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The third priority is establishment of adequate
circulation.
“Shock” is defined as inadequate organ perfusion
and tissue oxygenation. In the trauma patient, it is most often
due to haemorrhage and hypovolaemia.
The diagnosis of shock is based on clinical findings: hypotension,
tachycardia and tachypnoea, as well as hypothermia, pallor,
cool extremities, decreased capillary refill and decreased urine
production.
HAEMORRHAGIC (HYPOVOLAEMIC) SHOCK
Haemorrhagic (hypovolaemic) shock is due to acute loss of blood
or fluids. The amount of blood loss after trauma is often poorly
assessed and in blunt trauma is usually underestimated. Remember:
| :: |
Large
volumes of blood may be hidden in the abdominal and pleural cavity |
| :: |
Femoral
shaft fracture may lose up to 2 litres of blood |
| :: |
Pelvic
fracture often loses in excess of 2 litres of blood. |
CARDIOGENIC
SHOCK
Cardiogenic shock is due to inadequate heart function. This may result from
| :: |
Myocardial
contusion (bruising) |
| :: |
Cardiac
tamponade |
| :: |
Tension
pneumothorax (preventing blood returning to heart) |
| :: |
Penetrating
wound of the heart |
| :: |
Myocardial
infarction. |
Assessment
of the jugular venous pressure is essential in these circumstances and
an ECG should be recorded, if available.
NEUROGENIC SHOCK
Neurogenic shock is due to the loss of sympathetic tone, usually resulting from
spinal cord injury. The classical presentation is hypotension without
reflex tachycardia or skin vasoconstriction.
SEPTIC SHOCK
Septic shock is rare in the early phase of trauma, but is a common cause
of late death (via multi-organ failure) in the weeks following injury. It
is most commonly seen in penetrating abdominal injury and burns patients.
Hypovolaemia is a life-threatening emergency and must be recognized and treated
aggressively.
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