Carbogen Inhalation Therapy — CPB 0428 | AETNA Coverage Update

Aetna modified CPB 0428 governing carbogen inhalation therapy, effective September 26, 2025. Here's what billing teams need to know.

Aetna updated Clinical Policy Bulletin 0428 to address carbogen inhalation therapy coverage. The CPB 0428 policy spans a broad set of oncologic and non-oncologic diagnoses — 110 ICD-10-CM codes in total — covering conditions from head and neck malignancies to retinal vascular occlusions and sudden idiopathic hearing loss. If your practice treats any of these conditions and has billed or considered billing for carbogen therapy, this update deserves a close read before September 26, 2025.

Quick-Reference Table

Aetna Carbogen Inhalation Therapy Coverage Criteria 2025

Carbogen is a gas mixture — typically 95% oxygen and 5% carbon dioxide — used in clinical settings to increase tumor oxygenation during radiation therapy. The theory is straightforward: hypoxic tumors respond poorly to radiation, and carbogen may reverse that hypoxia. The clinical evidence, however, has been debated for decades.

The source policy summary for CPB 0428 does not detail specific coverage criteria or medical necessity requirements. Pull the full CPB 0428 text from Aetna's provider portal to review the complete clinical criteria before billing.

Prior authorization requirements are not detailed in the available policy data. Confirm directly with Aetna before billing.

The Aetna carbogen inhalation therapy coverage policy applies across multiple specialties. Oncologists, radiation oncologists, ophthalmologists treating retinal vascular occlusions, ENT practices treating sudden idiopathic hearing loss (H91.20–H91.22), and neurologists treating epilepsy (G40.001–G40.919) are all in scope here. That's an unusually wide net for a single CPB, and it means this policy touches more specialties than most billing teams expect.

Aetna Carbogen Inhalation Therapy Exclusions and Non-Covered Indications

The available policy data does not enumerate specific exclusions. Refer to the full CPB 0428 text on Aetna's provider portal for coverage limitations.

Coverage Indications at a Glance

Inclusion in the CPB 0428 ICD-10 code set does not guarantee coverage. Pull the full policy text from Aetna's provider portal to confirm coverage criteria, exclusions, and any indication-specific requirements before billing.

Aetna Carbogen Inhalation Therapy Billing Guidelines and Action Items 2025

These are direct steps your billing team should take before September 26, 2025.

CPT, HCPCS, and ICD-10 Codes for Carbogen Inhalation Therapy Under CPB 0428

The policy data for CPB 0428 does not list specific CPT or HCPCS procedure codes. Carbogen inhalation therapy billing typically runs through unlisted procedure codes or specific respiratory/inhalation therapy codes depending on the clinical setting. Confirm the correct procedure code with your billing consultant or Aetna directly, as the applicable billing code may vary by care setting.

Key ICD-10-CM Diagnosis Codes

The policy data notes 30 additional ICD-10-CM codes not reproduced in the source data above. Pull the full CPB 0428 text from Aetna's provider portal to confirm the complete code list before auditing your claims.