Thoracic injuries account for 20-25% of deaths due to trauma and contribute to 25-50% of the remaining deaths. Approximately 16,000 deaths per year in the United States alone are attributable to chest trauma.  Therefore, thoracic injuries are a contributing factor in up to 75% of all trauma-related deaths. The increased prevalence of penetrating chest injury (associated with the "drug war" in the United States) and improved prehospital and perioperative care have resulted in an increasing number of critically injured but potentially salvageable patients presenting to trauma centers.  The classic "trimodal" temporal distribution of trauma deaths has been questioned, even though it has been widely taught in the design of trauma systems. 
For more information, see the Trauma Resource Center.
History of the Procedure
One of the earliest writings of thoracic injury was noted in the Edwin Smith Surgical Papyrus, written in 3000 BCE. Galen reported attempts to treat gladiators with chest injuries with open packing. In 1635, Labeza de Vaca first described operative removal of an arrowhead from the chest wall of a Native American. In 1814, Larrey (Napoleon's military surgeon) reported various injuries to the subclavian vessels. Rehn performed the first successful human cardiorrhaphy in Germany in 1896. Hill performed the first cardiorrhaphy in the United States in 1902 and initiated the modern treatment of the wounded heart.
Penetrating trauma to the thoracic vessels was not extensively reported until the 20th century because of the absence of survivors. In 1934, Alfred Blalock was the first American surgeon to successfully repair an aortic injury. Guidelines for treating thoracic trauma were not established until World War II.
Additional experience in the treatment of penetrating trauma to the thorax was gained in later military experiences, including the conflicts in Korea and Vietnam, and, to a lesser degree, in US actions in Grenada, Panama, the Balkans, Somalia, and the Persian Gulf. Other large international experiences have derived from the Falkland Island conflict, various Middle Eastern engagements, and multiple conflicts in the African states.
Significant experience has also been gained from large US metropolitan areas as a result of assaults involving firearms and handheld weapons and impalements resulting from falls or leaps from elevations. Researchers from Houston, Tex; Los Angeles, Calif; Atlanta, Ga; Detroit, Mich; and Denver, Colo, have been particularly productive in their treatments of thoracic penetrating trauma. The number of trauma patients in these large metropolitan areas rose so rapidly in the 1970s and 1980s that the military sent its medical personnel to train caregivers at these centers. [4, 5]
With the advancement of wartime medical care and access to The Joint Theater Trauma Registry (JTTR), thoracic injury patterns have changed dramatically. As a result of advances in body armor and the establishment of excellent medical care at the battlefield, mortal thoracic wounds seem to have decreased, allowing patients who would have previously died to live long enough to receive treatment. 
Any entry wound below the nipples (front) and the inferior scapular angles (dorsum) should be considered an entry point for a course that may have carried the missile into the abdominal cavity. Missiles from gunshot wounds (GSWs) can penetrate all body regions regardless of the point of entry. Any patient with a gunshot entry wound for which a corresponding exit wound cannot be identified should be considered to have a retained projectile, which could embolize to the central or distal vasculature. A patient with combined intrathoracic and intra-abdominal wounds has a markedly greater chance of dying.
For information on treating penetrating abdominal wounds, see Abdominal Stab Wound Exploration.
Mechanism of injury
The mechanism of injury may be categorized as low, medium, or high velocity. Low-velocity injuries include impalement (eg, knife wounds), which disrupts only the structures penetrated. Medium-velocity injuries include bullet wounds from most types of handguns and air-powered pellet guns and are characterized by much less primary tissue destruction than wounds caused by high-velocity forces. High-velocity injuries include bullet wounds caused by rifles and wounds resulting from military weapons.
Shotgun injuries, despite being caused by medium-velocity projectiles, are sometimes included within management discussions for high-velocity projectile injuries. This inclusion is reasonable because of the kinetic energy transmitted to the surrounding tissue and subsequent cavitation, as described by the following equation in which KE is kinetic energy, M is mass, and V is velocity:
KE = ½ MV2
The 3 major subcategories of ballistics are internal, external, and terminal. Internal ballistics describe the characteristics of the projectile within the gun barrel. External ballistics examines the factors that affect the projectile during its path to the target, including wind resistance and gravity. Terminal ballistics evaluates the projectile as it strikes its target.
The amount of tissue damage is directly related to the amount of energy exchange between the penetrating object and the body part. The density of the tissue involved and the frontal area of the penetrating object are the important factors determining the rate of energy loss.
The energy exchange produces a permanent cavity inside the tissue. Part of this cavity is a result of the crushing of the tissue as the projectile passes through. The expansion of the tissue particles away from the pathway of the bullet creates a temporary cavity. Because this cavity is temporary, one must realize that it was once present in order to understand the full extent of injury.
Penetrations from blast fragments or from fragmentation weapons can be particularly destructive because of their extremely high velocities. Weapons designed specifically for antipersonnel effects (eg, mines, grenades) can generate fragments with initial velocities of 4500 ft/s, a far greater speed than even most rifle bullets. The tremendous energy imparted to tissue from fragments with such velocity causes extensive disruptive and thermal tissue damage. Weaponry of the 21st century consists mostly of improvised explosive devices (IEDs). These devices are homemade bombs and they create a deadly triad of penetrating, blast, and burn wounds. Of the thoracic trauma that is seen in the current Global War on Terror, 40% is penetrating chest trauma.
As noted by Inci and colleagues in a 1998 study of 755 patients with thoracic injuries, penetrating chest trauma (PCT) comprises a broad spectrum of injuries and severity.  The injuries and number of patients (some with >1 injury) is listed as follows: 
Hemothorax - 190
Hemopneumothorax - 184
Pneumothorax - 144
Diaphragmatic rupture - 121
Open hemopneumothorax - 95
Pulmonary contusion - 50
Open pneumothorax - 24
Rib fracture - Fewer than 2 fractures, 16; more than 2 fractures, 13
Subcutaneous emphysema - 14
Bilateral pneumothorax - 9
Open bilateral hemopneumothorax - 13
Pneumomediastinum - 6
Thoracic wall lacerations - 4
Bilateral hemopneumothorax - 3
Open bilateral pneumothorax - 3
Sternal fracture - 3
Bilateral diaphragmatic rupture - 2
The clinical consequences depend on the mechanism of the injury, the location of the injury, associated injuries, and underlying illnesses. Organs at risk, in addition to the intrathoracic contents, include the intraperitoneal viscera, the retroperitoneal space, and the neck.
As always in trauma, management begins with establishing ABCs. Indications for emergency endotracheal intubation include apnea, profound shock, and inadequate ventilation. Chest radiography is not indicated in patients with clinical signs of a tension pneumothorax, and immediate chest decompression is accomplished with either a large-bore needle at the second intercostal space or, more definitively, with a tube thoracostomy. A sucking chest wound must be appropriately covered to permit adequate ventilation and to prevent the iatrogenic development of a tension pneumothorax.
Damage control operation appears to be the new mantra in the advanced care of penetrating thoracic trauma. Damage control requires modification of the ABCs of trauma, in that resuscitative and diagnostic techniques are used simultaneously in the immediate time after the unstable patient's presentation. Quickly and solely controlling hemorrhage and contamination to expedite reestablishing a survivable physiology is the essence of thoracic damage control. Additionally, aggressive correction of the acidosis, coagulopathy, and hypothermia occurs in the ICU. 
Volume replenishment is the cornerstone of treating hemorrhagic shock but can also cause significant compromise of other organ systems. Continuous infusions of even blood or normotonic fluids cause significant peripheral tissue edema, frank acute respiratory distress syndrome (ARDS) or a tremendous increase in lung water ("soggy lungs"), and cardiac compromise. Newer approaches, described in both military and civilian literature, are emphasizing the use of hypertonic solutions in an effort to minimize these complications.
Alternatively, several groups have championed the concept of "scoop and run" when treating injuries in the field.  With the development of modern (civilian) emergency medical services, the field care of injured patients has improved. Rapid assessment to identify life-threatening injuries along with key interventions, namely management of the airway and control of hemorrhage, and avoidance of massive volume increases before rapid transport to the closest appropriate facility is the current standard of care. This is in contrast to the concept of "stay and play," during which trained personnel make major triage and treatment decisions in the field.
If the patient has persistently low systemic pressure, a source of ongoing blood loss or some other mechanisms to explain the hypotension (eg, cardiac tamponade, tension pneumothorax) should be preferentially sought. Additionally, some data suggest that continued volume resuscitation before surgical control of bleeding may worsen both the bleeding process and final outcome.
Fluid collections in either hemothorax should be treated with percutaneous thoracostomy tubes. See the image below and Hemothorax.
Thoracotomy may be indicated for acute or chronic conditions. Acute indications include the following:
Acute hemodynamic deterioration/cardiac arrest in the trauma center
Penetrating truncal trauma (resuscitative thoracotomy)
Vascular injury at the thoracic outlet
Loss of chest wall substance (traumatic thoracotomy)
Massive air leak
Endoscopic or radiographic evidence of significant tracheal or bronchial injury
Endoscopic or radiographic evidence of esophageal injury
Radiographic evidence of great vessel injury
Mediastinal passage of a penetrating object
Significant missile embolism to the heart or pulmonary artery
Transcardiac placement of an inferior vena caval shunt for hepatic vascular wounds
Patients who arrive in cardiac arrest or who arrest shortly after arrival may be candidates for emergency resuscitative thoracotomy. A right chest tube must be placed simultaneously. The use of emergency resuscitative thoracotomy has been reported to result in survival rates of 9-57% for patients with penetrating cardiac injuries and survival rates of 0-66% for patients with noncardiac thoracic injuries, but overall survival rates are approximately 8%. 
The Eastern Association for the Study of Trauma has developed an evidence-based practice management guideline for the use of emergency department thoracotomy in patients who present pulseless with signs of life after penetrating thoracic injury. 
The proportion of patients with PCT who can be treated without operation has been reported to vary from 29-94%. 
Chronic indications for thoracotomy include the following:
Nonevacuated clotted hemothorax
Chronic traumatic diaphragmatic hernia
Traumatic cardiac septal or valvular lesion
Chronic traumatic thoracic aortic pseudoaneurysm
Nonclosing thoracic duct fistula
Chronic (or neglected) posttraumatic empyema
Infected intrapulmonary hematoma (eg, traumatic lung abscess)
Missed tracheal or bronchial injury
Innominate artery/tracheal fistula
Traumatic arterial/venous fistula
Another indication for acute thoracostomy is often based on chest tube output. Immediate evacuation of 1500 mL of blood is a sufficient indication; however, the trend in output is more important. If bleeding persists with a steady trend of more than 250 mL/h, thoracotomy is probably indicated.
The role of video-assisted thoracoscopic surgery in the management of penetrating chest trauma is expanding rapidly. Initially promoted for the management of retained hemothoraces and the diagnosis of diaphragmatic injury, trauma and thoracic surgeons are now using thoracoscopy for treatment of chest wall bleeding, diagnosis of transmediastinal injuries, pericardial window, and persistent pneumothoraces.  The major contraindication to video-assisted thoracoscopic surgery is hemodynamic instability.
The anatomy of the thoracic cage is well-known and encompasses the area beneath the clavicles and superior to the diaphragm, bound laterally by the rib cage, anteriorly by the sternum and ribs, and posteriorly by the rib and vertebral bodies. Entry into the thorax may be made by sternotomy; thoracotomy (incising between selected ribs, most commonly the fourth and fifth) on either the right or left side; or a clamshell incision, consisting of left and right thoracotomy incisions traversing the sternum to join the two. Additional modifications of each of these approaches are not discussed in detail here.
Particular care must be exercised laterally near the sternum, where the internal thoracic (mammary) artery lies 2-4 cm on either side. Similarly, remember that immediately inferior to each rib body are the intercostal artery, vein, and nerve, from which voluminous bleeding can occur. Patients have required reexploration for injuries to these various vessels and have exsanguinated as a result of missed injuries to these vessels.
Anteriorly, injuries to the heart should be presumed to have occurred if entry points are present anywhere between the 2 midclavicular lines. On occasion, significant injury to the heart has occurred from entry points lateral to these margins, as in gunshot or missile injuries.
Exceptionally long penetrating instruments and weapons (eg, arrows, swords, lances) can also directly penetrate the heart from a distant entry point. Similarly, injuries to any of the intrathoracic structures can be effected with long penetrating devices; consider the possibility of injuries to the diaphragm, great vessels, or posterior mediastinal structures in these cases.
The right atrium and right ventricle are the anterior portions of the heart; these areas are the primary sites involved in penetrating injuries of the heart.
Contraindications to various explorations and techniques are discussed in their respective sections.
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