However, one likely mechanism involves an endotracheal tube catching in a fold of membrane and tearing it as it is advanced downward through the airway. When an endotracheal tube tears the trachea, it typically does so at the posterior (back) membranous wall. Unlike TBI that results from blunt trauma, most iatrogenic injuries to the airway involve longitudinal tears to the back of the trachea or tears on the side that pull the membranous part of the trachea away from the cartilage. Excessive pressure from the cuff of an endotracheal tube can reduce blood supply to the tissues of the trachea, leading to ischemia and potentially causing it to become ulcerated, infected, and, later, narrowed.The mucosal lining of the trachea may also be injured by inhalation of hot gases or harmful fumes such as chlorine gas. This can lead to edema (swelling), necrosis (death of the tissue), scar formation, and ultimately stenosis. However, TBI due to inhalation, foreign body aspiration, and medical procedures is uncommon. Mechanism
The structures in the tracheobronchial tree are well protected, so it normally takes a large amount of force to injure them. In blunt trauma, TBI is usually the result of violent compression of the chest. Rapid hyperextension of the neck, usually resulting from vehicle crashes, can also injure the trachea, and trauma to the neck can crush the trachea against the vertebrae.
However, even if the trachea is completely transected, the tissues surrounding it may hold it together enough for adequate air exchange to occur, at least at first. Anatomy
The trachea and bronchi form the tracheobronchial tree. The trachea is situated between the lower end of the larynx and the center of the chest, where it splits into the two bronchi at a ridge called the carina. The trachea is stabilized and kept open by rings made of cartilage that surround the front and sides of the structure; these rings are not closed and do not surround the back, which is made of membrane. The bronchi split into smaller branches and then to bronchioles that supply air to the alveoli, the tiny air-filled sacs in the lungs responsible for absorbing oxygen. An arbitrary division can be made between the intrathoracic and cervical trachea at the thoracic inlet, an opening at the top of the thoracic cavity. Anatomical structures that surround and protect the tracheobronchial tree include the lungs, the esophagus, large blood vessels, the rib cage, the thoracic spine, and the sternum. Children have softer tracheas and a more elastic tracheobronchial trees than adults; this elasticity, which helps protect the structures from injury when they are compressed, may contribute to the lower incidence of TBI in children. Diagnosis
Rapid diagnosis and treatment are important in the care of TBI; if the injury is not diagnosed shortly after the injury, the risk of complications is higher.