CPT Code 00546: Anesthesia for pulmonary resection with thoracoplasty

Key takeaways

CPT Code 00546 covers anesthesia for thoracotomy procedures on the lungs, pleura, diaphragm, and mediastinum when pulmonary resection is performed together with thoracoplasty.

This code carries 15 anesthesia base units, higher than the 12 base units assigned to CPT 00540, the standalone code for unspecified thoracotomy procedures.

Modifier selection is the most common denial trigger. Modifier AA applies when an anesthesiologist personally performs the service, while QK, QX, QY, or QZ apply under anesthesia care team and CRNA arrangements.

Practice management software like Pabau keeps pre-anesthesia evaluations, operative notes, and diagnosis documentation together in one patient record, supporting accurate CPT Code 00546 claims.

CPT Code 00546 is the anesthesia code for thoracotomy procedures involving the lungs, pleura, diaphragm, and mediastinum. It applies when the surgeon performs pulmonary resection together with thoracoplasty, and it carries 15 base anesthesia units within the 00540-00548 thoracotomy and thoracoscopy sub-group.

This reference guide covers the official descriptor, base unit value, and applicable modifiers. It also covers the Medicare reimbursement formula, ICD-10 crosswalk, related thoracotomy codes, and documentation requirements that most billing references skip. Anesthesia coders, billing specialists, and practice management teams running thoracic surgery programs will find the key facts needed for clean claim submission.

CPT Code 00546: definition, descriptor, and clinical context

The key clinical requirement for 00546 is that the operative report documents pulmonary resection performed together with thoracoplasty — not either procedure alone. Thoracoplasty involves the surgical removal or collapse of ribs to reduce the volume of the chest cavity. This typically closes a space left after lung tissue is removed. The code is selected by the procedure the surgeon performs, not by the patient’s underlying lung physiology. A patient’s overall respiratory status is instead captured separately, through the ASA physical status modifier (P1-P6) attached to the anesthesia claim. The added complexity of combining resection with chest-wall surgery is why this code carries 15 base units, per the AMA CPT code set.

Anesthesia base units and the reimbursement formula

CPT Code 00546 carries 15 anesthesia base units. This value reflects the relative complexity of anesthesia services compared to other procedures. Base units alone do not determine reimbursement: Medicare and most commercial payers use a formula that combines base units with time units.

The standard formula, as outlined in the CMS Physician Fee Schedule, is:

Time unit documentation is where many 00546 claims fail audit. The anesthesia start and stop times must be recorded in the anesthesia record and must match the time units billed. A two-hour procedure billed as 10 time units (150 minutes) without supporting documentation will trigger a take-back. Practice management software like Pabau keeps the pre-anesthesia evaluation, operative note, and anesthesia record together in one patient file. That makes it easier to confirm the documented times match what’s billed before a claim goes out.

Medicare reimbursement and fee schedule for CPT Code 00546

Medicare calculates anesthesia payments using the base-plus-time formula above, multiplied by a geographic locality conversion factor. The conversion factor is updated annually in the Medicare Physician Fee Schedule. It varies by state and by locality within states. Billing teams should always pull the current-year rate from the CMS fee schedule lookup tool rather than relying on prior-year figures. A single percentage-point change in the CF alters payment on every unit billed.

Unlike codes on the standard Medicare Physician Fee Schedule, anesthesia codes such as 00546 are not priced through the work/practice-expense/malpractice RVU methodology. They also carry no facility versus non-facility split. Payment instead uses the base-plus-time formula above, multiplied by the same locality conversion factor regardless of setting.

A thoracotomy combining pulmonary resection with thoracoplasty is a major procedure. It would essentially never be performed outside a hospital or ambulatory surgical center. As a result, the facility/non-facility distinction that applies to standard physician fee schedule codes does not come into play for this code in practice.

For Medicare Advantage plans and commercial payers, rates are negotiated separately and may differ substantially from Medicare fee schedule amounts. Always verify the applicable contract rate before estimating expected reimbursement for CPT Code 00546.

Applicable modifiers for CPT Code 00546

Modifier selection is the single most common reason CPT Code 00546 claims are denied. The correct modifier depends on who performed the anesthesia service and under what supervision arrangement. The Centers for Medicare and Medicaid Services (CMS) specifies these distinctions in Chapter 12 of the Medicare Claims Processing Manual.

The anesthesiologist bills QK and the CRNA bills QX on the same claim, and both submit simultaneously. Together, the two modifiers add up to 100% of the Medicare allowed amount. A common error is billing modifier AA when a CRNA was involved in any capacity. This misrepresents the service and creates a billing compliance risk under the False Claims Act.

CRNA scope of practice and billing authority under modifier QZ varies by state law. In opt-out states, CRNAs may bill 100% of the Medicare anesthesia fee without physician oversight. In non-opt-out states, the medical direction rules apply. Always confirm current state opt-out status before billing QZ for CPT Code 00546. Learn more about HIPAA-compliant billing workflows when managing these arrangements.

ICD-10 codes commonly paired with CPT Code 00546

Medical necessity for CPT Code 00546 hinges on the diagnosis code submitted with the claim. That diagnosis needs to support pulmonary resection combined with thoracoplasty specifically, not just a generic thoracic diagnosis. Payers look for ICD-10 codes tied to the conditions that most often require this combined procedure: chronic empyema, bronchiectasis, tuberculous cavitary disease, and thoracic malignancy. Submitting a diagnosis that only supports a resection, or only supports chest-wall surgery, without documentation that both were needed together, is a common crosswalk error. This error triggers medical necessity denials.

Always use the most specific ICD-10-CM code available. “Unspecified” codes are acceptable when clinical documentation does not support a more granular diagnosis, but they invite additional documentation requests from payers. The same specificity principle applies across unrelated ICD-10-CM crosswalks, including N83.8. A useful reference is the AAPC CPT-to-ICD-10 crosswalk tool.

CPT 00546 in the thoracotomy anesthesia code family

CPT Code 00546 sits within the thoracotomy subsection of the anesthesia code range. Understanding the sibling codes matters for accurate code selection. Choosing the wrong code within this family because of a shared procedure type is a common selection error. The codes below cover different clinical scenarios under the same surgical approach.

The selection between 00540 and 00546 trips up even experienced coders. The deciding factor is whether the operative note documents pulmonary resection performed together with thoracoplasty, not the patient’s underlying lung pathology. When both are present, 00546 applies. When the note describes a thoracotomy that doesn’t fit any of the more specific codes in this sub-group, 00540 is the correct choice.

Cardiothoracic anesthesia billing extends beyond this sub-group too. CPT 00566 covers anesthesia for off-pump coronary artery bypass grafting, a related but separate code family. For a broader procedure code lookup, billing teams can also consult the AAPC Codify CPT lookup.

Documentation requirements for CPT Code 00546 claims

Most CPT code reference pages stop at the base units and modifiers. The documentation requirements are where practices lose money in post-payment audits. For CPT Code 00546, the anesthesia record must support three distinct billing elements. These are the procedure performed, the time billed, and the medical necessity of anesthesia for a procedure combining pulmonary resection with thoracoplasty.

CMS requires the following documentation for a clean anesthesia claim:

• Pre-anesthesia evaluation: Documented before the procedure, covering the patient’s history, physical status (ASA classification), airway assessment, and planned anesthetic technique. This must be a separate note, not embedded in the surgical H&P.
• Anesthesia record (intraoperative): Continuous time-stamped monitoring of vital signs, drug administration, ventilator settings, and the anesthetist identity. Start and stop times must be explicitly recorded.
• Post-anesthesia note: A discharge evaluation documenting the patient’s status and any post-operative complications or concerns. Required within a defined period after emergence from anesthesia.
• Diagnosis documentation: The operative report must confirm that pulmonary resection was performed together with thoracoplasty, not either procedure alone. “Pulmonary resection with thoracoplasty for chronic empyema” in the surgeon’s note directly supports 00546. A note referencing only thoracoplasty, or only a resection, without linking the two, fails to establish medical necessity for 00546.
• Modifier justification: If billing under QK/QX (ACT arrangement), the record must document that the anesthesiologist met all seven conditions for medical direction during the case.

Practices that use standardized pre-anesthesia evaluation forms within their clinical documentation workflow reduce the risk of audit deficiencies. A template that prompts for ASA classification, airway assessment, and procedure-specific risk factors ensures nothing is omitted. For guidance on maintaining medical office compliance documentation standards, CMS’s Claims Processing Manual Chapter 12 is the authoritative reference.

Common billing errors and denial reasons for CPT Code 00546

Denials on CPT Code 00546 cluster around four patterns. Each is preventable with the right process controls in place.

When denials do occur, the remittance advice code points directly to the root cause. CARC-4 (“the procedure code is inconsistent with the modifier used, or a required modifier is missing”) points to the modifier error covered above. CARC-16 (claim lacks information) points to missing documentation.

RARC MA130 means the claim itself contains incomplete or invalid information and cannot be processed at all. This is not a prior-authorization denial. A missing authorization typically comes back as CARC-197 instead.

Tracking denial patterns by code helps billing managers identify whether the issue is systematic or case-specific. The same modifier and documentation scrutiny applies to other anesthesia codes, including CPT 01999 for unlisted anesthesia procedures.

Practices that keep operative notes, ICD-10 codes, and modifier details together in one patient record catch more mismatches before submission. That beats catching them after a denial comes back. Medical records management software like Pabau supports that kind of centralized record-keeping.

How Pabau keeps thoracic anesthesia documentation in one place

Anesthesia billing for a procedure like CPT Code 00546 touches a lot of separate records:

• The pre-anesthesia evaluation
• The surgeon’s operative note
• The anesthesia record with start and stop times
• The ICD-10 diagnosis that has to match all of it

When those live in different systems, or on paper, it’s easy for one detail to drift out of sync before a claim goes out.

Practice management software like Pabau keeps a patient’s full clinical record — evaluations, treatment notes, and supporting documentation — in a single digital file. That beats splitting the same information across paper charts and a separate billing system.

This makes it faster to confirm that a diagnosis, an operative note, and a recorded time all tell the same story. That check happens before the claim leaves the building.

The result is fewer last-minute scrambles to track down a missing note before a submission deadline. It also means fewer claims come back because two documents in the file didn’t agree. For a code family with as many moving parts as anesthesia billing, that consistency is worth having.

Practices in plastic surgery and physical therapy face similar pressure to keep procedure notes, diagnosis codes, and treatment records aligned before a claim goes out. That same discipline is what makes CPT Code 00546 claims easier to defend.

Keep thoracic anesthesia documentation audit-ready

Pabau brings pre-anesthesia evaluations, operative notes, and diagnosis documentation together in one patient record, so your team can confirm every detail matches the claim before it goes out.

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Conclusion

CPT Code 00546 rewards precision over speed. The code exists for one specific combination: pulmonary resection performed together with thoracoplasty. Billing it correctly means resisting the urge to reach for 15 units whenever a thoracotomy looks complex enough to justify them.

Get the underlying procedure right, and the rest of the claim tends to follow. The ICD-10 code aligns with a condition that calls for the combined procedure. The modifier reflects who was really in the room, and the documented time matches what’s billed. Skip that first step, and no amount of clean paperwork elsewhere in the claim will save it from a medical necessity denial.

Practices that build this check into their pre-submission workflow, rather than their appeals process, see the difference in first-pass acceptance rates. Book a demo to see how Pabau keeps thoracic anesthesia documentation consistent from the pre-anesthesia evaluation through to the claim.

Continue your research

Need a billing reference for related anesthesia codes? Coaching CPT codes provides an additional CPT billing reference covering documentation requirements and modifier application across outpatient procedure codes.

Looking to streamline pre-anesthesia intake documentation? Medical forms for healthcare practices covers how standardized digital forms reduce missing documentation and audit risk for clinical procedures.

Managing HIPAA compliance across your billing team? HIPAA and social media outlines the patient data handling obligations that apply to clinical documentation workflows, including billing records.

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