What are the common complications of a lung contusion and their recommended management?

Complications of Lung Contusion

Lung contusion leads to respiratory failure, pneumonia, and ARDS as its primary complications, requiring aggressive supportive management with lung-protective ventilation, pain control, and judicious fluid management to prevent deterioration.

Major Complications and Their Incidence

Respiratory Failure

• Respiratory insufficiency is the most common early complication, manifesting within hours of injury and typically peaking at 72 hours post-trauma 1
• Hypoxemia (PaO₂ < 60 mm Hg despite high-flow oxygen) and hypercarbia develop due to ventilation/perfusion mismatching and increased intrapulmonary shunting 2, 3
• Respiratory distress with increased work of breathing (respiratory rate > 35 breaths/minute) indicates need for intubation 2
• Refractory hypoxemia despite supplemental oxygen mandates mechanical ventilation 2

Pneumonia

• Pneumonia occurs in 5-50% of pulmonary contusion cases, representing a major source of morbidity 4, 5
• Risk increases with prolonged mechanical ventilation, inadequate pain control limiting pulmonary toilet, and secretion accumulation 6
• Aggressive pulmonary hygiene and pain management are essential preventive measures 7

Acute Respiratory Distress Syndrome (ARDS)

• ARDS develops in 5-20% of patients with pulmonary contusion 4
• The combination of alveolar hemorrhage, pulmonary parenchymal destruction, and inflammatory response creates the substrate for ARDS 1, 3
• ARDS can complicate the clinical course and delay radiographic clearing 6

Associated Complications from Concomitant Injuries

Flail Chest and Chest Wall Instability

• Underlying lung contusion combined with flail chest leads to respiratory compromise through multiple mechanisms: direct parenchymal injury plus splinting, shallow breathing, and poor cough due to pain 6
• This combination results in atelectasis, secretion accumulation, and ultimately respiratory failure 6
• Prolonged mechanical ventilation duration increases rates of pneumonia, sepsis, tracheostomy, and barotrauma 6

Pulmonary Laceration and Cavity Formation

• Both penetrating and blunt trauma can cause lung lacerations that may progress to cavity formation 8
• Most patients with lung lacerations can be managed with closed thoracic drainage 8
• Progressive hemothorax or persistent dyspnea despite drainage requires thoracotomy to identify and suture hemorrhage or air leak sites 8

Pleural Complications

• Empyema can develop as a metastatic infection complication 6
• Any patient with inadequate clinical response should have repeat chest radiograph or CT scan, with pleural fluid sampling if present 6

Management Strategy to Prevent and Treat Complications

Fluid Management

• Ensure adequate tissue perfusion without restriction during initial resuscitation, especially with concomitant flail chest 2, 7
• Once resuscitation is complete, avoid unnecessary fluid administration to prevent deterioration of pulmonary function 2, 7
• This balanced approach prevents both hypoperfusion and fluid overload-related respiratory compromise 2

Mechanical Ventilation Strategy

• Apply lung-protective ventilation with tidal volumes <6 mL/kg predicted body weight and moderate PEEP to prevent additional lung injury 2, 7
• Maintain plateau pressure ≤30 cmH₂O as an absolute ceiling, reducing tidal volume further if necessary 7
• Accept permissive hypercapnia with pH >7.20 rather than using injurious ventilation parameters 7
• Avoid routine hyperventilation even in head injury; PaCO₂ <27 mmHg causes cerebral vasoconstriction and cardiovascular collapse 2, 7

Pain Control

• Aggressive pain control is essential to reduce the risk of respiratory failure by enabling effective cough, deep breathing, and pulmonary toilet 2, 7
• Consider regional anesthesia techniques for severe chest wall pain, particularly with rib fractures 7
• Prescribe adequate oral and intramuscular analgesia 2

Surgical Stabilization of Rib Fractures (SSRF)

• SSRF is most beneficial in patients with anterolateral flail chest and respiratory failure WITHOUT severe pulmonary contusion 2, 7
• In presence of severe pulmonary contusion (Blunt Pulmonary Contusion score >7), SSRF does not demonstrate shorter mechanical ventilation time or ICU stay 2
• Early SSRF (within 48-72 hours) may benefit patients with minor to moderate pulmonary contusion, showing shorter hospital stays and lower morbidity 2, 7

Critical Pitfalls to Avoid

Ventilation Errors

• Never use high tidal volumes (>6 mL/kg): even short-term ventilation with 12 mL/kg promotes pulmonary inflammation and coagulopathy 7
• Avoid routine hyperventilation; brief intentional hyperventilation may only be used as temporary rescue therapy for imminent cerebral herniation 2

Oxygenation Extremes

• Avoid hypoxemia (Grade 1A recommendation) 7
• Avoid hyperoxemia except in imminent exsanguination 7

Delayed Recognition

• CT chest is the gold-standard imaging test; plain radiographs miss approximately 50% of contusions and fail to reliably identify those at risk for clinical deterioration 7
• Suspect pulmonary contusion in trauma patients with multiple rib fractures, rapid breathing, shock, and paradoxical chest wall movement when CT is unavailable 2

Timing of Surgical Intervention

• Do not delay surgical stabilization of rib fractures beyond 72 hours if indicated; early stabilization optimizes outcomes when appropriate 7

Long-Term Complications

• Long-term pulmonary disability is a frequent sequela of these injuries 1
• Clinical symptoms typically resolve within approximately 7 days, though radiographic improvement often lags behind clinical parameters 1, 6