GANGRENE

‘Necrosis of tissue + superadded putrefaction’

  • Complication of necrosis
  • In certain circumstances necrotic tissue is liable to be invaded by putrefactive organisms which are both saccharolytic and proteolytic
  • Foul smelling gases
  • Tissues become green or black (since breakdown of Hb)
  • The bacteria proliferate in and digest the dead tissues often with the production of gases

 

DRY GANGRENE

  • Distal part of limb
  • Toes and feet – old patient – severe atherosclerosis
  • Other causes – buerger’s disease, reynaud’s disease, trauma, ergot poisoning
  • So little blood that even the invading bacteria find it hard to grow in the necrosed tissue
  • The gangrene spreads slowly upwards until it reaches a point where the blood supply is adequate to keep the tissue viable
  • Line of separation

Morphologic features,

  • Dry, shrunken and dark black
  • Black (since liberation of Hb from haemolysed RBCs + H2S {bacteria} —- black iron sulphide
  • Line of separation – falling off or spontaneous amputation

Histologically,

  • Necrosis + smudging of tissue
  • Line of separation – inflammatory granulation

 

WET GANGRENE

  • Naturally moist tissues and organs
  • Bowel, lung, mouth, cervix, vulva
  • Diabetic foot – high blood glucose
  • Bed sores

Blockade of both venous and arterial blood

Affected part – stuffed with blood

Putrefactive bacteria

Systemic manifestation of septicaemia

Death

  • Lacks the line of demarcation

GAS GANGRENE

  • Gas forming clostridia
  • Entry – open contaminated wounds
  • Muscles, in colon as commensal

 

 

 

 

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