What is hyperbaric oxygen therapy (HBOT)?

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Last updated: September 13, 2026 • View editorial policy

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What is Hyperbaric Oxygen Therapy (HBOT)?

Hyperbaric oxygen therapy is a medical intervention in which patients breathe 100% oxygen at pressures of 2.0 atmospheres absolute (ATA) or higher—typically twice the atmospheric pressure at sea level—delivered in a specialized pressurized chamber. 1

Mechanism of Action

HBOT works by dramatically increasing the partial pressure of oxygen in both plasma and tissues, particularly in hypoxic or ischemic areas. The elevated pressure increases oxygen solubility in plasma to levels sufficient to support tissues with minimal reliance on hemoglobin-bound oxygen 2. This hyperoxic environment triggers several key biological processes:

  • Enhanced wound healing mechanisms: Oxygen is critical for angiogenesis (new blood vessel formation), collagen deposition and cross-linking, and epithelialization 1
  • Improved cellular function: Supports fibroblast activity and host antimicrobial defenses 3
  • Modulation of inflammation: Downregulates pro-inflammatory pathways and modulates redox signaling 3
  • Metabolic effects: Optimizes hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) dynamics 3

Treatment Parameters

Standard HBOT protocols typically involve:

  • Pressure: 2.0-2.5 ATA (atmospheres absolute)
  • Duration: 60-90 minutes per session
  • Course: 20-40 sessions depending on indication 3
  • Setting: Specialized hyperbaric chamber (hard-shell, pressurized unit)

Important Distinction: HBOT vs. Mild HBOT

HBOT and mild hyperbaric oxygen therapy (mHBOT) are NOT equivalent interventions. 4 True HBOT requires pressures ≥2.0 ATA, while mHBOT uses lower pressures (typically 1.2-1.5 ATA) and has fundamentally different mechanisms of action, regulatory requirements, and clinical effects. The evidence base discussed here applies specifically to true HBOT at therapeutic pressures.

Clinical Applications

Established Indications

HBOT is recognized for treating:

  • Decompression sickness and air embolism 2
  • Carbon monoxide poisoning 5
  • Chronic osteomyelitis 5
  • Fournier's gangrene 5
  • Radiation-induced tissue damage (late radiation tissue injury) 3

Conditional/Adjunctive Uses

For diabetic foot ulcers: The most recent 2024 IWGDF guidelines conditionally recommend HBOT as adjunctive therapy specifically for neuro-ischemic or ischemic diabetic foot ulcers where standard care has failed and where established hyperbaric facilities already exist 1. The evidence shows moderate benefits in wound healing and ulcer area reduction, though amputation reduction has not been demonstrated 1.

Key limitations in diabetic foot ulcer treatment:

  • Evidence quality is low overall
  • Only one high-quality study showed clear benefit
  • Many patients cannot complete the intensive treatment regimen due to frailty and comorbidities 1
  • No new quality evidence has emerged in the past 4 years 1

Emerging Applications

Recent research suggests potential benefits in:

  • Psychiatric disorders: Large effects seen in PTSD (d = -1.96) and depression (d = -0.82), but only at therapeutic pressures of 2.0 ATA—no benefit at 1.2 ATA 6
  • Surgical wound complications: Supports threatened flaps/grafts, aids burn management, and reduces complications in reconstructive procedures 3
  • Trauma and orthopedic settings: Mitigates ischemia-reperfusion injury 3

Not Recommended

For acute ischemic stroke: Multiple clinical trials and meta-analyses show HBOT does not improve outcomes in acute stroke patients, despite theoretical benefits 2. The American Heart Association/American Stroke Association guidelines state there is insufficient evidence to support its use 2.

Safety Profile

When used at standard therapeutic protocols, HBOT has a favorable safety profile with mostly mild, reversible adverse events 3:

Common side effects:

  • Transient myopia (temporary vision changes)
  • Middle ear or sinus barotrauma
  • Claustrophobia
  • Brief anxiety 6

Rare serious events:

  • Seizures (uncommon) 2

Patient selection is critical: Those with general frailty and significant comorbidities may need to be excluded due to increased risk of adverse events 1.

Practical Considerations

Access and Feasibility Barriers

  • Geographic limitation: Patients must live near established hyperbaric facilities
  • Time commitment: Requires weeks of intensive daily treatment
  • Cost: Expensive infrastructure; cost-effectiveness is only justified where units already exist for other medical conditions 1
  • Equity concerns: Limited availability reduces equitable access to care 1

Patient Assessment Requirements

Before initiating HBOT, patients require thorough assessment for:

  • Overall medical stability and ability to tolerate treatment
  • Absence of contraindications (e.g., untreated pneumothorax, certain medications)
  • Ability to commit to the full treatment course
  • Proximity to treatment facility 1

Evidence Quality and Future Directions

The evidence base for HBOT remains heterogeneous, with significant variability in:

  • Treatment protocols and pressure parameters
  • Patient selection criteria
  • Outcome measures
  • Study quality (many at high risk of bias) 1, 3

Future research priorities include:

  • Multicenter randomized controlled trials with standardized protocols
  • Biomarker-guided patient selection
  • Cost-effectiveness analyses
  • Long-term outcome data 3

References

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.