Crush Injury & Crush Syndrome

Topic Overview

Summary

Crush injury is compressive trauma to body parts causing direct tissue damage through mechanical disruption and ischemia. Crush syndrome is the life-threatening systemic manifestation that occurs after release from prolonged compression (typically > 1 hour). The pathophysiologic triad comprises rhabdomyolysis (muscle breakdown), acute kidney injury from myoglobin precipitation in renal tubules, and electrolyte disturbances—most critically hyperkalemia. The risk of sudden cardiac arrest from hyperkalemia is highest at the moment of release. Pre-hospital IV fluid resuscitation initiated before extrication is the cornerstone of prevention, targeting urine output 200-300 mL/hr to facilitate myoglobin clearance and prevent acute tubular necrosis. [1,2]

Crush syndrome accounts for significant mortality in mass casualty disasters (earthquakes, building collapses, armed conflicts). Historical case-fatality rates approached 50% without treatment; modern aggressive resuscitation protocols have reduced mortality to less than 10% in resourced settings. [3,4]

Key Facts

• Mechanism: Prolonged compression → muscle ischemia → cellular energy failure → toxin accumulation → reperfusion injury on release with systemic toxin flood
• Life-threatening components: Hyperkalemia (cardiac arrest within minutes), AKI from myoglobinuria (hours to days), hypovolemia from third-spacing
• Critical timing: Risk of sudden death is highest at moment of release—continuous cardiac monitoring essential during extrication
• Pathophysiologic triad: Rhabdomyolysis + hyperkalemia + acute kidney injury
• Treatment cornerstone: Aggressive IV normal saline (1-1.5 L/hr targeting urine output 200-300 mL/hr), immediate hyperkalemia treatment, early renal replacement therapy threshold
• Pre-hospital imperative: IV fluids BEFORE extrication if entrapment > 1 hour
• Diagnosis: CK typically > 5,000 U/L (often > 50,000 U/L), myoglobinuria (urine dipstick positive for blood but microscopy shows no RBCs), hyperkalemia, metabolic acidosis

Clinical Pearls

Timing of Death: Cardiac arrest risk is HIGHEST at the moment of release when systemic circulation is suddenly flooded with potassium, hydrogen ions, and myoglobin—continuous ECG monitoring during extrication is mandatory. [5]

Pre-Hospital Fluids Save Lives: Start IV normal saline 1L/hr BEFORE extrication if entrapment > 1 hour. This dilutes toxins, maintains urine output, and may be the single most important intervention. [6]

Calcium First: If hyperkalemia is suspected (prolonged entrapment, ECG changes), give IV calcium gluconate 10mL of 10% BEFORE other treatments—it provides immediate cardioprotection without lowering potassium. [7]

"Tea-Colored Urine": Classic sign of myoglobinuria—urine dipstick shows "blood" positive but microscopy reveals no red blood cells. This distinguishes myoglobinuria from hematuria and mandates aggressive fluid resuscitation. [8]

Bicarbonate Controversy: Urinary alkalinization with sodium bicarbonate to prevent myoglobin precipitation is theoretically attractive but lacks robust clinical evidence and risks worsening hypocalcemia. Aggressive saline volume expansion alone is more evidence-based. [9,10]

Compartment Syndrome is Different: Compartment syndrome is a LOCAL ischemic emergency requiring fasciotomy; crush syndrome is a SYSTEMIC metabolic emergency requiring fluids and renal support. They can coexist but require different interventions. [11]

Why This Matters Clinically

Crush syndrome is the leading cause of preventable death in mass casualty disasters (earthquakes, terrorist attacks, building collapses). The 1988 Armenian earthquake, 1999 Marmara earthquake, 2005 Pakistan earthquake, 2010 Haiti earthquake, and 2011 Van earthquake all demonstrated that crush syndrome mortality is inversely related to speed of medical intervention and availability of renal replacement therapy. [12,13]

Understanding the pathophysiology guides time-critical interventions: pre-hospital fluid loading prevents hypovolemia and renal injury, immediate hyperkalemia treatment prevents cardiac arrest, and early dialysis corrects refractory metabolic derangements. Every clinician involved in trauma, critical care, or disaster response must master these principles—they are directly translatable to saved lives in both individual trauma cases and mass casualty settings.

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Visual Summary

Visual assets to be added:

• Crush syndrome pathophysiology flowchart (compression → ischemia → reperfusion injury cascade)
• Pre-hospital management algorithm (entrapment duration-based decision tree)
• Hyperkalemia ECG changes progression (peaked T → flat P → wide QRS → sine wave)
• Fluid resuscitation protocol diagram (target urine output 200-300 mL/hr)
• Compartment syndrome vs crush syndrome differentiation diagram

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Epidemiology

Incidence

Peacetime Settings:

• Rare in routine emergency practice (individual industrial accidents, entrapment RTCs)
• Estimated incidence: less than 1 per 100,000 population annually in developed nations
• Higher rates in regions with active construction, mining, or industrial sectors

Disaster Settings:

• Major earthquakes: 2-15% of survivors requiring medical care have crush injuries; among trapped survivors, 20-40% develop crush syndrome [14]
• Building collapses (terrorism, structural failure): High incidence depending on entrapment duration
• Armed conflicts: Historically documented in World War II London Blitz (Bywaters' original description in 1941)

Historical Examples:

• 1988 Armenian earthquake: > 3,000 cases of crush syndrome
• 1999 Marmara (Turkey) earthquake: 477 crush syndrome cases, 20.1% mortality
• 2010 Haiti earthquake: Hundreds of cases, limited dialysis availability contributed to high mortality
• 2023 Turkey-Syria earthquakes: Thousands of entrapment victims, crush syndrome a major contributor to mortality

Demographics

• Age: All ages affected; working-age adults (20-60 years) overrepresented in occupational settings
• Sex: Male predominance (65-70%) reflects occupational exposure patterns
• Occupation: Construction workers, miners, industrial workers at higher risk
• Geographic: Higher incidence in seismically active regions, conflict zones, areas with aging infrastructure

Risk Factors for Crush Syndrome Development

Patient Factors:

Injury Factors:

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Pathophysiology

Cellular and Molecular Mechanisms

Phase 1: Compression & Ischemia (During Entrapment)

Direct mechanical trauma and vascular compression lead to:

1. Energy Crisis:

   • Arterial occlusion → tissue hypoxia → anaerobic metabolism
   • ATP depletion → Na+/K+-ATPase pump failure
   • Intracellular sodium accumulation → cellular swelling
   • Calcium influx → activation of proteases and phospholipases

2. Muscle Cell Death:

   • Sarcolemmal disruption (mechanical + ischemic)
   • Mitochondrial dysfunction
   • Myocyte necrosis releasing intracellular contents:
     • Potassium (intracellular concentration ~150 mEq/L)
     • Myoglobin (oxygen-carrying heme protein, MW 17.8 kDa)
     • Phosphate (from ATP breakdown)
     • Purines → metabolized to uric acid
     • Creatine kinase (marker of muscle damage)

3. Compartmental Sequestration:

   • Edema fluid accumulates in compressed tissue
   • Up to 12L of fluid can sequester in severe bilateral lower limb crush injuries
   • Sequestered fluid contains high concentrations of potassium, myoglobin, and inflammatory mediators

Phase 2: Reperfusion Injury (On Release)

Release of compression causes sudden restoration of blood flow:

1. Systemic Toxin Flood:

   • Potassium (K+): 5-10 mEq/L increase possible within minutes [16]
   • Myoglobin: Massive release (> 100 mg/dL)
   • Organic acids: Lactic acid, purines
   • Inflammatory cytokines: TNF-α, IL-1, IL-6

2. Reactive Oxygen Species (ROS):

   • Reperfusion generates superoxide radicals (O2•−)
   • Hydroxyl radicals (•OH) cause lipid peroxidation
   • Further membrane damage and microvascular injury

3. Systemic Effects:

Renal Injury Mechanism (Myoglobin-Induced AKI)

Myoglobin causes AKI through multiple mechanisms: [17,18]

1. Renal Vasoconstriction:

   • Myoglobin scavenges nitric oxide (NO) → vasoconstriction
   • Hypovolemia (third-spacing) → prerenal azotemia
   • Intrarenal vasoconstriction reduces GFR

2. Direct Tubular Toxicity:

   • Myoglobin generates ROS via Fenton reaction (heme iron)
   • Lipid peroxidation of tubular cells
   • Tubular cell apoptosis

3. Tubular Obstruction:

   • pH-dependent: In acidic urine (pH less than 5.6), myoglobin precipitates with Tamm-Horsfall protein
   • Forms pigmented casts in distal tubules and collecting ducts
   • Intratubular pressure increases → GFR reduction
   • Rationale for alkalinization: Target urine pH > 6.5 to prevent precipitation (though clinical benefit debated)

4. Acute Tubular Necrosis:

   • Combined ischemic and toxic injury
   • Patchy necrosis of proximal tubular epithelium
   • Tubular basement membrane remains intact (distinguishes from cortical necrosis)

Critical Threshold:

• Myoglobin levels > 100 mg/dL associated with AKI risk
• CK levels > 5,000 U/L correlate with myoglobin levels sufficient for renal injury
• CK > 15,000-20,000 U/L strongly predicts AKI development [19]

The "Lethal Triad" on Release

1. Hyperkalemia → Cardiac arrest (most immediate threat)
2. Hypovolemia → Shock, renal hypoperfusion
3. Metabolic acidosis → Potentiates hyperkalemia cardiotoxicity

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Clinical Presentation

Pre-Release (During Entrapment)

Scene Assessment Critical:

• Duration of entrapment (key predictor of syndrome development)
• Body parts trapped (lower limbs, torso highest risk)
• Mechanism (earthquake, building collapse, machinery, vehicular)
• Conscious level (may be drowsy from metabolic derangement if partially released)

Visible Injury:

• Limb appearance may be deceptively normal or minimally injured
• Swelling may not be apparent until after release
• Pulses may be present if compression is venous rather than arterial

Immediate Post-Release (Minutes to Hours)

Cardiovascular Instability:

• Hypotension: Third-spacing of up to 10-12L into injured tissue causes hypovolemic shock
• Arrhythmias: Hyperkalemia → bradycardia, heart blocks, VF, asystole
• Cardiac arrest: Reported in up to 8% of patients at moment of release in disaster settings [20]

Metabolic Derangements:

• Severe metabolic acidosis (pH less than 7.2 common)
• Hyperkalemia (K+ 6-8 mmol/L or higher)
• Hypocalcemia (phosphate binding)
• Hyperphosphatemia
• Elevated uric acid

Renal Manifestations:

• Myoglobinuria: "Tea-colored," "cola-colored," or dark red-brown urine
• Urine dipstick: Positive for "blood" but microscopy shows NO red blood cells (distinguishes from hematuria)
• Oliguria or anuria (if hypovolemia severe or AKI developing)

Local Limb Findings:

• Progressive swelling (edema accumulation)
• Pain disproportionate to visible injury
• Sensory deficit (ischemic neuropathy)
• Motor weakness or paralysis
• Tense compartments (compartment syndrome developing)
• Pulses may be diminished or absent

Delayed Phase (Hours to Days)

Acute Kidney Injury:

• Oliguria (less than 400 mL/24hr) or anuria
• Rising creatinine (typically peaks 3-7 days post-injury)
• Uremia symptoms: Nausea, confusion, pericarditis
• Fluid overload if resuscitation exceeds output

Compartment Syndrome:

• Progressive limb swelling
• Pain with passive stretch
• Paraesthesias
• Pulselessness (late finding—"5 P's")
• Compartment pressure > 30 mmHg or within 30 mmHg of diastolic BP

Disseminated Intravascular Coagulation (DIC):

• Bleeding (venipuncture sites, GI tract)
• Thrombocytopenia
• Prolonged PT/APTT
• Low fibrinogen, elevated D-dimer
• Reported in 20-30% of severe crush syndrome cases [21]

Hypocalcemia (Early) → Hypercalcemia (Late):

• Early phase (0-48 hours): Calcium precipitates with phosphate in damaged tissue → symptomatic hypocalcemia (tetany, arrhythmias)
• Late phase (days to weeks): Calcium mobilizes from necrotic tissue → hypercalcemia during recovery

Red Flags Requiring Immediate Action

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Clinical Examination

Pre-Hospital Assessment (Before Extrication)

History from Patient/Witnesses:

1. Duration of entrapment (MOST IMPORTANT)
2. Body parts trapped
3. Mechanism of injury
4. Medical comorbidities (especially kidney disease)
5. Symptoms: Pain, numbness, inability to move limb

Preliminary Assessment:

• Level of consciousness
• Visible injuries
• Estimated muscle mass involved
• Anticipated release time

Immediate Post-Release Examination

Primary Survey (ABCDE):

• A: Airway patent (may require intubation if depressed consciousness)
• B: Respiratory rate and effort (acidosis causes Kussmaul breathing)
• C: Pulse, BP, capillary refill, peripheral perfusion
• D: GCS, pupillary response
• E: Exposure of injured limbs, other injuries

Cardiovascular:

• Heart rate: Bradycardia suggests hyperkalemia
• Blood pressure: Hypotension from hypovolemia
• JVP: Low if hypovolemic
• Heart sounds: Muffled if pericardial effusion (uremia)
• ECG: Immediate 12-lead ECG mandatory (see below)

Limb Examination:

Compartment Syndrome "5 P's" (Late Findings):

1. Pain (disproportionate, increased with passive stretch)
2. Pressure (tense, swollen compartment)
3. Paraesthesias (early sign)
4. Pallor (late)
5. Pulselessness (very late—irreversible damage)

Clinical Pearl: Presence of pulses does NOT exclude compartment syndrome—paraesthesias and pain with passive stretch are earlier, more sensitive signs.

Urine Assessment:

• Color: Normal (yellow) vs tea/cola-colored (myoglobin) vs red (blood)
• Dipstick: "Blood" positive without RBCs on microscopy = myoglobin
• Output: Measure hourly (target 200-300 mL/hr)

ECG Changes in Hyperkalemia (Progressive Sequence)

Critical to recognize early changes: [7]

1. Mild (K+ 5.5-6.5 mmol/L):

   • Peaked, narrow, symmetric T waves (earliest sign)
   • Shortened QT interval

2. Moderate (K+ 6.5-7.5 mmol/L):

   • Flattened or absent P waves
   • Prolonged PR interval (first-degree AV block)
   • Widened QRS complex (> 120 ms)

3. Severe (K+ > 7.5 mmol/L):

   • Further QRS widening → merges with T wave ("sine wave" pattern)
   • Bradycardia
   • High-grade AV blocks

4. Critical (K+ > 8.0 mmol/L):

   • Ventricular fibrillation
   • Asystole

Emergency Principle: ECG changes correlate better with cardiotoxicity than absolute K+ level—widened QRS mandates immediate calcium regardless of lab values.

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Investigations

Immediate (Pre-Hospital/Emergency Department)

Priority Investigations (less than 15 minutes):

Blood Gas Interpretation:

• pH: Often less than 7.3 (metabolic acidosis from lactic acid, released organic acids)
• Bicarbonate: Low (less than 18 mmol/L)
• Base excess: Negative (often -10 to -15 mmol/L)
• Potassium: Elevated (> 5.5 mmol/L, can be > 7.0 mmol/L)
• Lactate: Elevated (tissue ischemia, shock)
• Ionized calcium: Low (precipitation with phosphate)

Hospital Laboratory Investigations

Initial Panel (on arrival):

Coagulation Panel:

• PT/APTT: Prolonged if DIC developing
• Fibrinogen: Low (less than 2 g/L if DIC)
• D-dimer: Markedly elevated
• Platelet count: Thrombocytopenia if DIC

Urinalysis:

Myoglobin Quantification:

• Serum myoglobin: > 100 mg/dL indicates significant rhabdomyolysis
• Urine myoglobin: Can be quantified but often inferred from dipstick-microscopy discrepancy
• CK is more readily available and correlates well with myoglobin levels

Serial Monitoring

First 24-48 Hours (Every 4-6 Hours):

• Potassium (can fluctuate rapidly)
• Creatinine (track AKI progression)
• Calcium (may worsen before improving)
• Phosphate
• CK (peaks at 24-36 hours, then declines)
• Urine output (hourly)

Days 2-7:

• Daily renal function (creatinine, urea)
• Daily electrolytes
• Daily CK (should decline; persistent elevation suggests ongoing muscle damage)

Imaging

Indications:

• Ultrasound: Assess for compartment syndrome (limited utility; clinical diagnosis primary)
• CT scan: Identify associated injuries (fractures, internal bleeding, visceral injury)
• MRI: If available, can delineate muscle necrosis extent (rarely used acutely)

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Classification & Staging

Risk Stratification by Entrapment Duration

Entrapment duration is the single best predictor of crush syndrome development:

Severity Classification by Muscle Mass Involved

AKI Staging (KDIGO Criteria Post-Crush)

Stage 1:

• Creatinine 1.5-1.9× baseline OR
• ≥26.5 μmol/L (0.3 mg/dL) increase OR
• Urine output less than 0.5 mL/kg/hr for 6-12 hours

Stage 2:

• Creatinine 2.0-2.9× baseline OR
• Urine output less than 0.5 mL/kg/hr for ≥12 hours

Stage 3:

• Creatinine 3.0× baseline OR
• ≥353.6 μmol/L (4.0 mg/dL) OR
• Initiation of RRT OR
• Urine output less than 0.3 mL/kg/hr for ≥24 hours OR anuria for ≥12 hours

In crush syndrome, AKI is typically Stage 2-3 and develops within 24-72 hours.

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Management

Pre-Hospital / Before Extrication

Critical Principle: Initiate treatment BEFORE release if entrapment > 1 hour.

Step 1: Establish IV Access (Two Large-Bore Cannulae)

• Preferably in non-injured limbs
• 14-16G cannulae
• Proximal veins (antecubital fossa) preferred

Step 2: Fluid Resuscitation (BEFORE Release) [6,22]

• Fluid of choice: 0.9% normal saline
• Rate: 1-1.5 L/hr (adults)
• Timing: Start minimum 30-60 minutes BEFORE anticipated release
• Volume: Administer at least 1-2L before release if possible
• Rationale: Pre-emptive volume expansion prevents hypovolemic shock, dilutes toxins, initiates myoglobin washout

Evidence: Sever et al. demonstrated reduced mortality with pre-extrication IV fluids in earthquake crush syndrome cohorts. [22]

Step 3: Continuous ECG Monitoring

• Attach cardiac monitor BEFORE release
• Watch for peaked T waves, QRS widening

Step 4: Prophylactic Calcium (Consider) [7]

• Indication: Entrapment > 4 hours OR ECG changes
• Dose: Calcium gluconate 10mL of 10% IV over 2-5 minutes
• Rationale: Cardioprotective; does not lower K+ but stabilizes myocardial membrane
• Caution: Avoid calcium chloride in pre-hospital setting (more irritating, requires central access)

Step 5: Document and Communicate

• Time of entrapment
• Time of IV fluid initiation
• Volume administered pre-release
• ECG findings
• Alert receiving hospital to prepare for crush syndrome (dialysis availability)

Controversial: Tourniquet Use

• NOT routinely recommended
• Potential role: If entrapment > 6-8 hours and release will cause immediate cardiac arrest, tourniquet applied BEFORE release may delay toxin flood, allowing stabilization
• Risks: Limb ischemia, may worsen local injury
• Decision: Made by experienced physician; typically considered only in austere environments or if rescue amputation contemplated

At Point of Release

Immediate Actions:

1. Continue/escalate IV fluids (1.5 L/hr)
2. Repeat 12-lead ECG immediately
3. Obtain venous blood gas (K+, pH, lactate, Ca2+)
4. Inspect limb: Color, swelling, pulses, sensation
5. Insert urinary catheter → measure output hourly
6. Check urine color (myoglobinuria?)

If Cardiac Arrest Occurs:

• Standard CPR
• Immediate calcium gluconate 10-20mL of 10%
• Insulin + dextrose: 10 units regular insulin + 50mL 50% dextrose IV
• Sodium bicarbonate: 50 mmol (50 mL of 8.4%) IV if severe acidosis
• Prepare for emergent dialysis if ROSC achieved

In-Hospital Management

1. Fluid Resuscitation (Cornerstone of Treatment)

Goals:

• Maintain urine output 200-300 mL/hr (higher than standard 0.5 mL/kg/hr) [1,2]
• Prevent myoglobin precipitation in renal tubules
• Correct hypovolemia from third-spacing

Fluid Protocol:

Fluid Choice:

• Preferred: 0.9% normal saline [1]
• Avoid: Lactated Ringers (lactate adds metabolic burden, contains potassium)
• Avoid: Dextrose solutions alone (insufficient sodium, no volume expansion)
• Controversial: Mannitol (osmotic diuretic; theoretical benefit but no proven outcome benefit; risk of volume overload) [10]

Monitoring:

• Hourly urine output
• 4-hourly electrolytes (first 24 hours)
• CVP/fluid balance (prevent overload if oliguric)
• Serial weights

Target Endpoint:

• Urine clears (no longer dark)
• CK declining
• Urine output stable at 1-2 mL/kg/hr
• No further fluid responsiveness

2. Urinary Alkalinization (Controversial)

Theory:

• Myoglobin solubility increases in alkaline urine (pH > 6.5)
• Prevents myoglobin-Tamm-Horsfall precipitation and cast formation

Protocol (If Used):

• Add 50-100 mmol sodium bicarbonate to each liter of 0.9% saline
• Target urine pH 6.5-7.0 (check with pH paper/urinometer)
• Monitor serum pH (avoid pH > 7.5)
• Monitor ionized calcium (bicarbonate worsens hypocalcemia)

Evidence:

• Animal studies support alkalinization [9]
• NO randomized controlled trials in humans
• Observational data mixed; some series show benefit, others no difference vs saline alone [10]
• Current consensus: Aggressive saline volume expansion is MORE important than alkalinization; alkalinization is OPTIONAL and should NOT delay fluid resuscitation [2,22]

Risks of Alkalinization:

• Worsens hypocalcemia (symptomatic tetany)
• Metabolic alkalosis
• Volume overload (sodium load)
• Delays definitive fluid therapy if provider focused on pH target

Clinical Recommendation: Prioritize aggressive saline (1-1.5 L/hr) over alkalinization. If bicarbonate used, treat as adjunct, not replacement for volume.

3. Hyperkalemia Management [7]

Hyperkalemia is the most immediate life threat. Treat empirically if:

• K+ > 6.5 mmol/L OR
• ECG changes (peaked T, wide QRS) OR
• Prolonged entrapment > 4 hours (even before labs available)

Three-Tiered Approach:

Tier 1: Membrane Stabilization (MOST URGENT—Does NOT Lower K+)

• Calcium gluconate 10mL of 10% IV over 2-5 minutes
• Onset: 1-3 minutes; duration: 30-60 minutes
• Repeat if ECG changes persist after 5 minutes
• Monitor: Continuous ECG

Tier 2: Shift K+ Intracellularly (Temporary—Lowers K+ by ~1 mmol/L)

• Combination therapy more effective than single agent
• Check glucose after insulin (risk of hypoglycemia)
• Salbutamol less effective in acidosis

Tier 3: Remove K+ from Body (Definitive)

Dialysis Indications (See Section 5):

• Refractory hyperkalemia (K+ > 7.0 mmol/L despite medical therapy)
• ECG changes despite treatment
• Anuria with rising K+

4. Acute Kidney Injury & Renal Replacement Therapy

AKI Incidence: 50-85% of crush syndrome patients develop AKI; of those, 30-50% require RRT. [18,21]

Indications for RRT (Lower Threshold in Crush Syndrome):

Absolute Indications:

• Refractory hyperkalemia (K+ > 7.0 mmol/L unresponsive to medical therapy)
• Severe metabolic acidosis (pH less than 7.1)
• Symptomatic uremia (encephalopathy, pericarditis)
• Anuria (no urine output despite fluid resuscitation)
• Fluid overload refractory to diuretics (pulmonary edema)

Relative Indications (Consider Early):

• Rapidly rising creatinine (> 100 μmol/L/day)
• Severe oliguria (less than 200 mL/12hr) despite fluids
• Hyperphosphatemia (> 2.5 mmol/L) with symptomatic hypocalcemia
• CK > 100,000 U/L (predicts prolonged AKI)

RRT Modality:

• Preferred in hemodynamically unstable patients: CRRT
• Preferred if life-threatening hyperkalemia: Intermittent HD (faster K+ removal)

Dialysis Timing:

• Early initiation (before severe complications) associated with improved outcomes in observational studies [13,21]
• In disaster settings, dialysis availability is major determinant of survival

Duration:

• Average 7-14 days of RRT
• Renal recovery in 50-70% of survivors
• Minority progress to ESKD requiring long-term dialysis

5. Electrolyte Management

Hypocalcemia (Early Phase):

• Asymptomatic: Monitor; often improves with alkalosis correction
• Symptomatic (tetany, prolonged QT): Calcium gluconate 10mL 10% IV slowly
• Caution: Avoid aggressive replacement in early phase—calcium may precipitate in damaged tissue and worsen later hypercalcemia [2]

Hypercalcemia (Late Phase—Days to Weeks):

• Mobilization of calcium from necrotic tissue
• Usually mild; occasionally requires treatment (hydration, furosemide, bisphosphonates if severe)

Hyperphosphatemia:

• Common; often severe (> 2.5 mmol/L)
• Treat with phosphate binders if symptomatic or extremely elevated
• Dialysis if refractory

Hyperuricemia:

• Typically does not require acute treatment
• May predispose to gout in recovery phase

6. Limb and Compartment Syndrome Management

Compartment Syndrome vs Crush Syndrome:

• Different pathophysiology: Compartment syndrome = LOCAL ischemia from elevated intracompartmental pressure
• Different treatment: Compartment syndrome requires fasciotomy; crush syndrome requires fluids and metabolic support
• Can coexist: Crush injury can cause compartment syndrome

Compartment Syndrome Diagnosis:

• ΔP (perfusion pressure) less than 30 mmHg is most sensitive threshold [11]

Fasciotomy Indications:

• Compartment syndrome confirmed (clinical or pressure measurement)
• Prolonged ischemia with limb-threatening signs
• Should be performed within 6 hours of symptom onset for optimal outcomes

Fasciotomy Technique:

• Lower leg: 4-compartment release (anterior, lateral, superficial posterior, deep posterior)
• Forearm: Volar and dorsal incisions
• Leave wounds open; delayed primary closure or skin grafting

Limb Elevation:

• Elevate to heart level (not above—reduces arterial inflow)

Amputation:

• Indications: Nonviable limb (6-hour rule for ischemia), life-threatening sepsis from necrotic limb
• Timing: Damage control surgery if patient unstable

7. Other Supportive Care

ICU Admission:

• All patients with crush syndrome (entrapment > 2 hours or evidence of systemic syndrome)
• Monitoring: ECG, hourly urine output, BP, central venous access

Antibiotics:

• NOT routinely indicated
• Consider if open wounds, gross contamination, or developing sepsis

Analgesia:

• Multimodal approach (opioids, paracetamol, regional anesthesia if appropriate)
• Avoid NSAIDs (nephrotoxic)

Thromboprophylaxis:

• Mechanical (pneumatic compression devices) initially
• Pharmacologic VTE prophylaxis once bleeding risk assessed (caution if DIC)

Nutritional Support:

• High catabolic state; early enteral nutrition if tolerated
• Protein requirements elevated

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Complications

Immediate (Minutes to Hours)

Early (Hours to Days)

Late (Days to Weeks)

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Prognosis & Outcomes

Mortality

Overall Mortality:

• Historical (no treatment): 50% [3]
• Modern resourced settings: 5-10% [4,13]
• Disaster settings with limited dialysis: 20-40% [13,14]

Mortality Predictors:

• Duration of entrapment (> 6 hours significantly worse)
• Delay to fluid resuscitation
• Development of AKI requiring RRT
• Availability of dialysis (major determinant in disasters)
• Age > 65 years
• Pre-existing renal disease

Cause of Death:

• Early (less than 24 hours): Hyperkalemic cardiac arrest, refractory shock
• Days 2-7: AKI complications (uremia, fluid overload, refractory acidosis)
• Late (> 1 week): Sepsis, multi-organ failure

Renal Outcomes

Acute Phase:

• 50-85% develop AKI
• 30-50% of AKI patients require RRT
• Average dialysis duration: 7-14 days

Recovery:

• Complete renal recovery: 60-70%
• Partial recovery (CKD Stage 2-3): 15-20%
• ESKD requiring long-term dialysis: 5-10%

Recovery Timeframe:

• Renal function typically begins improving 7-14 days post-injury
• Full recovery can take weeks to months

Predictors of Renal Recovery:

• Shorter entrapment duration
• Early aggressive fluid resuscitation
• Early RRT initiation
• Absence of prolonged anuria
• Lower peak CK levels

Limb Outcomes

Functional Recovery:

• Depends on severity of initial injury, compartment syndrome development, and time to fasciotomy
• Complete functional recovery: 40-60%
• Partial disability (weakness, contracture, neuropathy): 30-40%
• Amputation: 5-15%

Amputation Indications:

• Nonviable limb (prolonged ischemia > 6 hours)
• Life-threatening sepsis from necrotic tissue
• Failed limb salvage

Long-Term Quality of Life

• Physical disability from limb injury, neuropathy
• Chronic kidney disease requiring monitoring or dialysis
• Psychological sequelae (PTSD, depression) common in disaster survivors
• Many patients return to near-normal function with early aggressive treatment

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Prevention & Pre-Hospital Preparedness

Disaster Preparedness

Mass Casualty Incident Planning:

• Anticipate crush syndrome in earthquakes, building collapses, terrorist attacks
• Pre-position dialysis resources in disaster-prone regions
• Train first responders in pre-extrication fluid resuscitation
• Establish protocols for early dialysis triage

International Response:

• Renal Disaster Relief Task Force coordinates dialysis deployment in disasters
• Mobile dialysis units can be deployed within 24-72 hours
• Early international assistance critical in resource-limited settings

Occupational Safety

• Industrial safety regulations (construction, mining)
• Machine guarding to prevent entrapment
• Rapid rescue protocols to minimize entrapment duration

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Special Populations

Pediatric Considerations

• Pathophysiology identical to adults
• Fluid resuscitation: 20 mL/kg boluses, then 1.5-2× maintenance targeting urine output 2-3 mL/kg/hr
• Smaller muscle mass: Syndrome may develop with shorter entrapment
• Dialysis: Pediatric RRT expertise required

Elderly

• Higher mortality due to reduced physiologic reserve
• Pre-existing CKD common—lower threshold for dialysis
• Higher risk of fluid overload—monitor closely

Pregnancy

• Rare but reported
• Standard resuscitation principles apply
• Fetal monitoring if viable gestation
• Multidisciplinary care (obstetrics, nephrology, critical care)

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Evidence & Guidelines

Key Guidelines

1. Sever MS, Vanholder R; RDRTF. Recommendation for the management of crush victims in mass disasters. Nephrol Dial Transplant. 2012;27 Suppl 1:i1-67. [PMID: 22287695]

   • Comprehensive consensus guideline from Renal Disaster Relief Task Force
   • Evidence-based recommendations for all phases of crush syndrome management

2. ICRC War Surgery Manual: Crush Syndrome Chapter

   • Practical field guidance for resource-limited settings
   • Pre-hospital management algorithms

3. European Renal Best Practice (ERBP) Position Statement on Management of Crush Victims

   • Focuses on renal aspects and RRT

Landmark Studies & Key Evidence

Pre-Hospital Fluid Resuscitation:

4. Sever MS et al. The Marmara earthquake: epidemiological analysis of the victims with nephrological problems. Kidney Int. 2001;60(3):1114-1123. [PMID: 11532109]

   • 477 crush syndrome patients from 1999 Marmara earthquake
   • Mortality 20.1%; pre-hospital IV fluids associated with reduced AKI and mortality

5. Better OS, Stein JH. Early management of shock and prophylaxis of acute renal failure in traumatic rhabdomyolysis. N Engl J Med. 1990;322(12):825-829. [PMID: 2407958]

   • Seminal paper establishing aggressive early fluid resuscitation as standard of care

Pathophysiology & Myoglobin-Induced AKI:

6. Bosch X, Poch E, Grau JM. Rhabdomyolysis and acute kidney injury. N Engl J Med. 2009;361(1):62-72. [PMID: 19571284]

   • Comprehensive review of rhabdomyolysis pathophysiology
   • Mechanisms of myoglobin nephrotoxicity

7. Zager RA. Rhabdomyolysis and myohemoglobinuric acute renal failure. Kidney Int. 1996;49(2):314-326. [PMID: 8821790]

   • Animal model studies demonstrating myoglobin tubular precipitation in acidic urine
   • Basis for urinary alkalinization theory

Urinary Alkalinization Controversy:

8. Brown CVR et al. Preventing renal failure in patients with rhabdomyolysis: do bicarbonate and mannitol make a difference? J Trauma. 2004;56(6):1191-1196. [PMID: 15211124]

   • Retrospective study: No benefit of bicarbonate or mannitol over saline alone
   • Challenged routine alkalinization practice

9. Homsi E et al. Prophylaxis of acute renal failure in patients with rhabdomyolysis. Ren Fail. 1997;19(2):283-288. [PMID: 9101611]

   • Small study suggesting benefit of alkalinization
   • Methodologic limitations

10. Beetham R. Biochemical investigation of suspected rhabdomyolysis. Ann Clin Biochem. 2000;37(Pt 5):581-587. [PMID: 11026510]

    • CK > 5,000 U/L indicates clinically significant rhabdomyolysis
    • CK > 15,000-20,000 U/L predicts AKI risk

Compartment Syndrome:

11. McQueen MM, Gaston P, Court-Brown CM. Acute compartment syndrome: who is at risk? J Bone Joint Surg Br. 2000;82(2):200-203. [PMID: 10755426]
    • Clinical diagnosis of compartment syndrome
    • Pressure measurement thresholds

Hyperkalemia Management:

12. Weisberg LS. Management of severe hyperkalemia. Crit Care Med. 2008;36(12):3246-3251. [PMID: 18936701]
    • Evidence-based approach to hyperkalemia treatment
    • Calcium for membrane stabilization, insulin/dextrose for K+ shift

Disaster Medicine & Epidemiology:

13. Gunal AI et al. Early and vigorous fluid resuscitation prevents acute renal failure in the crush victims of catastrophic earthquakes. J Am Soc Nephrol. 2004;15(7):1862-1867. [PMID: 15213273]

    • Data from multiple Turkish earthquakes
    • Early fluid resuscitation reduced AKI incidence from 58% to 18%

14. Sever MS et al. Crush syndrome in the Marmara, Turkey earthquake. Clin Nephrol. 2002;57(5):340-346. [PMID: 12036190]

    • Detailed analysis of 639 crush injury patients
    • Identified duration of entrapment as key predictor

15. Gonzalez D. Crush syndrome. Crit Care Med. 2005;33(1 Suppl):S34-S41. [PMID: 15640677]

    • Comprehensive review of pathophysiology and management

Renal Replacement Therapy:

16. Oda J et al. Analysis of 372 patients with crush syndrome caused by the Hanshin-Awaji earthquake. J Trauma. 1997;42(3):470-475. [PMID: 9095115]

    • 1995 Kobe earthquake data
    • 50% developed AKI; 30% required dialysis
    • Mortality 8.7% with dialysis availability

17. Shoaf KI, Rottman SJ. Public health impact of disasters. Aust J Emerg Manage. 2000;15(3):58-63.

    • Epidemiology of crush syndrome in disasters

Historical & Seminal Papers:

18. Bywaters EGL, Beall D. Crush injuries with impairment of renal function. BMJ. 1941;1(4185):427-432.
    • Original description during London Blitz (World War II)
    • First recognition of crush syndrome as distinct clinical entity

Recent Systematic Reviews:

19. Chavez LO et al. Beyond muscle destruction: a systematic review of rhabdomyolysis for clinical practice. Crit Care. 2016;20(1):135. [PMID: 27209145]

    • Modern systematic review of rhabdomyolysis
    • Evidence synthesis for fluid therapy, alkalinization

20. Torres PA et al. Rhabdomyolysis: pathogenesis, diagnosis, and treatment. Ochsner J. 2015;15(1):58-69. [PMID: 25829882]

    • Clinical review for practitioners

Compartment Syndrome:

21. Schmidt AH. Acute compartment syndrome. Injury. 2017;48 Suppl 1:S22-S25. [PMID: 28449856]
    • Modern review of diagnosis and management

DIC in Crush Syndrome:

22. Oda Y et al. Hemostatic abnormalities in crush syndrome. J Trauma. 2002;53(4):720-725. [PMID: 12394871]
    • DIC occurs in 20-30% of severe crush syndrome
    • Associated with worse outcomes

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Patient & Family Information

What is Crush Syndrome?

Crush syndrome happens when a part of your body (usually a leg or arm) is trapped under a heavy weight for a long time—typically more than one hour. While trapped, the muscles are damaged and harmful chemicals build up. When you are freed, these chemicals suddenly enter your bloodstream and can affect your heart and kidneys.

Why is Release Dangerous?

The moment you are released from the weight, your blood starts flowing again through the damaged area. This releases:

• Potassium (can cause your heart to stop)
• Myoglobin (a protein that can damage your kidneys)
• Acids (make your blood too acidic)

This is why doctors and paramedics may give you fluids and monitor your heart BEFORE freeing you.

Warning Signs After Release

• Dark urine (like tea or cola)—this means myoglobin is in your urine
• Reduced urination or no urination
• Numbness, tingling, or weakness in the affected limb
• Irregular heartbeat or chest discomfort
• Confusion or drowsiness

Treatment

Immediate:

• IV fluids: Large amounts given quickly to flush harmful chemicals from your body and protect your kidneys
• Heart monitoring: To watch for dangerous heart rhythms
• Medications: To protect your heart and lower potassium levels

Hospital:

• Kidney dialysis: May be needed if your kidneys stop working (temporary in most cases)
• Surgery: If the limb has severe swelling (compartment syndrome), surgery may be needed to release pressure
• ICU care: Close monitoring for several days

Recovery

• Kidneys: Most people's kidneys recover fully, though it may take weeks to months
• Limb: Recovery depends on how severe the injury was; physical therapy helps
• Psychological: Being trapped can be traumatic—counseling and support are available

Resources

• NHS: https://www.nhs.uk
• National Kidney Foundation: https://www.kidney.org
• Trauma Support: PTSD support resources available through your hospital

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Related Topics

Prerequisites

• Acute Kidney Injury (AKI)
• Rhabdomyolysis
• Hyperkalemia
• Compartment Syndrome

Consequences & Complications

• Acute Tubular Necrosis
• Chronic Kidney Disease
• DIC (Disseminated Intravascular Coagulation)
• ARDS (Acute Respiratory Distress Syndrome)

Differential Diagnoses

• Isolated traumatic rhabdomyolysis (exertion, seizures, drugs)
• Acute limb ischemia (vascular injury)
• Traumatic compartment syndrome without systemic syndrome
• Acute kidney injury from other causes (sepsis, nephrotoxins)

Related Conditions

• Earthquake disaster medicine
• Mass casualty incident management
• Traumatic shock
• Metabolic emergencies

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MCQ Self-Assessment

Question 1

A 45-year-old construction worker is trapped under a collapsed wall for 5 hours. Paramedics establish IV access. What is the MOST important pre-extrication intervention?

A. Prophylactic antibiotics B. IV calcium gluconate 10mL 10% C. IV normal saline 1L/hr D. Nebulized salbutamol E. IV sodium bicarbonate

Answer: C. IV normal saline 1L/hr

Explanation: Pre-extrication fluid resuscitation is the single most important intervention to prevent hypovolemia, dilute toxins, and protect kidneys. Target is 200-300 mL/hr urine output. Calcium is important if hyperkalemia suspected but fluids are the cornerstone.

Question 2

A crush syndrome patient arrives in ED 30 minutes after release. ECG shows peaked T waves and widened QRS complex. Initial blood gas: pH 7.15, K+ 7.8 mmol/L. What is the FIRST medication to give?

A. Insulin 10 units + dextrose 50mL 50% B. Sodium bicarbonate 50 mmol IV C. Calcium gluconate 10mL 10% IV D. Salbutamol 10mg nebulized E. Furosemide 40mg IV

Answer: C. Calcium gluconate 10mL 10% IV

Explanation: Calcium provides immediate cardioprotection by stabilizing myocardial membrane. It does not lower potassium but prevents arrhythmias. Insulin/dextrose and salbutamol shift K+ intracellularly (Tier 2) but calcium is Tier 1 (most urgent).

Question 3

A 30-year-old earthquake survivor has dark urine 4 hours after extrication. Labs: CK 85,000 U/L, creatinine 150 μmol/L (baseline 80), K+ 5.9 mmol/L. Urine dipstick: blood +++, microscopy: no RBCs. What is the target urine output?

A. 0.5 mL/kg/hr B. 1 mL/kg/hr C. 30 mL/hr D. 200-300 mL/hr E. 500 mL/hr

Answer: D. 200-300 mL/hr

Explanation: Higher urine output than standard resuscitation (0.5 mL/kg/hr) is required to flush myoglobin and prevent tubular precipitation. Target is 200-300 mL/hr, requiring aggressive IV fluids (often 1-1.5 L/hr initially).

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Viva Voce Scenarios

Scenario 1: Pre-Hospital Management

Examiner: "You are called to a building collapse. A 50-year-old man has been trapped under concrete for 3 hours with both legs crushed. He is conscious. Extrication will take another 30 minutes. What are your priorities?"

Model Answer: "My priorities are to prevent life-threatening complications of crush syndrome upon release—specifically hyperkalemic cardiac arrest and acute kidney injury. I would:

1. Establish IV access (two large-bore cannulae, non-injured sites)
2. Start aggressive IV fluids BEFORE extrication: 0.9% normal saline 1-1.5 L/hr to pre-emptively volume expand, dilute toxins, and prime kidneys for myoglobin load
3. Attach cardiac monitoring: Continuous ECG to detect hyperkalemia immediately upon release
4. Consider prophylactic calcium gluconate 10mL of 10% given 3-hour entrapment and bilateral lower limbs (high risk)
5. Communicate with receiving hospital: Alert ED and ICU; ensure dialysis availability
6. Document: Time of entrapment, time of IV fluids started, volume given pre-release

The goal is to mitigate reperfusion injury—the flood of potassium, myoglobin, and acids when circulation is restored."

Examiner: "He arrests immediately upon release. What do you do?"

Model Answer: "I assume hyperkalemic cardiac arrest. I would:

• Start CPR immediately
• Give IV calcium gluconate 10-20mL of 10% (or calcium chloride 10mL of 10% if central access)—cardioprotective, may restore rhythm
• Give insulin 10 units + 50mL 50% dextrose IV to shift K+ intracellularly
• Give sodium bicarbonate 50 mmol IV to buffer acidosis and shift K+
• Continue CPR and advanced life support
• If ROSC achieved, arrange emergent hemodialysis for definitive K+ removal"

Scenario 2: Alkalinization Controversy

Examiner: "A 35-year-old crush syndrome patient has CK 60,000 U/L and myoglobinuria. Should you alkalinize the urine?"

Model Answer: "This is a controversial area. The theoretical rationale is strong: myoglobin solubility increases in alkaline urine (pH > 6.5), preventing myoglobin-Tamm-Horsfall protein precipitation and cast formation in distal tubules. Animal studies support this.

However, there are NO randomized controlled trials in humans. Observational data are mixed—some series show benefit, others show no difference compared to aggressive saline alone. Current consensus guidelines prioritize aggressive volume expansion with normal saline as the cornerstone—this is evidence-based and proven to reduce AKI.

Urinary alkalinization is OPTIONAL. If used, I would:

• Add 50-100 mmol sodium bicarbonate to each liter of saline
• Target urine pH 6.5-7.0
• Monitor serum pH (avoid alkalemia > 7.5)
• Monitor ionized calcium (bicarbonate worsens hypocalcemia)

Critically, alkalinization should NEVER delay or replace aggressive saline resuscitation targeting 200-300 mL/hr urine output. Volume is more important than pH."

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References

1. Sever MS, Vanholder R; RDRTF of ISN. Recommendation for the management of crush victims in mass disasters. Nephrol Dial Transplant. 2012;27 Suppl 1:i1-67. doi:10.1093/ndt/gfr156. PMID: 22287695

2. Bosch X, Poch E, Grau JM. Rhabdomyolysis and acute kidney injury. N Engl J Med. 2009;361(1):62-72. doi:10.1056/NEJMra0801327. PMID: 19571284

3. Bywaters EGL, Beall D. Crush injuries with impairment of renal function. Br Med J. 1941;1(4185):427-432. PMCID: PMC2161734

4. Better OS, Stein JH. Early management of shock and prophylaxis of acute renal failure in traumatic rhabdomyolysis. N Engl J Med. 1990;322(12):825-829. doi:10.1056/NEJM199003223221207. PMID: 2407958

5. Gonzalez D. Crush syndrome. Crit Care Med. 2005;33(1 Suppl):S34-S41. doi:10.1097/01.ccm.0000151065.13564.6f. PMID: 15640677

6. Gunal AI, Celiker H, Dogukan A, et al. Early and vigorous fluid resuscitation prevents acute renal failure in the crush victims of catastrophic earthquakes. J Am Soc Nephrol. 2004;15(7):1862-1867. doi:10.1097/01.ASN.0000129336.09976.73. PMID: 15213273

7. Weisberg LS. Management of severe hyperkalemia. Crit Care Med. 2008;36(12):3246-3251. doi:10.1097/CCM.0b013e31818f222b. PMID: 18936701

8. Beetham R. Biochemical investigation of suspected rhabdomyolysis. Ann Clin Biochem. 2000;37(Pt 5):581-587. doi:10.1177/000456320003700501. PMID: 11026510

9. Zager RA. Rhabdomyolysis and myohemoglobinuric acute renal failure. Kidney Int. 1996;49(2):314-326. doi:10.1038/ki.1996.48. PMID: 8821790

10. Brown CVR, Rhee P, Chan L, et al. Preventing renal failure in patients with rhabdomyolysis: do bicarbonate and mannitol make a difference? J Trauma. 2004;56(6):1191-1196. doi:10.1097/01.ta.0000130761.78627.10. PMID: 15211124

11. McQueen MM, Gaston P, Court-Brown CM. Acute compartment syndrome: who is at risk? J Bone Joint Surg Br. 2000;82(2):200-203. doi:10.1302/0301-620x.82b2.9799. PMID: 10755426

12. Sever MS, Erek E, Vanholder R, et al. The Marmara earthquake: epidemiological analysis of the victims with nephrological problems. Kidney Int. 2001;60(3):1114-1123. doi:10.1046/j.1523-1755.2001.0600031114.x. PMID: 11532109

13. Sever MS, Erek E, Vanholder R, et al. Clinical findings in the renal victims of a catastrophic disaster: the Marmara earthquake. Nephrol Dial Transplant. 2002;17(11):1942-1949. doi:10.1093/ndt/17.11.1942. PMID: 12401852

14. Sever MS, Vanholder R, Lameire N. Management of crush-related injuries after disasters. N Engl J Med. 2006;354(10):1052-1063. doi:10.1056/NEJMra054329. PMID: 16525142

15. Michaelson M. Crush injury and crush syndrome. World J Surg. 1992;16(5):899-903. doi:10.1007/BF02066988. PMID: 1462628

16. Homsi E, Barreiro MF, Orlando JM, Higa EM. Prophylaxis of acute renal failure in patients with rhabdomyolysis. Ren Fail. 1997;19(2):283-288. doi:10.3109/08860229709026286. PMID: 9101611

17. Vanholder R, Sever MS, Erek E, Lameire N. Rhabdomyolysis. J Am Soc Nephrol. 2000;11(8):1553-1561. doi:10.1681/ASN.V1181553. PMID: 10906171

18. Chavez LO, Leon M, Einav S, Varon J. Beyond muscle destruction: a systematic review of rhabdomyolysis for clinical practice. Crit Care. 2016;20(1):135. doi:10.1186/s13054-016-1314-5. PMID: 27209145

19. Singh U, Scheld WM. Infectious etiologies of rhabdomyolysis: three case reports and review. Clin Infect Dis. 1996;22(4):642-649. doi:10.1093/clinids/22.4.642. PMID: 8729203

20. Oda J, Tanaka H, Yoshioka T, et al. Analysis of 372 patients with crush syndrome caused by the Hanshin-Awaji earthquake. J Trauma. 1997;42(3):470-475. doi:10.1097/00005373-199703000-00015. PMID: 9095115

21. Oda Y, Shindoh M, Yukioka H, et al. Hemostatic abnormalities in crush syndrome. J Trauma. 2002;53(4):720-725. doi:10.1097/00005373-200210000-00017. PMID: 12394871

22. Sever MS, Vanholder R, Lameire N. Management of crush victims in mass disasters: highlights from recently published recommendations. Clin J Am Soc Nephrol. 2013;8(2):328-335. doi:10.2215/CJN.07340712. PMID: 23085722

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Last updated: 2025-01-08
Evidence level: High (multiple systematic reviews, international consensus guidelines, large disaster cohort studies)
Target examination: MRCP, FRCEM, EDIC, MRCS