Re-breathing of Inert Gas for Measurement of Cardiac Output and Validation of Intra-Cardiac Shunt — CPB 0714 | AETNA Coverage Update

Aetna modified CPB 0714 covering inert gas rebreathing for cardiac output measurement and intra-cardiac shunt validation, effective November 27, 2025. All three clinical applications remain non-covered — here's what your billing team needs to know before submitting claims.

Aetna, a CVS Health company, updated Clinical Policy Bulletin CPB 0714 Aetna system on November 27, 2025. The policy addresses rebreathing of inert gas across three distinct indications: measuring cardiac output, predicting survival in pulmonary hypertension, and validating intra-cardiac shunt. All three remain classified as experimental, investigational, or unproven. If your practice bills these services for Aetna members — particularly patients with diagnoses under ICD-10 codes I27.x (pulmonary hypertension) or Q21.x (congenital cardiac septal defects) — this coverage policy directly affects your denial exposure.

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Quick-Reference Table

Field	Detail Copy
Payer	Aetna, a CVS Health company
Policy	Re-breathing of Inert Gas for Measurement of Cardiac Output and Validation of Intra-Cardiac Shunt
Policy Code	CPB 0714
Change Type	Modified
Effective Date	November 27, 2025
Impact Level	Medium
Specialties Affected	Cardiology, Pulmonology, Congenital Heart Disease Programs
Key Action	Flag all inert gas rebreathing claims for Aetna members and route to denial management before submission

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Aetna Inert Gas Rebreathing Coverage Criteria and Medical Necessity Requirements 2025

The Aetna inert gas rebreathing coverage policy is unambiguous: there is no covered indication. Aetna does not recognize rebreathing of inert gas as meeting medical necessity for any of the three applications addressed in CPB 0714.

This isn't a documentation problem. There's no set of supporting records, physician attestations, or prior authorization requests that unlocks reimbursement here. Aetna's position is that the clinical evidence doesn't support effectiveness — full stop.

The three applications covered under CPB 0714 are measurement of cardiac output, prediction of survival in pulmonary hypertension, and validation of intra-cardiac shunt. Each one carries the same experimental designation. If your team has been submitting these claims hoping for case-by-case review, stop. The denial will come, and the policy gives Aetna a clear basis to issue it.

For practices treating pulmonary hypertension patients — coded under the I27.x range — or patients with congenital cardiac septal defects under Q21.x, this is the policy governing Aetna's position on non-invasive cardiac output measurement via inert gas. If you're using this modality in your clinical workflow, your billing guidelines need to reflect that it's a non-covered service for Aetna members.

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Aetna Inert Gas Rebreathing Exclusions and Non-Covered Indications

Every clinical application in CPB 0714 is excluded from coverage. There are no carve-outs, no subpopulation exceptions, and no pathway to prior authorization approval — because Aetna doesn't offer one for services it classifies as experimental.

Rebreathing of inert gas for cardiac output measurement is non-covered. This applies regardless of whether the patient has heart failure, pulmonary arterial hypertension, or a hemodynamic monitoring indication that seems clinically straightforward.

Rebreathing of inert gas for survival prediction in pulmonary hypertension is non-covered. Patients coded under I27.0 through I27.29 — the full range of pulmonary hypertension ICD-10 codes in this policy — don't have a covered pathway for this application under Aetna.

Rebreathing of inert gas for intra-cardiac shunt validation is non-covered. This affects patients with congenital cardiac septal defects coded under Q21.0 through Q21.9. If your cardiology or congenital heart program uses inert gas rebreathing to quantify shunt fraction, Aetna will not reimburse it.

The real issue here is workflow. Practices that use inert gas rebreathing as a standard diagnostic step may not have flagged it as a non-covered service for Aetna. The November 27, 2025 effective date makes this a good moment to audit your charge capture and your ABN (Advance Beneficiary Notice equivalent — in this case, a patient financial responsibility notice for commercial plans) processes.

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Coverage Indications at a Glance

Indication	Status	Relevant ICD-10 Codes	Notes Copy
Inert gas rebreathing for cardiac output measurement	Not Covered — Experimental	I27.0–I27.29 (when pulmonary hypertension is the underlying indication)	No prior authorization pathway available
Inert gas rebreathing for survival prediction in pulmonary hypertension	Not Covered — Experimental	I27.0, I27.20–I27.29	Applies to full I27.x subcategory range
Inert gas rebreathing for intra-cardiac shunt validation	Not Covered — Experimental	Q21.0–Q21.9	Applies to all congenital cardiac septal defect codes

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Aetna Inert Gas Rebreathing Billing Guidelines and Action Items 2025

The November 27, 2025 effective date has passed. If your team hasn't already reviewed your Aetna inert gas rebreathing billing workflow, do it now.

Copy Action Items

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CPT, HCPCS, and ICD-10 Codes for Inert Gas Rebreathing Under CPB 0714

The CPB 0714 policy document does not list specific CPT or HCPCS procedure codes. Aetna's bulletin addresses this service at the clinical technique level. Your billing team should work with your clinical and compliance staff to identify which procedure codes your practice uses to bill inert gas rebreathing services, then confirm how Aetna's non-coverage position applies to those codes.

Key ICD-10-CM Diagnosis Codes

These are the diagnosis codes explicitly listed in CPB 0714. They represent the patient populations most likely to receive inert gas rebreathing services.

Pulmonary Hypertension (I27.x)

Congenital Cardiac Septal Defects / Intra-Cardiac Shunt (Q21.x)

A note on the Q21.x descriptions: the policy data labels all Q21 codes uniformly as "congenital malformations of cardiac septa [intra cardiac shunt]." Your clinical documentation team should use the most specific code that matches the patient's confirmed defect. The specific Q21 subcodes carry distinct clinical meanings, even if Aetna's policy groups them together for non-coverage purposes.

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A Note on the Absence of CPT Codes in CPB 0714

The fact that CPB 0714 lists no CPT or HCPCS codes is itself worth flagging. Most Aetna clinical policy bulletins include specific procedure codes. This one doesn't — and that creates a gray zone.

Your billing team can't just look up a code, see it listed as non-covered, and move on. You need to identify what codes your practice currently uses for inert gas rebreathing services, then apply Aetna's experimental designation to those codes in your internal payer rules. That's a clinical-billing collaboration, not a unilateral billing decision.

If your documentation refers to inert gas rebreathing by a specific method name — inert gas rebreathing cardiac output, or a branded device name — make sure your compliance officer reviews how that maps to your procedure codes before the next claim goes out. A claim denial based on experimental designation is recoverable. A pattern of claims that should have been patient-pay creates a different kind of problem.

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