- Gas gangrene is a rapid spreading infective gangrene of the muscles characterized by collection of gas in the muscles and subcutaneous tissue. It is also called "Clostridial myonecrosis".
- Gas Gangrene is most likely to develop in wounds where there has been extensive laceration or devitalization of muscle mass with gross contamination of the wound by soil and other foreign bodies.
- Clostridial organisms can be divided into two groups - namely Saccharolytic and Proteolytic. Of the Saccharolytic group of anaerobes, Clostridium perfringes (Cl. welchii) plays the main part in gas gangrene.
- Other organisms that cause gas gangrene are Clostridium oedematiens, Clostridium septicum, Clostridium histolyticum, and Clostridium bifermentans.
- Two important factors necessary for the formation of gas gangrene include :
- Entry of Clostridial organisms, particularly Clostridium perfringes (Cl. welchii), and
- Anaerobic conditions within the wound
- Diabetes and other occlusive arterial diseases predispose to gas gangrene.
- The various exotoxins produced by these organisms (particularly Clostridium welchii) are:
| Alpha toxin (Lecithinase) | Is hemolytic, and splits lecithin to phosphocholine and diglyceride. |
| Collagenase | Is a proteinase and breaks down collagen |
| Hyaluronidase | Breaks down hyaluronic acid |
| Theta toxin | Is hemolytic, lethal and necrotic |
| Leucocidin | Kills the leucocytes |
- Clostridial invasion affects the whole of the involved muscle from origin to insertion producing a foul smelling necrosis of the muscle which becomes dull red to green and ultimately black in appearance.
- The muscle becomes green to black due to the action of the sulphurated hydrogen on iron liberated from broken down muscle hemoglobin. The gas is chiefly hydrogen, being odorless in the beginning, but soon it becomes fetid due to the liberation of sulphurated hydrogen (H2S), ammonia and volatile gases.
TYPES OF GAS GANGRENE
| Clostridial cellulitis | Crepitant infection involving necrotic tissue, but healthy muscle is not involved and is characterized by foul smelling, seropurulent infection of a wound. |
| Single muscle type | Limited to one muscle only |
| Group type | Limited to one group of muscles, eg. extensors of the thigh |
| Massive type | Involves almost whole muscle mass of one limb |
| Fulminating type | Spreads very rapidly even beyond the limb, associated with intense toxemia |
- The most characteristic feature of gas gangrene is profuse discharge of brownish, foul smelling fluid between the sutures and the presence of crepitus due to presence of gas in the muscle and subcutaneous tissue.
- The first prophylactic step in the prevention of gas gangrene wound is excision or debridement in which all the devitalized tissues, blood clots, dead and damaged muscles and foreign bodies should be removed.