Compartment syndrome

Pathophysiology

Cycle: Increased pressure-->impaired perfusion-->disruption of cellular metabolism-->cytolysis with release of osmotically active contents into compartment-->additional fluid drawn into compartment-->increased pressure

Presentation

1. 5 Ps: pain, paresthesias, pallor, poikilothermia, pulselessness
   1. NB: pain, paresthesias are NOT reliable
   2. Pain at rest or with passive ROM
   3. Sensory nerves are first to lose conductive ability

Etiology

1. Most often develops soon after significant trauma (particularly involving long bone fractures of the lower leg or forearm)
2. May also occur following minor trauma or from nontraumatic causes:
   1. ischemia-reperfusion injury
   2. coagulopathy
   3. certain animal envenomations and bites
   4. extravasation of IV fluids
   5. injection of recreational drugs
   6. prolonged limb compression

Diagnosis

1. Non-invasive tests are NOT reliable
2. Striker
   1. Normal = 0-8mm Hg
   2. Capillary blod flow starts to be compromised at 20mmHg
      1. -Symptoms and signs may develop with pressures above approximately 20 mmHg
   3. Muscles and nerve fibers at risk at >30-40mmHg

1. interpret in light of SBP
2. The pressure necessary for injury varies
3. Higher pressures may be necessary with systemic hypertension
4. May develop at lower pressures in those with hypotension or peripheral vascular disease
5. A single normal compartment pressure reading, early in the course of the disease, does NOT rule out comp sy.
6. Serial or continuous measurements are important when patient risk is moderate to high or clinical suspicion exists.

Specific Syndromes

Forearm (<5%)

(most frequent injuries associated with comp sy in forearm are supracondylar humerus fractures in children and distal radius fractures in adults)

1. deep volar
   1. at highest risk for comp sy
   2. contains the digital flexors
   3. decreased wrist extension
   4. includes flexor digitorum profundus (responsible for distal interphalangeal joint flexion) and the flexor pollicis longus (responsible for interphalangeal joint flexion of the thumb)
2. superficial volar
3. dorsal
   1. contains the digital extensors
4. lateral

Lower (Leg 2-12% tibia)

1. Anterior
   1. most common site compartment sy
   2. contains the four extensor muscles of the foot, the anterior tibial artery, and the deep peroneal nerve
   3. sx include loss of sensation between the 1st and 2nd toes and weakness of foot dorsiflexion
   4. late sequelae include foot drop, claw foot, and deep peroneal nerve dysfunction
2. Lateral
   1. contains muscles for foot eversion and some plantar flexion (ie, peroneus brevis, peroneus longus), the peroneal artery, the superficial peroneal nerve, and the proximal portion of the deep peroneal nerve
   2. sx include deep peroneal nerve deficit (weakness in dorsiflexion and inversion of the foot and sensory loss in the web space between the great toe and the adjacent toe)
   3. superficial peroneal nerve also travels through this compartment and supplies sensation to the lower leg and foot
3. Deep posterior
   1. muscles that aid in foot plantar flexion, as well as the posterior tibial artery, peroneal artery, and the tibial nerve
   2. sx include plantar hypesthesia, weakness of toe flexion, and pain with passive extension of the toes
4. Superficial posterior
   1. the major muscles of plantar flexion (ie, gastrocnemius, soleus)
   2. no major arteries or nerves in this compartment.
   3. least likely to develop ACS in lower leg
   4. sx include pain and a palpably tense and tender compartment

Treatment

1. Raise limb to level of heart
2. AVOID ice (will further compromise microcirculation)
3. Bivalve or remove cast if present
4. Surgery consult
5. Definitive: Fasciotomy
6. Goal: < 6hours

Source

Adapted from KajiQuestions and Donaldson; Perron (ACEP '09)