A Classic Image of Complete Right Main Bronchus Avulsion: Diagnosis

Most tracheobronchial tears are associated with crushing injuries suffered in high-speed motor vehicle accidents. Their true incidence is unknown because patients often die (from the disruption or from associated injuries) before getting to the hospital. The overall mortality is estimated at 30 percent, but 90 percent of patients reaching the hospital alive can expect full recovery. Prompt recognition of the injury and early treatment greatly reduce morbidity and increase the chances of restoring normal pulmonary function.

Several early radiologic signs indicating the possibility of a traumatic transection of a main bronchus have been described (Table 1). Although most of those signs provide only indirect evidence of bronchial rupture, they may facilitate an early diagnosis when associated with a typical clinical presentation. For example, a tension pneumothorax is not in itself a sign of bronchial injury, but when the pneumothorax does not improve with proper pleural space drainage or there is a large air leak through the chest tube, bronchial rupture must be suspected. The presence of deep cervical emphysema on lateral roentgenograms of the cervical soft tissues is also one of the earliest and most reliable signs indicating a possible rupture.-2 Obstruction in the course of an air-filled bronchus or the presence of a sleeve of air surrounding a ruptured bronchus are more specific signs, but both may be difficult to appreciate especially on poor-quality radiographs.
Kumpe et al described the only radiologic sign considered to be characteristic of unilateral complete bronchial avulsion. In such cases, the affected lung not only collapses but it also drops inferiorly to the diaphragm, having lost the anchoring support normally provided by the bronchus. This is in contrast with simple pneumothoraces, where the apex of the lung remains above the level of the main bronchus. Since that original description, several authors have acknowledged this sign as providing direct evidence of complete bronchial rupture.
The case presented in this article demonstrates that this sign must be interpreted with caution and in the light of the clinical presentation, because it can be associated with tension pneumothoraces from other causes. When bronchial rupture is suspected, bronchoscopy remains the most useful procedure to confirm its diagnosis, determine the location and extent of the tear, and plan the operative repair. It should always be done prior to thoracotomy.
Table 1—Early Radiologic Signs of Bronchial Rupture

Indirect signs Tension pneumothorax, unilateral or bilateral
Fracture of upper ribs (1 to 3)
Mediastinal emphysema
Deep cervical emphysema
More direct signs Obstruction of an air-filled bronchus
Sleeve of air surrounding the ruptured
Direct sign Affected lung drops inferiorly