Crush Injuries Flashcards
Define crush injury
- Damage and death of compressed muscle tissue following the application of a compressive force. Cell death occurs as a result of traumatic injuries i.e. blunt injury.
- Cells become hypoxic and necrotic, releasing toxins including K+ and by products = arrhythmias and death.
Define crush syndrome
Crush syndrome occurs after a prolonged compression force impairs muscle metabolism and circulation for
four hours or longer. The syndrome is precipitated after release of an entrapped muscle.
Characterised by rhabdo, lactic acidosis, hyperkalaemia, renal failure, shock, dysarythmias and death.
Define Compartment Syndrome
- Compromised perfusion to tissues within an anatomical compartment due to increased pressure within that compartment.
Circulation and function of tissues within a closed fascial space are compressed and increased pressure in that space.
Characterised by: - Tissue pressure rising above venous pressure, therefore, a decrease in blood flow.
- Release of vasodilator (kinins) and increased capillary permeability causes further increases in pressure.
- Resulting in ischaemia of muscle and nerves.
Crush injury management for <30mins
- <30 mins or involving head/torso - remove object immediately
Crush injury management for >30mins
- Supplementary O2
- IV access and commence 500mL NaCL (gold standard)
- Analgesia
- Look for and manage haemorrhage (May require CAT prior to removal)
- Cardiac monitoring (for progressively widening QRS)
- In inadequately refused - manage
- ICP back up for NaBicarb
S&S of compartment syndrome
5 P’s: Pallor, parasthesia, paralysis, pain, absent pulse
Crush syndrome pathophysiology
- a crush injury creates a compartment-like syndrome in the areas peripheral to the crushing force
- the tissue becomes ischaemic, releases inflammatory mediators, becoming acidotic with RBC
sludging and possibly rhabdomyolysis - the blood vessels dilate and once the crushing force is removed the blood volume re-distributes
systemically including to the severely vasodilated peripheral areas, creating a relative hypovolaemia - hypotension decreases coronary artery perfusion pressure and may precipitate arrhythmias
- later consequences include bleeding of previously controlled vessels, re-perfusion of ischaemic tissue
and re-distribution of the acidotic, hyperkalaemic and myoglobinaemic blood - as a result of reperfusion and toxin release, plasma leaks out of capillaries due to the crush injury and
swelling, this causes third space fluid loss - hypovolemia and shock are the most common cause of death in the first four days after crush injury
- damage to vessels due to the initial mechanism may cause haemorrhage
- there is a decrease in blood pH due to elevated levels of lactic acid
- when the pH is decreased, the heart is vulnerable to fibrillation, which is resistant to treatment due
to the acidosis - there is a large toxin load with potassium leaking out of the damaged cells into the extracellular fluid
- increased potassium makes the heart prone to cardiotoxicity and dysrhythmias
- hyperkalaemia coupled with hypocalcaemia causes muscle weakness or paralysis and are an electrical depressant
- myoglobin is released from damaged muscle tissue, as it increases in the systemic circulation, the
kidneys are unable to filter it all as waste (rhabdomyolysis) - the large protein molecules block glomerular filtration and renal function is impaired
- acute renal failure is one of the most serious complications of rhabdomyolysis
Compartment syndrome clinical features
5 P’s
- Palpable tension or swelling of an anatomical compartment
- Pain disproportionate to the injury
- Pain on passive stretching of muscles within the anatomical compartment
- Paraesthesia of skin and paresis of muscles supplied
Crush syndrome clinical features
- Compartment syndrome
- Haemodynamic instability
- Lactic acidosis & hyperkalaemia; dysrythmias; renal failure
- Shock
- Hypothermia
- Hypovolaemia
