CPT Code 00400: Under Anesthesia for Procedures on the Thorax (Chest Wall and Shoulder Girdle)

What is CPT Code 00400?

CPT code 00400 describes anesthesia services provided during surgical or procedural interventions on the integumentary system of the extremities, anterior trunk, or perineum, when no other specific anesthesia CPT code applies. Certified registered nurse anesthetists (CRNAs) and anesthesiologists commonly use this code when providing general anesthesia, monitored anesthesia care (MAC), or regional anesthesia for procedures such as biopsies, lesion removals, or wound repairs on the chest wall or shoulder girdle. Providers choose the appropriate anesthesia technique based on patient factors ranging from minimal anesthesia risk to those with severe systemic disease or severe cardiopulmonary disease.

Proper reporting of the 00400 CPT code ensures accurate billing for anesthesia personnel involved in these moderately to markedly invasive surgical procedures.

What is anesthesia for thoracic procedures?

Anesthesia for thoracic procedures involves general, regional, or local anesthesia administered by qualified anesthesia personnel to manage pain and patient comfort during surgical interventions on the chest wall or shoulder girdle. These anesthesia services provide effective pain control, muscle relaxation, and patient safety throughout the surgery.

Thoracic procedures may range from minimally invasive integumentary system surgeries with minimal anesthesia risk to more complex interventions associated with severe pain or severe cardiopulmonary disease.

CPT code 00400 documentation requirements

Comprehensive and clear documentation supports medical necessity and accurate anesthesia billing.

Preoperative evaluation

Clearly document the preoperative evaluation, including patient medical history, physical examination findings, anesthesia risk assessment, and indication for surgery.

Procedure performed and surgical CPT code

Include the exact surgical procedure performed along with the corresponding surgical CPT code to clearly link anesthesia services related to the specific procedure.

Anesthesia time (time in and time out)

Precisely record anesthesia time from the moment anesthesia personnel begin preparing the patient for anesthesia until patient care transfers postoperatively. Clearly document start and end times.

Anesthesia technique

Document the type of anesthesia administered—general anesthesia, regional anesthesia, local anesthesia, or monitored anesthesia care—along with the rationale for the chosen approach.

Drugs administered and monitoring details

List all medications administered during anesthesia, including dosages, routes, and patient responses. Document monitoring methods used to ensure patient safety throughout the anesthesia procedure.

Postoperative status and patient disposition

Provide details of the patient's immediate postoperative status, including recovery conditions, complications, and disposition (e.g., discharged home, transferred to recovery room or ICU).

CPT code 00400 billing guidelines

Accurate billing guidelines ensure compliance with payer policies and correct reimbursement for anesthesia codes.

Base unit value and time reporting

CPT 00400 has a base unit value of 7. Add additional time units calculated in 15-minute increments of actual anesthesia care provided to the base units to determine total billing units.

Modifier usage for provider role

Use anesthesia modifiers (e.g., -AA, -QX) to specify the role of anesthesia personnel providing the anesthesia services. Accurate modifier application ensures clarity in claims processing.

Report surgical CPT code for medical necessity

Always pair CPT 00400 with the surgical CPT code for the procedure performed. This clearly establishes medical necessity and justifies the provision of anesthesia care.

Physical status modifiers

Append physical status modifiers (P1–P6) to indicate the patient’s health condition, from mild systemic disease to severe systemic disease or severe cardiopulmonary disease, providing important context for anesthesia complexity and reimbursement.

Verify payer guidelines

Always confirm specific payer policies regarding anesthesia time reporting protocols, concurrency limits, and allowable modifiers to prevent denials or reimbursement delays.

Other relevant CPT codes

• 00520 – Anesthesia for thoracotomy involving lungs
• 00300 – Anesthesia for neck procedures
• 01967 – Neuraxial labor anesthesia
• 00402 – Anesthesia for procedures on the integumentary system, reconstructive procedures on breast
• 00450 – Anesthesia for procedures on the clavicle and scapula