Compartment syndrome

Background

Compartment Syndrome Indications

• Consider whenever pain or paresthesia occurs in an extremity after:
  • fracture (most common risk factor) - can occur with open fracture
  • crush injury
  • immobilization
  • snake bites
  • burns
  • prolonged tourniquet application
  • fluid extravasation into a limb
  • soft tissue infection
  • extreme exertion

• Immediate threat is viability of nerve and muscle; later threat is infection, gangrene, rhabdomyolysis, renal failure

Pathophysiology

• Tissue perfusion is difference between diastolic BP and compartment pressure
  • As compartment pressure increases, tissue perfusion decreases

Etiology

• Most commonly caused by tibia fracture (anterior compartment)
• Usually develops soon after significant trauma
  • May be delayed up to 48hr after the event
• Causes:

1. Orthopedic
   1. Tibial fractures
   2. Forearm fractures
2. Vascular
   1. Ischemic-reperfusion injury
   2. Hemorrhage
3. Iatrogenic
   1. Vascular puncture in anticoagulated patients
   2. IV/intra-arterial drug injection
   3. Constrictive casts
4. Soft tissue injury
   1. Prolonged limb compression
   2. Crush injury
   3. Burns

Clinical Features

• Pain
  • Severe, out of proportion to physical findings
  • Worse w/ passive movement (muscle extension > increased volume > increased pressure)
• Paresthesia
  • Occurs in sensory distribution of affected nerve
• Compartment is swollen, firm, tender w/ squeezing
• 5 P's (pain, paresthesias, pallor, pulselessness, paralysis)
  • Classic signs of disruption in arterial flow, not of compartment syndrome
    • Only found once arterial flow has stopped (very late finding)

Interpretation of Compartment Pressure

• Normal is <10 mm Hg
• Pressures <20 mmHg can be tolerated w/o significant damage
• Exact level of pressure elevation that causes cell death is unclear. It was previously thought pressure >30 mmHg was toxic although the "delta pressure" may be better predictor than absolute pressure

ΔPressure = [Diastolic Pressure] – [Compartment Pressure]

• ΔPressure < 30 mm Hg is suggestive of compartment syndrome

Work-Up

• Compartment pressure (take serial measurements if needed)
• Total CK, UA (rhabdo)
• Chemistry (hyperkalemia)

Specific Syndromes

Lower Leg

1. Anterior
   1. Nerve: Deep fibular (peroneal)
      1. Sensation of 1st webspace
   2. Muscle: tibialis anterior
      1. Foot/ankle dorsiflexion
2. Lateral
   1. Nerve: Superficial fibular (peroneal) nerve
      1. Sensation of lateral aspect of lower leg, dorsum of foot
   2. Muscle: Peroneus
      1. Foot plantarflexion
3. Deep posterior
   1. Nerve: Posterior tibial nerve
      1. Sensation of plantar aspect of foot
   2. Muscle: Flexor hallucis/digitorum longus
      1. Pain with passive extension of the toes
4. Superficial posterior
   1. Nerve: Sural cutaneous nerve
      1. Sensation of lateral aspect of foot
   2. Muscle: Gastrocnemius
      1. Weakness of plantarflexion

http://www.wikem.org/wiki/File:lower_leg_compartment.png

Hand

• Crush injury, w/ or w/o associated fracture
• Involved compartments: thenar, hypothenar, adductor pollicis, and 4 interossei muscles
• Diagnosis
  • Clinical, not based on actual compartment pressure
  • Pain
    • Deep, constant, poorly localized, out of proportion to exam
  • "Intrinsic minus" position at rest
    • MCP joint extended w/ proximal IP joint slightly flexed
  • Pain w/ passive stretch of involved compartmental muscles
    • Interosseus: performed w/ MCP joint extended and PIP jionts fully flexed
    • Thenar, hypothenar: performed by extension of MCP joint
  • Tense swelling of affected compartment

Forearm

• Associated w/ supracondylar fx (peds), distal radius fx (adults)
• Compartments
  • Dorsal (highest risk)
  • Volar

forearm compartments

Other

• Thigh (quadriceps compartment)

Compartments of the thigh

• Buttock (gluteal compartment)
• Arm (deltoid, biceps compartments)
• Abdominal

Treatment

1. Fasciotomy
   1. Perform as soon as diagnosis is made by history/physical or by measurement
   2. Permanent damage results from >8hr of ischemia
2. Support blood pressure in hypotensive pt
3. Place affected limb at the level of the heart or slightly dependent
4. AVOID ice (will further compromise microcirculation)
5. Bivalve or remove cast if present

See Also

• Compartment Syndrome
• Compartment Pressure Measurement
• Burns
• Rhabdomyolysis
• Fractures (Main)