Pulmonary Contusion

Pulmonary contusion is bruising of lung parenchyma, with alveolar haemorrhage and oedema without a laceration, after blunt or blast thoracic injury. It is the commonest lung injury after blunt chest trauma.

Epidemiology. It is found in about 30 to 75% of severe blunt chest trauma and is frequently associated with rib fractures (although it can occur in children with a pliable chest wall without fractures). Mortality is 10 to 25%.

Pathophysiology. Injury disrupts alveolar capillary membranes, causing haemorrhage, interstitial oedema, surfactant loss, atelectasis and an inflammatory response. Shunt and reduced compliance cause hypoxia. Changes peak at 24 to 72 hours and resolve over 7 to 10 days. Complications are pneumonia, ARDS and respiratory failure.

Presentation is tachypnoea, hypoxia, haemoptysis, crackles, reduced air entry and chest wall bruising. Symptoms often worsen over the first 24 to 48 hours. Initial radiograph may under estimate the extent.

Red flags.

• PF ratio under 200 or rising oxygen requirement.
• Contusion over 20% of lung volume on CT.
• Age over 60, associated flail chest, or fluid overload.

Chest radiograph (patchy non-segmental opacity, appearing within 6 hours), CT chest (more sensitive, helps estimate volume), arterial gas with PF ratio, and lung ultrasound.

Differential diagnosis. Aspiration, pneumonia, haemothorax, atelectasis and fat embolism.

Oxygen and respiratory support. Oxygen to saturation of 94 to 98%. High flow nasal oxygen or NIV for moderate hypoxia in cooperative patients. Intubate for PF ratio under 150 despite support, exhaustion or shock.

Ventilation. Lung protective: tidal volume 6 mL/kg predicted body weight, plateau pressure 30 cmH2O or less, PEEP 8 to 12 cmH2O. For severe unilateral contusion, independent lung ventilation or prone position may be considered by specialists.

Fluids. Aim for euvolaemia. Avoid fluid overload, but do not withhold resuscitation in shock.

Analgesia. Multimodal with regional block (erector spinae plane or paravertebral catheter, paracetamol, ketamine 0.1 to 0.3 mg/kg IV and cautious opioid) to allow deep breathing and clearance of secretions.

Pulmonary hygiene. Chest physiotherapy, incentive spirometry, early mobilisation and suction.

Not advised. Prophylactic antibiotics and corticosteroids. Treat pneumonia on evidence (new fever, purulent secretions, rising inflammatory markers): piperacillin-tazobactam 4.5 g IV every 6 hours, adjusted to eGFR and cultures.

ECMO. Venovenous support for severe refractory hypoxaemia, with anticoagulation risks weighed against bleeding.

Monitoring. Oximetry, PF ratio every 6 to 12 hours, radiographs every 24 to 48 hours and fluid balance.

Referral and escalation. High dependency or intensive care for moderate or severe contusion, especially with rib fractures.

Special groups. Older adults and those with chronic lung disease deteriorate faster. In children, contusion can be severe without rib fractures.