HBOT AND NECROTIZING SOFT TISSUE INFECTIONS

Aggressive and often fatal, necrotizing soft tissue infections involve subcutaneous
tissues, fascia and, occasionally, muscles. They are almost always polymicrobial,
involving multiple strains of gram-positive and gram-negative organisms. These are
often synergistic infections caused by mixtures of aerobes, facultative aerobes, and
anaerobes (the aerobes consume oxygen resulting in a reduced environment in
which anaerobes thrive). Infections usually arise in ischemic areas, such as those
existing as a consequence of trauma, peripheral vascular disease, burns,
malignancy, foreign body introduction, or operative wounds. In addition, patients
with altered host defence mechanisms, such as diabetics, are at increased risk.
Endarteritis will occur, causing tissues to become hypoxic, hypovascular and
hypocellular. Leukocytes may become sequestered in vessels, impairing local
immunity, and incomplete substrate oxidation results in hydrogen and methane
accumulation in the tissues. Tissue necrosis occurs, with purulent discharge and gas
production, and reports of mortality range from 30% to 75%. A review of the
available literature was done by Jallali in 2005 and concluded that there were
“encouraging results” when adding hyperbaric oxygen therapy as an adjunct to the
standard treatment.
Conventional treatments may include surgical debridement with systemic antibiotics.
In animal studies, hyperbaric oxygen therapy has a direct antibiotic effect, improving
tissue oxygen tension, leukocyte function and bacterial clearance. Integrin
inhibition decreases leukocyte adherence, reducing systemic toxicity. Hyperbaric
oxygen therapy has been reported to reduce mortality by up to two-thirds.
Hyperbaric oxygen therapy is particularly indicated in bacterial gangrene and non
clostridial myonecrosis (which have high mortality and morbidity), and in
compromised or unresponsive hosts.