Summary & Overview
CPT 94727: Pulmonary Function Test, Gas Dilution/Washout
CPT code 94727 designates a pulmonary function test that measures lung volumes through gas dilution or washout methods and may assess ventilation distribution and closing volumes. This test provides quantitative evaluation of lung volumes and gas mixing, informing diagnosis and management of obstructive and restrictive lung diseases, respiratory muscle weakness, and air trapping. Nationally, standardized reporting of PFTs like CPT code 94727 supports consistent clinical assessment, quality measurement, and payer coverage determinations.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of the clinical purpose of the test, typical sites of service, and the contexts in which CPT code 94727 is used. The publication also outlines common billing considerations, frequently associated modifiers (listed separately), and where to find related procedure coding for comprehensive pulmonary function testing.
This summary provides clinical context and coding focus for clinicians, billing professionals, and policy analysts seeking clarity on how CPT code 94727 is described and applied in practice. Data not available in the input is noted where applicable.
Billing Code Overview
CPT code 94727 describes a pulmonary function test (PFT) that measures lung volumes using gas dilution or washout techniques, comparing a known concentration of an inhaled gas with the patient’s exhaled breath. The procedure may include assessment of ventilation distribution and closing volumes to evaluate gas mixing and areas of air trapping.
Service type: Pulmonary function testing using gas dilution/washout techniques.
Typical site of service: Pulmonary function laboratory, hospital outpatient department, or other outpatient respiratory testing facility.
Clinical & Coding Specifications
Clinical Context
A 62-year-old male with a long smoking history and progressive exertional dyspnea is referred by his pulmonologist for laboratory-based pulmonary function testing to quantify lung volumes and assess for restrictive versus obstructive physiology. The patient presents to an outpatient pulmonary function laboratory affiliated with a hospital. After registration and review of indications and recent clinical history, a respiratory therapist or pulmonary function technologist explains the gas dilution/washout technique and performs pre-test screening (recent bronchodilator use, ability to perform maneuvers, contraindications such as recent myocardial infarction or hemoptysis). The provider obtains baseline measurements including spirometry and then performs gas dilution or washout measurements to determine total lung capacity (TLC), functional residual capacity (FRC) and residual volume (RV). The provider may also measure ventilation distribution and closing volumes if clinically indicated. Results are reviewed by the interpreting clinician, integrated with prior studies and imaging, and a report with interpretation and comparison is sent to the referring pulmonologist. Typical sites of service include an outpatient pulmonary function laboratory, hospital-based pulmonary lab, or ambulatory clinic with PFT capabilities.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
25 | Significant, separately identifiable evaluation and management service by the same physician on the same day of the procedure | Use when a separate E/M visit is performed and medically necessary on the same day as the PFT |