A 34-year-old man is brought to the emergency department following a high-speed motor vehicle collision. He was found lying outside the car and was intubated by the paramedics. Upon arrival, the patient has absent breath sounds in the right chest, normal breath sounds in the left chest, and hypotension. A right-sided chest tube is placed, resulting in a loud rush of air. Physical examination reveals multiple bruises over the anterior chest wall, with crepitus on palpation. The patient is initially stabilized. Over the next hour, the patient's oxygen saturation progressively declines. Repeat chest x-ray reveals appropriate endotracheal and chest tube placement, reaccumulation of air in the right pleural space, pneumomediastinum, and increased subcutaneous emphysema. Which of the following is the most likely diagnosis?

Question

A 34-year-old man is brought to the emergency department following a high-speed motor vehicle collision.  He was found lying outside the car and was intubated by the paramedics.  Upon arrival, the patient has absent breath sounds in the right chest, normal breath sounds in the left chest, and hypotension.  A right-sided chest tube is placed, resulting in a loud rush of air.  Physical examination reveals multiple bruises over the anterior chest wall, with crepitus on palpation.  The patient is initially stabilized.  Over the next hour, the patient's oxygen saturation progressively declines.  Repeat chest x-ray reveals appropriate endotracheal and chest tube placement, reaccumulation of air in the right pleural space, pneumomediastinum, and increased subcutaneous emphysema.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

This patient with blunt chest trauma (high-speed motor vehicle collision, anterior chest wall bruises) initially has a tension pneumothorax (absent breath sounds, hypotension) and subcutaneous air (crepitus). Despite appropriate tube thoracostomy, repeat chest x-ray shows rapid pneumothorax reaccumulation (leading to declining oxygen saturation) and increased subcutaneous emphysema. This suggests a tracheobronchial injury in which a large quantity of air escapes with each breath. The rapidity of extrapulmonary air accumulation in this patient is consistent with proximal (eg, bronchial) airway rupture because the larger diameter of the more proximal airway leads to more air leakage. Tracheobronchial injury should be considered in trauma patients with extensive extrapulmonary air. Classic findings are rapid, large air leak into the chest-tube drainage system and persistent pneumothorax/pneumomediastinum despite tube thoracostomy. Bronchoscopy is the definitive test for diagnosis; high-resolution CT scan can diagnose major injuries but may miss small tears. Most patients require operative repair. (Choices A and B) Aspiration pneumonitis (eg, aspiration of inflammatory gastric acid during post-collision unconsciousness) and trauma can lead to acute respiratory distress syndrome (ARDS). Both aspiration pneumonitis and ARDS may cause progressive desaturation and increased oxygen requirement; however, infiltrates (rather than extensive extrapulmonary air) would be expected on chest x-ray. (Choice D) Diaphragmatic rupture with migration of abdominal organs into the hemithorax can cause mass-effect compression of the lung, potentially compromising oxygenation. However, chest x-ray typically shows abdominal viscera above the diaphragm and/or loss of the diaphragmatic contour. (Choice E) Esophageal rupture may allow efflux of esophageal air into surrounding tissues, potentially resulting in pneumomediastinum and pneumothorax. However, the quantity and rapidity of leaked air in esophageal rupture is significantly less than with bronchial rupture. Therefore, in this patient, the rapid reaccumulation of pleural air in the presence of a chest tube makes esophageal rupture unlikely. (Choice F) Fat embolism may occur with trauma, especially with long bone and pelvic fractures. Although it may cause hypoxemia, fat embolism classically has associated neurologic abnormalities and a petechial rash. In addition, it typically takes 24-72 hours to manifest following the traumatic insult. (Choice G) Hemothorax may present with hypotension and decreased breath sounds; however, it would cause bloody chest tube drainage and pleural effusion on chest x-ray. Educational objective: Persistent pneumothorax and large air leak despite tube thoracostomy in the setting of blunt chest trauma suggest tracheobronchial rupture. Bronchoscopy can confirm the diagnosis prior to operative repair. References: Blunt tracheobronchial trauma. (http://www.ncbi.nlm.nih.gov/pubmed/30054080) Update on the diagnosis and treatment of tracheal and bronchial injury. (http://www.ncbi.nlm.nih.gov/pubmed/28203437)

A 34-Year-Old Man Is Brought to the Emergency Department Following