What counts as HBOT?
For clinical hyperbaric oxygen therapy, the entire body is placed in a pressurized chamber while the patient breathes prescribed medical oxygen. It is different from topical oxygen and from consumer “mild” or soft-sided chamber claims. Protocol pressure, oxygen periods, air breaks, frequency, and total sessions are indication-specific and must be prescribed by the treating hyperbaric team.[1]
Refer urgently—do not wait for routine HBOT screening
Suspected gas embolism or decompression sickness; severe CO poisoning; rapidly progressive necrotizing soft-tissue infection; gas gangrene; acute limb-threatening ischemia or crush injury; a threatened graft/flap; sudden monocular vision loss; or sudden sensorineural hearing loss require emergency or same-day specialty pathways. HBOT may be one component of care, but transfer, surgery, oxygen, resuscitation, antimicrobials, stroke/eye evaluation, or steroids must not be delayed.
Recognized clinical indications: the UHMS list
The UHMS overview lists 15 indications. This is a clinical-recognition list, not a universal mandate, protocol, or payment guarantee. Evidence strength and urgency vary substantially by condition.[1]
| Condition | Clinical role / essential guardrail |
|---|---|
| Air or gas embolism | Emergency; immediate specialist/emergency pathway. |
| Carbon monoxide poisoning, including CO with cyanide poisoning | Emergency consultation; severity is clinical, not a COHb number alone. |
| Clostridial myositis and myonecrosis (gas gangrene) | Adjunct to immediate surgery and antimicrobials; never a substitute for source control. |
| Crush injury, compartment syndrome, and acute traumatic ischemias | Adjunct when limb or function is threatened. |
| Decompression sickness | Emergency recompression pathway. |
| Central retinal artery occlusion; selected problem wounds | Time-sensitive specialist evaluation; wound use requires standard wound care and vascular assessment. |
| Severe anemia | Reserved for selected situations when transfusion is not possible or must be delayed. |
| Intracranial abscess | Adjunct in selected, refractory, or high-risk cases with neurosurgical/infectious-disease management. |
| Necrotizing soft-tissue infection | Adjunct to urgent debridement, resuscitation, and antibiotics. |
| Chronic refractory osteomyelitis | After appropriate medical and surgical management has failed or is not feasible. |
| Delayed radiation injury (soft-tissue and bony necrosis) | Adjunct for established late radiation injury; not prophylaxis. |
| Compromised grafts and flaps | Salvage of a threatened graft/flap—not routine management of a healthy graft or primary wound care. |
| Acute thermal burn injury | Specialist burn-center decision; coverage varies. |
| Idiopathic sudden sensorineural hearing loss | Adjunct to steroid-based management; treatment window matters. |
| Avascular necrosis (aseptic osteonecrosis) | UHMS-listed; evidence, protocol, and coverage require case-specific specialist review. |
What current guidance says in high-interest use cases
Diabetes-related foot ulcers
IWGDF advises clinicians to consider systemic HBOT only as an adjunct for a neuro-ischemic or ischemic diabetes-related foot ulcer when best standard care has failed and appropriate hyperbaric resources are already available. The recommendation is conditional with low-certainty evidence. HBOT is not a substitute for vascular assessment/revascularization when indicated, debridement, off-loading, infection treatment, glucose management, and longitudinal wound measurement.[3]
Important distinction: IWGDF/IDSA advises against HBOT when the sole reason is treatment of diabetic foot infection; infection requires source control and evidence-based antimicrobial management.[4]
Carbon monoxide poisoning
Give 100% oxygen promptly and assess clinical severity. CDC advises considering HBOT for COHb >25–30%, cardiac involvement, severe acidosis, transient or prolonged unconsciousness, neurologic impairment, or abnormal neuropsychiatric testing; treatment can be considered at lower COHb levels when clinical context warrants. COHb does not correlate reliably with outcome or response, and HBOT is the treatment of choice in pregnancy according to CDC guidance.[5]
Idiopathic sudden sensorineural hearing loss
The AAO-HNS guideline says clinicians may offer, or refer for, HBOT combined with steroid therapy within two weeks of onset. This is an option within an urgent otologic pathway—not a treatment to start after prolonged delay or instead of steroid-based management.[6]
Central retinal artery occlusion
CRAO is an acute retinal ischemic stroke. The emergency evaluation, stroke-risk workup, and ophthalmology/neurology coordination come first. Do not frame HBOT as a routine outpatient treatment for vision change; evidence and local access vary, while time to definitive evaluation is critical.[11]
Contraindications and pre-treatment safety screening
The major safety error is treating a screening list as an automatic yes/no rule. The hyperbaric clinician balances the urgency and expected benefit against a condition-specific risk assessment. Untreated pneumothorax is the generally accepted absolute contraindication; pressure change can convert it to life-threatening tension pneumothorax during ascent.[8]
Do not proceed until resolved / specialist-directed
- Untreated pneumothorax.
- Intraocular gas after eye surgery or retinal procedure: obtain ophthalmology and hyperbaric direction; risk may outweigh benefit outside life-saving treatment.
- Inability to safely tolerate chamber care, uncontrolled agitation, or unacceptable risk to the patient or chamber team.
Relative risks that require individualized review
- Active URI, sinus disease, otitis, eustachian-tube dysfunction, or inability to equalize ears.
- Asthma, COPD with air trapping, bullae/blebs, prior spontaneous pneumothorax, or recent thoracic surgery.
- Seizure risk, high fever, severe claustrophobia, or poorly controlled anxiety.
- Heart failure or pulmonary-edema risk; diabetes and hypoglycemia risk.
- Implanted devices: verify pressure compatibility with the manufacturer and facility policy.
- Recent/current chemotherapy or other drugs with possible oxygen-toxicity or wound-healing interactions—obtain oncology/pharmacy review.
Minimum clinical screening before elective HBOT
- 1. Confirm the diagnosis and urgency. Identify whether the patient needs emergency transfer or specialty treatment first.
- 2. Document standard care. For wounds, record vascular assessment, infection management, off-loading, debridement, nutrition/glycemia, and objective healing trajectory.
- 3. Screen pressure-related risk. Ear/sinus symptoms, pulmonary history, imaging when clinically indicated, and ability to equalize.
- 4. Reconcile medications and devices. Include cancer therapies, insulin plan/glucose monitoring, and implant/manufacturer guidance.
- 5. Establish monitoring and rescue capability. Define chamber type, staffing, emergency plan, oxygen breaks, and what will stop or modify a treatment.
- 6. Obtain informed consent. Discuss alternatives, anticipated burden, likely benefit, adverse effects, and coverage uncertainty.
Adverse effects and treatment-day safety
Most adverse effects are mild and manageable, but the patient must be taught to report symptoms early. Pressure-related effects include ear, sinus, dental, and rarely pulmonary barotrauma. Oxygen-related effects include temporary myopic shift, rare central-nervous-system oxygen toxicity/seizure, and—in susceptible patients—pulmonary oxygen toxicity. Claustrophobia, hypoglycemia, and pulmonary edema are additional clinical concerns. A systematic review of RCTs found more reported adverse effects with HBOT than comparators, with ear discomfort the most frequent event.[9]
Before compression
Assess new respiratory or ear/sinus symptoms, glucose when relevant, current medications, device status, and ability to clear ears. Do not conceal congestion or chest symptoms to “get through” a session.
During treatment
Report ear/sinus pain, chest pain, dyspnea, neurologic symptoms, visual change, panic, nausea, or hypoglycemic symptoms immediately. The team can pause compression, adjust, or terminate according to protocol.
After treatment
Assess for persistent ear pain/hearing change, sinus symptoms, dyspnea, chest pain, confusion, or visual symptoms. Escalate concerning symptoms rather than automatically proceeding with the next session.
Fire safety
High-concentration oxygen increases fire risk. The facility must use approved processes and follow the device manufacturer’s instructions; patients should follow facility rules for clothing, products, electronics, and prohibited items.[7]
Medicare coverage: a separate question from clinical appropriateness
CMS National Coverage Determination 20.29 limits Medicare reimbursement to chamber-based HBOT for the conditions below. Other insurers can use different criteria, and local coverage or prior-authorization requirements may add documentation rules. Never promise coverage from a web page.[2]
Medicare’s diabetic lower-extremity wound criteria
CMS requires type 1 or 2 diabetes, a lower-extremity wound due to diabetes, Wagner grade III or higher, and failure of adequate standard wound therapy. HBOT is covered only as adjunctive treatment after at least 30 days without measurable healing; standard care includes vascular assessment/correction when possible, nutritional and glucose optimization, debridement, moist wound care, off-loading, and infection treatment. Continued coverage depends on documented healing within each 30-day period.[2]
Examples of Medicare NCD noncoverage include pressure/stasis ulcers, chronic peripheral vascular insufficiency, thermal burns, smoke inhalation with pulmonary insufficiency, pulmonary emphysema, and several other conditions. This does not establish coverage with another payer or answer whether an emergency treatment is clinically indicated.[2]
How to avoid overclaiming HBOT
- Do not confuse oxygen wellness claims with clinical HBOT. A consumer chamber, topical oxygen product, or an unvalidated protocol is not equivalent to medically supervised, indication-specific HBOT.
- Do not call a condition “approved” without naming the authority. UHMS recognition, FDA device clearance, guideline recommendation, Medicare coverage, and commercial-payer authorization are distinct concepts.
- Do not use HBOT as a replacement for definitive care. Necrotizing infection needs source control; limb ischemia needs vascular assessment; CO poisoning needs emergency oxygen and clinical evaluation; sudden hearing loss needs urgent otologic care.
- Do not promise a fixed number of treatments. Pressure, oxygen dose, air breaks, treatment count, and reassessment intervals are diagnosis- and patient-specific.
Frequently asked clinical questions
Is untreated pneumothorax the only absolute contraindication?
It is the generally accepted absolute contraindication. Other factors—such as retained intraocular gas, significant pulmonary air trapping, inability to equalize, severe claustrophobia, device issues, or medication interactions—may make elective treatment unsafe or require specialist mitigation.
Can HBOT treat a diabetic foot infection?
Not as the sole indication. HBOT may be considered in selected neuro-ischemic or ischemic ulcers after standard care fails, but IWGDF/IDSA advises against its use when the sole purpose is treating the infection. Infection management requires source control and antimicrobial care.
Does a high carboxyhemoglobin level alone determine HBOT for CO poisoning?
No. CDC notes that COHb does not correlate well with illness severity, outcome, or treatment response. The history, neurologic findings, cardiac involvement, acidosis, pregnancy, and trajectory matter.
Does Medicare cover every UHMS-recognized indication?
No. The current CMS NCD list differs from the UHMS list. Verify the active national policy, applicable local policy, and payer-specific prior-authorization rules before promising coverage.
Should this page be used to decide whether a patient is qualified?
No. It is an educational triage and documentation reference. Individual decisions require a treating clinician and qualified hyperbaric service.
Sources and evidence base
Primary guidelines and government policies are prioritized. Links are provided for source review; this page should be reviewed whenever a core guideline or payer policy changes.
- 1. Undersea & Hyperbaric Medical Society — HBO Indications
Current UHMS indications overview and facility definition.
- 2. CMS National Coverage Determination 20.29 — Hyperbaric Oxygen Therapy
U.S. Medicare covered and noncovered conditions; diabetic lower-extremity wound requirements.
- 3. IWGDF 2023 Wound Healing Guideline
Conditional, low-certainty recommendation for selected neuro-ischemic or ischemic diabetes-related foot ulcers after standard care fails.
- 4. IWGDF/IDSA 2023 Diabetes-Related Foot Infection Guideline
Recommends against HBOT when the sole indication is treatment of diabetic foot infection.
- 5. CDC — Clinical Guidance for Carbon Monoxide Poisoning
Current clinician guidance for oxygen treatment, HBOT consideration, pregnancy, and assessment.
- 6. AAO-HNS Clinical Practice Guideline: Sudden Hearing Loss (Update)
HBOT may be offered with steroids within two weeks of idiopathic sudden sensorineural hearing-loss onset.
- 7. FDA — Safe Use of Hyperbaric Oxygen Therapy Devices
Manufacturer instructions and fire-prevention requirements.
- 8. StatPearls — Hyperbaric Oxygen Therapy Contraindications
Clinical review of absolute and relative contraindications and medication/device considerations.
- 9. Adverse effects of HBOT: systematic review and meta-analysis
RCT synthesis of adverse effects, including ear discomfort and ocular effects.
- 10. European Committee for Hyperbaric Medicine consensus recommendations
International consensus on accepted, nonaccepted, and investigational uses.
- 11. American Heart Association — Central Retinal Artery Occlusion statement
CRAO should be treated as an acute ischemic stroke pathway; it is not a routine outpatient vision complaint.