We had an incidence of 42 out of 17,520 registered thoracic trauma patients (0.24%) reported having major airway injuries. The worldwide reported incidence in many works of literature is between 0.35 and 5.3%. We can explain our incidence as cases that might be diagnosed as a major airway injury but dies before surgery is conducted. Besides, the cases that passed unregistered or undiagnosed by the trauma team were not obvious and required a high degree of suspicion.
Most studies report that the most common cause of TBI is blunt trauma. In the present study, TBI was caused by blunt trauma in 73.8% of trauma cases. Approximate figures were reported by many authors such as Richardson [3], Scaglione et al, [4], and Koletsis et al. [5] who had found, respectively, that 76.7%, 67%, and 66.7% of injuries were due to blunt trauma. However, few authors reported their cases to be caused mainly by penetrating trauma such as Fatimi et al. [6] and Saad et al. [7]. We think that the accuracy of these figures was biased by the small sample size in most of the studies.
In our study, the age ranged from 8 to 43 years old with a mean age of 22.3 ± 0.8 and 11 patients (39.3%) were under 18 years old. Similar results were reported by Balci et al. [8] and Saad et al. [7] as they had a mean age of 22.3 years (range 4–53) and 26 years (range 17–38), respectively.
Several mechanisms causing tracheal injury have been suggested: tracheal compression between the sternum and the vertebral column or abrupt increase in intraluminal pressure due to forced expiration against a closed glottis [9]. Direct trauma to the cervical trachea also causes tracheal injury [10]. Tracheobronchial injuries involve mostly the main bronchus within 2 cm close to the carina; the right bronchus is more commonly affected [11]. Chest compression squeezes the right main bronchus that is seated in front of the vertebral bodies and increases the risk of tear during blunt incidents, while the left main bronchus gets protection by the arch riding above it. Also, the longer air column with the left bronchus buffers the increasing intraluminal pressure and reduces the tear incidence [10].
In our cohort, the injuries were more common at the upper airways especially the cervical part of the trachea and this finding was consistent with almost all previous reports. Some authors like Farzanegan et al. who studied 35 patients with major airway injury and included 16 (45%) of them with a laryngeal injury [12]. We have excluded such patients as they are out of our scope of care being managed by the ENT surgeons.
Injuries ranged from contusion, a small laceration, to complete avulsion of the airways. Once the injury violates the integrity of the mediastinal pleura, it will produce persistent air leak and desaturation, but if it remains intact, it might go unnoticed as both ends are connected by the peribronchial tissues but later on stenosis endures and patients come with dyspnea at rest [9].
In our population, surgical emphysema was the most frequent presentation followed by dyspnea. Many authors reported the same findings even with more distress in the form of tachypnea and stridor [8, 13, 12, 5]. The incidence of hemodynamic instability and shock was 60.7% which is higher than those documented in many studies as we included only cases of blunt trauma that commonly involved other systems.
In our study, pneumothorax was present in 24 (85.7%) of cases and lung contusion was reported in 22 (78.6%) of them. Few patients displayed no signs or symptoms until one or 2 days post-injury [10[. Serious associated other injuries included multiple ribs fracture, flail chest, and head or abdominal injuries; they occur in more than 50% of patients as similarly reported by others [14].
The chest CT is able to detect the site of blunt tracheobronchial injuries in more than 90% of cases. However, bronchoscopic examination remains the standard tool for diagnosing TBI not only to detect but also to define the site and the extent of any tear or laceration [15]. Bronchoscopic findings may be in the form of single transverse (between the rings) or longitudinal along the membranous segment or maybe complex with rupture in more than one site or form [16].
Immediate surgical repair was chosen in most cases to avoid airway and pulmonary complications. In a few selected cases, surgical intervention was postponed if the patient did not have major injury suspicious criteria or did not have a large tracheobronchial tear by bronchoscopic examination. The latest ATLS guidelines recommended the immediate operative intervention in such injuries except for more stable patients; operative treatment of TBI may be delayed until the acute inflammation and edema resolve [2]. Although conservative treatment may be an option in selected patients, it is crucial to bear in mind that it may be a one-way choice, as the success of subsequent surgical treatment in case of failure may be limited by the progression of sepsis, reduced vascularization of the margins of the airway laceration, and the development of adhesions [17].
The following is a decision-making flow chart for managing chest trauma with keeping major TBI in mind:
A cervical tracheal tear can be approached by collar cervical incision while right posterolateral thoracotomy provides good access to the intrathoracic trachea, right main bronchus, and proximal part of the left main bronchus [17]. Some authors reported a high rate of pneumonectomy, 23%, and referred that to the high rate of gun-shot injuries [3].
All cases were managed by direct repair after trimming of tear edges without much dissection to keep reasonable blood supply to the suture lines. We have used absorbable 3/0 interrupted sutures with ties outside and in few cases; we covered the suture line with mediastinal pleura. Using of absorbable sutures in repairing of the tracheal tear is best with less chance for the formation of granulation tissue than the non-absorbable suture. Also, it is liable to cause abscess, infection, or dehiscence. Interrupted sutures with knots outside are commonly performed than the continuous technique. The suture line can be supported by Teflon or a pleural flap [18].
Postoperative use of bronchoscopic examination, nasotracheal suction, or forced coughing is important, and the patients should be reassessed by bronchoscope 3 months after repair [18, 19]. Tracheal stenosis is diagnosed if the diameter decreased to 50% and clinically it does dyspnea only on exertion but if it reaches below one quarter, stridor and dyspnea will occur at rest especially if little secretions or inflammatory swelling was seated inside [17].
In our patients, the postoperative morbidity and mortality rates were significantly higher in the delayed repair group (p value < 0.001). These rates were affected by the longer time of lung collapse, lung and surgical site infection, and presence of retained hemothorax. We had three cases of tracheal stenosis; one of them responded to multiple bronchoscopic dilatations, and the other two needed surgery for disabling dyspnea. The two empyema cases in the urgent repair group managed by tube thoracostomy drainage and medical treatment and showed a complete cure. The only case of empyema in the delayed repair group died after developing septic shock. One case with massive air leakage with significant lung collapse underwent early thoracoscopic repair. The other two cases required no further intervention rather than physiotherapy and observation. They improved and discharged after 2 weeks. Local granulation appeared over the anastomosis in two patients and was successfully removed with the bronchoscope.
There were non-comparable reasons for mortality in both groups. In the urgent repair group, the mortality of three cases was attributed to the involvement of other organ damage; two cases died because of brain injury, one case because of increased abdominal bleeding and shock after thoracic surgery and the fourth one died after adult respiratory distress syndrome (ARDS). In the delayed group, one patient developed complicated acute renal failure and the other two patients died after septic shock; one of them due to pneumonia after surgical airway repair and the other patient due to prolonged empyema.
The mortality varied according to the anatomical location of the airway injury, studies show a higher rate of fatality if the thoracic portion of the trachea was injured compared to the cervical part and higher mortality if injury with lower bronchus is injured [4]. Because it is difficult to ventilate/oxygenate, even after tracheal intubation and mechanical ventilation, and even get worsened [18]. Thus, those who survive the accident were those with upper injuries while those who die at the scene were those with lower injuries [19].
