Medicare Claims Processing Manual (Pub. 100-04), Ch. 12 § 50
Payment for Anesthesiology Services
50 - Payment for Anesthesiology Services
(Rev. 3747; Issued: 04-14-17; Effective: 01-01-17; Implementation: 05-15-17)
A. General Payment Rule
The fee schedule amount for physician anesthesia services furnished is, with the exceptions
noted, based on allowable base and time units multiplied by an anesthesia conversion factor
specific to that locality. The base unit for each anesthesia procedure is communicated to the
A/B MACs by means of the HCPCS file released annually. CMS releases the conversion
factor annually. The base units and conversion factor are available on the CMS website at:
https://www.cms.gov/Center/Provider-Type/Anesthesiologists-Center.html.
B. Payment at Personally Performed Rate
The A/B MAC must determine the fee schedule payment, recognizing the base unit for the
anesthesia code and one time unit per 15 minutes of anesthesia time if:
• The physician personally performed the entire anesthesia service alone;
• The physician is involved with one anesthesia case with a resident, the physician is a teaching
physician as defined in §100;
• The physician is involved in the training of physician residents in a single anesthesia case, two
concurrent anesthesia cases involving residents or a single anesthesia case involving a resident
that is concurrent to another case that meets the requirements for payment at the medically
directed rate. The physician meets the teaching physician criteria in §100.1.4;
• The physician is continuously involved in a single case involving a student nurse anesthetist;
• If the physician is involved with a single case with a qualified nonphysician anesthetist (a
certified registered nurse anesthetist (CRNA) or an anesthesiologist’s assistant)), A/B MACs
may pay the physician service and the qualified nonphysician anesthetist service in accordance
with the requirements for payment at the medically directed rate;
Or
• The physician and the CRNA (or anesthesiologist’s assistant) are involved in one anesthesia
case and the services of each are found to be medically necessary. Documentation must be
submitted by both the CRNA and the physician to support payment of the full fee for each of
the two providers. The physician reports the AA modifier and the CRNA reports the QZ
modifier.
C. Payment at the Medically Directed Rate
The A/B MAC determines payment at the medically directed rate for the physician on the basis
of 50 percent of the allowance for the service performed by the physician alone. Payment will
be made at the medically directed rate if the physician medically directs qualified individuals
(all of whom could be CRNAs, anesthesiologists’ assistants, interns, residents, or combinations
of these individuals) in two, three, or four concurrent cases and the physician performs the
following activities.
• Performs a pre-anesthetic examination and evaluation;
• Prescribes the anesthesia plan;
• Personally participates in the most demanding procedures in the anesthesia plan, including, if
applicable, induction and emergence;
• Ensures that any procedures in the anesthesia plan that he or she does not perform are
performed by a qualified individual;
• Monitors the course of anesthesia administration at frequent intervals;
• Remains physically present and available for immediate diagnosis and treatment of
emergencies; and
• Provides indicated post-anesthesia care.
The physician must document in the medical record that he or she performed the pre-anesthetic
examination and evaluation. Physicians must also document that they provided indicated post-
anesthesia care, were present during some portion of the anesthesia monitoring, and were
present during the most demanding procedures in the anesthesia plan, including induction and
emergence, where indicated.
NOTE: Concurrency refers to to the maximum number of procedures that the physician is
medically directing within the context of a single procedure and whether these other procedures
overlap each other. Concurrency is not dependent on each of the cases involving a Medicare
patient. For example, if an anesthesiologist medically directs three concurrent procedures, two
of which involve non-Medicare patients and the remaining a Medicare patient, this represents
three concurrent cases.
The requirements for payment at the medically directed rate also apply to cases involving
student nurse anesthetists if the physician medically directs two concurrent cases, with each of
the two cases involving a student nurse anesthetist, or the physician directs one case involving
a student nurse anesthetist and another involving a qualified individual (for example: CRNA,
anesthesiologist’s assistant, intern or resident).
The requirements for payment at the medically directed rate do not apply to a single resident
case that is concurrent to another anesthesia case paid at the medically directed rate or to two
concurrent anesthesia cases involving residents.
If anesthesiologists are in a group practice, one physician member may provide the pre-
anesthesia examination and evaluation while another fulfills the other criteria. Similarly, one
physician member of the group may provide post-anesthesia care while another member of the
group furnishes the other component parts of the anesthesia service. However, the medical
record must indicate that the services were furnished by physicians and identify the physicians
who furnished them.
A physician who is concurrently furnishing services that meet the requirements for payment at
the medically directed rate cannot ordinarily be involved in furnishing additional services to
other patients. However, addressing an emergency of short duration in the immediate area,
administering an epidural or caudal anesthetic to ease labor pain, periodic (rather than
continuous) monitoring of an obstetrical patient, receiving patients entering the operating suite
for the next surgery, checking or discharging patients in the recovery room, or handling
scheduling matters, do not substantially diminish the scope of control exercised by the
physician and do not constitute a separate service for the purpose of determining whether the
requirements for payment at the medically directed rate are met.
However, if the physician leaves the immediate area of the operating suite for other than short
durations or devotes extensive time to an emergency case or is otherwise not available to
respond to the immediate needs of the surgical patients, the physician’s services to the surgical
patients would not meet the requirements for payment at the medically directed rate. A/B
MACs may not make payment under the fee schedule.
D. Payment at Medically Supervised Rate
The A/B MAC may allow only three base units per procedure when the anesthesiologist is
involved in furnishing more than four procedures concurrently or is performing other services
while directing the concurrent procedures. An additional time unit may be recognized if the
physician can document he or she was present at induction.
E. Billing and Payment for Multiple Anesthesia Procedures
Physicians bill for the anesthesia services associated with multiple bilateral surgeries by
reporting the anesthesia procedure with the highest base unit value with the multiple procedure
modifier -51. They report the total time for all procedures in the line item with the highest base
unit value.
If the same anesthesia CPT code applies to two or more of the surgical procedures, billers enter
the anesthesia code with the -51 modifier and the number of surgeries to which the modified
CPT code applies.
Payment can be made under the fee schedule for anesthesia services associated with multiple
surgical procedures or multiple bilateral procedures. Payment is determined based on the base
unit of the anesthesia procedure with the highest base unit value and time units based on the
actual anesthesia time of the multiple procedures. See
§§40.6-40.7 for billing and claims processing instructions for multiple and bilateral surgeries.
F. Payment for Medical and Surgical Services Furnished in Addition to Anesthesia
Procedure
Payment may be made under the fee schedule for specific medical and surgical services
furnished by the anesthesiologist as long as these services are reasonable and medically
necessary or provided that other rebundling provisions (see §30 and Chapter 23) do not
preclude separate payment. These services may be furnished in conjunction with the anesthesia
procedure to the patient or may be furnished as single services, e.g., during the day of or the
day before the anesthesia service. These services include the insertion of a Swan Ganz catheter,
the insertion of central venous pressure lines, emergency intubation, and critical care visits.
G. Anesthesia Time and Calculation of Anesthesia Time Units
Anesthesia time is defined as the period during which an anesthesia practitioner is present with
the patient. It starts when the anesthesia practitioner begins to prepare the patient for anesthesia
services in the operating room or an equivalent area and ends when the anesthesia practitioner
is no longer furnishing anesthesia services to the patient, that is, when the patient may be
placed safely under postoperative care. Anesthesia time is a continuous time period from the
start of anesthesia to the end of an anesthesia service. In counting anesthesia time for services
furnished, the anesthesia practitioner can add blocks of time around an interruption in
anesthesia time as long as the anesthesia practitioner is furnishing continuous anesthesia care
within the time periods around the interruption.
Actual anesthesia time in minutes is reported on the claim. For anesthesia services furnished,
the A/B MAC computes time units by dividing reported anesthesia time by 15 minutes. Round
the time unit to one decimal place. The A/B MAC does not recognize time units for CPT code
01996 (daily hospital management of epidural or subarachnoid continuous drug administration).
For purposes of this section, anesthesia practitioner means:
• a physician who performs the anesthesia service alone,
• a CRNA who is furnishing services that do not meet the requirements for payment at the
medically directed rate,
• a qualified nonphysician anesthetist who is furnishing services that meet the requirements for
payment at the medically directed rate.
The physician who medically directs the qualified nonphysician anesthetist would ordinarily
report the same time as the qualified nonphysician anesthetist reports for the service.
H. Monitored Anesthesia Care
Monitored anesthesia care involves the intra-operative monitoring by a physician or qualified
individual under the medical direction of a physician or of the patient’s vital physiological
signs in anticipation of the need for administration of general anesthesia or of the development
of adverse physiological patient reaction to the surgical procedure. It also includes the
performance of a pre-anesthetic examination and evaluation, prescription of the anesthesia care
required, administration of any necessary oral or parenteral medications (e.g., atropine,
demerol, valium) and provision of indicated postoperative anesthesia care.
The A/B MAC pays for reasonable and medically necessary monitored anesthesia care services
on the same basis as other anesthesia services. If the physician personally performs the
monitored anesthesia care case, payment is made under the fee schedule using the payment
rules for payment at the personally performed rate. If the physician medically directs four or
fewer concurrent cases and monitored anesthesia care represents one or more of these
concurrent cases, payment is made under the fee schedule using the payment rules for payment
at the medically directed rate. Anesthesiologists use the QS modifier to report monitored
anesthesia care cases, in addition to reporting the actual anesthesia time and one of the payment
modifiers on the claim.
I. Anesthesia Claims Modifiers
Physicians report the appropriate modifier to denote whether the service meets the
requirements for payment at the personally performed rate, medically directed rate, or
medically supervised rate.
AA - Anesthesia Services performed personally by the anesthesiologist
AD - Medical Supervision by a physician; more than 4 concurrent anesthesia procedures
G8 - Monitored anesthesia care (MAC) for deep complex, complicated, or markedly invasive
surgical procedures
G9 - Monitored anesthesia care for patient who has a history of severe cardio- pulmonary condition
QK - Medical direction of two, three or four concurrent anesthesia procedures involving qualified
individuals
QS - Monitored anesthesia care service
NOTE: The QS modifier can be used by a physician or a qualified nonphysician anesthetist
and is for informational purposes. Providers must report actual anesthesia time and one of the
payment modifiers on the claim.
QY - Medical direction of one qualified nonphysician anesthetist by an anesthesiologist
GC - These services have been performed by a resident under the direction of a teaching physician.
NOTE: The GC modifier is reported by the teaching physician to indicate he/she rendered the
service in compliance with the teaching physician requirements in §100 of this chapter. One of
the payment modifiers must be used in conjunction with the GC modifier.
The A/B MAC must determine payment for anesthesia in accordance with these instructions.
They must be able to determine the uniform base unit that is assigned to the anesthesia code
and apply the appropriate reduction where the anesthesia procedure meets the requirements for
payment at the medically directed rate. They must also be able to determine the number of
anesthesia time units from actual anesthesia time reported on the claim. The A/B MAC must
multiply allowable units by the anesthesia-specific conversion factor used to determine fee
schedule payment for the payment area.
J. Moderate Sedation Services Furnished in Conjunction with and in Support of
Procedural Services
Anesthesia services range in complexity. The continuum of anesthesia services, from least
intense to most intense in complexity is as follows: local or topical anesthesia, moderate
(conscious) sedation, regional anesthesia and general anesthesia. Moderate sedation is a drug
induced depression of consciousness during which the patient responds purposefully to verbal
commands, either alone or accompanied by light tactile stimulation. Moderate sedation does
not include minimal sedation, deep sedation or monitored anesthesia care.
Practitioners will report the appropriate CPT and/or HCPCS code that describes the moderate
sedation services furnished during a patient encounter, which are furnished in conjunction with
and in support of a procedural service, consistent with CPT guidance.
Refer to §50 and §140 of this chapter for information regarding reporting of anesthesia services
furnished in conjunction with and in support of procedural services.
K. Anesthesia for Diagnostic or Therapeutic Nerve Blocks and Services Lower in
Intensity than Moderate Sedation
If the anesthesiologist or CRNA provides anesthesia for diagnostic or therapeutic nerve blocks
or injections and a different provider performs the block or injection, then the anesthesiologist
or CRNA may report the anesthesia service using the appropriate CPT code consistent with
CPT guidance. The service must meet the criteria for monitored anesthesia care as described in
this section. If the anesthesiologist or CRNA provides both the anesthesia service and the block
or injection, then the anesthesiologist or CRNA may report the anesthesia service and the
injection or block. However, the anesthesia service must meet the requirements for moderate
sedation and if a lower level complexity anesthesia service is provided, then the moderate
sedation code should not be reported.
If the physician performing the medical or surgical procedure also provides a level of
anesthesia lower in intensity than moderate sedation, such as a local or topical anesthesia, then
the moderate sedation code should not be reported and no separate payment should be allowed
by the A/B MAC.