II. Epidemiology

  1. Accounts for 1 in 600 hand injuries
  2. Most common in young male laborers working with paint, automotive grease, solvents, diesel oil

III. Background

  1. Associated with occupational paint or spray gun use
  2. Nozzle pressures are very high (up to 10,000 psi, much higher than rated psi)
    1. Injection substances are delivered at speeds approaching 400 mph
    2. By comparison, even forces as low as 100 psi are strong enough to break through skin
  3. Injected materials typically spread broadly
    1. Spread along planes of least resistance
      1. Neurovascular bundles
      2. Tendon sheaths
      3. Hand compartments
    2. Results in direct injury, local ischemia, chemical inflammation and Granulomatous reaction
    3. Risk of vascular necrosis and local soft tissue necrosis
    4. Also sets the stage for secondary infection

IV. Risk Factors: Amputation

  1. High pressure >1000 psi (43% versus 19% with low pressure injections)
  2. Delay to operating room >6 hours (58% versus 38% with earlier surgery)
  3. Injected solvents are at highest risk of amputation (50%)
    1. Organic solvents (paint thinner, paint and oil-based products, diesel fuel, jet fuel, oil)
    2. Water or air injections are not associated with amputations
  4. References
    1. Hogan (2006) J Orthop Trauma 20(7): 503-11 [PubMed]

V. History

  1. Time of injury
    1. Delayed presentation is common (mean 9 hours after injury)
    2. Delays (esp. >6 to 10 hours) are associated with high amputation and infection rates
  2. Injected substance
    1. Clean water and air are considered lower risk injection injuries
    2. Paint is associated with large inflammatory responses and high amputation rates
    3. Grease is associated with less inflammatory response and lower amputation rates

VI. Symptoms

  1. Non-dominant index finger most commonly affected
  2. Initial injury appears relatively mild
  3. Patient develops numbness, burning or pain over time

VII. Signs

  1. Deceptively small entry wound despite severe subcutaneous damage
  2. With toxic injections, injury site becomes pale, edematous and very tender to palpation

VIII. Labs: Agent injected has risk of hepatotoxicity and nephrotoxicity

IX. Imaging

  1. XRay
    1. May demonstrate radiopaque substance
    2. Subcutaneous Emphysema may be present

X. Management

  1. Immediate surgical Consultation (e.g. hand surgery)
    1. Emergent surgical intervention is per surgeon's discretion
    2. Most injection injuries require surgical management (>50%)
      1. Early surgical decompression and Debridement of caustic injections
    3. Injection injuries (water and air only) without Compartment Syndrome may not require surgery
  2. Poison control Consultation (if indicated by substance injected)
  3. High risk injury!
  4. General measures
    1. Tetanus Prophylaxis
    2. Elevate the affected extremity
    3. Splint and immobilize the affected limb
    4. Broad-spectrum empiric antibiotics
    5. Parenteral antibiotics
    6. Leave wounds open
  5. Avoid measures that results in decreased perfusion (excessive swelling and vasospasm)
    1. Avoid Digital Blocks
    2. Avoid local ice

XI. Complications

  1. Limb Amputation (approaches 30%)
  2. Pyogenic Flexor Tensynovitis
    1. Staphylococcus aureus is most common
  3. Other rare delayed complications
    1. Oleogranuloma
    2. Fibrohistiocytic tumor
    3. Squamous Cell Carcinoma

XII. Course

  1. Precaution
    1. Most high pressure washers provide >2000 psi at the nozzle (which may be >10x higher than rated psi)
  2. Amputation Incidence
    1. Amputation rate: 50% if injection psi >2000
    2. Amputation rate: <40% if injection psi <2000

XIII. References

  1. Hori (2015) Crit Dec Emerg Med 29(3): 2-7
  2. Kiel (2023) Crit Dec Emerg Med 37(11): 18-9
  3. Hogan (2006) J Orthop Trauma 20(7): 503-11 [PubMed]
  4. Vasilevski (2000) Am J Emerg Med 18:820-4 [PubMed]

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