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