Summary

Crush injury is compressive trauma to body parts causing direct tissue damage. Crush syndrome is the systemic manifestation that occurs on reperfusion after release — myoglobin, potassium, phosphate, and lactate enter the systemic circulation causing hyperkalaemia, AKI, DIC, and potentially fatal cardiac arrest. The risk of cardiac arrest is highest at the moment of release. Pre-hospital IV fluid resuscitation before extrication can be life-saving.

Key Facts

• Mechanism: Compression → ischaemia → toxin accumulation → reperfusion injury on release
• Life-threatening components: Hyperkalaemia (cardiac arrest), AKI (myoglobinuria)
• Critical timing: Risk is highest at moment of release — cardiac monitoring essential
• Triad: Rhabdomyolysis + hyperkalaemia + AKI
• Treatment: Aggressive IV saline (1L/hr), treat hyperkalaemia, anticipate AKI/RRT
• Pre-hospital: IV fluids BEFORE extrication if entrapment over 1 hour

Clinical Pearls

Cardiac arrest risk is HIGHEST at the moment of release — continuous ECG monitoring is mandatory

Start IV fluids BEFORE extrication if possible in prolonged entrapment (pre-hospital 4.5%)

Calcium is cardioprotective — give early if hyperkalaemia suspected (even prophylactically)

Why This Matters Clinically

Crush syndrome is a major cause of death in disasters (earthquakes, building collapse). Understanding the pathophysiology guides treatment — the goal is to prevent hyperkalaemic arrest at release and protect the kidneys from myoglobin-induced AKI. Every clinician involved in trauma or disaster response must understand these principles.

Pre-Hospital Assessment

1. Duration of entrapment
2. Body parts trapped
3. Level of consciousness
4. Signs of life in trapped limbs

Post-Release Assessment

ECG Changes in Hyperkalaemia (Progressive)

1. Peaked T waves
2. Flattened P waves
3. Widened QRS
4. Sine wave pattern
5. VF/asystole

Risk Stratification by Entrapment Duration

AKI Staging (Post-Crush)

Use KDIGO criteria based on:

• Serum creatinine rise
• Urine output

Mortality

• Without treatment: Up to 50% from hyperkalaemic arrest
• With aggressive management: <10% in resourced settings
• Disaster settings: Higher mortality due to delayed treatment, resource constraints

Renal Outcomes

• 50-70% develop AKI
• 50% of those require RRT
• Most recover renal function if survive acute phase

Limb Outcomes

• Depends on severity and compartment syndrome development
• Fasciotomy may be limb-saving
• Amputation may be required if severe ischaemic necrosis

Key Guidelines

1. ICRC War Surgery Manual: Crush Syndrome
2. JESIP/UK HART Guidance for Entrapment
3. Renal Disaster Relief Task Force Guidelines

Key Evidence

• Pre-release IV fluid administration reduces mortality in prolonged entrapment
• Alkalinisation reduces myoglobin-induced AKI (animal studies, clinical consensus)
• Early dialysis improves outcomes

What is Crush Syndrome?

Crush syndrome happens when part of your body is trapped for a long time (usually over an hour). When released, harmful chemicals from damaged muscles enter the blood and can affect the heart and kidneys.

Warning Signs

• Dark urine (like cola or tea)
• Reduced urination
• Numbness or weakness in the affected limb
• Irregular heartbeat

Treatment

• IV fluids to flush out the harmful chemicals
• Medications to protect the heart
• Sometimes kidney dialysis is needed

Resources

• NHS