Hyperbaric Medicine in Austere Environments
In austere medicine—care delivered in resource-limited, remote, or combat settings where definitive facilities are hours to days away—hyperbaric interventions are used primarily as field-expedient pressure therapies to buy time, reverse life-threatening hypoxia, and stabilize patients for evacuation. The two main modalities are portable hyperbaric bags (e.g., Gamow/CERT bag) for altitude illness and deployable recompression/HBOT chambers for diving injuries, combat wounds, and select trauma.
Core Roles of Hyperbaric Therapy in Austere Settings
- High-Altitude Illness (HAPE/HACE/AMS)
Portable inflatable hyperbaric bags simulate rapid descent by increasing ambient pressure around the patient, typically by 2–3 psi (≈105–220 mmHg), which is physiologically equivalent to descending 1,500–2,000 m.
High-altitude pulmonary edema (HAPE) and high-altitude cerebral edema (HACE) can improve within 1–4 hours of bag treatment, reversing hypoxia and reducing capillary leak.
Field protocols (e.g., mountain rescue, military high-altitude operations) use the bag as a bridge to descent or evacuation, especially when weather or terrain precludes immediate movement.
The bag preserves oxygen supplies compared to prolonged high-flow normobaric oxygen, an important logistic advantage in remote settings.
- Decompression Sickness (DCS) and Arterial Gas Embolism (AGE)
In remote dive sites, offshore platforms, and special operations, portable recompression chambers enable on-scene or near-scene treatment of DCS and AGE.
Recompression reduces bubble size per Boyle’s Law and accelerates inert gas washout per Henry’s Law, mitigating neurologic and cardiopulmonary injury.
Navy and commercial diving manuals emphasize early recompression; in austere contexts, portable chambers allow initiation of Table 6–type profiles before transfer to a fixed facility.
- Combat and Trauma Wounds
Military R&D has explored HBOT as an adjunct for crush injuries, compartment syndrome, severe burns, and necrotizing soft tissue infections when surgery and blood products are limited.
HBOT increases dissolved oxygen, supports neutrophil killing, reduces edema, and can neutralize clostridial alpha-toxin, improving outcomes in gas gangrene and other necrotizing infections.
In severe blood loss, HBOT can temporarily sustain tissue oxygenation independent of hemoglobin, serving as a bridge when transfusion is delayed or unavailable.
Field-deployable monoplace or small multiplace chambers have been evaluated for forward surgical teams and expeditionary hospitals, though airway management and fire safety remain constraints.
- Disaster and Humanitarian Relief
In earthquakes, building collapses, and mass-casualty events, hyperbaric therapy has been used for:
Crush syndrome and traumatic ischemia: interrupting the edema–ischemia cycle, preserving marginally viable tissue, and reducing amputation rates.
Compromised flaps/grafts and refractory osteomyelitis in prolonged field care when reconstructive options are delayed.
Portable Hyperbaric Systems Used in Austere Medicine
1. System: Gamow / CERT bag
Typical Use: Altitude illness (AMS, HAPE, HACE)
Operating Pressure: +2-3 psi (~1.14–1.2 ATA)
Key Advantages: Lightweight, foot-pump inflation, no external gas needed
Limitations: Mimics descent; limited to altitude indications; patient claustrophobia; requires monitoring
2. System: Portable recompression chambers (e.g., SOS, lightweight Navy-type)
Typical Use: DCS/AGE in remote dive/expedition sites
Operating Pressure: Up to 2.8–3 ATA (depending on model)
Key Advantages: Enables on-scene recompression; can be air-transported
Limitations: Requires compressed air/O₂ supply; trained operator; limited interior space
3. Monoplace field HBOT units
Typical Use: Combat wounds, trauma, infection
Operating Pressure: adjunct 2.0–2.5 ATA
Key Advantages: Can be deployed with forward surgical teams; simple logistics (single patient)
Limitations: Airway/fire constraints; limited to stable patients; power/gas needs
4: System: Expeditionary multiplace modules
Typical Use: Humanitarian/disaster, large-scale operations
Operating Pressure: 2.0–2.8 ATA
Key Advantages: Treat multiple patients; allow attendants inside for critical care
Limitations: Heavier logistics footprint; requires robust support
Physiology That Makes Hyperbaric Therapy Valuable in the Field
Dissolved oxygen surge: At 2–3 ATA on 100% O₂, arterial
can exceed 1,500–2,000 mmHg, delivering enough dissolved oxygen to sustain vital organs even with severe anemia or shock.
Bubble physics: Elevated pressure shrinks gas bubbles (Boyle’s Law) and increases their dissolution into blood (Henry’s Law), critical for DCS, AGE, and some trauma-related intravascular gas.
Anti-edema and anti-inflammatory effects: HBOT induces vasoconstriction in healthy beds while improving microcirculatory flow in ischemic tissue, reducing edema and mitigating reperfusion injury—key in crush injury and compartment syndrome.
Antimicrobial synergy: Hyperoxia is directly bacteriostatic/bactericidal to anaerobes and enhances certain antibiotics, supporting infection control when surgical debridement is delayed.
Operational Considerations and Constraints
Training: Effective use requires personnel trained in hyperbaric physiology, chamber operation, and recognition/treatment of barotrauma and oxygen toxicity.
Gas and power logistics: Even portable systems need reliable compressed gas and, for some units, electrical support—challenging in prolonged field care.
Patient selection: In austere settings, HBOT is prioritized for time-critical, life- or limb-threatening indications (DCS/AGE, gas gangrene, severe CO poisoning, crush syndrome) rather than chronic wounds.
Safety: Fire risk with 100% O₂, CO₂ accumulation in sealed bags, and limited access to the patient mandates strict protocols, especially in combat or disaster scenes.
Example Austere Scenarios
Mountain rescue team at 4,500 m treats a climber with HACE using a Gamow bag for 60–90 minutes, improving consciousness and allowing safe helicopter evacuation.
Special operations dive mission in a remote littoral zone: a diver develops Type II DCS; a portable recompression chamber is inflated on a support vessel, and a Navy-style treatment table is initiated during medevac.
Forward surgical team in a conflict zone uses a monoplace HBOT unit as an adjunct for a soldier with extensive crush injury and evolving compartment syndrome, reducing tissue loss while awaiting definitive orthopedic care.
Evert Randall Bentley, DO, MS, FACOI
