Gangrene

Pathology

• Gangrene is a form of necrotic tissue death
• Two types of cellular/tissue death: Necrosis and Apoptosis
  1. Necrosis (poorly controlled tissue death —> cell content leakage —> inflammation)
  • Coagulative necrosis
    • nuclear loss but cell remains it’s general shape
  • Liquefactive necrosis
    • complete loss of struction leading to soft semi-solid mash (seen in cerebral infarction)
  • Casceous necrosis
    • Coagulative necrosis + Liquefactive necrosis = Cottage cheese apparance macroscopically; classically seen in TB as granulomatous inflammation
  • Gangrene
    • Coagulative necrosis modified by exposure to air resulting in drying (dry gangrene)
    • Dry gangrene + infection leads to wet gangrene
    • Gas gangrene: A subtype of wet gangrene caused by Clostrodial species, most commonly C. perfingens
      1. Apoptosis (programmed cell death)
  • Controlled cell death

Aetiology of gangrene

• Dry gangrene (aka ischaemic gangrene, mainly arterial)
  • Atherosclerosis
    • PAD
    • Diabetes
    • Smoking
  • Thrombosis
    • Vasculitis
    • IVDU
    • Trauma
    • Malignancy
• Wet gangrene
  • Dry gangrene + polymicrobial superadded infection
• Gas gangrene
  • Most commonly Clostridium perfringens

Management

Management depends on the subtype.

Dry gangrene

• Heparin bolus and then infusion
• Threatened (limb salvagable with intervention)
  • Surgical revascularisation (bypass) +/- Amputaition if life expectancy >2 yrs
  • Percutaneous Transluminal Angioplasty (PTS) +/- Amputation if life expectancy <2 yrs
• Non-viable limb (major tissue loss; limb not salvagable)
  • Amputation

Wet gangrene

• Broad-spectrum iv antibiotics
• surgical debridement ± amputation

Gas gangrene

• Surgical debridement ± amputation
• IV Benzylpenicillin + Clindamycin
• Hyperbaric O2 therapy can improve survival

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