Tracheobronchial injury due to blunt chest trauma.

Tracheobronchial avulsion resulting from blunt trauma is a very rare and serious condition, mostly due to high-speed traffic crashes. In this article, we briefly report the case of an 18-year-old man who was injured in a car accident and because of massive persistent air leakage (despite appropriate chest tube drainage), deemed to have a deep tracheobronchial injury. Due to a rapid drop in the patient's O2 saturation, he underwent an anterolateral thoracotomy. Endotracheal intubation was performed under direct visualization. The right mainstem bronchus was disrupted from the carina with a 1.5-cm stump remaining on the carina, and the remainder was crushed to the origin of the right superior lobe bronchus. Hence, a right superior lobectomy was performed and the postoperative course was uneventful.

INTRODUCTION

Tracheobronchial injury (TBI)—damage to the tracheobronchial tree—is a serious condition.[1] Penetrating injuries to the tracheobronchial tree are common, but severe injuries such as tracheobronchial laceration or bronchial avulsion due to a blunt trauma are very rare. Most penetrating injuries to the tracheobronchial tree occur in the cervical area, but most blunt injuries occur in the distal trachea or the right main bronchus.[2]

Deep pulmonary laceration occurs in 3.0–4.4% of all cases of blunt chest trauma[345], whilst tracheobronchial avulsion accounts for only 1–2% of these.[6] A high index of suspicion is the cornerstone in rapid diagnosis and successful surgical management of patients with TBI.[27]

In this article, we briefly report a case of blunt trauma-related tracheobronchial avulsion to draw the readers’ attention to this very rare phenomenon.

CASE REPORT

An 18-year-old man was injured in a car crash and was transported to the emergency department. On arrival, the patient was suffering from severe respiratory distress. Following initial examination, a chest tube was inserted immediately into the right hemithorax. However, there was a severe persistent air leak requiring a second chest tube. Despite the appropriate chest tube drainage, the patient was still in respiratory distress and tachypneic, indicating a need for intubation. The patient's condition improved clinically after endotracheal intubation. The patient also underwent imaging. Chest radiography showed collapsed right lung (thick arrows), left deviated trachea (short arrows), and shifted heart (narrow long arrows; Figure 1, Panel A), which was confirmed by computed tomography of the chest (Figure 1, Panel B). Considering the high-energy nature of the crash, continued severe air leak, and failure of lung expansion with chest tube insertion, a tracheobronchial injury was suspected; the patient was taken emergently to operating room for bronchoscopic evaluation. Upon arrival to the operating room, the patient's saturation precipitously dropped with hemodynamic compromise; therefore, an anterolateral thoracotomy was performed without prepping and positioning. The right mainstem bronchus was completely detached from the carina and the tip of the endotracheal tube was in the mediastinum. Under direct visualization, the tracheal tube was advanced into the left mainstem bronchus with a rapid improvement in hemodynamics and saturations. Then, the patient was positioned for posterolateral thoracotomy, and a posterolateral thoracotomy was performed in line with the previous incision. The right mainstem bronchus was disrupted from the carina with a 1.5-cm stump remaining on the carina, and the rest of it was crushed as far as the origin of the right superior lobe bronchus. Hence, a right superior lobectomy was performed. Thereafter, an end-to-end anastomosis was done between the bronchus intermedius and the carinal stump. The postoperative course was uneventful. A six-month follow up revealed no complications.

Figure 1

(Panel A) Chest radiography showed collapsed right lung (thick arrows), left deviated trachea (short arrows), and shifted heart (narrow long arrows) (Panel B) Computed tomography of the chest illustrating the collapsed right lung (thick arrows) and shifted heart (narrow long arrows)

DISCUSSION

We have reported a very rare case of bronchial avulsion due to blunt chest trauma. Similar cases with tracheobronchial avulsion due to blunt chest trauma have been reported.[89101112]

Several mechanisms were suggested for tracheobronchial injury in blunt trauma, including sudden deceleration of the pendulous lungs fixed at the hilum; transverse widening of the chest due to decrease in anteroposterior diameter causing lateral movement of the lungs and traction of the trachea, which is fixed at the level of carina; direct pressure from the sternum on the vertebral column, which may crush the trachea or the main bronchi in theory. Also, trauma from the direct external force on the chest may cause closure of the glottis, resulting in increased airway pressure. When this increased pressure surpasses the dilatability of the airways, a rupture in the wall of trachea and/or main bronchi occurs.[913]

Kiser et al. have reviewed cases with TBI following blunt chest trauma and reported 265 cases from 1873 until 1996. As is in our case, most severe injuries to the tracheobronchial tree in the study of Kiser et al. were a consequence of high-speed traffic crashes. Motor vehicle accidents were responsible for the injury in 59% of cases.[14] In another study on necropsy reports of 585 fatal traffic accidents[15], laceration of trachea was seen in 5 of these.

Of those patients who can reach the hospital, overall mortality has declined in past decades, from 36% before 1950 to 9% after the 1970s[14]; however, Nishiumi et al. have still reported a mortality rate of 31% in their cohort of 42 blunt trauma-related TBI cases in the time period between 1988 and 2008.[16]

No significant difference was seen between the time to hospital arrival for the survivors and non-survivors from TBI due to blunt trauma. The same lack of difference existed between the two groups for the time interval between hospital arrival and thoracotomy.[14]

In our case, the patient underwent emergency thoracotomy to avoid imminent respiratory insufficiency. Prompt diagnosis is the most important factor to prevent any potential respiratory insufficiency in critically ill cases or to prevent any late complications (bronchial stenosis, recurrent pneumonia, and bronchiectasis) resulted from untreated TBI in less severe cases.[1]

In terms of clinical manifestations, according to the study of Nishiumi et al., hemorrhagic shock with systolic blood pressure less than 80 mmHg and heart rates more than 120 beats/min are the best predictors of poor outcome in TBI. Hypoxemia (↓PaO2 on ABG) is shown not to be a poor prognostic factor for TBI.[4]

No radiographic finding in plain X-rays is pathognomic of deep tracheobronchial injury. Some suggested radiographic findings are hemopneumothorax, with the extent of pneumothorax limited to within 5 cm of the apex area and the collapse rate never exceeding 30%.[317] The absence of collapse of the injured lung due to the pulmonary parenchymal edema and hemorrhage is the most specific radiological characteristic.[4]

Flexible bronchoscopy is recommended in cases with severe blunt trauma and is the key to early diagnosis in suspected patients. However, bronchoscopic findings in TBI could be unclear even for an experienced thoracic surgeon who is not well-acquainted with bronchoscopy.[18]

Kiser et al.'s review suggested the ability to successfully repair the TBIs many months after their occurrence, since they did not observe an association between delay in treatment and unsuccessful repair of the injury.[14]

TBI in blunt trauma is commonly associated with injuries of the other vital organs, which should be evaluated carefully before making any decision on the treatment options. Massive hemothorax or massive air leakage are two indications for rapid surgical intervention in TBI.[3]

CONCLUSION

In general, as in our case, when a massive air leakage continues despite appropriate chest tube drainage in cases with blunt chest trauma, laceration of the tracheobronchial tree should be suspected, and an earlier decision for surgery is warranted and could be more secure and safe.