1

What are the main causes of cardiothoracic trauma?

Major trauma (defined by an Injury Severity Score >15) can be caused by:

a)

blunt injury – which is usually secondary to a fall or road traffic accident (RTA). These patients are more often managed non-operatively with chest drainage, with or without intubation and ventilation. Recovery from blunt injuries tends to be prolonged and management is supportive, especially as they are associated with a higher incidence of injuries to other body systems;

b)

penetrating injury – which is usually secondary to a stabbing or gunshot wound. These patients more often require emergent or urgent operative intervention and tend to recover quickly without prolonged ITU support.

Thoracic trauma can affect all structures within the thorax, with rib fractures being the most common (Table 1).

2

What is the incidence of major cardiothoracic trauma?

Although there are no complete data on the incidence of major cardiothoracic trauma in the UK, the National Audit Office (NAO) estimates that there were approximately 20,000 cases in 2007.

Overall there were 5400 deaths, which represent a 27% mortality, comprising a 12% pre-hospital mortality and a 15% in-hospital mortality.

In the UK, blunt injury (98%) accounts for the majority of cardiothoracic trauma, with the remainder caused by penetrating trauma (2%). This distribution, however, varies considerably in different countries.

3

What are the main physiological causes of death following thoracic trauma?

Tissue hypoxia – which may result from:

a)

hypovolaemia with subsequent hypoperfusion and shock – such as major blood loss;

b)

ventilation/perfusion mismatch – such as pulmonary contusion;

c)

loss of negative intrathoracic pressure – such as tension pneumothorax or open pneumothorax.

Hypercarbia – which may result from:

a)

inadequate ventilation;

b)

depressed level of consciousness.

Metabolic acidosis – which is the direct consequence of shock, usually hypovolaemic shock, but may be caused by cardiogenic shock or neurogenic shock.

4

What are the principles of managing a patient with thoracic trauma?

All patients with thoracic trauma, whether isolated or in association with polytrauma, should be treated according to the Advanced Trauma Life Support (ATLS^®) guidelines of assessment and resuscitation, including:

a)

preparation;

b)

triage;

c)

primary survey (A, B, C, D, E);

d)

resuscitation;

e)

adjuncts to primary survey and resuscitation;

f)

consideration of the patient’s need for transfer;

g)

secondary survey;

h)

adjuncts to secondary survey;

i)

continued post-resuscitation monitoring and re-evaluation;

j)

definitive care.

In clinical scenarios, these steps occur simultaneously, although not all patients will require all the steps.

It is also important to frequently repeat the primary and secondary surveys to identify any changes or deterioration requiring an adjustment in strategy.

5

What are the principles of the primary survey?

The vital functions and level of consciousness of the patient must be assessed rapidly and efficiently.

During this phase, any immediately life-threatening injuries should be identified and treated, before progressing to a subsequent phase of the initial assessment sequence:

a)

A – airway maintenance and cervical spine protection;

b)

B – breathing and ventilation;

c)

C – circulation with haemorrhage control;

d)

D – disability or neurological status;

e)

E – exposure and environmental control – completely undress the patient to assess for other injuries but prevent hypothermia.

6

What are the important differences when managing a paediatric patient, elderly patient and pregnant woman following thoracic trauma?

Paediatric patient:

a)

volume of blood and fluid administered needs to be adjusted according to body weight;

b)

degree and rate of ensuing hypothermia can vary in relation to the body surface area;

c)

injury pattern may differ.

Elderly patient:

a)

reduced physiological reserve (cardiac, respiratory or metabolic);

b)

presence of multiple comorbidities, including diabetes, hypertension, coronary artery disease, congestive heart failure, chronic obstructive pulmonary disease (COPD), liver disease, vascular disease and renal impairment;

c)

long-term medication may alter significantly the physiological response to stress, such as the heart rate response by β-blockade.

Pregnant woman:

a)

anatomical and physiological changes of pregnancy may alter the patterns of injury;

b)

early identification of pregnancy is paramount, as the best protection for the foetus is the provision of adequate care to the mother and early assessment of foetal status;

c)

pregnancy should warrant the presence of an obstetrician from admission following the trauma.

7

What are the important thoracic injuries that should be identified during the primary survey?

Airway obstruction.

Tension pneumothorax.

Open pneumothorax or ‘sucking’ chest wound.

Flail chest.

Massive haemothorax.

Cardiac tamponade (which is discussed in Key Questions in Cardiac Surgery).

8

What are the characteristic features of a tension pneumothorax?

Tension pneumothorax is caused by accumulation of air in the pleural space that cannot escape, which leads to a progressive increase in intracavitary pressure, resulting in (Figure 1):

a)

mediastinal shift, towards the contralateral side;

b)

kinking and obstruction of the low pressure venae cavae;

c)

reduced venous return to the heart;

d)

reduced cardiac output and profound hypotension;

e)

ultimately, cardiac arrest.

It can be caused by either blunt or penetrating injury and may be exacerbated by positive pressure ventilation.

The signs of tension pneumothorax include:

a)

deviated trachea – towards the contralateral side;

b)

decreased expansion on the ipsilateral side;

c)

decreased breath sounds on the ipsilateral side;

d)

increased percussion note on the ipsilateral side;

e)

distended neck veins and raised jugular venous pressure.

As these signs may be difficult to detect, especially in a noisy emergency department, the diagnosis of a tension pneumothorax should be suspected in a patient with hypoxia, hypotension, tachycardia or tachypnoea.

In addition, the presence of a chest drain does not always exclude a tension pneumothorax.

Immediate treatment with a needle thoracostomy in the 2nd intercostal space, mid-clavicular line, on the side of the tension pneumothorax, should not be delayed for radiological confirmation (Figure 2), with a ‘hiss’ of air confirming the diagnosis.

This converts a tension pneumothorax into a simple pneumothorax, which then requires definitive treatment with a chest drain.

9

What are the characteristic features of an open pneumothorax or ‘sucking’ chest wound (Figure 3)?

Large defects in the chest wall that remain open may result in a ‘sucking’ chest wound, collapse of the underlying lung and possibly a tension pneumothorax.

If the defect is greater than two-thirds of the tracheal diameter, air will preferentially enter the thoracic cavity through the wound rather than via the central airway, due to its reduced resistance to flow, resulting in profound hypoxia and hypercarbia.

At the primary survey, the initial management of an open pneumothorax or ‘sucking’ chest wound is to promptly seal the ‘sucking’ defect with a sterile occlusive dressing, taped on three sides, to provide a flutter-type valve effect that will drain the cavity and prevent further suction of air.

This should be followed by the placement of a chest tube at a site remote to the ‘sucking’ chest wound.