Penetrating Chest Trauma

Updated: Dec 18, 2017
  • Author: Rohit Shahani, MD, MS, MCh; Chief Editor: Jeffrey C Milliken, MD  more...
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Overview

Background

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. [1] Therefore, thoracic injuries are a contributing factor in as many as 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. [2] The classic "trimodal" temporal distribution of trauma deaths has been questioned, even though it has been widely taught in the design of trauma systems. [3]

One of the earliest written descriptions of thoracic injury was in the Edwin Smith Surgical Papyrus (~3000 BCE). Galen reported attempts to treat gladiators with chest injuries with open packing. In 1635, Cabeza 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, 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, Los Angeles, Atlanta, Detroit, and Denver, 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 advances in wartime medical care and access to the Joint Theater Trauma Registry (JTTR), thoracic injury patterns have changed dramatically. As a result of improvements in body armor and the establishment of excellent medical care at the battlefield, mortal thoracic wounds seem to have decreased, allowing many patients who previously would have died to live long enough to receive treatment. [6]

For more information, see the Trauma Resource Center. For patient education resources, see the Procedures Center and Skin, Hair, and Nails Center, as well as Bronchoscopy and Puncture Wound.

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Anatomy

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. The thorax may be entered via three main approaches, as follows:

  • Sternotomy
  • Thoracotomy (incising between selected ribs, most commonly the fourth and fifth) on either the right or left side
  • Clamshell incision, consisting of left and right thoracotomy incisions traversing the sternum to join the two

Additional modifications of each of these approaches exist but 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, it must be remembered 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 structures.

Anteriorly, injuries to the heart should be presumed to have occurred if entry points are present anywhere between the two 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; accordingly, the possibility of injuries to the diaphragm, great vessels, or posterior mediastinal structures must be considered 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.

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Pathophysiology

As noted by Inci et al in a 1998 study of 755 patients with thoracic injuries, penetrating chest trauma (PCT) comprises a broad spectrum of injuries and severity. [7] The injuries and the number of patients (some with more than one injury) in this study were as follows:

  • Hemothorax - 190
  • Hemopneumothorax - 184
  • Pneumothorax - 144
  • 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.

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Etiology

Mechanism of injury

The mechanism of injury may be categorized as low, medium, or high velocity, as follows:

  • 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:

  • KE = ½mv 2

where KE is kinetic energy, m is mass, and v is velocity.

Ballistics may be divided into three major categories, as follows:

  • Internal ballistics describes 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 and 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.

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Prognosis

The outcomes of treating patients with PCT are directly related to the extents of patients' injuries and the timeliness of initiation of treatments. Patients arriving in a stable condition may expect full recovery, but patients presenting with lesser levels of stability have diminishing probabilities of survival. No attempt should be made to resuscitate, let alone definitively treat, patients presenting with no vital signs or with obviously nonsurvivable injuries (eg, massive cardiac destruction).

Guidelines for initiation of emergency department thoracotomy were published in 2003 and 2014, [8, 9]  and the Eastern Association for the Study of Trauma published its own guideline in 2015. [10]

In a 2010 report from a single center that included 158 patients who underwent thoracotomy within 24 hours after PCT, those patients who died had a significantly lower systolic blood pressure (42 ± 36 mm Hg) than those who survived (83 ± 27 mm Hg). [11]

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