HBOT for Necrotizing Soft Tissue Infections | NorCal Hyperbarics Concord, CA

Necrotizing soft tissue infections (NSTIs) are a spectrum of rapidly progressing bacterial infections that destroy fascia, subcutaneous tissue, and in some cases muscle, spreading along tissue planes with extraordinary speed. The best-known types include necrotizing fasciitis (the “flesh-eating bacteria” of media headlines), gas gangrene (clostridial myonecrosis), and Fournier’s gangrene (affecting the perineum and genitalia). These infections can be caused by a single pathogen (most commonly Group A Streptococcus pyogenes in type I monomicrobial NSTI) or by a polymicrobial mix of aerobic and anaerobic organisms (type II).

NSTIs are rare but catastrophic. They carry mortality rates of 20 to 40% even with immediate surgical intervention and intensive care, rising dramatically when diagnosis is delayed or surgical débridement is incomplete. Predisposing factors include diabetes mellitus, immunosuppression, peripheral vascular disease, obesity, cirrhosis, and intravenous drug use — but NSTIs also occur in previously healthy individuals following minor trauma, insect bites, or surgical procedures. The Bay Area's diverse patient population includes individuals with all of these risk factors.

HBOT is recognized by the UHMS as an approved indication for clostridial myositis and myonecrosis (gas gangrene) and for other necrotizing soft tissue infections. It is always used as an adjunct to — never a replacement for — aggressive surgical débridement, which remains the single most important intervention for survival in NSTI.

HBOT is adjunctive in NSTI treatment — surgery is the cornerstone and must never be delayed for HBOT. However, multiple lines of evidence establish that HBOT significantly improves outcomes when added to surgical and antibiotic management.

The primary mechanisms are microbiological. Many NSTIs involve anaerobic or microaerophilic organisms — including Clostridium perfringens (gas gangrene), Bacteroides fragilis, and other obligate anaerobes that cannot survive in high-oxygen environments. At 2.0 to 2.5 atmospheres breathing 100% oxygen, tissue oxygen tensions rise well above the threshold lethal to these organisms. HBOT also directly suppresses the production of alpha-toxin and theta-toxin — the clostridial toxins responsible for the membrane destruction and myonecrosis that define gas gangrene — by inhibiting the toxin-producing metabolic pathways that depend on anaerobic conditions.

Beyond its direct microbial effects, HBOT restores neutrophil oxygen-dependent killing capacity in the peri-wound tissue, improves the demarcation between necrotic and viable tissue (making surgical débridement planning more accurate), and promotes angiogenesis and tissue repair in the massive wounds that débridement creates. A systematic review and multiple retrospective cohort analyses have found significantly reduced mortality in NSTI patients receiving HBOT as an adjunct to surgery and antibiotics, compared to surgery and antibiotics alone. HBOT protocols for NSTI typically involve 3 sessions in the first 24 hours (to maximize early antimicrobial effect) followed by twice-daily sessions for 3 to 5 days, then daily until wound closure and clinical stability are achieved.