59: Tracheobronchial Injuries

Introduction

Tracheobronchial injuries are rare but potentially lethal injuries associated with (1) thoracic trauma, (2) iatrogenic damage, and (3) inhalation injuries.¹ Most traumatic tracheobronchial injuries are associated with a high-energy impact; typically, a motor vehicle accident or fall. These injuries often are associated with significant thoracic compression injuries including fractures to the ribs and clavicle as well as cardiac and pulmonary contusions.

There are several potential traumatic mechanisms for tracheobronchial injury. Based on the types of associated injury, the most likely mechanism is related to shear forces created by rapid deceleration. The highest incidence of airway injury occurs at the sites of mediastinal attachment; that is, within 2.5 cm of the carina. A plausible explanation is that shear develops between restrained and unrestrained airways leading to disruption of the bronchus. Secondary sites of airway injury include the right middle lobe bronchus and the superior segmental bronchi bilaterally. These airways are relatively long and similarly susceptible to differential deceleration forces. Finally, spiral tears of the right mainstem and bronchus intermedius can occur. These injuries are presumably caused by rotational as well as compressive forces.

Diagnosis

The common presenting signs of blunt tracheobronchial injury include dyspnea, subcutaneous emphysema, and hemoptysis. Also, patients with blunt injury commonly present with sternal tenderness or focal rib pain. Patients presenting with these symptoms, in the context of a high-energy impact, should have a chest CT scan and bronchoscopic examination. Stridor is generally restricted to extrathoracic tracheal injuries, subglottic edema, or bilateral vocal cord dysfunction. These patients are typically intubated soon after the development of stridor.

The radiographic findings may include pneumothorax, pneumomediastinum, and fractures of the bony thorax. The chest CT scan in a patient who has survived a high-energy impact may reveal evidence of a pulmonary contusion and mediastinal hematoma, but free rupture of the airway into the pleural space is rare. In most cases, the soft tissues of the mediastinum and hilum contain the rupture. The airway discontinuity is reflected only by a small amount of extraluminal air and edema. These findings are often missed in a patient with multiple associated injuries.

The difficulty of establishing a radiographic diagnosis of tracheobronchial injury mandates bronchoscopy in any patient who has sustained a high-energy impact injury to the thorax and presents with any sign or symptom of intrathoracic injury. The procedure must be performed by an experienced bronchoscopist. The aspiration of blood and mucus in the proximal airways often complicates the initial trauma bronchoscopy; it is common for the airway injury to be missed at the initial bronchoscopy. In addition, airway injuries frequently present as a subtle separation in the airway cartilage that is contained by mediastinal soft tissue. Repeat bronchoscopy is frequently required to unequivocally establish the diagnosis of airway injury.

Indications for Surgery

The absolute indication for surgery is the ...