1986 Volume 8 Issue 2 Pages 267-273
Two cases of tracheal injury caused by blunt chest trauma were presented with particular references to their bronchoscopic findings. Case No.1, a 21-year-old male, had fallen half asleep driving a car, and collided head on with a bus. The steering wheel hit his chest and he developed acute respiratory distress. Bronchoscopy revealed tracheal disruption 6 cm above the carina. The trachea was sutured and he recovered with moderate stricture. Previous reporters pointed out two major mechanisms of tracheobronchial injuries. The first is that the injuries occur because of a decrease in the anterior diameter of thorax with a concomitant widening of the transverse diameter. Lateral motion pulls the two lungs apart, producing traction on the trachea at the carina. The second mechanism is that the glottis is closed when impact occurs. A sudden increase of intratracheal pressure is produced by compression of air within the tracheobronchial tree. When the elasticity of the tracheobronchial tree is exceeds a certain level injury occurs. These mechanisms explain the fact that most tracheobronchial injuries occur within 2 cm of the carina. The tracheal disruption of case No.1 occured 6 cm above the carina, which is unusual. Possibly his special condition at impact, half asleep, caused a sudden hyperextension of the neck without the increase of intratracheal pressure because of the lack of glottis closure. It is believed that complete disruption of the trachea occurs if there is been hyperextension of the neck. Case No.2, a 18-year-old male, ran into a car on a motorcycle and his chest was crushed. His chest roentgenogram showed severe subcutaneous emphysema in the chest and neck. His left clavicle was dislocated and bilateral multiple ribs were fractured. Bronchoscopy revealed many oval shaped mucosal hematomas located between cartilaginous rings 2 to 4 cm above the carina. Each hematoma had a longitudinal laceration in the center where bleeding was seen. They disappeared completely 10 days after injury without any special treatment. In this case, it is considered that the crushing force might injure the trachea directly when multiple ribs were fractured. This mechanisms could result in the formation of the mucosal hematomas. These two cases indicated that blunt chest traumas present different features of tracheal injuries in site and nature. It is very important to perform bronchoscopy in cases of blunt chest trauma in order to clarify the exact condition before treatment.
