The absolute indication for surgery is the free rupture of a proximal bronchus into the pleural space. In most cases, the patient presents with a pneumothorax. The diagnosis of a proximal airway injury is readily established by the large air leak discovered when the tube thoracostomy is placed within the pleural space. In these patients, the airway injury is commonly associated with pulmonary contusion and diminished lung compliance over the ensuing 24 to 72 hours. Prompt repair has the potential advantage of allowing single-lung ventilation during the surgery—an option that may not be tolerated hours later. In addition, the repaired airway will permit greater flexibility in mechanical ventilation strategies as the patient recovers from the acute lung injury.
In general, all contained mainstem bronchial injuries should be repaired as soon as the patient is hemodynamically stabilized and more life-threatening injuries have been excluded. Injuries to the right mainstem bronchus have the potential to rupture into the right pleural space necessitating prolonged or high-pressure mechanical ventilation. In contrast, injuries to the left mainstem bronchus rarely rupture into the pleural space, but are associated with larger gaps in the airway. In both cases, failure to repair the airway can result in functional pneumonectomy secondary to bronchomalacia, stricture, or both. Furthermore, failure to repair the injury promptly can lead to poor airway clearance, chronic infection, and contracted airways, further limiting repair options. Finally, chronic infection can lead to vascular erosion and a fatal bronchovascular fistula.
In patients with severe bilateral pulmonary contusions, hemodynamic and ventilatory instability may preclude any attempt at acute repair of the mainstem bronchus. The only therapeutic option in these patients is to optimize ventilatory support and hope for the opportunity of a late repair.
The indication for repair of a middle lobe or superior segmental airway is less an attempt to salvage distal lung tissue, and more an attempt to prevent secondary complications of stricture and chronic infection. In some patients, the airway separation is minimal and they can be managed without surgery. In other cases, semi-elective repair can be performed when the patient is stabilized and pulmonary compliance has improved. Although mechanical stents have been used successfully in this setting, an ongoing concern is the risk of erosion and bronchovascular fistula.