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Deleted. To report see 94729

Official Description

Carbon monoxide diffusing capacity (eg, single breath, steady state)

© Copyright 2025 American Medical Association. All rights reserved.

Common Language Description

The Carbon Monoxide Diffusing Capacity test, identified by CPT® Code 94720, is a pulmonary function test that measures the ability of the lungs to transfer carbon monoxide (CO) from the air into the bloodstream. This test is performed by having the patient inhale a specific air mixture that contains a known quantity of carbon monoxide. The amount of CO that is absorbed by the body is then determined by comparing the concentration of CO in the inhaled air with that in the exhaled air. This process provides valuable information about the efficiency of gas exchange in the lungs, which is crucial for diagnosing and monitoring various respiratory conditions. The test is particularly useful in assessing conditions that may affect lung function, such as emphysema, pulmonary fibrosis, and other forms of chronic obstructive pulmonary disease (COPD). Understanding the diffusing capacity of the lungs helps healthcare providers evaluate the severity of lung disease and guide treatment decisions.

© Copyright 2025 Coding Ahead. All rights reserved.

1. Indications

The Carbon Monoxide Diffusing Capacity test is indicated for various clinical scenarios where assessment of lung function is necessary. The following conditions may warrant the performance of this test:

  • Chronic Obstructive Pulmonary Disease (COPD) - To evaluate the extent of lung impairment and monitor disease progression.
  • Interstitial Lung Disease - To assess the impact of lung tissue scarring on gas exchange capabilities.
  • Emphysema - To determine the degree of alveolar damage and its effect on diffusing capacity.
  • Pulmonary Fibrosis - To evaluate the severity of lung function impairment due to fibrotic changes.
  • Preoperative Assessment - To assess lung function prior to surgical procedures, especially in patients with known respiratory issues.

2. Procedure

The procedure for conducting the Carbon Monoxide Diffusing Capacity test involves several key steps to ensure accurate measurement of lung function. The following outlines the procedural steps:

  • Step 1: Patient Preparation - The patient is instructed to avoid smoking and certain medications that may affect lung function for a specified period before the test. This preparation is crucial to obtain reliable results.
  • Step 2: Baseline Measurements - Initial lung function measurements may be taken to establish a baseline. This can include spirometry to assess overall lung capacity and function.
  • Step 3: Inhalation of Test Gas - The patient is then asked to inhale a gas mixture that contains a known concentration of carbon monoxide. This inhalation is typically done in a controlled environment to ensure safety and accuracy.
  • Step 4: Breath Hold - After inhalation, the patient holds their breath for a specified duration, allowing the carbon monoxide to diffuse across the alveolar-capillary membrane into the bloodstream.
  • Step 5: Exhalation and Measurement - The patient then exhales into a collection device, and the concentration of carbon monoxide in the exhaled air is measured. This measurement is compared to the initial concentration inhaled to determine the diffusing capacity.

3. Post-Procedure

After the Carbon Monoxide Diffusing Capacity test, the patient may be monitored briefly to ensure there are no immediate adverse reactions, particularly since carbon monoxide is a toxic gas. Patients are typically advised to resume normal activities unless otherwise directed by their healthcare provider. Results from the test are analyzed and interpreted by a qualified healthcare professional, who will discuss the findings with the patient and determine any necessary follow-up actions or treatments based on the results.

Short Descr MONOXIDE DIFFUSING CAPACITY
Medium Descr CARBON MONOXIDE DIFFW/CAP
Long Descr Carbon monoxide diffusing capacity (eg, single breath, steady state)
Status Code Active Code
Global Days XXX - Global Concept Does Not Apply
PC/TC Indicator (26, TC) 1 - Diagnostic Tests for Radiology Services
Multiple Procedures (51) 0 - No payment adjustment rules for multiple procedures apply.
Bilateral Surgery (50) 0 - 150% payment adjustment for bilateral procedures does NOT apply.
Physician Supervisions 09 - Concept does not apply.
Assistant Surgeon (80, 82) 0 - Payment restriction for assistants at surgery applies to this procedure...
Co-Surgeons (62) 0 - Co-surgeons not permitted for this procedure.
Team Surgery (66) 0 - Team surgeons not permitted for this procedure.
Diagnostic Imaging Family 99 - Concept Does Not Apply
APC Status Indicator Discontinued Code
Type of Service (TOS) 5 - Diagnostic Laboratory
Berenson-Eggers TOS (BETOS) none
MUE Not applicable/unspecified.
CCS Clinical Classification 233 - Laboratory - Chemistry and Hematology
Date
Action
Notes
2012-01-01 Deleted Deleted. To report see 94729
2002-01-01 Changed Code description changed.
Pre-1990 Added Code added.
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