The Adjunctive Role of Hyperbaric Oxygen in a Time-Critical Surgical and Infectious Disease Emergency
Necrotizing soft tissue infections, commonly abbreviated as NSTIs, are rapidly progressive infections that cause tissue destruction along the fascia, subcutaneous tissue, or muscle. This clinical category includes necrotizing fasciitis, clostridial myonecrosis, commonly called gas gangrene, and Fournier gangrene involving the perineal or genital region.
These infections can progress from localized pain and swelling to septic shock, multiorgan dysfunction, limb loss, or death. Successful treatment depends on immediate surgical source control, broad-spectrum antimicrobial therapy, and intensive physiologic support. Hyperbaric oxygen therapy, or HBOT, may be considered as an adjunct at appropriately equipped centers, but it must never delay resuscitation, operative exploration, or debridement.
The Undersea and Hyperbaric Medical Society recognizes HBOT as an adjunct to surgery, antibiotics, and goal-directed critical care for necrotizing soft tissue infections. Medicare also lists progressive necrotizing infections and gas gangrene among its covered conditions for chamber-based HBOT. These classifications do not mean every patient with an NSTI should receive hyperbaric treatment. The decision remains dependent on clinical urgency, surgical timing, transport risk, chamber availability, and the patient’s physiologic stability. (UHMS)
Necrotizing Soft Tissue Infection Is a Surgical Emergency
The most important intervention for a suspected NSTI is prompt surgical evaluation. The infection can spread beneath skin that initially appears only mildly inflamed, making early recognition difficult.
Clinical findings that should increase concern include:
- Severe pain that appears disproportionate to the visible skin findings
- Rapidly increasing swelling, erythema, or tenderness
- Firm or wooden-feeling subcutaneous tissue
- Edema extending beyond the apparent area of redness
- Bullae, ecchymosis, skin discoloration, or necrosis
- Crepitus or gas within the soft tissues
- Altered mental status, hypotension, or other systemic toxicity
- Failure to improve with treatment for presumed cellulitis
Severe pain may occur before substantial cutaneous changes become visible. As tissue and superficial nerves are destroyed, pain may later diminish and the affected area can become anesthetic. IDSA recommends prompt surgical consultation whenever an aggressive soft tissue infection is associated with systemic toxicity or suspected necrotizing fasciitis or gas gangrene. (Infectious Diseases Society of America)
Laboratory tests and imaging can assist with diagnosis, define the extent of disease, and identify gas or fluid collections. They should not postpone surgical exploration when clinical suspicion is high. The definitive findings are often established in the operating room, where the surgeon may observe necrotic fascia, abnormal tissue fluid, poor bleeding, loss of normal fascial resistance, or tissue planes that separate easily with blunt dissection. (Infectious Diseases Society of America)
Why Necrotizing Infections Cause Severe Tissue Hypoxia
NSTIs create an environment in which oxygen demand rises while oxygen delivery deteriorates.
Bacterial proliferation, inflammatory activity, edema, thrombosis, and microvascular injury can reduce local perfusion. Pressure within swollen tissue may further compress small vessels. As oxygen tension falls, leukocyte function becomes less effective, antibiotic delivery may become impaired, and viable tissue surrounding the infection becomes increasingly vulnerable.
Some organisms produce enzymes and toxins that accelerate tissue destruction or contribute to shock. Clostridial organisms can produce rapidly progressive myonecrosis accompanied by gas formation and profound systemic toxicity. Other infections are polymicrobial, involving combinations of aerobic and anaerobic organisms. Monomicrobial disease may be caused by group A streptococci, methicillin-resistant Staphylococcus aureus, or other invasive pathogens. (Infectious Diseases Society of America)
The resulting injury is not limited to the bacteria themselves. The host inflammatory response, endothelial dysfunction, impaired microcirculation, and tissue hypoxia can continue to drive damage even after antimicrobial treatment begins.
How Hyperbaric Oxygen May Support NSTI Treatment
During HBOT, the patient breathes medical oxygen while exposed to increased atmospheric pressure inside a hyperbaric chamber. This raises arterial oxygen partial pressure and substantially increases the amount of oxygen dissolved directly in plasma.
The oxygen-rich plasma can reach functioning microvessels surrounding the infected area and create a stronger diffusion gradient into hypoxic tissue. Proposed and observed effects relevant to NSTIs include:
- Increased oxygen tension in viable but hypoxic tissue
- Support for oxygen-dependent leukocyte microbial killing
- Direct inhibition of selected anaerobic organisms
- Improved activity of certain antimicrobial agents
- Reduction of edema through hyperoxic vasoconstriction
- Modulation of inflammatory and endothelial responses
- Support for demarcation between viable and nonviable tissue
- Improved oxygen availability for later wound repair
Hyperbaric oxygen may reduce hypoxia-related leukocyte dysfunction and improve oxygenation in ischemic tissue surrounding the infection. These effects provide the physiologic rationale for its use as an adjunct, particularly when microvascular injury and severe tissue hypoxia are prominent. (UHMS)
HBOT does not penetrate or revive completely necrotic tissue in a way that eliminates the need for surgery. Dead fascia, muscle, foreign material, and infected fluid collections still require removal or drainage.
Surgical Debridement Must Never Be Delayed for HBOT
The central treatment for an NSTI is early and aggressive surgical source control. All clearly necrotic and infected tissue must be excised until viable tissue is reached. Depending on the extent and location of the infection, this may require fasciotomy, muscle excision, removal of infected hardware, bowel or urologic procedures, amputation, or extensive perineal debridement.
One operation is frequently not enough. IDSA notes that many patients should return to the operating room within approximately 24 to 36 hours after the initial debridement and continue to undergo reassessment and additional debridement until no further necrotic tissue remains. (Infectious Diseases Society of America)
Hyperbaric treatment should be coordinated around surgery, not placed ahead of it. A patient should not be transferred away from an available operating room or critical care team merely to receive HBOT.
A practical sequence may include:
- Immediate resuscitation and broad-spectrum antibiotics.
- Urgent operative exploration and debridement.
- Postoperative stabilization and critical care.
- HBOT when available without compromising another operation or essential support.
- Repeated surgical assessment and additional debridement as needed.
At centers with established emergency hyperbaric capability, HBOT may sometimes be delivered soon after the first operation and repeated during the period of active source control. The exact sequence must remain flexible because surgical findings and physiologic stability take priority.
Broad-Spectrum Antibiotics and Critical Care Remain Essential
Empiric antimicrobial therapy should begin promptly and provide broad activity against gram-positive, gram-negative, aerobic, and anaerobic organisms. IDSA recommendations include an anti-MRSA agent combined with broad gram-negative and anaerobic coverage while microbiology remains uncertain. Documented group A streptococcal necrotizing fasciitis is generally treated with penicillin plus clindamycin, while clostridial myonecrosis requires urgent surgery and appropriate toxin-suppressing antimicrobial therapy. (Infectious Diseases Society of America)
Antibiotic treatment should be refined when operative cultures, blood cultures, Gram stain findings, and susceptibility results become available. Superficial wound cultures may not accurately represent the organisms driving infection within the fascia or muscle. Deep operative tissue is generally more clinically useful.
Critical care management may include:
- Aggressive fluid resuscitation
- Vasopressor support
- Mechanical ventilation
- Renal support
- Correction of electrolyte, glucose, and acid-base abnormalities
- Blood-product administration
- Nutritional support
- Pain management
- Thromboembolism prevention
- Management of concurrent cardiac, pulmonary, or renal disease
HBOT cannot replace any of these interventions. Its potential value exists within a coordinated system capable of delivering surgery, infectious disease care, anesthesia, critical care, wound management, and hyperbaric treatment without dangerous delay.
Which Patients May Be Considered for HBOT?
There is no single test that determines whether HBOT should be added. The decision is made by the surgical, critical care, infectious disease, and hyperbaric teams based on the entire clinical situation.
HBOT may be considered when:
- Necrotizing infection has been confirmed surgically or is strongly suspected
- Initial surgical source control has been performed
- Additional debridement remains available whenever needed
- The infection involves extensive hypoxic or ischemic tissue
- Clostridial myonecrosis or another anaerobic component is suspected
- The patient can be transported and monitored safely
- A medically staffed hyperbaric program can provide timely treatment
- HBOT will not interfere with resuscitation, antibiotics, or repeat surgery
Patients with severe shock, unstable airways, active hemorrhage, uncontrolled arrhythmia, or other immediate threats may require further stabilization before chamber treatment. In some hospital-based multiplace chambers, critically ill and mechanically ventilated patients can be treated with trained personnel and chamber-compatible equipment. Other facilities may not have this capability.
An untreated pneumothorax is generally considered an absolute contraindication to HBOT. Pulmonary air trapping, implanted devices, seizure risk, hemodynamic instability, glucose abnormalities, and the ability to manage infusions or ventilation under pressure also require assessment.
The appropriate question is not simply whether HBOT might help. It is whether it can be integrated safely without weakening the interventions that have the clearest lifesaving role.
HBOT Protocols for Necrotizing Soft Tissue Infections
Treatment protocols vary according to the organism, disease severity, surgical course, chamber capability, and patient stability.
Clinical hyperbaric oxygen treatments are generally delivered at pressures between 2.0 and 3.0 atmospheres absolute. For necrotizing infections, treatment may be provided more frequently during the early, rapidly progressive phase and reduced as infection control and physiologic stability improve. Oxygen-breathing periods and air breaks are selected by the hyperbaric physician. (UHMS)
Treatment planning must account for:
- Timing of the next operative exploration
- Ventilator and airway requirements
- Vasopressor and infusion needs
- Hemodynamic stability
- Chest tubes and other drains
- Chamber-compatible monitoring
- Glucose management
- Ear-pressure equalization
- Fire-safety requirements
- Safe transport between the ICU, operating room, and chamber
The number of sessions is not standardized for every NSTI. Treatment should be guided by surgical findings, clinical response, control of systemic toxicity, progression of tissue necrosis, and the ongoing judgment of the multidisciplinary team.
Evidence for HBOT Remains Promising but Inconclusive
The role of HBOT in NSTIs remains debated because randomized controlled trial evidence is lacking. Existing studies are primarily retrospective cohorts, registry analyses, case series, and observational comparisons. These designs are vulnerable to selection bias, differences in disease severity, variation in surgical timing, and differences between hospitals that do and do not have hyperbaric capability.
A 2024 analysis of more than 60,000 surgically treated NSTI admissions in the United States found that fewer than 1 percent received HBOT. After statistical adjustment, HBOT was associated with lower in-hospital mortality and amputation risk, but it was also associated with longer hospitalization and higher cost. The study could not identify treatment pressure, number of sessions, or timing in relation to surgery, and its authors called for a multicenter randomized trial. (PLOS)
A 2025 Scandinavian prospective observational cohort also reported an association between HBOT and lower 30-day mortality. Because treatment was not randomly assigned, the authors still considered a randomized trial necessary to establish whether HBOT itself caused the observed difference. (PubMed)
Professional guidance reflects this uncertainty. UHMS recognizes HBOT as an accepted adjunct to surgery, antibiotics, and critical care for NSTIs. In contrast, the IDSA guideline does not recommend HBOT for clostridial gas gangrene because benefit had not been proven and treatment could delay resuscitation and debridement. (UHMS)
These positions are less contradictory than they initially appear. Both place immediate surgery and resuscitation first. The difference is whether HBOT should be incorporated after those priorities have been protected.
Recovery Often Continues After Infection Control
Surviving the acute infection is only the first stage of recovery. Extensive debridement may leave large wounds, exposed structures, functional impairment, or loss of a limb. Patients may require negative-pressure wound therapy, additional debridement, skin grafting, flap reconstruction, ostomy care, rehabilitation, prosthetic services, or long-term wound management.
The psychological impact can also be substantial. A patient may awaken after emergency surgery with a dramatically altered body, prolonged hospitalization, or uncertainty about future function. Clear communication, pain control, rehabilitation planning, and mental health support should be treated as core components of care.
HBOT may support oxygenation and host response during the active infection, but it is only one part of a much larger clinical effort. The strongest treatment plan remains one that moves quickly, prioritizes source control, coordinates multidisciplinary care, and introduces hyperbaric oxygen only when it can be delivered without compromising lifesaving treatment.
