• Compartment syndrome: Interstitial tissue pressures within osteofascial compartments are elevated to sustained, non-physiologic pressures. Can be caused by fractures, soft tissue injury, compression, arterial injury, reperfusion, snakebites, electrical burns, infections, hematologic disorders, tourniquets, casts or dressings, intraoperative positioning, or even exercise. 
• Pathophysiology: increased compartment pressures → venous outflow obstruction → increased capillary permeability → further increase in compartment pressures → arterial obstruction and decreased tissue oxygenation → reversible and then irreversible ischemia 
• Anatomic compartments

             ◊   Brachium: Deltoid (anterior, middle, and posterior); anterior; and posterior
             ◊   Antebrachium: Dorsal; volar; and mobile wad
             ◊   Hand: Carpal tunnel / distal ulnar tunnel; thenar; hypothenar; dorsal and palmar interosseous; and digital

• Diagnosis is made clinically – pain with passive stretch (or pain out of proportion), paresthesias (subjective numbness → hypesthesias to light touch → motor weakness → anesthesia), pallor, paralysis, and pulselessness 

             ◊   Differential diagnosis: Arterial insufficiency (will not have pain), acute carpal tunnel syndrome, nerve lacerations (typically                       will not have pain or swelling)

• Objective testing 

             ◊   Needle manometry, indwelling wick catheter, slit catheter, or Stryker hand-held manometer
             ◊   Abnormal if absolute value is over 40 mm Hg, or if within 30 mm Hg of the diastolic blood pressure. Normal pressure is 0-                12 mm Hg.
             ◊   Indicated in patients who are unreliable or uncooperative, unresponsive / obtunded, or with neurologic deficits from                    other conditions.

• Treatment – Emergent surgical decompression / fasciotomies 

             ◊   Debride nonviable / devitalized structures
             ◊   Decompress subcompartments and perform epimysiotomy to maximize tissue viability
             ◊   Use caution when closing skin primarily
             ◊   Forearm
                    ♦   Volar incision (Henry approach) is used to release lacertus fibrosus, pronator quadratus, deep flexors, and carpal                                          tunnel.  
                    ♦   Dorsal incision is also longitudinal to mid-distal third; preserve extensor retinaculum.
             ◊   Hand  
                    ♦   Carpal tunnel release  
                    ♦   Two dorsal longitudinal incisions (index-long and long-ring) to release septae between dorsal and palmar interossei  
                    ♦   Longitudinal incision on radial thumb (thenar compartment) and ulnar hand (hypothenar compartment)  
                    ♦   Release adductor pollicis through incision perpendicular to skin crease of thumb-index web space
             ◊   Digits  
                    ♦   Index, long, and ring through ULNAR midaxial incision  
                    ♦   Thumb and small fingers through RADIAL midaxial incision

• Post-op: Elevate extremity, consider functional orthosis and early ROM, and return to OR at 48 hours for re-evaluation and repeat debridement. Multiple debridements may be needed before closure. 
• Late diagnosis – see irreversible ischemic changes. Surgery may not be indicated in subacute phase (risk of infection).