33. Chest injuries, pneumothorax and haemothorax

1. Definition

• Chest injury → trauma to the chest wall, pleura, lungs, heart, great vessels, oesophagus or diaphragm
• Pneumothorax → air in the pleural cavity
• Haemothorax → blood in the pleural cavity
• Chest injuries → about 25% of trauma deaths
• 50% of patients dying of multiple injuries have a significant chest injury
• Most treated without thoracotomy → chest drain alone in about 85%

2. Aetiology and risk factors

• Blunt → road traffic accidents (most common), falls, crush, blast, deceleration
• Penetrating → stab, gunshot
• Iatrogenic → central line insertion, lung biopsy, positive pressure ventilation

3. Pathogenesis

• Loss of negative intrapleural pressure → lung collapse
• Tension: one-way valve → air enters on inspiration, cannot leave
  1. Rising pressure in the hemithorax
  2. Mediastinal shift to the opposite side
  3. Kinking of the venae cavae → reduced venous return
  4. Low cardiac output → obstructive shock, cardiac arrest
• Open pneumothorax → wound > 2/3 of the tracheal diameter; air goes through the wound instead of the trachea
• Flail chest → paradoxical movement of a free segment; hypoxia mainly from the underlying pulmonary contusion
• Haemothorax → bleeding from intercostal or internal thoracic arteries, lung, heart, great vessels

4. Classification

By mechanism

• Blunt
• Penetrating

By structure

• Chest wall → rib fractures, flail chest, sternal fracture
• Pleura → pneumothorax, haemothorax
• Lung → contusion, laceration
• Heart → tamponade, blunt cardiac injury
• Great vessels → traumatic aortic rupture
• Airway → tracheobronchial rupture
• Oesophagus, diaphragm

Pneumothorax types

1. Simple (closed)
2. Tension
3. Open (sucking chest wound)

Haemothorax by volume on chest X-ray

1. Small → < 500 mL, blunting of the costophrenic angle
2. Medium → 500–1500 mL
3. Massive → > 1500 mL

Immediately life-threatening (primary survey)

• Airway obstruction
• Tension pneumothorax
• Open pneumothorax
• Massive haemothorax
• Flail chest with pulmonary contusion
• Cardiac tamponade

5. Clinical picture

Symptoms

• Chest pain, worse on breathing
• Dyspnoea
• Haemoptysis

Signs

• Tachypnoea, cyanosis, low oxygen saturation
• Bruising, seat belt sign, wounds
• Subcutaneous emphysema → crepitus under the skin
• Simple pneumothorax → reduced breath sounds, hyperresonance
• Tension pneumothorax:
  • Respiratory distress, tachycardia, hypotension
  • Absent breath sounds, hyperresonance on the affected side
  • Tracheal deviation to the opposite side (late sign)
  • Distended neck veins
• Haemothorax → reduced breath sounds, dullness on percussion, shock
• Flail chest → paradoxical segment, crepitus of ribs
• Cardiac tamponade → Beck's triad: hypotension, distended neck veins, muffled heart sounds; pulsus paradoxus
• Traumatic aortic rupture → deceleration injury, unequal arm pulses, widened mediastinum
• Diaphragmatic rupture → blunt seat belt injury, mostly left side; raised left hemidiaphragm or bowel in the chest
• Tracheobronchial rupture → persistent large air leak after chest drain

6. Diagnosis

• Tension pneumothorax → clinical diagnosis; treat before any X-ray

Imaging

• Extended focused assessment with sonography for trauma (eFAST):
  • Pneumothorax → absent lung sliding; barcode sign on M-mode
  • Haemothorax, pericardial fluid
  • More sensitive than chest X-ray for pneumothorax
• Chest X-ray:
  • Visceral pleural line, no lung markings beyond → pneumothorax
  • Deep sulcus sign → pneumothorax on a supine film
  • Haemothorax → diffuse haziness on a supine film; meniscus when erect
  • Widened mediastinum > 8 cm → aortic injury
• CT chest with contrast → stable patient; occult pneumothorax, contusion, aorta
• Electrocardiogram (ECG), troponin → blunt cardiac injury
• Bronchoscopy → tracheobronchial injury
• Oesophagoscopy or contrast swallow → oesophageal injury

Laboratory

• Arterial blood gas
• Full blood count, cross-match

7. Differential diagnosis

• Spontaneous pneumothorax
• Pleural effusion
• Lung collapse, endobronchial intubation
• Diaphragmatic rupture with bowel in the chest
• Pulmonary embolism, myocardial infarction

8. Treatment

Primary survey (ATLS)

• High-flow oxygen, cervical spine control
• Airway → intubate if needed
• Tension pneumothorax → immediate decompression:
  • Needle decompression with a 12G cannula → 5th intercostal space between anterior and mid-axillary lines (current ATLS, adults), or 2nd intercostal space, midclavicular line (classic site)
  • Finger thoracostomy → 5th intercostal space, same position
  • Always followed by a chest drain in the 5th intercostal space
• Open pneumothorax → 3-sided occlusive dressing, then chest drain away from the wound and closure of the wound
• Massive haemothorax → 2 large-bore cannulas, blood transfusion, chest drain
• Cardiac tamponade → pericardiocentesis (ultrasound-guided) or thoracotomy

Chest drain (tube thoracostomy)

• Indications (British Thoracic Society):
  • Pneumothorax in a ventilated patient
  • Tension pneumothorax after needle decompression
  • Persistent or recurrent pneumothorax after aspiration
  • Traumatic haemopneumothorax
  • Simple traumatic pneumothorax that is large, symptomatic, or before general anaesthesia
  • Empyema, malignant effusion, after thoracic surgery
• Patient at 45°, arm abducted; pulse oximetry
• Triangle of safety → anterior border of latissimus dorsi, lateral border of pectoralis major, line of the 5th intercostal space (nipple level), apex below the axilla
• Local anaesthetic down to the parietal pleura
• 2 cm incision; blunt dissection over the upper border of the rib below → avoids the neurovascular bundle
• Pierce the pleura with a blunt clamp; finger sweep for adhesions
• Insert the tube without a trocar → upwards for air, downwards for blood
• Underwater seal; secure with suture; check swing and bubbling; chest X-ray
• Smaller tubes (12–20 Fr) are effective; wide-bore drain for massive haemothorax
• Too low or too posterior → injury to liver, spleen, diaphragm

Indications for thoracotomy

1. Initial drainage > 1500 mL of blood
2. Continued drainage > 200 mL/h for 2–4 h
3. Need for repeated transfusion
4. Cardiac tamponade
5. Large air leak → tracheobronchial injury
6. Oesophageal, great vessel or diaphragm injury
7. Emergency department (resuscitative) thoracotomy → penetrating chest trauma with arrest in the department

Other injuries

• Simple pneumothorax → chest drain; small and stable → observe
• Retained haemothorax → video-assisted thoracoscopic surgery (VATS) within 3–7 days
• Rib fractures, flail chest:
  • Small segment, adequate breathing → high-dependency unit, analgesia, physiotherapy, early mobilisation, serial blood gases
  • Analgesia → epidural, paravertebral or serratus anterior block
  • Severe → intubation and positive pressure ventilation
  • Surgical rib fixation → selected flail chest
• Pulmonary contusion → most common chest injury that can become lethal; oxygen, analgesia, physiotherapy, avoid fluid overload, ventilation if hypoxic
• Tracheobronchial, aortic, cardiac or diaphragmatic injury → CT, cardiothoracic referral
• Traumatic aortic rupture → blood pressure control, endovascular stent graft

9. Complications

• Empyema → infected retained haemothorax
• Fibrothorax, trapped lung → decortication
• Pneumonia, acute respiratory distress syndrome (ARDS)
• Persistent air leak, bronchopleural fistula
• Re-expansion pulmonary oedema
• Chest drain → malposition, organ injury, bleeding from intercostal vessels
• Chronic chest wall pain