Tracheobronchial Injury

Tracheobronchial injury is a tear or disruption of the trachea or main bronchi from blunt or penetrating trauma, intubation, or ingestion or inhalation of foreign material. It is uncommon, and many patients die before reaching hospital.

Epidemiology. It is found in under 3% of major chest trauma. Most blunt injuries occur within 2.5 cm of the carina. Iatrogenic injury follows endotracheal intubation, tracheostomy and bronchoscopy, and most often affects the membranous posterior wall of the trachea.

Pathophysiology. Blunt mechanisms include sudden anteroposterior compression with closed glottis, shearing at fixed points (cricoid, carina) and rapid deceleration. Air leaks into the mediastinum and pleura. A complete transection can be held in continuity by peribronchial tissue.

Presentation is dyspnoea, stridor, hoarseness, haemoptysis, subcutaneous emphysema (neck and chest), pneumomediastinum and pneumothorax. A pneumothorax with a persistent large air leak after chest drainage, or lung that does not re-expand, suggests bronchial rupture. A "fallen lung" sign (the lung hanging toward the hilum, not collapsing toward the mediastinum) is typical. Hamman crunch is a clue.

Red flags.

• Subcutaneous emphysema increasing with ventilation.
• Persistent air leak after drain, or failure of lung re-expansion.
• Difficulty ventilating after intubation.

Chest radiograph (pneumothorax, pneumomediastinum, deep cervical emphysema, endotracheal cuff displacement or overdistension). CT chest with multiplanar and 3D airway reconstruction. Flexible bronchoscopy confirms the injury and its site and size, and is done through the tube or with spontaneous breathing under topical anaesthesia where possible.

Differential diagnosis. Oesophageal perforation, simple pneumothorax, ruptured bulla and alveolar rupture.

Airway. The airway is secured by the most experienced operator.

• Intubate under direct bronchoscopic vision, placing the cuff distal to the tear, or by selective intubation of the uninjured main bronchus.
• Avoid blind intubation, excessive cuff pressure, high ventilation pressures and positive pressure when possible.
• Use extracorporeal support if oxygenation fails.

Chest drains. For pneumothorax, insert one or more large drains with suction. A persistent large leak may require two drains.

Surgery.

• Immediate repair for most injuries: thoracotomy or cervical approach with primary closure, or resection with end-to-end anastomosis.
• Conservative treatment for small (under 2 cm), non-circumferential tears with minimal air leak, in a spontaneously breathing patient, with intubation avoided and prophylactic antibiotics.
• Delayed repair after stabilisation, for late presenting injury with stenosis.

Antibiotic. Cefazolin 2 g IV (3 g if weight is over 120 kg) or amoxicillin-clavulanate 1.2 g IV every 8 hours for mediastinal contamination.

Monitoring. Respiratory status, cuff pressure, air leak, subcutaneous emphysema and signs of mediastinitis (fever, tachycardia, chest pain).

Referral and escalation. Thoracic surgery, anaesthesia and interventional bronchoscopy at once.

Special groups. In children, a short narrow airway makes injury more likely during intubation, and surgical teams with paediatric experience should repair it.