Presentation

A variety of clinical presentations result after injury to the tracheobronchial tree, with most depending on the severity and the location of the injury. Patients with cervical tracheal injuries may present with stridor and severe respiratory distress or with hoarseness, hemoptysis, or cervical subcutaneous emphysema. The presentation of thoracic tracheobronchial injury depends on whether the injury is confined to the mediastinum or communicates with the pleural space. Thoracic tracheobronchial injuries confined to the mediastinum usually present with massive pneumomediastinum. Pneumopericardium is occasionally described. Injuries that perforate into the pleural space usually create an ipsilateral pneumothorax that may or may not be under tension. A pneumothorax that persists despite adequate placement of a thoracostomy tube and has a continuous air leak is suggestive of tracheobronchial injury and bronchopleural fistula. Dyspnea may actually worsen after insertion of the chest tube due to the loss of total volume via the tube. In 1969, Oh and colleagues described a highly specific finding of bronchial rupture, which they termed the “fallen lung” sign. Its characteristic radiographic features show the lung falling away from the hilum, laterally and posteriorly, in contrast to the usual simple pneumothorax, which collapses toward the hilum. This sign results from the disruption of the normal central anchoring attachments of the lung and, although pathognomonic, it is rarely seen. Other radiographic clues to possible airway injury are seen with endotracheal intubation and show abnormal migration of the tube tip or overdistension of the endotracheal tube balloon outside the confines of the normal tracheal diameter.

Some retrospective reports show that up to two thirds of these intrathoracic tracheobronchial tears will go unrecognized longer than 24 hours and up to 10% of tracheobronchial tears will not produce any initial clinical or radiological signs and are recognized months later after stricture occurs. Immediate intubation of patients with multisystem trauma can mask laryngeal or high cervical tracheal injuries and contribute to a delay in the diagnosis. After tracheobronchial transection, the peribronchial connective tissues may remain intact and allow continued ventilation of the distal lung analogous to the way perfusion is maintained after traumatic aortic transection. If unrecognized, this injury heals with scarring and granulation tissue and may possibly create bronchial stenosis or obstruction such as in the duck reported by Winslow. After a latent period, granulation tissue and stricture of the bronchus will develop. Distal to the stricture, pneumonia, bronchiectasis, abscesses, and even empyema can result. Complete obstruction without infection leads to prolonged atelectasis and diminished pulmonary function.

While concomitant injury is the rule rather than the exception, patterns of associated injuries vary widely. Major vascular, cardiac, pulmonary, esophageal, bony thoracic, and neurologic injuries are common and reflect the site, magnitude, and mechanism of the trauma. The mechanisms of trauma may alert one to search for the presence of injury. For example, transcervical and transmediastinal penetrating injuries pose particular danger to the respective traversing structures. Associated injuries may be severe, and in at least one series, were responsible for all of the deaths. It has been suggested that corresponding rib fractures would be seen in all patients over 30 years old who had a rupture of the tracheobronchial tree, but this is not always true. The absence of a chest wall injury does not exclude serious chest trauma, but the presence of such an injury should alert one to investigate further for a major underlying injury. A high index of suspicion must be maintained in order to diagnose and treat an injury promptly and appropriately.

Evaluation

Diagnosis should be suspected based on the clinical history and the constellation of signs and symptoms previously listed. Evaluation of the patient with a suspected injury to the tracheobronchial tree is shown in the algorithm in Figure 1. The advent of spiral computed tomography (CT) has created interest in evaluation of injury with this technique. Three-dimensional reconstruction has been used to elegantly demonstrate the site and extent of injuries in case reports. While tracheobronchial injury may be well demonstrated on CT in some cases, there is no evidence that CT is adequate to exclude an injury and obviate the need for diagnostic bronchoscopy. CT scans suggesting injury should prompt bronchoscopy for definitive diagnosis. In addition to visualization of possible tracheal injury on CT, indications for bronchoscopy include large pneumomediastinum, refractory pneumothorax, large air leak, persistent atelectasis, or, occasionally, marked subcutaneous emphysema. Bronchoscopy, whether rigid or flexible, is the best-studied means of establishing the diagnosis and determining the site, nature, and extent of the tracheobronchial disruption. A potential disadvantage of rigid bronchoscopy is that it requires general anesthesia, as well as a stable ligamentous and bony cervical spine. A rigid scope has the advantage of direct visualization and the ability to provide ventilation. Flexible bronchoscopy may be performed without general anesthesia, and offers the potential for controlled insertion of a nasal or orotracheal tube while maintaining cervical stabilization. The most critical determinant seems to be the experience and comfort level of the endoscopist. It has been shown that, in the hands of an experienced bronchoscopist, either technique can be performed with a high degree of accuracy. Lesions may be missed initially or their severity may be underestimated. These lesions may evolve into more obvious or severe injuries, and for this reason bronchoscopy should be liberally repeated as needed.

Figure 1 Algorithm for evaluation and management of suspected tracheobronchial injury.

Initial Management

Airway management, as in all injuries, is the first priority in the management of a patient with injury to the tracheobronchial tree. If the patient is maintaining his or her own airway and is ventilating adequately, a cautious approach of nonintervention is probably the best initial choice until further diagnostic work-up can be completed or other life-threatening injuries can be stabilized. Careless handling or mishandling of the airway, such as inadvertently placing an endotracheal tube through a transected or ruptured airway into the soft tissue, may compound the injury. If the injury is suspected, the airway should be evaluated carefully with the patient awake in order to plan for appropriate intervention. A bronchoscope may be passed into the trachea to evaluate for injury. In the case of less severe injuries, an endotracheal tube may be carefully passed distal to the injury over the bronchoscope. Blind nasal intubation or use of standard rapid sequence intubation (RSI)/endotracheal intubation should not be attempted in the case of known or suspected laryngotracheal injury because of the danger of creating a complete tracheal transection by pushing the tube against or through the injury.

Tracheostomy performed in the operating room is advocated by many as the safest and securest way to obtain airway control. This may be done in the awake patient to avoid airway loss in those with adequate airway protection. If the trachea is completely transected, the distal trachea can usually be found in the superior mediastinum and grasped for insertion of a cuffed tube. The approach taken must vary with the resources and expertise available at each institution. One must also be aware that even though the airway is secured, the injury may still be exacerbated with mechanical ventilation if the injury is distal to the tube. Tube thoracostomies should be appropriately placed at this time and connected to suction. After the airway is controlled, there is time for an orderly identification of concurrent injuries, performance of interventions such as esophagoscopy, laryngoscopy, arteriography, celiotomy as necessary, and transport to definitive care areas. Guidelines for the management of tracheobronchial injuries are given in Figure 1.

Nonoperative Management

On occasion, asymptomatic tracheobronchial injuries will be found incidentally on bronchoscopy or other imaging. Nonoperative management is reserved only for these highly selected patients with unexpected small tracheobronchial tears. Lesions selected for observation must involve less than one-third the circumference of the tracheobronchial tree. For patients to be candidates for nonoperative care, tube thoracostomy must fully re-expand the lung, and air leaks should stop soon after insertion of the tube. Prophylactic antibiotics, humidified oxygen, voice rest, frequent suctioning, and close observation for sepsis and airway obstruction are required.

Small stab wounds with no evidence of loss or devitalization of tracheal tissue and with well-opposed edges may be treated effectively with temporary endotracheal intubation. The cuff of the endotracheal tube should be inflated below the level of injury and left undisturbed for 24 to 48 hours while the wound seals. Bronchoscopy should be liberally repeated to evaluate the conservatively managed patient whose clinical condition deteriorates. Even small tears may heal but produce an excess of granulation tissue, which will require late endobronchial excision.

Operative Management

As with emergency management of the airway, intraoperative management requires substantial coordination with the anesthesiologist. All of the same principles apply. After the airway is initially secured, manipulation during the repair creates additional challenges. A sterile anesthesia circuit and tube may be needed to pass off the table after regaining control of the airway at the level of transection once the peritracheal connective tissue has been disrupted or entered for repair. If orotracheal intubation is performed, a single- or doublelumen endotracheal tube may be used. A double-lumen tube offers the benefit of independent lung ventilation but, because of the large size, it may create further disruption and is less desirable. A long, single-lumen tube may be passed beyond the area of injury for proximal levels of rupture, or for distal injuries, may be advanced into the contralateral mainstem bronchus for single-lung ventilation. Intubation over a flexible bronchoscope adds safety and diagnostic capability to the procedure. If a tracheostomy is performed, it should be placed two to three rings caudally to high tracheal or laryngeal injuries and brought out through an incision separate from the surgical repair wound. Tracheostomy proximal to an injury is probably not necessary to protect the suture lines after repair of the thoracic trachea or major bronchus, and its prophylactic use is discouraged for distal tracheobronchial injuries. In the most difficult of cases, in which airway management is unsatisfactory, or during complex repairs, cardiopulmonary bypass may be instituted. The potential risks and benefits of this procedure must be weighed, including the need for systemic anticoagulation, especially in the multitrauma patient.

After repair, airway management ideally should be accomplished by removal of the endotracheal tube immediately after the operation. Otherwise, it should be removed and spontaneous respirations resumed as soon as the patient can breathe effectively. Occasionally, the patient will require ongoing positive pressure ventilation, which may require creative techniques of critical care and ventilation, such as positioning of the endotracheal tube distal to the repair, dual-lung ventilation, high-frequency jet ventilation, or extracorporeal membrane oxygenation. Every effort must be made to improve lung compliance by providing good pulmonary toilet, appropriate fluid management, and aggressive treatment of pneumonia.

Most extrathoracic airway injuries can be approached through a transverse collar incision. Occasionally, for added exposure, this incision may be extended up the neck for carotid repair or teed off down the sternum, with partial or complete sternotomy being performed for more central exposure. Intrathoracic tracheal, right bronchial, and proximal left mainstem bronchus injuries are best repaired through a right posterolateral thoracotomy at the fourth or fifth intercostal space. This approach avoids the heart and aortic arch. Complex or bilateral injuries should be approached through the right chest for this same reason. Distal left bronchial injuries more than 3 cm from the carina are approached through a left posterolateral thoracotomy in the fifth intercostal space.

Optimal repair includes adequate debridement of devitalized tissue, including cartilage, and primary end-to-end anastomosis of the clean tracheal or bronchial ends. This anastomosis can be accomplished free of tension by mobilizing anteriorly and posteriorly, thereby preserving the lateral blood supply. Tension may also be released with cervical flexion. This may be maintained postoperatively by securing the chin to the chest with a suture. Many investigators have recommended completion of the anastomosis with interrupted absorbable suture. We have found, however, that the use of a running, continuous, absorbable monofilament suture offers a secure repair and better visibility during construction of the anastomosis. The membranous portion may be repaired without tension and then brought together as the cartilaginous portion is begun. Sutures may be placed around or through the cartilage but must ensure approximation of mucosa to mucosa. Tying the suture knots on the outside of the lumen helps prevent suture granulomata and subsequent stricture. To prevent subsequent leak and fistula formation, the suture line may be reinforced with a patch of pericardium, a vascularized pedicle from the pleura, intercostal muscle, strap muscles, omentum, or vascularized pleura in late repairs to protect the repair and to aid in bronchial healing. During early repairs, the pleura is flimsy and usually not suitable as reinforcement. The vascularized pedicle of intercostal muscle offers both better protection and added healing potential for the repair. For this reason, the intercostal muscle should routinely be preserved during thoracotomy with the corresponding vein, artery, and nerve. This is accomplished by entering the chest through the bed of the rib. The rib may be preserved or sacrificed. An incision is made directly over the rib and the periosteum stripped off. At the superior border of the rib, the incision is carried through the posterior layer of the periosteum to enter the pleural space. The intercostal muscle is then divided from the ribs above and below and used as a flap to be wrapped around and tacked to the trachea. In this manner, viable tissue is placed between the repair and surrounding vital structures and blood supply in the area of the repair is increased, facilitating healing (Figure 2).

Figure 2 Injuries to thoracic trachea (A) are best repaired by debridement of devitalized tissue and repair with absorbable suture (B). Debridement may include removal of several rings if necessary. The repair is protected with a vascularized pedicle of intercostal muscle (C).

Injuries to the cervical trachea may be managed by repair with or without tracheostomy. Simple anterior lacerations may undergo primary repair without tracheostomy if possible. Tracheostomy alone, without repair, occasionally may serve as the sole source of treatment in patients with isolated injuries to the anterior cervical trachea. Such circumstances are uncommon owing to the presence of exit wounds and the variable level at which the trachea may be injured. For these reasons, anterior tracheal injuries are generally repaired. Placement of a tracheostomy through these injuries should be avoided except in the case of short term need for airway control via such a maneuver. In patients with severe injury to the proximal trachea, immediate repair with protective distal tracheostomy should be performed. Consideration should be given to stenting laryngeal injuries. Occasionally, the injury may cause extensive devitalization of the trachea and contamination of the field. In these rare instances, end tracheostomy, oversewing of the proximal trachea, and drainage may be the most prudent course of action. This allows for possible definitive repair later, after resolution of scarring and inflammation. However, attempts at primary repair should be exhausted first.