DEFINITION:

It is a form of necrosis of tissue with superadded putrefaction. It is a usually coagulative type of necrosis due to ischemia.
Gangrenous or necrotizing inflammation is characterized by primary inflammation provoked by virulent bacteria resulting in massive tissue necrosis. In all types of gangrene, necrosis undergoes liquefaction by the action of putrefactive bacteria.

TYPES OF GANGRENE:-

1. Dry Gangrene:- 

  • Site:- It begins in the distal part of the limb.
  • Cause:- It is due to arterial occlusion. May occur due to trauma, ergot poisoning, Raynaud’s disease.
  • Features:- The affected part is dry, shrunken, and dark black resembling the food of a mummy.
  • Purification:- It is very little due to the limited supply of blood.
  • Bacteria:- Invading bacteria find difficult to server due to little blood supply.
  • Line of Demarcation:- The line of separation usually brings about complete separation with eventually falling off of the gangrenous tissue.
  • Prognosis:- Generally better due to little septicemia.
  • Examples:- Gangrene of toes and feet. 

2. Wet Gangrene:-

  • Site:- It occurs naturally moist tissues and organ such as mouth, bowel, lung, cervix, etc.
  • Cause:- It usually develops rapidly due to blockage of venous. 
  • Features:- The affected part is soft, swollen, putrid rotten and dark.
  • Putrefaction:- it is Mark due to stuffing of organ with blood.
  • Bacteria:- Rapid growth of Putrefactive bacteria causing the profound systematic manifestation of septicemia.
  • Line of Demarcation:- The line of Demarcation between the gangrenous membrane and viable bowel is generally not clear cut.
  • Prognosis:- Generally poor due to the profound toxemia.
  • Examples:- Diabetic foot, Gangrene of Bowel, Bedsores in bedridden pt.

Gas Gangrene:-

It is a variant form of wet Gangrene caused by gas-forming clostridia (gm +ive anaerobic bacteria) which gain entry in the tissue through an open contaminated wound, especially in the muscles.
Clostridia produces various toxins that produce necrosis and edema locally.
The affected area is swollen, edematous,  painful, and crepitates due to the accumulation of a gas bubble within the tissue.