Rhabdomyolysis and compartment syndrome

Question 1

Rhabdomyolysis

Answer 1

Destruction of skeletal muscle that -> injury to myocytes and membrane -> release intracellular contents into circulation
1. Crush injuries/entrapment -> acute renal failure

Question 2

Rhabdomyolysis pathophysiology

Answer 2

1. Skeletal muscle injury
  A. Direct damage
  B. ATP depletion
  C. Leads to unregulated inc intracellular [Ca2+] -> constant contraction, energy depletion, and eventual necrosis
2. Release intracellular contents -> circulation
  A. Myoglobin
  B. Electrolytes - K+ and phosphorus
  C. Enzymes
    1. CK
    2. AST
    3. ALT
    4. LDH
    5. Aldolase

Question 3

Rhabdomyolysis causes

Answer 3

1. Direct muscle injury
   A. Entrapment/crush
   B. Confined in same position (elderly fall)
   C. Restrained
   D. Compression -> ischemia -> inc Ca2+ -> cell death
2. Excessive muscle contraction
   A. Athletes, new military recruits, marathon runners
   B. Medical conditions, status seizures, mental health issues, restraints
   C. ATP depletion -> failure Na+-K+ ATP and Ca2+ pump -> inc Ca2+ and cell necrosis
3. Meds
   A. Statins: block CoQ production - used for ATP production in mitochondria
4. Drug abuse
   A. Alcohol: direct muscle toxicity and altered mental status -> prolonged immobilization
   B. Sedatives: immobilization and external compression
   C. Sypathomimetic drugs: inc demands on cell
5. Snake venom
6. Metabolic/genetic disorders: mitochondria dysfunction
7. Viral syndromes : influenza (kids)

Question 4

Rhabdomyolysis signs/symptoms

Answer 4

1. Myalgia
2. Weakness
3. Red/brown urine
4. Obvious trauma
5. OD
6. Compartment syndrome
7. Statins

Question 5

Rhabdomyolysis Dx criteria

Answer 5

1. Inc CK levels - #’s variable
  A. Results 1-2 hrs
  B. Rise 2-12 hr after injury
  C. Dec 3-5 days after injury
2. Myoglobin
  A. Rise w/in 1 hr
  B. Results take longer

Question 6

Rhabdomyolysis complications

Answer 6

1. Renal failure
  A. Tubular obstruction - myoglobin
  B. Dehydration, heat, stress, trauma
    1. Dec blood flow
2. Electrolytic imbalance
  A. Inc K+ -> heart problems
3. Compartment syndrome
4. Intravascular coagulation

Question 7

Rhabdomyolysis tx

Answer 7

1. Hydration -> inc urine output
2. Eval electrolytes
3. Eval metabolic acidosis
4. Treat associated injuries
5. Monitor extremities
6. Lab tests
   A. Electrolytes
   B. BUN
   C. Creatine
   D. CBC
   E. Ca2+
   F. CPK

Question 8

Compartment syndrome

Answer 8

Inc pressure in muscle compartments separated by fascia

Question 9

Compartment syndrome pathophysiology

Answer 9

1. Inc pressure in compartment -> mismatch volume of space and contents
2. Tissue and venous pressure inc
3. Dec circulation -> hypoxia
4. Histamine released to dilate capillaries
   A. Inc permeability -> inc pressure => worse
5. Necrosis
6. Normal pressure = 0 mmHg
7. Microcirculation dec when pressure > or = 30 mmHG

Question 10

Compartment syndrome causes

Answer 10

1. Bleeding
2. Trauma
3. Intensive muscle use, exercise, seizures
4. Burns
5. Complications ortho surgery
6. Snakebite
7. External pressure
   A. Tight cast, tourniquet, etc.
   B. Lying on limb

Question 11

Compartment syndrome presentation

Answer 11

1. Pain out of proportion
  A. Most reliable early sign
2. Pain w/ passive stretching
3. Paresthesia in nerves crossing compartment
4. Pallor and pulses diminished
5. Paralysis

Question 12

5 P’s of compartment syndrome

Answer 12

1. Pain
2. Paresthesia
3. Pallor
4. Pulselessness
5. Paralysis

Question 13

Compartment syndrome Dx

Answer 13

1. Clinical exam and inc suspicion
  A. Pain
2. Ortho consult
3. Measure compartment pressure
  A. Stryker monitor
  B. P>30 mmHg or difference between diastolic and compartment <30 mmHg

Question 14

Compartment syndrome tx

Answer 14

1. Remove tight casts, etc
2. Maintain at level of heart- do not elevate
3. Fasciotomy
4. Hydration
5. Watch for rhabdomyolysis

Question 15

Volkmann’s contracture

Answer 15

Result of compartment syndrome if left untreated

1. Muscle necrosis/atrophy
2. Joint permanently contracted