Thoracic Trauma

Introduction

Thoracic trauma accounts for about 25% of all cases of trauma.
Most of the thoracic injuries are life theratening, where the commonest cause of morbidity and mortality is hypoxia and haemorrhage.
However, ironically upto 80% of the cases can be managed conservatively.
The key to succesful management here is early physiological resuscitation and accurate diagnosis.

Investigations

An approach towards chest injuries is the same as any other injuries in primary and secondary survey, as noted by the Advanced Trauma Life Support Protocol (ATLS). History and examination will be important, and probably the most useful tool is a chest radiography.

In an unstable patient, chest radiography can be done first, provided that it didn't interfere with the process of resuscitation. An ultrasound can give useful information about the presence of hematoma together with a contusion or just contusion alone. Chest drain can be both diagnostic and therapeutic, where the benefits outweights the risks.

Some pitfalls during investigations :

a) Failed to identify tracheal shift
b) Failed to pass NG tube due to failure to recognise diagphramatic rupture
c) During hemothorax, must auscultate both anterior and posterior chest
d) Failed to resuscitate the patient first before investigations are done (both should be done hand in hand)

Nowadays, CT scan made an important role in the management of chest injuries.
Not only it can provide details about ribs and verterbral fractures, it can pick up contusions, hematomas, pneumothoraces easily. In penetrating injuries, eg gunshot wounds, CT can even trace the track of penetration through the thorax. Though aortogram is the 'gold standard' in diagnosing disruption of thoracic aorta, CT scan yields the similar results.

Immediately life threatening chest injuries :

a) Airway obstruction

The commonest cause of early preventable death in a case of thoracic injury is airway obstruction, which blood, clots, secretions, dentures, teeth or even tongue can be a source of obstruction. Rapid removal usually relieves the obstruction.

Examples of injuries potentially causing airway obstruction :

a) Expanding neck hematomas
b) Bilateral mandibular fractures

Both a and b causing pharyngeal deviation and tracheal compression

c) Laryngeal injury with thyroid/cricoid cartilage fracture, and other tracheal injuries

What need to be done immediately is endotracheal intubation, as early as possible.
Since most of these conditions are insidious and yet progressive, and delay will render increased difficulty in inserting the ET tube.

b) Tension pneumothorax

Tension pneumothorax occurs when "one-way" valve is created in such a way that air is collected within the pleural cavity, without any means of escape. The source of air leakage can be originating from the chest wall or lung parenchyma. This results in significant compression over the affected lung, obstruction of the great veins compromising the venous return, mediastinal shift and eventually, compression of the opposite lung.

Common causes includes, penetrating chest injuries, blunt chest trauma with parenchymal injury, iatrogenic causes includes a central subclavian venepuncture or mechanical positive pressure ventilation that has gone wrong.

The clinical presentation is dramatic, with a panicky patient, complaints of dyspnoea, and with distended neck veins. Clinical signs : Tracheal shift to the opposite side (late presentation), diminished lung expansion over affected side, hyperresonant note on percussion, absence breath sounds.

Tension pneumothorax is a clinical diagnosis, NEVER EVER proceed to radiological investigations first.
If clinical diagnosis is establish, one should use a large bore needle, puncture the anterior chest and the 2nd intercostal space, along the midclavicular line. This is followed by inserting a chest tube over the 5th intercostal space at the anterior axillary line.

c) Pericardial tamponade

In a case of patient with shock and distended vein, pericardial tamponade must be differentiated from tension pneumothorax.  Pericardial tamponade is usually caused by penetrating chest injuries, and due to the non-distensible feature of the pericardial sac, even accumulation of small volume of blood is going to cause significant mechanical obstruction which renders cardiac pump failure.

The typical presentation will be : Features of hemorrhagic shock, Raised JVP and CVP, muffled heart sounds. Some pitfalls of these presentation must be remembered :

i) In case where there's active bleeding from a site distant to site of pathology, the neck veins are not distended.

ii) In case where the patient is having circulatory collapse, CVP will not be raised

To buy time for preparing the patient for definite operative management, which is left thoracotomy and sternotomy, a needle pericardiocentesis and resuscitation can be done. Needle pericardiocentesis is NOT a substitute for surgical management, and is done with ECG guidance (related with high incidence of iatrogenic myocardial injury)

d) Open pneumothorax

This means an opening chest wound is present, where the size of the defect is > 3cm.
Every breath that is inhaled, more air will be accumulated within the affected hemithorax.
This eventually causes significant hypoventilation, and eventually hypoxia.
The signs and symptoms are directly proportional to the size of the defect.
Initial management includes covering the chest wound is a sterile plastic occlusive dressing, which is only adhered at 3 sites, creating a flutter-wave valve, while suction is continued, where the tube is connected to an underwater seal drainage bottle.
Remember, no 'sucking' chest wound should be covered completely before a controlled drainage is established..
Definite management : pulmonary debridement and closure of the wound.

Some pit falls regarding this conditions :

For adults, a larger tube is required (>28 FG in size)
Some patients may require 2 chest drains
In case where patient's condition doesn't improve despite adequate drainage, try reducing the pressure within the seal drainage bottle to 5cm H20.
Early mobilisation and physiotherapy is required

e) Massive hemothorax

Defined by : initial blood collection by chest drain of > 1500 ml or in on-going hemorrhage, > 200-300 ml/h of blood collected over a period of 2-3 hours.

Massive hemothorax usually occurs due to blunt injuries, rupturing the intercostal and internal mammary vessels. Blood is hence collected within the affected hemithorax, causing significant respiratory distress. It's recognised by signs of haemorrhagic shock, flat neck veins, diminished expansion, dullness on percussion, absence of breath sounds.

Initial management of massive hemothorax includes chest drain, resuscitation and sometimes, intubation. Blood from the pleural cavity must be drained as rapid and as complete as possible, in order to prevent possibility of empyema and later, fibrothorax.

Pit falls regarding massive hemothorax :

1) One must examine both anterior and posterior chest when the patient is lying in a supine position, since there's a chance where the affected lung 'floats' within the BLOODY thoracic cavity.
If you only auscultate the anterior chest - it'll be normal

2) Even after draining out about 500ml of blood, dullness still persist and radio-opacity still present -> emergency thoracotomy

f) Flial chest

Flial chest is defined as a loss of bony continuity of a chest wall segment with the rest of thoracic cage, caused by a blunt trauma, which occurs when there's :

i) 3 or more rib fractures
ii) occurs in more than 2-3 places

Flial chest is a clinical diagnosis, not by chest radiography.
It's done by observing few respiratory cycles, where the flial segment will be drawn inwards during inspiration.

Causes of hypoxia in flial chest : voluntary splinting due to pain, pulmonary contusion, defect in the mechanical movement of the rib cage

Initial management : opiate analgesics, oxygen support. If a chest drain is present, intrapleural local analgesia can be given. Ventilation is reseved for patients with respiratory failure despite optimal treatment given. Surgical fixation is done in severe thoracic injury or in cases where pulmonary contusion is present.