SUMMARY
Crush syndrome is a life-threatening systemic condition caused by prolonged skeletal muscle compression, leading to traumatic rhabdomyolysis and the release of intracellular muscle contents into the systemic circulation. The resulting metabolic and inflammatory cascade may cause acute kidney injury, fatal electrolyte disturbances, shock, and multiorgan failure.
Crush syndrome must be clearly distinguished from acute compartment syndrome, which is a local perfusion disorder; however, both conditions frequently coexist and may complicate one another in severe trauma.
ETIOLOGY
Common causes include situations involving prolonged compression of large muscle groups:
· Earthquakes and building collapse
· Motor vehicle collisions with entrapment
· Industrial and mining accidents
· Prolonged immobilization (intoxication, coma, stroke)
· Surgical positioning with sustained pressure
RISK FACTORS
· Compression duration longer than 4–6 hours
· Involvement of large muscle masses (thigh, gluteal region, trunk)
· Hypovolemia or hemorrhagic shock
· Delayed extrication or delayed fluid resuscitation
· Associated polytrauma
PATHOPHYSIOLOGY
Prolonged muscle ischemia results in sarcolemmal membrane disruption and myocyte necrosis. Upon release of compression and reperfusion, large quantities of intracellular components enter the systemic circulation:
· Myoglobin → renal tubular obstruction and direct nephrotoxicity
· Potassium → life-threatening cardiac arrhythmias
· Phosphate → secondary hypocalcemia
· Creatine kinase (CK) → marker of muscle injury
· Organic acids → metabolic acidosis
Mechanisms of Acute Kidney Injury
1. Myoglobin-induced tubular obstruction
2. Direct nephrotoxic effects
3. Renal vasoconstriction
4. Intravascular volume depletion
CLINICAL PRESENTATION
Local Findings
· Painful, swollen, tense extremity
· Reduced active motion
· Possible concomitant acute compartment syndrome
Systemic Findings
· Oliguria or anuria
· Dark (“tea-colored”) urine
· Nausea and vomiting
· Cardiac arrhythmias
· Hypotension and shock
LABORATORY FINDINGS
· Creatine kinase (CK) often >5,000 IU/L
o Severe cases may exceed 10,000–20,000 IU/L
· Hyperkalemia
· Hyperphosphatemia
· Hypocalcemia (early phase)
· Metabolic acidosis
· Elevated creatinine and urea
· Urinalysis: heme-positive urine with few or no red blood cells (myoglobinuria)
MANAGEMENT
INITIAL MANAGEMENT (CORNERSTONE)
Early aggressive fluid resuscitation is the most critical intervention and should be initiated as soon as possible.
· Isotonic saline
· Target urine output: 200–300 mL/hour
· Ideally started before extrication in disaster settings
ADJUNCTIVE MEASURES
· Urine alkalinization with sodium bicarbonate
o Target urine pH >6.5
· Mannitol (selective use only)
o Osmotic diuresis
o Free radical scavenging
· Avoid nephrotoxic medications
HYPERKALEMIA MANAGEMENT
· Calcium gluconate (cardiac membrane stabilization)
· Insulin with glucose
· Beta-agonists
· Sodium bicarbonate (in acidotic patients)
RENAL REPLACEMENT THERAPY
Indications include:
· Refractory hyperkalemia
· Severe metabolic acidosis
· Oliguric or anuric renal failure
· Volume overload
ROLE OF FASCIOTOMY
· Crush syndrome alone is NOT an indication for fasciotomy
· Fasciotomy should be performed only when there is clinical or objective evidence of acute compartment syndrome
· Prophylactic or delayed fasciotomy increases the risk of:
o Infection
o Sepsis
o Mortality
COMPLICATIONS
· Acute kidney injury
· Fatal hyperkalemia
· Disseminated intravascular coagulation (DIC)
· Sepsis
· Multiorgan failure
· Death
PROGNOSIS
Outcome is primarily determined by:
· Time to initiation of fluid resuscitation
· Severity of metabolic derangements
· Presence of shock and renal failure
Early and aggressive volume therapy significantly reduces mortality and the need for long-term dialysis.
HIGH-YIELD PEARLS
· Crush syndrome is a systemic condition, not a local injury
· Fluid resuscitation takes priority over surgical decisions
· Myoglobinuria may be absent despite severe rhabdomyolysis
· Fasciotomy is indicated for compartment syndrome, not elevated CK alone
· Hyperkalemia is the most immediate and common cause of death