TL;DR: The Centers for Medicare & Medicaid Services modified NCD 43, the National Coverage Determination governing Medicare coverage of oxygen and carbon dioxide inhalation therapy for inner ear conditions, effective January 9, 2026. The policy confirms this therapy is non-covered under Medicare. Here's what billing teams need to do.
CMS oxygen treatment for inner ear coverage policy under NCD 43 is straightforward: this therapy does not meet medical necessity standards under Medicare. The Centers for Medicare & Medicaid Services classifies oxygen (95%) and carbon dioxide (5%) inhalation therapy for inner ear disease — including endolymphatic hydrops and fluctuant hearing loss — as not reasonable and necessary. No specific CPT or HCPCS codes are listed in the policy document itself, which creates its own billing challenge.
Quick-Reference Table
| Field | Detail |
|---|---|
| Payer | CMS (Centers for Medicare & Medicaid Services) |
| Policy | Oxygen Treatment of Inner Ear/Carbon Therapy |
| Policy Code | NCD 43 |
| Change Type | Modified |
| Effective Date | January 9, 2026 |
| Impact Level | Low-Medium — low volume procedure, but high denial risk if billed |
| Specialties Affected | Otolaryngology (ENT), Audiology, Neurotology |
| Key Action | Flag any claims for O2/CO2 inhalation therapy for inner ear conditions as non-covered before billing Medicare |
CMS Oxygen and Carbon Dioxide Inhalation Therapy Coverage Criteria and Medical Necessity Requirements 2026
NCD 43 is the National Coverage Determination governing Medicare coverage of oxygen and carbon dioxide inhalation therapy for inner ear disease. The policy is unambiguous: this treatment does not meet medical necessity under Medicare.
CMS reviewed the therapeutic benefit of inhaled oxygen (95%) and carbon dioxide (5%) for conditions including endolymphatic hydrops and fluctuant hearing loss. Their conclusion is that the benefit is "highly questionable." That language is deliberate — it signals that no amount of clinical documentation will flip this to a covered service at the national level.
This is a national, top-down coverage determination. It isn't subject to Medicare Administrative Contractor discretion the way a local coverage determination (LCD) would be. There is no regional variation here. Every MAC must follow NCD 43.
Prior authorization is not the issue. You won't get a prior auth denial on this one — you'll get a claim denial on the back end because the service is categorically excluded from Medicare reimbursement. The distinction matters for how you counsel patients before the encounter.
The coverage policy applies under the Physicians' Services benefit category. That means if a physician or qualified practitioner performs or supervises this therapy and bills under a professional fee schedule, the claim will not be reimbursed. There is no pathway to coverage under this NCD as written.
CMS Inner Ear Oxygen Therapy Exclusions and Non-Covered Indications
The entire therapeutic category is excluded. CMS doesn't carve out specific clinical presentations that might qualify — it draws a line around the full procedure.
These are the conditions specifically named in the policy as not covered:
| # | Excluded Procedure |
|---|---|
| 1 | Endolymphatic hydrops — a condition involving fluid pressure changes in the inner ear, often associated with Ménière's disease |
| 2 | Fluctuant hearing loss — hearing loss that changes over time, sometimes linked to endolymphatic hydrops |
If a patient presents with either condition and a provider wants to use O2/CO2 inhalation therapy, Medicare will not pay. The clinical rationale for the denial is that CMS has determined the therapeutic benefit is not established.
This is not the same as a service being "investigational" in the traditional sense — CMS doesn't call it experimental here. They call it not reasonable and necessary. That's a medical necessity determination, not a research-exclusion determination. The practical result is the same: no reimbursement, full stop.
Providers who believe a patient may benefit from this therapy can still offer it. But if the patient is a Medicare beneficiary, you need to issue an Advance Beneficiary Notice of Noncoverage (ABN) before delivering the service. Without an ABN, you cannot bill the patient if Medicare denies the claim. Get the ABN signed first.
Coverage Indications at a Glance
| Indication | Status | Relevant Codes | Notes |
|---|---|---|---|
| Endolymphatic hydrops treated with O2/CO2 inhalation | Not Covered | Not specified in policy | Not reasonable and necessary per NCD 43; issue ABN before service |
| Fluctuant hearing loss treated with O2/CO2 inhalation | Not Covered | Not specified in policy | Not reasonable and necessary per NCD 43; issue ABN before service |
| Inner ear disease (general) treated with O2/CO2 inhalation | Not Covered | Not specified in policy | CMS finds therapeutic benefit "highly questionable"; no coverage pathway under this NCD |
CMS Inner Ear Oxygen Therapy Billing Guidelines and Action Items 2026
The effective date for this modified policy is January 9, 2026. Here's what your billing team needs to do right now.
| # | Action Item |
|---|---|
| 1 | Audit your charge master for any O2/CO2 inhalation therapy charges. If your facility or practice has ever billed this therapy — or has it set up in your charge capture system — pull those records. Check whether any were billed to Medicare and whether denials came back. NCD 43 has existed in some form for years, so this may not be a new problem, but the January 9, 2026 modification is the right trigger to do the audit now. |
| 2 | Issue ABNs for any Medicare patients before delivering this service. If a provider plans to offer O2/CO2 inhalation therapy to a Medicare beneficiary for inner ear disease, the ABN must be signed before the service is delivered. Do not deliver the service and then try to collect — that approach fails legally and practically. |
| 3 | Do not seek prior authorization for this therapy under Medicare. Prior authorization won't help here. This is a medical necessity exclusion at the NCD level. No amount of PA documentation will override NCD 43. Pursuing prior auth wastes time and creates false patient expectations. |
| 4 | Brief your ENT, audiology, and neurotology providers directly. Physicians ordering or performing this therapy may not know the Medicare billing guidelines under NCD 43. Send a one-pager to any provider who treats Ménière's disease, endolymphatic hydrops, or fluctuant hearing loss. Include the policy effective date of January 9, 2026, and the ABN requirement. |
| 5 | Check your payer mix beyond Medicare. NCD 43 is a CMS determination only. Commercial payers — Aetna, Cigna, UnitedHealthcare — may have their own policies on this therapy. Some may cover it with conditions; others may follow Medicare's lead. If your practice treats patients with inner ear conditions across multiple payers, pull each payer's coverage policy before assuming this non-coverage applies universally. |
| 6 | Document the clinical picture even for non-covered services. Even when a service isn't covered, documentation matters for two reasons: ABN validity and potential appeals on any claim you submit on behalf of secondary payers. Strong documentation of the diagnosis — including ICD-10 codes for endolymphatic hydrops and fluctuant sensorineural hearing loss — supports the patient's medical record and any secondary billing. |
| 7 | Talk to your compliance officer if your practice has billed this therapy to Medicare in the past. If you find historical claims that went through — whether paid or denied — your compliance officer needs to know. Depending on the volume and timing, there may be overpayment exposure. Don't sit on that finding. Loop in your compliance officer and, if the exposure is significant, your healthcare counsel. |
| Previous Version | Current Version |
|---|---|
| Coverage is considered experimental and investigational for all indications | Coverage is considered medically necessary when specific criteria are met |
| Prior authorization is not required | Prior authorization is required for initial treatment |
| Documentation must include clinical history | Documentation must include clinical history |
| Re-review every 24 months | Re-review every 12 months with updated clinical documentation |
CPT, HCPCS, and ICD-10 Codes for Inner Ear Oxygen Therapy Under NCD 43
Covered CPT Codes
The policy does not list any covered CPT or HCPCS codes. No covered indication exists under NCD 43 for this therapy.
Not Covered — No Specific Codes Listed in Policy
This is worth flagging plainly: NCD 43 does not specify CPT or HCPCS codes in its current version. The policy is written at the procedure-description level, not the code level. That creates a real billing challenge.
Without explicit codes in the NCD, your billing team has to apply clinical judgment to determine which codes would represent this service if a provider attempted to bill it. Common candidates from other contexts might include inhalation therapy administration codes, but CMS has not tied specific codes to this NCD.
What this means for your team: If a provider performs and documents O2/CO2 inhalation therapy for an inner ear condition, and your team selects a code to bill, that code will not have NCD 43 explicitly attached as a denial trigger in your claims editor. The denial may come back on other grounds — or not at all if the code isn't flagged. Either way, the service is non-covered, and billing it to Medicare without an ABN is a compliance problem.
Talk to your compliance officer or billing consultant to identify which codes your practice would use for this service, and manually tie them to the non-covered status in your system. Don't rely on the claims editor to catch this automatically.
Key ICD-10-CM Diagnosis Codes
The policy does not list specific ICD-10-CM codes. However, the conditions named in NCD 43 map to the following diagnoses. Use these to identify at-risk claims in your system:
| Diagnosis | Relevant ICD-10 Direction |
|---|---|
| Endolymphatic hydrops / Ménière's disease | Search ICD-10-CM H81 category (Disorders of vestibular function) |
| Fluctuant sensorineural hearing loss | Search ICD-10-CM H90 category (Conductive and sensorineural hearing loss) |
These are directional — not policy-specified codes. Your coding team should confirm the right ICD-10 codes against the current ICD-10-CM code set and your clinical documentation. But these categories are where you'll find the diagnoses NCD 43 names.
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