidity and mortality due to chest trauma occurs because injuries interfere with respiration, circulation, or both.

Respiration can be compromised by

  • Direct damage to the lungs or airways

  • Altered mechanics of breathing

Injuries that directly damage the lung or airways include pulmonary contusion and tracheobronchial disruption. Injuries that alter the mechanics of breathing include hemothorax, pneumothorax, and flail chest. Injury to the lung, tracheobronchial tree, or rarely esophagus may allow air to enter the soft tissues of the chest and/or neck (subcutaneous emphysema) or mediastinum (pneumomediastinum). This air itself rarely has significant physiologic consequence; the underlying injury is the problem. Tension pneumothorax impairs respiration as well as circulation.

Circulation can be impaired by

  • Bleeding

  • Decreased venous return

  • Direct cardiac injury

Bleeding, as occurs in hemothorax, can be massive, causing shock (respiration is also impaired if hemothorax is large). Decreased venous return impairs cardiac filling, causing hypotension. Decreased venous return can occur due to increased intrathoracic pressure in tension pneumothorax or to increased intrapericardial pressure in cardiac tamponade. Heart failure and/or conduction abnormalities can result from blunt cardiac injury that damages the myocardium or the heart valves.

Complications

Because chest wall injuries typically make breathing very painful, patients often limit inspiration (splinting). A common complication of splinting is atelectasis, which can lead to hypoxemia, pneumonia, or both.

Patients treated with tube thoracostomy, particularly if a hemothorax is incompletely drained, may develop purulent intrathoracic infection (empyema).

Symptoms and Signs

Symptoms include pain, which usually worsens with breathing if the chest wall is injured, and sometimes shortness of breath.

Common findings include chest tenderness, ecchymoses, and respiratory distress; hypotension or shock may be present.

Neck vein distention can occur in tension pneumothorax or cardiac tamponade if patients have sufficient intravascular volume.

Decreased breath sounds can result from pneumothorax or hemothorax; percussion over the affected areas is dull with hemothorax and hyperresonant with pneumothorax.

The trachea can deviate away from the side of a tension pneumothorax.

In flail chest, a segment of the chest wall moves paradoxically—that is, in the opposite direction of the rest of the chest wall (outward during expiration and inward during inspiration); the flail segment is often palpable (see Flail Chest ).

Subcutaneous emphysema causes a crackling or crunch when palpated. Findings may be localized to a small area or involve a large portion of the chest wall and/or extend to the neck. Most often, pneumothorax is the cause; when extensive, injury to the tracheobronchial tree or upper airway should be considered. Air in the mediastinum may produce a characteristic crunching sound synchronous with the heartbeat (Hamman sign or Hamman crunch). Hamman sign suggests pneumomediastinum and often tracheobronchial tree injury or, rarely, esophageal injury.

Diagnosis

  • Clinical evaluation

  • Chest x-ray

  • Sometimes other imaging studies (eg, CT, ultrasonography, aortic imaging studies)

Clinical evaluation

Five conditions are immediately life threatening and rapidly correctable:

  • Massive hemothorax

  • Tension pneumothorax

  • Open pneumothorax

  • Flail chest

  • Pericardial tamponade

Diagnosis and treatment begin during the primary survey (see Approach to the Trauma Patient ) and are based first on clinical findings. Depth and symmetry of chest wall excursion are assessed, the lungs are auscultated, and the entire chest wall and neck are inspected and palpated. Patients in respiratory distress should be monitored with serial assessments of clinical status and of oxygenation plus ventilation (eg, with pulse oximetry, ABGs, capnometry if intubated).

Penetrating chest wounds should not be probed. However, their location helps predict risk of injury. High-risk wounds are those medial to the nipples or scapulae and those that traverse the chest from side to side (ie, entering one hemithorax and exiting the other). Such wounds may injure the hilar or great vessels, heart, tracheobronchial tree, or rarely the esophagus.

Patients with symptoms of partial or complete airway obstruction following blunt trauma should be immediately intubated to control the airway.

In patients with difficulty breathing, severe injuries to consider during the primary survey include the following:

  • Tension pneumothorax

  • Open pneumothorax

  • Massive hemothorax

  • Flail chest

There is a simplified, rapid approach to help differentiate these injuries (see Figure: A simple, rapid assessment of patients with thoracic trauma and respiratory distress during the primary survey.).

A simple, rapid assessment of patients with thoracic trauma and respiratory distress during the primary survey.

In patients with thoracic trauma and impaired circulation (signs of shock), severe injuries to consider during the primary survey include the following:

  • Massive hemothorax

  • Tension pneumothorax

  • Cardiac tamponade

Other chest injuries (eg, blunt cardiac injury, aortic disruption) may cause shock but are not treated during the primary survey. Simplified, rapid approaches can help differentiate among rapidly correctable causes of shock due to chest injuries (see Figure: A simple, rapid assessment for chest injuries in patients with shock during the primary survey.). However, hemorrhage should be excluded in all patients who have shock after major trauma, regardless of whether a chest injury that could cause shock is identified.

A simple, rapid assessment for chest injuries in patients with shock during the primary survey.

*Hemorrhage should be excluded in all patients who are in shock after major trauma, regardless of whether a chest injury that could cause shock is identified

Neck vein distention may be absent in patients with hypovolemic shock.

Treatment of injuries affecting the airway, breathing, or circulation begins during the primary survey. After the primary survey, patients are clinically assessed in more detail for other severe chest injuries as well as less severe manifestations of the injuries considered during the primary survey.

Imaging

Imaging studies are typically required in patients with significant chest trauma. Chest x-ray is virtually always done. Results are usually diagnostic of certain injuries (eg, pneumothorax, hemothorax, moderate or severe pulmonary contusion, clavicle fracture, some rib fractures) and suggestive for others (eg, aortic disruption, diaphragmatic rupture). However, findings may evolve over hours (eg, in pulmonary contusion and diaphragmatic injury). Plain x-rays of the scapula or sternum are sometimes done when there is tenderness over those structures.

In trauma centers, ultrasonography of the heart is typically done during the resuscitation phase to look for pericardial tamponade; some pneumothoraces can also be seen.

CT of the chest is often done when aortic injury is suspected (see Aortic Disruption (Traumatic) ) and to diagnose small pneumothoraces, sternal fractures, or mediastinal (eg, heart, esophageal, bronchial) injuries; thoracic spine injuries also will be identified.

Other tests for aortic injury include aortography and transesophageal echocardiography.

Laboratory and other testing

CBC is often done but is mainly valuable as a baseline for detecting ongoing hemorrhage. ABG results help monitor patients with hypoxia or respiratory distress. Cardiac markers (eg, troponin, CPK-MB) can help exclude blunt cardiac injury.

ECG is typically done for chest trauma that is severe or compatible with cardiac injury. Cardiac injury may cause dysrhythmia, conduction abnormalities, ST segment abnormalities, or a combination.

Treatment

  • Supportive care

  • Treatment of specific injuries

Immediately life-threatening injuries are treated at the bedside at the time of diagnosis:

  • Suspected tension pneumothorax: Needle decompression.

  • Respiratory distress or shock and decreased breath sounds: Tube thoracostomy (see How to Do Tube Thoracostomy ).

  • Shock with suspected cardiac tamponade: Pericardiocentesis.

  • Suspected hypovolemic shock: Fluid resuscitation (see Intravenous Fluid Resuscitation ).

Immediate resuscitative thoracotomy can be considered for trauma victims if the clinician is proficient in the procedure (see Thoracotomy ) and the patient has one of the following indications:

  • Penetrating thoracic injury with a need for CPR of < 15 min

  • Penetrating nonthoracic trauma with a need for CPR of < 5 min

  • Blunt trauma with a need for CPR of < 10 min

  • Persistent systolic BP of < 60 mm Hg due to suspected cardiac tamponade, hemorrhage, or air embolism

Pearls & Pitfalls

  • In trauma patients with respiratory distress or shock and decreased breath sounds, tube thoracostomy can be done before imaging studies are obtained.

In the absence of any of these criteria, resuscitative thoracotomy is contraindicated because the procedure has significant risks (eg, transmission of blood-borne diseases, injury to clinician) and costs.

Specific treatment is directed at the injury. Supportive therapy typically includes analgesics, supplemental O2, and sometimes mechanical ventilation.

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* This is the Professional Version. *