Pulmonary injury

Pulmonary Contusion

• Epidemiology & Risk Factors
  • High-energy blunt chest trauma (e.g., MVC, falls from height, blast injuries).
  • Commonly co-occurs w/ rib fractures, flail chest, hemothorax, or pneumothorax.
  • Most common potentially lethal chest injury in children/young adults.
• Clinical Features
  • Onset: Rapidly develops within 24 hours of trauma (often <15 mins to 6 hrs).
  • Sx: Dyspnea, tachypnea, pleuritic chest pain, hemoptysis (rare but possible).
  • PE: Localized chest wall ecchymosis, chest wall tenderness, decreased breath sounds, and crackles over the injured lung segment.
• Diagnosis
  • Initial: CXR showing patchy, non-segmental alveolar infiltrates/consolidation (described as “patchy opacification”) not restricted by anatomical lobar borders.
    • Note: CXR may be normal in the first 6 hours; serial CXRs or CT indicated if clinical suspicion is high.
  • Confirmatory/Most Sensitive: Chest CT (reveals patchy ground-glass opacities or consolidation immediately after trauma).
  • Key Labs/Monitoring:
    • ABG: Hypoxemia ($Pa{O}_2$ < 60 mmHg or $Sa{O}_2$ < 90% on room air), hypocapnia (due to hyperventilation).
    • Continuous pulse oximetry.
• Differential Diagnostics
  • ARDS: Diff by bilateral infiltrates, delayed onset (typically 24–72 hours post-insult), and systemic inflammatory trigger (e.g., sepsis, pancreatitis). Pulmonary contusion is localized to the trauma site and presents <24 hours.
  • Hemothorax: Diff by dullness to percussion, decreased breath sounds, and CXR showing pleural fluid/layering rather than parenchymal infiltrates.
  • Aspiration Pneumonitis: Diff by history of witnessed aspiration/emesis, altered mental status, and infiltrates localized to dependent lung segments (e.g., RLL).
  • Myocardial Contusion: Diff by signs of cardiogenic shock, elevated troponins, and ECG abnormalities (e.g., new BBB, arrhythmia).
• Management
  1. Initial/Supportive:
     • Supplemental $O_2$ (maintain $Sa{O}_2$ > 92%).
     • Aggressive pain control (systemic analgesics or epidural/intercostal nerve blocks) to prevent splinting, atelectasis, and hypoventilation.
     • Pulmonary toilet (incentive spirometry, chest physiotherapy).
  2. Fluid Optimization: Judicious IVF administration. Avoid volume overload as injured capillaries are hyperpermeable, which can worsen pulmonary edema.
  3. Refractory/Severe:
     • Non-invasive positive pressure ventilation (NIPPV/CPAP) for moderate hypoxemia.
     • Intubation w/ mechanical ventilation + low-tidal-volume ($V_T$) ventilation + PEEP if refractory hypoxemia, severe flail chest, or respiratory failure occurs.
• Complications
  • Secondary bacterial pneumonia.
  • ARDS.
  • Respiratory failure requiring prolonged mechanical ventilation.

Tracheobronchial injury

• Epidemiology & Risk Factors
  • Most blunt injuries occur within 2 cm of the carina (usually R mainstem bronchus).
• Clinical Features
  • Symptoms: Dyspnea, hemoptysis, hoarseness, chest/neck pain.
  • Signs:
    • Subcutaneous emphysema (crepitus in neck/chest wall).
    • Respiratory distress, cyanosis.
    • Hamman sign (crunching sound synchronized w/ heartbeat due to pneumomediastinum).
    • Persistent PTX or progressive tension PTX despite functional chest tube placement. c
• Diagnosis
  • Initial: CXR (shows pneumomediastinum, subcutaneous emphysema, PTX, or “falling lung sign” where the collapsed lung sinks away from the hilum).
  • Key Labs/Monitoring: ABG (shows hypoxia, respiratory acidosis).
  • Imaging: CT Chest (shows airway disruption, “windsock sign”, persistent air outline outside the tracheobronchial tree).
  • Confirmatory/Gold Standard: Bronchoscopy (directly visualizes the location, size, and extent of the airway tear).
• Differential Diagnostics
  • Simple/Tension Pneumothorax: Diff by rapid lung re-expansion and cessation of air leak after chest tube insertion (tracheobronchial injury has persistent massive air leak and failure of lung to re-expand). c
  • Esophageal Rupture: Diff by presence of hydropneumothorax, pleural fluid analysis (↑ amylase, low pH), and contrast esophagography/CT w/ oral contrast (no persistent large-volume air leak).
  • Diaphragmatic Rupture: Diff by CXR showing abdominal contents (stomach/bowel loops) in the hemithorax, w/ NG tube tip positioned in the chest.
• Management
  1. Immediate Airway Stabilization (ABC):
     • Secure airway via bronchoscopy-guided intubation (advancing ET tube distal to the site of injury/tear to prevent positive-pressure ventilation from worsening the pneumomediastinum/PTX).
     • Place large-bore chest tubes (often multiple required due to massive air leak).
  2. Surgical Intervention (Definitive):
     • Emergent operative primary repair (thoracotomy) for large tears (>1/3 airway circumference), persistent major air leak, respiratory failure, or associated esophageal/vascular injury.
  3. Conservative Management:
     • Nonoperative observation for stable pts w/ small (<2 cm or <1/3 circumference) lesions, minimal air leak, and fully expanded lung on chest tube suction.
• Complications
  • Mediastinitis (high mortality risk).
  • Bronchial/tracheal stenosis (leading to atelectasis and dyspnea weeks/months later).
  • Persistent empyema or pneumonia.
  • Sepsis & MODS.