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Anesthesia Billing Guide


Payment and Reimbursement

Anesthesia Claim Billing Instructions

Claims must be submitted on the claim CMS-1500 claim form or electronic media claim equivalent.

The following are specific to anesthesia claims submission:

  • Item 24D – the appropriate anesthesia CPT code followed by the modifier  
  • Item 24G – the actual anesthesia time, in minutes

Total time should always be accurately reported in minutes. NGS will convert your minutes and will be shown on your remittance advice as units when your claim(s) is processed.

For example: You submit 95 minutes on line Item 24G or the electronic equivalent and NGS will convert the units to 6.3.

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Multiple Anesthesia Procedures

Payment may be made under the fee schedule for anesthesia services associated with multiple surgical procedures or multiple bilateral procedures. Payment is based on the base unit of the anesthesia procedure with the highest base unit value and the total time units based on the multiple procedures with the exception of the new add-on codes.

On the CMS-1500 claim form, report the anesthesia procedure code with the highest base unit value in Item 24D. In Item 24G, indicate the total time for all the procedures performed.

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Multiple CRNAs Same Procedure

If multiple CRNAs perform services in the same operative session, only one can bill (the CRNA that started the anesthesia), with the total time indicated. Records should show when the first CRNA switched over to the second CRNA (and subsequent CRNAs if applicable). This does not apply when an Anesthesiologist and CRNA are involved. In this case, the appropriate modifier should be used that allows 50% for each claim.

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Payment at Personally Performed Rate

The fee schedule payment for a personally performed procedure is based on the full base unit and one time unit per 15 minutes of service if the physician personally performed the entire procedure. Modifier AA is appropriate when services are personally performed.

  • AA: Anesthesia service personally performed by the anesthesiologist or physician.

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Payment at Medically Directed Rate

When the physician is medically directing a qualified anesthetist (CRNA, anesthesiologist assistant [AA]) in a single anesthesia case or a physician is medically directing two, three, or four concurrent procedures, the payment amount for each is 50 percent of the allowance otherwise recognized had the service been performed by the physician alone.

These services are to be billed as follows:

  1. The physician should bill using modifier QY, medical direction of one CRNA by a physician or QK, medical direction of two, three, or four concurrent procedures.
  2. The CRNA/AA should bill using modifier QX, CRNA service with medical direction by a physician.
Code Description
AA Physician personally performs
QK Medical direction of two, three or four concurrent anesthesia procedures, 50% cutback
QX CRNA with medical direction by a physician
QY Medical direction of one Qualified Nonphysician Anesthetist by an anesthesiologist

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Payment at Nonmedically Directed Rate

In unusual circumstances, when it is medically necessary for both the anesthesiologist and the CRNA/AA to be completely and fully involved during a procedure, full payment for the services of each provider are allowed. Documentation must be submitted by each provider to support payment of the full fee.

These services are to be billed as follows:

  1. The physician should bill using modifier AA, anesthesia services personally performed by anesthesiologist, and modifier 22, with attached supporting documentation.
  2. The CRNA/AA should bill using modifier QZ, CRNA/AA services; without medical direction by a physician, and modifier 22, with attached supporting documentation.
Code Description
AA Physician personally performs
QZ Anesthesia, Qualified Nonphysician Anesthetist not medically directed.

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Payment at Medically Supervised Rate

Only three base units per procedure are allowed when the anesthesiologist is involved in rendering more than four procedures concurrently or is performing other services while directing the concurrent procedures. An additional time unit can be recognized if the physician can document s/he was present at induction. Modifier AD is appropriate when services are medically supervised.

  • AD: Supervision, more than four procedures

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Payment Rules

The fee schedule allowance for anesthesia services is based on a calculation that includes the anesthesia base units assigned to each anesthesia code, the anesthesia time involved, and appropriate area conversion factor. The following formulas are used to determine payment is to take the time units, add the RVU, also known as base units, and multiply the total allowance per unit (conversion factor). Time units are calculated by the total number of minutes divided by 15. Base units for each anesthesia procedure code are set up in the Medicare computer system as determined by CMS.

  • Participating Physician not Medically Directing (Modifier AA)
    (Base Units + Time Units) x Participating Conversion Factor = Allowance
  • Participating Physician Medically Directing (Modifier QY, QK)
    (Base Units + Time Units) x Participating Conversion Factor = Allowance x 50%
  • CRNA Medically Directed (Modifier QX)
    (Base Units + Time Units) x Participating Conversion Factor = Allowance x 50%
  • Nonmedically Directed CRNA (Modifier QZ)
    (Base Units + Time Units) x Participating Conversion Factor = Allowance
  • Nonparticipating Physician not Medically Directing (Modifier AA)
    (Base Units + Time Units) x Nonparticipating Conversion Factor = Allowance
  • Nonparticipating Physician Medically Directing (Modifier QY, QK)
    (Base Units + Time Units) x Nonparticipating Conversion Factor = Allowance x 50%

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Base Units

Anesthesia base unit values have been assigned to each anesthesia procedure code and reflect the difficulty of the anesthesia services, including the usual preoperative and postoperative care and evaluation. The base unit is used to determine a portion of the reimbursement amount of the anesthesia procedure. Anesthesia services are paid on the basis of a relative value system, which include both base and actual time units. Base units take into account the complexity, risk, and skill required to perform the service.

Note: Base units are automatically calculated and should not be reported on the claim form.

For the most current list of base unit values for each anesthesia procedure code can be found on the Anesthesiologist Center page on the CMS website at Anesthesiologist Center.

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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 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.

For anesthesia claims, the elapsed time, in minutes, must be reported. You shall convert hours to minutes and enter the total minutes required minutes for the procedure in Item 24G of the CMS-1500 claim form or electronic media claim equivalent.

Time units for physician, CRNA services—both personally performed and medically directed are determined by dividing the actual anesthesia time by 15 minutes or fraction thereof. Since only the actual time of a fractional unit is recognized, the time unit is rounded to one decimal place.

NGS will quantity bill based on the minutes in 24G. When you receive a remittance advice you will see the appropriate quantity billed converted by NGS.

Time Units are not recognized for the following CPT codes:

  • 01995 ‒ Regional IV administration of local anesthetic agent or other medication upper or lower extremity
  • 01996 ‒ Daily hospital management of epidural or subarachnoid continuous drug administration

Note: An anesthesia claim cannot be date ranged. For instance, if anesthesia began at 11:00 p.m. on 2/5/2019 and ended at 2:00 a.m. on 2/6/2019, only the date anesthesia began should be reported on the claim; in this case, you would use 2/5/2019 as the date of service.

The table on the next page will illustrate the conversion from minutes to units used by NGS for claims processing.

Remember, you will need to list the total time in minutes on line Item 24G of the CMS-1500 claim form or electronic media claim equivalent and NGS will convert your minutes to the appropriate quantity billed (QB) units.

Time Units Reference

Anesthesia Time (Hours and Minutes) Provider Reports 24G in Total Minutes NGS Converts Total Minutes into Units (QB)
15 minutes 15 00010
30 minutes 30 00020
45 minutes 45 00030
1 hour 60 00040
1 hour 15 minutes 75 00050
1 hour 30 minutes 90 00060
1 hour 45 minutes 105 00070
2 hours 120 00080
2 hours 15 minutes 135 00090
2 hours 30 minutes 150 00100
2 hours 45 minutes 165 00110
3 hours 180 00120
3 hours 15 minutes 195 00130
3 hours 30 minutes 210 00140
3 hours 45 minutes 225 00150
4 hours 240 00160
4 hours 15 minutes 255 00170
4 hours 30 minutes 270 00180
4 hours 45 minutes 285 00190
5 hours 300 00200
5 hours 15 minutes 315 00210
5 hours 30 minutes 330 00220
5 hours 45 minutes 345 00230
6 hours 360 00240
6 hours 15 minutes 375 00250
6 hours 30 minutes 390 00260
6 hours 45 minutes 405 00270
7 hours 420 00280

Extra Minute Time Units

MINUTES QB
1 00001
2 00001
3 00002
4 00003
5 00003
6 00004
7 00005
8 00005
9 00006
10 00007
11 00007
12 00008
13 00009
14 00009

Remember the 15-minute time interval will be divided into the total time indicated on the claim. Total time should always be accurately reported in minutes. Actual time units will be paid; no rounding will be done up to the next whole number – only round to the next tenth. 

Example:

95 minutes/15 = 6.33 = 6.3

79 minutes/15 = 5.26 = 5.3

Conversion Factors

The anesthesia conversion factors for each calendar year are listed by payment locality and are effective for the date the service was provided. The participating physician anesthesia conversion factor is listed first, the nonparticipating physician anesthesia conversion factor is second, and the non-medically directed conversion factor is listed in the third column.

The nonparticipating physician conversion factor is computed at 95 percent of the participating physician conversion factor. The limitation in the statute requires that qualified nonphysician anesthetist services not exceed the conversion factor for physicians’ anesthesia services.

The anesthesia conversion factors can be found at CMS Anesthesiologist Center.

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Anesthesia Billing Guide: Payment and Reimbursement
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