INTRODUCTION AND EPIDEMIOLOGY
Blunt thoracic trauma produces damage by direct injury, compression, and forces of acceleration or deceleration, whereas penetrating thoracic trauma causes direct injury along the path of a stab wound or projectile. Injuries most often involve the lungs and, less frequently, the heart and great vessels. Regardless of mechanism, stabilization and treatment of these patients follow a similar pathway. In general, patients with penetrating injuries who survive to reach the hospital have better outcomes than those who have sustained blunt injuries. Blunt chest trauma from blast injuries is discussed in Chapter 7, “Bomb, Blast, and Crush Injuries.” Presume penetrating chest injuries in the “cardiac box” (see Figure 262-1), an area bounded by the sternal notch, xiphoid process, and nipples, to involve the heart or great vessels until proven otherwise.
Blunt thoracic injuries account for up to one fourth of all deaths, and chest wall trauma is a component of 10% of trauma admissions.1,2 Penetrating injuries that violate the pleura typically result in pneumothorax, with an accompanying hemothorax in most cases. In polytrauma patients, thoracic trauma is the third leading cause of death after abdominal trauma and head trauma.3 The mechanism of injury and severity of tissue damage predict the clinical course and outcome.2,4
The thorax is bordered superiorly by the clavicles and inferiorly by the diaphragm. There are 12 paired sets of ribs projecting forward from the thoracic vertebrae, with the upper 10 ending in a cartilaginous joint with the sternum and the bottom 2 “floating” freely. The muscular diaphragm has muscle fibers inserting into ribs 6 to 12 and posteriorly into the T12, L1, and L2 vertebrae. The thoracic cavity is created by a pleural membrane covering the inner thoracic cavity (the parietal pleura) and folding back over the lungs and other intrathoracic structures (the visceral pleura). The lungs have three lobes on the right and two lobes on the left. The mediastinum in the center of the thoracic cavity between the lungs contains the heart and its associated blood vessels, the trachea, the phrenic and cardiac nerves, the esophagus, and the thoracic duct. The trachea descends from the larynx and branches into several tiers of bronchi before ending in alveoli where gases are exchanged in the lung (Figure 261-1).
Chest trauma can disrupt the respiratory mechanism, which can have an immediate negative impact on resuscitation and patient outcomes. Bleeding or free air in any portion of the thoracic cavity can limit lung excursion as well as lung volumes. Injury to the chest wall can decrease chest recoil, restricting the ability to generate the negative intrathoracic pressure needed for ventilation and gas exchange. Similarly, disruption of the diaphragm can ...