Crush Injury

Crush injury occurs when a significant extremity or aspect of a patient has been crushed for a period of time causing either ischaemic or muscle damage to the crush injury site. Crush injury may also occur when a patient has been laying on a hard surface for such a long time that he or she has developped a non-traumatic crush injury, which inolves anearobic metabolism in the areas that are laying on the hard surface. Crush injury syndrome is a life-threatening complication of crush injuries and results in high mortality rates.

Crush Injury Phases of Mortality

 

Early (minutes to an hour) as a result of:

1. Hyopovolaemia after compressive force is realeased

2. Sudden release of potassium ions from the area distal to the compressive forces, which then travels to the heart causing fatal arrythmias

3. Sudden release of lactic accid within the circulatory system

Secondary causes of mortality following release of the crushing force include:

Delayed: (hours to weeks) as a result of the:

Release of myoglobin as a result of muscle compression at injury site and distally, leads to large myoglobin cells circulating and becoming blocking the glomerelus from filtering blood within the kidneys, this results in renal failure. This is fundamentally, rhabdomylosis.as a result of renal failure (due to rhabdomyolysis, and myoglibnaemia) and complications due to trauma, such as infection.

Monitor  ECG changes in crush syndrome for signs of hyperkalaemia such as:

1. Tall peaked T-waves

2. Absent P-waves

3. QRS widening

4. Sine wave patern

5. VF/assystole

Treatment of crush injury with ECG changes and evidence of hyperkalaemia require Sodium Bicarbonate (1mmol/kg) and Calcium Chloride 1g: 10ml over two minutes)

Crush injury – local affect: compartment’s syndrome

Crush injury – systemic affect: rhabdomyolysis

Established Signs and Symptoms of Crush Injury

The following are six well defined signs and symptoms of crush injury:

1. Ischaemic muscle necrosis
2. Circulating myoglobin and myoglobinuria
3. Raised serum potassium (hyperkalaemia)
4. Metabolic acidosis
5. Hypovolaemic shock
6. Renal failure.