Overview of Thoracic Trauma

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

• Aortic disruption

• Blunt cardiac injury

• Cardiac tamponade

• Flail chest

• Hemothorax

• Pneumothorax (traumatic pneumothorax, open pneumothorax, and tension pneumothorax)

• Pulmonary contusion

Many patients have simultaneous hemothorax and pneumothorax (hemopneumothorax).

Bone injuries are common, typically involving the ribs and clavicle, 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.

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. Pulmonary contusion creates a ventilation and perfusion mismatch because of lung hemorrhage and edema.

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.

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 from the rest of the chest wall (outward during expiration and inward during inspiration); the flail segment is often palpable.

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.

• History and physical examination

• Chest x-ray

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

Initial 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, arterial blood gas tests, 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 Simplified, apid Approach to Assessment of Patients With Chest Trauma).

A Simplified, 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 Simplified, Rapid Assessment for Chest Injuries in Patients With Shock...). 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 Simplified, 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.

• Supportive care

• Treatment of specific injuries

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

• Respiratory distress with suspected tension pneumothorax: Needle decompression or finger thoracostomy.

• Respiratory distress or shock with decreased breath sounds and suspected hemothorax: Tube thoracostomy  

• Respiratory distress with suspected open pneumothorax: Partially occlusive dressing followed by tube thoracostomy

• Respiratory distress with suspected flail chest: Mechanical ventilation

• Shock with suspected cardiac tamponade: Pericardiocentesis

• Suspected hypovolemic shock: Fluid resuscitation and blood products when available

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

• Penetrating thoracic injury with a need for cardiopulmonary resuscitation (CPR) of < 15 minutes

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

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

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

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 oxygen, and sometimes mechanical ventilation (1, 2).