CPT code 94681: Gas-exchange analysis, CO2 output and derived measures2026 Medicare rate & RVUs in Texas
Reports expired-gas analysis measuring oxygen uptake, carbon dioxide output, oxygen extraction, and derived values at rest or during exercise.
Medicare pays $46.21–$52.46 for 94681 in the office in Texas, from Beaumont, TX to Austin, TX. Which amount applies depends on the service address.
Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.
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On this page 9 sections
What 94681 covers
This test analyzes expired gas to quantify oxygen uptake, carbon dioxide output, oxygen extraction percentage, and related derived values. It may be performed at rest or with exercise, often in a pulmonary function or exercise physiology laboratory when a clinician needs detailed metabolic gas-exchange data. Pulmonary laboratory staff, such as respiratory therapists, typically operate the analyzer, with a qualified professional interpreting the results.
Select 94681 when the performed analysis includes carbon dioxide output, oxygen extraction, and other derived gas-exchange measures; document the test conditions, whether exercise was used, the measurements, and the interpretation. Distinguish it from simpler oxygen-uptake analysis and indirect resting measurement. CMS recognizes professional and technical components: report modifier 26 for interpretation, TC for equipment and staff, or neither modifier for the global service.
This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.
Where 94681 pays more and less in Texas
The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.
8 payment localities
$46.21 to $52.46
8 of 8 payment localities
| Payment locality | Office | Facility |
|---|---|---|
| Austin, TX | $52.46 | Unavailable |
| Beaumont, TX | $46.21 | Unavailable |
| Brazoria, TX | $49.55 | Unavailable |
| Dallas, TX | $49.85 | Unavailable |
| Fort Worth, TX | $49.44 | Unavailable |
| Galveston, TX | $49.69 | Unavailable |
| Houston, TX | $50.23 | Unavailable |
| Rest of Texas | $47.84 | Unavailable |
How the 94681 rate is calculated
Each of 94681’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.
How the rate is built · 94681
RVUs × geographic indexes × conversion factor
Work0.20
0.20 RVUs× 1.000 GPCI
Practice expense1.27
1.27 RVUs× 1.000 GPCI
Malpractice0.03
0.03 RVUs× 1.000 GPCI
Adjusted RVUs
1.5000
Conversion factor
$33.4009
Medicare rate
$50.10
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 94681
The CMS indicators that decide how 94681 is paid alongside other services.
CMS payment indicators · 94681
Gas-exchange analysis, CO2 output and derived measures
| Rule | CMS value | What it means |
|---|---|---|
| Global period | XXX | The global surgery concept doesn’t apply. |
| Multiple procedures | 0 | No multiple-procedure reduction. |
| Bilateral (modifier 50) | 0 | The 150% bilateral adjustment doesn’t apply. |
| Assistant at surgery (80/81/82/AS) | 0 | Not paid without supporting documentation. |
| Co-surgeons (62) | 0 | Not permitted. |
| Team surgery (66) | 0 | Not permitted. |
| Professional/technical | 1 | Diagnostic test with separate professional (26) and technical (TC) components. |
What modifiers do to the payment
Modifier 26 · payment effect
With and without the modifier
94681 without 26 · national office
$50.10
Gas-exchange analysis, CO2 output and derived measures
94681-26 · Professional component
$9.69
Pays only the interpretation and report.
94681 compared with similar codes
Compare codes · National
4 codes, side by side
How to choose
- 94680Oxygen uptake testDirect, rest and exercise
- 94680 represents simpler oxygen-uptake analysis. 94681 includes carbon dioxide output, oxygen extraction, and related derived measures.
- 94690Metabolic testingResting oxygen uptake
- 94690 is an indirect oxygen-uptake measurement at rest. 94681 analyzes a broader set of expired-gas measures and may be performed with or without exercise.
- 94621Exercise testCardiopulmonary gas analysis
- 94621 is a broader cardiopulmonary exercise test with electrocardiographic recording. Use 94681 for the expired-gas analysis when that full exercise-testing service is not performed.
94681 billing questions
How does 94681 differ from 94680?
94681 captures carbon dioxide output, oxygen extraction, and additional derived gas-exchange values. Use 94680 for the simpler oxygen-uptake analysis described by that code.
Can 94681 be performed without exercise?
Yes. The analysis may be performed at rest or with exercise; document the conditions under which the gas measurements were obtained.
Which modifiers identify the professional and technical components?
Append modifier 26 for the interpretation and TC for the equipment and staff portion. Without either modifier, the claim represents the global service.
Are oxygen uptake and the derived gas measurements separate units?
No. Report the analysis as one service rather than separate units for each gas measurement or derived value.
When would 94621 be a better fit?
94621 describes cardiopulmonary exercise testing with electrocardiographic recording and gas-exchange measurements. Choose it when that broader exercise test is performed rather than an expired-gas analysis alone.
Where these rates come from
FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.
CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027
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