Part B Insider (Multispecialty) Coding Alert

CPT® simplifies reporting by combining two codes into one.

Have you ever struggled with differentiating between pulmonary function tests such as carbon monoxide diffusing capacity (DLCO) and membrane diffusion capacity (DMCO)? If your answer to this is yes, then you'll be pleased to hear that effective Jan.1, 2012, CPT® has reduced your burden by combining these two codes into a single code.

Read on for more on this change and how to adjust your reporting of these tests.

Note Benefits of Single Add-on Code

Prior to the changes initiated in 2012, you needed to report carbon monoxide diffusing capacity and membrane

diffusion capacity using different codes. This necessitated complex understanding of the procedures as well as knowing the differentiation between the two codes.

"There was speculation that the codes were being reported incorrectly since the increase in utilization for 94725 was identified as 14% more than that of 94720 over a six year time period," says Carol Pohlig, BSN, RN, CPC, ACS, senior coding and education specialist at the University of Pennsylvania Department of Medicine in Philadelphia. "Given the limited clinical indications and use for 94725, this surge seemed unreasonable."

The old codes (prior to Jan, 1, 2012) that have now been deleted include the following:

• 94720 -- Carbon monoxide diffusing capacity [e.g., single breath, steady state]
• 94725 -- Membrane diffusion capacity

Under CPT® 2012, you will now need to report these procedures under a single code:

• +94729 -- Diffusing capacity [e.g., carbon monoxide, membrane][List separately in addition to code for primary procedure]

Benefit: This CPT® 2012 change has made the task easier as there is no need to go into the procedure details to understand whether it is a test for carbon monoxide diffusing capacity or membrane diffusion capacity. Both are now reported with +94729. The reimbursement and relative value units for the new code (~$53, 1.57 total RVUs) are similar to 94720.

Coding tip: Since many providers consider DLCO and DMCO to be a routine part of PFTs, they have now been grouped together as an add-on code, and cannot be reported alone. You must therefore report +94729 in conjunction with other pulmonary function tests, such as:

• 94010 (Spirometry, including graphic record, total and timed vital capacity, expiratory flow rate measurement[s], with or without maximal voluntary ventilation)
• 94060 (Bronchodilation responsiveness, spirometry as in 94010, pre- and post-bronchodilator administration)
• 94070 (Bronchospasm provocation evaluation, multiple spirometric determinations as in 94010, with administered agents [eg, antigen[s], cold air, methacholine])
• 94375 (Respiratory flow volume loop)
• 94726 (Plethysmography for determination of lung volumes and, when performed, airway resistance)
• 94727 (Gas dilution or washout for determination of lung volumes and, when performed, distribution of ventilation and closing volumes)
• 94728 (Airway resistance by impulse oscillometry)

Example: Take a look at this procedure scenario to help you understand how the measure of DLCO is performed:

"The patient was asked to be seated in a comfortable position. He was asked to exhale to a maximal extent such that it reached residual volume levels following which he was quickly asked to inhale a mixture of air, 0.3% carbon monoxide and a tracer gas of 5% helium. The patient was then instructed to hold his breath for about 10 seconds and then asked to exhale rapidly. The first 1000 ml of exhaled air was disposed and the rest was collected and used for analysis.

DLCO was measured by analyzing and measuring the exhaled air for calculating the concentration of carbon monoxide and tracer gas. To ensure that all the carbon monoxide is cleared, the procedure was then repeated at 5 minute intervals till the DLCO measurements between two subsequent procedures differed by 3ml/min/mm Hg."

Membrane diffusion capacity will involve two DLCO measurements. The first DLCO measurement will be similar to the example described above. Following the first procedure, the patient will then be asked to inhale highly concentrated oxygen for a period of 5 minutes following which the second DLCO measurement is performed. Using these two results, the DMCO is calculated using an appropriate formula.

It was earlier very difficult for coders to differentiate between the two procedures and report the correct one, as prior to the CPT® 2012 change these were to be reported with separate codes. Both involved multiple DLCO measurements differentiated by the type of gases used throughout the testing. However, the CPT® 2012 change should make it easy for you to report either of the procedures as you need to use only +94729. Under most circumstances, you can only report one unit of the code per day.