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February 15, 2018

Billing Instruction - Oxygen CMN Question 5

Joint DME MAC Publication

The Medicare Certificate of Medical Necessity (CMN) (CMS-484/DME 484.3) is used to collect selected information necessary to ascertain that basic coverage is appropriate and to make correct payment determinations for oxygen equipment. Question 5 requests the prescribed flow rate. The instructions on the Oxygen CMN for Question 5 state:

    5. Enter the highest oxygen flow rate ordered for this patient in liters per minute. If less than 1 LPM, enter an "X".

CMS has recently clarified the instructions in the Claim Processing Manual (CMS Internet-only manual 100-04), Ch. 20, §30.6.1) related to payment for low liter flow rates (less than 1 LPM) and high liter flow rates (greater than 4 LPM). This clarification requires that the reported flow rate in Oxygen CMN Question 5, used when the awake and asleep (at night) prescribed flow rates differ, be calculated based on the average rate from the awake and asleep prescribed rate. Modifiers QA, QB and QR listed below are new and are effective for dates of service on or after April 1, 2018.

Oxygen modifiers that must be used to comply with the requirements in §30.6.1 are:

  • QE - PRESCRIBED AMOUNT OF STATIONARY OXYGEN WHILE AT REST IS LESS THAN 1 LITER PER MINUTE (LPM)
  • QF - PRESCRIBED AMOUNT OF STATIONARY OXYGEN WHILE AT REST EXCEEDS 4 LITERS PER MINUTE (LPM) AND PORTABLE OXYGEN IS PRESCRIBED
  • QG - PRESCRIBED AMOUNT OF STATIONARY OXYGEN WHILE AT REST IS GREATER THAN 4 LITERS PER MINUTE (LPM)
  • QA - PRESCRIBED AMOUNTS OF STATIONARY OXYGEN FOR DAYTIME USE WHILE AT REST AND NIGHTTIME USE DIFFER AND THE AVERAGE OF THE TWO AMOUNTS IS LESS THAN 1 LITER PER MINUTE (LPM)
  • QB - PRESCRIBED AMOUNTS OF STATIONARY OXYGEN FOR DAYTIME USE WHILE AT REST AND NIGHTTIME USE DIFFER AND THE AVERAGE OF THE TWO AMOUNTS EXCEEDS 4 LITERS PER MINUTE (LPM) AND PORTABLE OXYGEN IS PRESCRIBED
  • QR - PRESCRIBED AMOUNTS OF STATIONARY OXYGEN FOR DAYTIME USE WHILE AT REST AND NIGHTTIME USE DIFFER AND THE AVERAGE OF THE TWO AMOUNTS IS GREATER THAN 4 LITERS PER MINUTE (LPM)

When there are differing awake and asleep prescribed flow rates, the current Oxygen CMN instruction to list the "highest oxygen flow rate" for Question 5 is not the correct value to report. In this situation, the calculated average flow rate is the value that must be reported as the answer to Question 5.

There are several scenarios regarding how the Oxygen CMN Question 5 must be answered:

  • For beneficiaries with a single flow rate for day and night (Modifiers – QE, QF & QG):
    • Report the prescribed flow rate in CMN Question 5.
  • For beneficiaries with differing day and night flow rates (Modifiers – QA, QB & QR):
    • Calculate the average of the day and night flow rates. The resulting average value is reported in CMN Question 5.
    • Day and night average flow rates may be calculated as follows:
      • (day flow rate + night flow rate) / 2 = average flow rate

        (apply arithmetic rounding rules, if necessary)

For claims with dates of service (DOS) on or after April 1, 2018:

  • For beneficiaries currently on oxygen with differing day and night flow rates (Modifiers QA, QB & QR), if the calculated average is different from a previously reported flow rate on the Oxygen CMN Question 5, a Revised CMN reporting the correctly calculated average flow rate must be submitted.
  • For beneficiaries currently on oxygen with a single (unchanged) flow rate (Modifiers QE, QF & QG), no Revised CMN is necessary.

Refer to the Oxygen and Oxygen Equipment Local Coverage DeterminationExternal Website (L33797) and related Policy ArticlesExternal Website for additional information on coverage, coding and documentation requirements.


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