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

• 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)
• 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
• Paralysis and Pulselessness: late findings

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)

Lower Leg Specific Syndromes

1. Anterior
   1. Nerve: deep fibular (peroneal): sensation of 1st webspace
   2. Muscle: tibialis anterior: foot/ankle dorsiflexion
2. Lateral
   1. Nerve: superficial fibular (peroneal) nerve: sensation of lateral aspect of lower leg, dorsum of foot
   2. Muscle: peroneus longus and brevis: foot plantarflexion
3. Deep posterior
   1. Nerve: posterior tibial nerve: sensation of plantar aspect of foot
   2. Muscle: tibialis posterior/flexor hallucis longus/flexor digitorum longus: Pain with passive extension of the toes
4. Superficial posterior
   1. Nerve: sural cutaneous nerve: sensation of lateral aspect of foot
   2. Muscle: gastrocnemius/soleus/plantaris: weakness of plantar flexion

Lower Leg Compartment

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

forearm compartments

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

Foot

Compartments of the foot

• Number of compartments is controversial, but at least 4, up to 9
  • Medial, lateral, central, interosseous, adductor
  • Mechanism - crush injuries
  • Other mechanisms - foot surgery, Lisfranc fx, cast immobilization, prolonged extremity positioning, snake bites, severe ankle sprains with arterial disruption
  • 5-17% of calcaneus fractures result in compartment syndrome
  • Diagnosis
    • Pain out of proprtion
    • Pain worse with passive dorsiflexion (stretching intrinsic musculature of foot); concurrent metatarsal fx cloud this finding
    • Do not rely on absent pulse or complete anesthesia, which are late findings
    • Measure absolute compartment pressures in insertion sites found here
  • Treatment
    • Elevate extremity to level of heart (above the heart, and there will be reduction of O2 perfusion)
    • SCDs may help decrease interstitial pressure, improve venous return/arterial flow
    • Fasciotomy within 24 hrs of injury if pressures > 30 mmHg

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)