7 Mar 2018

Anesthesia Coding Guidelines


  Anesthesia is a state of temporary induced (Drug/Gas) loss of sensation or awareness. The CPT code range from 00100 – 01999 plus “Anesthesia modifier”.  

  An Anesthesiologist, Anesthesia assistant or qualified non-physician anesthetist can provide Anesthesia service.

Types of Anesthesia:


  Regional and


(General anesthesia suppresses the CNS, Regional and local anesthesia block transmission of nerve impulses)

Included services
        1.   Preoperative & Postoperative care
        2.   Administration of fluids and/or Blood
        3.   Monitoring services (Eg: BP, Temperature, ECG, Oximetry, Mass Spectrometry, and Capnography)

Excluded services
       1.   Other Monitoring services like Central venous, Intra-arterial and Swan-Ganz

Anesthesia coding Guidelines:

  Select the appropriate CPT code for the surgical procedure performed, and then select the appropriate ASA crosswalk code.

  Select the base unit and time unit.

  Select the appropriate modifier to identify the anesthesia provider.

  Assign the appropriate Physical status modifier

  Assign the appropriate qualifying circumstances codes if applicable.

How to calculate the Anesthesia Service for reimbursement is given below, 
(Base unit + Total Time unit) x Conversion Factor = Allowance

Anesthesia Base Unit:

        Base units are assigned to anesthesia CPT codes by the CMS. Base units are determined based on complexity of the procedures. Easier the case it’s less base unit and difficult cases have the high base unit.

Multiple procedures at the same session:

        If multiple surgical procedures are performed during a single anesthesia administration, then only the highest base unit value CPT code should be reported. But the total time spent for all procedures would be considered for Anesthesia Time unit.

Anesthesia Time Unit:

         1.   Start Time: The anesthesiologist begins to prepare the patient for the induction of anesthesia in the operating room.  (Note: reviewing Medical Record before surgery is not considered)

         2.   End Time: The anesthesiologist is no longer in personal attendance; the patient may be safely placed under postoperative supervision.  

Time of anesthesia is calculated in units (Each 15 min = 1 unit)
Total anesthesia time should be recorded in minutes. Each 15 min is equal to one unit

Eg: A 45 minutes procedure (From start to finish) it is 3 units of anesthesia time. Do not round up or down the total time.  (Total procedure time divided by 15)
Eg: For a 63-minute procedure, it is 4.2 time units
                For a 79 minute procedure, it is 5.3 time units

Note: For certain insurance there may be round up or round down concepts applicable, anything below 7.5 minutes round down and above 8 min round up.

For Eg: 39 min should be considered as 3 units (15+15+9). And 37 min should be considered as 2 units (15+15+7).

Discontinuous Time

      There may be some interruptions in anesthesia care during a procedure; if the provider is no longer personally attending the patient should be recorded correctly about the interrupted timings.

Eg: The anesthesiologist begins care at 9.00, care interrupted at 9.25 (25 minutes) and resumes care at 9.30 ending care at 9.55 (25 minutes), there would be 50 minutes of anesthesia time. This would be 3.3 Time units.

Conversion Factor:

CMS releases annually and is specific to the locality where the anesthesia service is rendered

Anesthesia Modifiers:

For Anesthesiologist

       1.   AA: Anesthesia services performed personally by anesthesiologist (or) an anesthetist assists a physician in the care of a single patient.

       2.   QY: Medical direction of one Qualified Non-physician

       3.   QK: Medical direction of two, three or four concurrent anesthesia procedures involving qualified individuals.

       4.   AD: Medical supervision by a physician: more than four concurrent anesthesia procedures.

For Non-physician Anesthetist

       1.   QX: Qualified Non-physician Anesthetist service: with medical direction by a physician.

       2.   QZ: Qualified Non-physician Anesthetist service: without medical direction by a physician.

For MAC (Monitored Anesthesia Care)
       1.   QS: MAC (Can be billed by Qualified Non-physician Anesthetist / Anesthesia Assistant/physician)
       2.   G8: MAC for deep complex or complicated / markedly invasive surgical procedure
       3.   G9: MAC for a patient who has severe cardiopulmonary conditions

Physical Status Modifiers:

Physical status modifiers are used for reporting the overall physical health of a patient at the time of a procedure.

    P1 - A normal healthy person (units = 0) 

    P2 - A patient with mild systemic disease (units = 0) 
    P3 - A patient with severe systemic disease (units = 1) 

    P4 - A patient with severe systemic disease that is a constant threat to life (units = 2) 

    P5 - A moribund patient who is not expected to survive without the operation (units = 3) 

    P6 - A declared brain-dead patient whose organs are being removed for donor purposes (units = 0)

Eg: A patient has hypertension. Append modifier P2 (Systemic disease is not stated as uncontrolled)

A patient has uncontrolled DM – Append modifier P3 (Due to the severe systemic disease)

A patient met with an accident and is dead on arrival to the hospital – Append modifier P6 (is an organ donor)

Billing Guidelines: Except Medicare all other insurance allow physical status modifiers to receive additional total units of anesthesia service reported for patients.

Qualifying Circumstances:

      Many anesthesia services are provided under complicated circumstances, Depending on the risk factors there are few Qualifying circumstances add on codes are coded along with anesthesia procedures in order to get a higher payment.

+99100 Anesthesia for a patient of extreme age, younger than 1 year and older than 70 (List separately in addition to code for primary anesthesia procedure) is 1 unit of anesthesia.

(Some exceptions are 00326, 00561, 00834, 00836 procedures performed on infants younger than 1 year of age at the time of surgery).

+99116 Anesthesia complicated by utilization of total body hypothermia (List separately in addition to code for primary anesthesia procedure)

+99135 Anesthesia complicated by utilization of controlled hypotension (List separately in addition to code for primary anesthesia procedure)

+99140 Anesthesia complicated by emergency conditions (specify) (List separately in addition to code for primary anesthesia procedure)

Important Abbreviations:

CRNA: Certified registered nurse anesthelogist

SRNA: Student registered nurse anesthetist

MAC: Monitored anesthesia care


Test your Knowledge:

            A. Anesthesia CPC Sample Quiz