‘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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