Waitematā DHB Slark Hyperbaric Unit
Clostridial Myositis & Myonecrosis (Gas Gangrene)
Clostridial myositis and myonecrosis is an acute, rapidly progressive infection of the soft tissues commonly known as “gas gangrene.” The infection is caused by one of several bacteria in the group known as “clostridium.” While over 150 species of clostridium have been identified, only a few commonly cause gas gangrene.
The infection typically spreads from a discrete focus of clostridium within the body. The original source can actually be within the body, as clostridium normally live in the gastrointestinal tract. Alternatively, the infection can originate outside the body, such as when infection results from contamination of wounds during trauma (e.g. motor vehicle accidents). Gas gangrene infection is severe and can advance quickly. Besides replicating and migrating, the organisms which cause gas gangrene produce poisons known as exotoxins. Exotoxins are capable of liquefying adjacent tissue and inhibiting local defence mechanisms which might normally contain a less virulent infection. As such, the advancing infection of gas gangrene may simply destroy healthy tissue in its path and spread over the course of hours.
Clostridium bacteria are “anaerobic,” meaning that they prefer low oxygen concentrations to grow. If clostridia are exposed to high amounts of oxygen, their replication, migration, and exotoxin production can be inhibited. This is the rationale for the use of hyperbaric oxygen in the treatment of gas gangrene.
Repeated treatment in the hyperbaric chamber has the potential to slow the progress of the infection while the two primary therapies, antibiotics and surgical resection of infected tissue, control it. The advantages of hyperbaric oxygen treatment in gas gangrene are two-fold. First, it may be lifesaving because exotoxin production is rapidly halted and less heroic surgery may be needed in gravely ill patients. Second, it may be limb and tissue-saving, possibly preventing limb amputation that might otherwise be necessary.
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