Chest trauma

Overview

Chest injury is involved in a large share of trauma deaths. Bailey & Love notes that thoracic trauma makes up about a quarter of all severe injuries and contributes to death in a further quarter.

The good news: about 80% of chest injuries are managed without an operation, using oxygen, pain relief and a chest drain. Only a minority need a thoracotomy. The physiological end result of a bad chest injury is hypoxia, hypercarbia and acidosis.

The deadly dozen

ATLS lists simple pneumothorax and haemothorax among the secondary-survey injuries, and adds tracheobronchial injury and traumatic circulatory arrest to the primary survey list.

Investigations in chest trauma

• Chest X-ray is the first investigation. In an unstable patient or with spinal risk it is a supine AP film. An erect film shows a small pneumothorax, a fluid level or gas under the diaphragm better.
• eFAST looks for pericardial fluid, haemothorax and pneumothorax at the bedside.
• CT with contrast is the most reliable test in a stable patient (aorta, contusion, fractures).
• In a crashing patient, a chest drain is both diagnostic and therapeutic.

Immediately life-threatening injuries

Tension pneumothorax

Mechanism: a one-way valve lets air into the pleural space but not out. The lung collapses, the mediastinum shifts away, venous return falls and the other lung is squeezed. Causes: penetrating or blunt injury with a lung leak, positive pressure ventilation, central line insertion.

Clinical features: air hunger, tachypnoea, tachycardia, hypotension, distended neck veins, hyper-resonance, absent breath sounds on one side, tracheal deviation away from the affected side (a late sign), cyanosis (late).

Treatment:

1. Immediate decompression without waiting for imaging.
2. Adults (ATLS 10th): large over-the-needle catheter in the 5th intercostal space just anterior to the mid-axillary line (an 8 cm cannula reaches the pleura far more often than a 5 cm one). Finger thoracostomy is the alternative if the needle fails.
3. Children: 2nd intercostal space in the mid-clavicular line.
4. Follow with a chest drain.

Open pneumothorax (sucking chest wound)

• A chest wall defect large enough to stay open. When the hole is about two-thirds of the tracheal diameter or more, air enters through the wound rather than the trachea, and ventilation fails.
• First aid: cover with a sterile occlusive dressing taped on three sides so it acts as a flutter valve (air leaves on expiration, cannot enter on inspiration).
• Then insert a chest drain away from the wound, and later close the defect surgically.

Massive haemothorax

• Definition: over 1500 mL of blood gathering quickly, or a third or more of blood volume, in one hemithorax.
• Source: penetrating injury to systemic or hilar vessels; in blunt injury, torn intercostal or internal mammary vessels with rib fractures.
• Signs: shock, flat neck veins, dullness to percussion, absent breath sounds.
• Treatment: restore volume (blood), insert a large-bore drain (28–32 Fr in ATLS) in the 5th space just anterior to the mid-axillary line; consider autotransfusion.

Indications for thoracotomy:

• 1500 mL or more drained at once, or
• continuing loss of about 200 mL/h for 2–4 hours (Bailey & Love: 3–4 hours), or
• continuing need for transfusion, or deteriorating physiology.

#### Tension pneumothorax vs massive haemothorax

Cardiac tamponade

• Blood in the non-stretchable pericardium stops the heart from filling. Usually penetrating; a small volume is enough.
• Beck triad: hypotension, raised venous pressure (distended neck veins) and muffled heart sounds. Also pulsus paradoxus and Kussmaul sign (venous pressure rises on inspiration). Neck veins may be flat if the patient is also hypovolaemic.
• PEA in trauma suggests tamponade, tension pneumothorax or profound hypovolaemia.
• Diagnosis: FAST/eFAST (fast and reliable), echo, or a pericardial window.
• Definitive treatment: operation: thoracotomy or sternotomy by a qualified surgeon.
• Pericardiocentesis (subxiphoid needle) is only a temporising step when no surgeon is available; clotted blood often makes it "dry".

Flail chest

• Definition: a chest wall segment without bony continuity with the rest of the cage. ATLS: two or more adjacent ribs each broken in two or more places (or costochondral separation). Bailey & Love sets the bar higher at three or more ribs, each broken at two points.
• Sign: paradoxical movement: the segment sinks in on inspiration and bulges on expiration. It is a clinical diagnosis; muscle spasm may hide it early.
• The real danger: the underlying pulmonary contusion and pain-limited breathing, which cause hypoxia.
• Treatment: oxygen, good analgesia (opioids, intercostal or epidural blocks), physiotherapy, cautious fluids. Intubation and ventilation only for respiratory failure. Surgical rib fixation helps selected patients.

Potentially life-threatening injuries

Pulmonary contusion

• Bruised lung with blood and oedema in the alveoli. The commonest potentially lethal chest injury (ATLS) and the main cause of hypoxia after blunt chest trauma.
• Children have springy ribs, so contusion can occur without rib fractures.
• Hypoxia worsens over the first 24–48 hours; X-ray changes may be late.
• Treatment: oxygen, chest physiotherapy, analgesia; ventilation if it fails. Monitor saturation and blood gases.

Blunt cardiac injury

• Contusion, chamber rupture, valve damage or coronary dissection. Suspect it with a sternal fracture.
• Signs: arrhythmias (unexplained tachycardia, AF, ventricular ectopics, ST changes), hypotension.
• ECG and echo guide care; troponin adds little for diagnosing contusion.
• Patients with ECG changes need monitoring for 24 hours for sudden arrhythmia.

Traumatic aortic disruption

• Cause of sudden death in high-speed crashes and falls. Survivors usually have an incomplete tear just distal to the left subclavian artery, near the ligamentum arteriosum, held by intact adventitia or a contained haematoma.

Chest X-ray signs:

• Widened mediastinum (commonest)
• Obliterated aortic knob, trachea and NG tube pushed to the right
• Left main bronchus depressed, right main bronchus raised
• Obliterated aortopulmonary window, widened paratracheal stripe
• Left apical cap, left haemothorax
• Broken 1st or 2nd rib, or a broken scapula

Diagnosis: helical contrast CT of the chest (very sensitive); transoesophageal echo if the patient cannot go to CT.

Management: control pain, then heart rate below 80/min and mean pressure 60–70 mmHg with a short-acting beta-blocker (esmolol); then endovascular stent or open repair.

Traumatic diaphragmatic rupture

• Left side is diagnosed more often (the liver protects and hides the right).
• Blunt injury makes large tears with herniation of stomach, colon or spleen into the chest. Penetrating injury makes small holes that may present years later as a strangulated hernia.
• X-ray: raised or blurred hemidiaphragm, bowel gas in the chest, NG tube coiled above the diaphragm.
• Best diagnosis: laparoscopy or thoracoscopy (CT, ultrasound and DPL can all miss it).
• Repair all of them; repair penetrating injuries through the abdomen so hollow viscus injury is not missed.

Tracheobronchial injury

• Most occur within about 2.5 cm of the carina.
• Clues: haemoptysis, subcutaneous emphysema in the neck, tension pneumothorax, and a persistent large air leak with a lung that will not re-expand after drain insertion (may need a second drain).
• Bronchoscopy confirms; intubate the healthy side and repair.

Oesophageal injury

• Usually penetrating. Blunt rupture comes from a hard blow to the upper abdomen forcing gastric contents up.
• Suspect it with a left pneumothorax or haemothorax without rib fractures, mediastinal air, or particulate matter in the drain.
• Confirm with contrast swallow and oesophagoscopy; treat by early repair and wide drainage.

Other chest wall injuries

• Rib fractures: the commonest chest injury. Pain stops coughing and leads to atelectasis and pneumonia. In the elderly, pneumonia and death are about twice as common. Give strong analgesia.
• Sternal and scapular fractures: markers of high energy; look for cardiac and lung injury.
• Subcutaneous emphysema: needs no treatment itself, but find the cause; if the patient needs ventilation, consider a drain on that side.
• Traumatic asphyxia (crush): plethora and petechiae of the face, neck and upper chest from sudden compression of the superior vena cava.

Procedures

Chest drain

• Site: the safe triangle: lateral border of pectoralis major, anterior border of latissimus dorsi, and a line at the level of the nipple (about the 5th intercostal space), with the apex below the axilla. Insert just anterior to the mid-axillary line.
• Pass just above the lower rib of the space; the intercostal vessels and nerve run under each rib.
• Use blunt dissection and a finger sweep; no trocar.
• A 28 Fr or larger tube suits haemothorax in adults.
• Connect to an underwater seal; never clamp a drain that is still bubbling.

Emergency department (resuscitative) thoracotomy

• Best results in penetrating chest injury with signs of life; very poor after blunt trauma with no signs of life at the scene.
• Aims: release tamponade, control cardiac or lung bleeding, internal cardiac massage, cross-clamp the descending aorta.
• Approach: left anterolateral thoracotomy, extended to a clamshell if needed. Median sternotomy suits planned surgery on the anterior heart and great vessels.

Quick revision

• Tension pneumothorax: clinical; adult needle at 5th space anterior to mid-axillary line (older answer: 2nd space mid-clavicular); then drain.
• Open pneumothorax: three-sided dressing, drain away from wound.
• Massive haemothorax: >1500 mL; thoracotomy if 1500 mL at once or 200 mL/h for 2–4 h.
• Tamponade: Beck triad; FAST; surgery is definitive, pericardiocentesis is a stopgap.
• Flail: paradoxical segment; treat the contusion and pain.
• Contusion: commonest potentially lethal; worsens over 24–48 h.
• Aorta: tear near ligamentum arteriosum; widened mediastinum; CT; beta-blocker, then stent.
• Diaphragm: left, NG tube in chest, laparoscopy, repair via abdomen.

Written by The House Job from standard references (ATLS Student Course Manual, 10th edition; Bailey & Love's Short Practice of Surgery, 27th edition).

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