Waitematā DHB Slark Hyperbaric Unit
Necrotising Soft Tissue Infections
A number of types of infections of soft tissue may benefit from adjunct treatment with hyperbaric oxygen and are included in the category of “necrotizing soft tissue infections.” Names of such clinical syndromes include crepitant anaerobic cellulitis, progressive bacterial gangrene, necrotizing fasciitis, and nonclostridial myonecrosis. Gas gangrene (Clostridial myositis and myonecrosis) is a separate entity and is reviewed elsewhere in this site.
Necrotizing soft tissue infections may result from either a single strain or a mixed population of bacteria, typically occurring after trauma, surgery, and/or around foreign bodies. The individual affected by such infections is frequently compromised by conditions such as diabetes or vascular disease.
In addition to pre-existing host compromise, necrotizing soft tissue infections themselves may induce conditions adverse to control of the infection by normal host defence mechanisms. The infections commonly lower tissue oxygen levels, impairing the ability of the white blood cells (neutrophils) to fight infection. Toxins produced by bacteria involved may also inhibit neutrophil activity.
The primary treatments for necrotizing soft tissue infection are surgical excision of infected tissue and administration of appropriate antibiotics. In selected cases, addition of hyperbaric oxygen therapy may be both lifesaving and cost effective. Hyperbaric oxygen may be beneficial in several ways. Some of the bacteria involved in necrotizing soft tissue infections are “anaerobic,” growing most rapidly in a low oxygen environment. In the hyperbaric chamber, tissue oxygen levels may be raised sufficiently to inhibit bacterial growth. In addition, hyperbaric oxygen treatment may enhance the ability of neutrophils to kill bacteria, by a number of different mechanisms.
The use of hyperbaric oxygen for treatment of necrotizing soft tissue infections should be individualised. In specific instances where risk of morbidity and mortality are high, adjunct hyperbaric oxygen therapy should be considered.
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