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 |
| 26 | Professional component | Use when reporting only the professional interpretation component separate from the technical component
| TC | Technical component | Use when reporting only the facility/technical portion of the test
| 52 | Reduced services | Use when the test is partially reduced or not fully completed for documented clinical reasons
| 53 | Discontinued procedure | Use when the test is started but discontinued due to patient factors or safety concerns
| 59 | Distinct procedural service | Use when multiple diagnostic tests on the same day are distinct and not bundled
| 76 | Repeat procedure or service by same physician or other qualified health care professional | Use for an immediate repeat of the test due to equipment or technique failure
| 78 | Unplanned return to the operating/procedure room by the same physician following initial procedure (use rarely) | Use only if an unexpected complication mandates return to a procedure area (rare for PFTs)
| 22 | Increased procedural services | Use when the test requires substantially greater resources than usual with documentation
| 59 | Distinct procedural service | Use to indicate procedures/services not normally reported together but permitted when distinct (listed for clinical relevance)
| XE | Separate encounter, a different encounter, same physician | Use when the PFT is performed during a separate encounter unrelated to other services on the same day
| XU | Unusual non-overlapping service | Use when diagnostic services are separate and do not overlap with other billed services
| QK | Medical direction of 2–4 qualified health care professionals by a physician/other qualified health care professional | Use when the physician medically directs multiple respiratory therapists performing tests
| QX | CRNA service: with medical direction by a physician (when applicable) | Rarely applicable; include if anesthesia personnel are involved for high-risk testing
| Taxonomy Code | Specialty | Notes |
|---|
| 207RC0000X | Pulmonary Disease | Pulmonologists interpret and supervise complex PFTs and pre/post-test clinical correlation |
| 174400000X | Respiratory Therapy | Respiratory therapists and pulmonary function technologists perform testing and data collection
| 2084P0800X | Internal Medicine | Hospitalists and primary care physicians may order and occasionally interpret PFTs for chronic lung disease
| 207L00000X | Critical Care Medicine | Intensivists may order bedside or specialized lung volume testing in complex cases
| 207K00000X | Allergy & Immunology | Allergists may order PFTs for evaluation of asthma and related airway disorders
Related Diagnoses
| ICD-10 Code | Description | Clinical Relevance |
|---|
J44.9 | Chronic obstructive pulmonary disease, unspecified | PFT lung volume testing helps quantify hyperinflation and air trapping in COPD |
| J45.909 | Unspecified asthma, uncomplicated | Lung volumes and ventilation distribution aid assessment of severity and response to therapy
| J84.10 | Pulmonary fibrosis, unspecified | Restrictive physiology is evaluated by measuring TLC and other lung volumes
| R06.02 | Shortness of breath | Objective lung volume measurements help determine restrictive vs obstructive causes
| J98.4 | Other disorders of lung (eg, dependent atelectasis, ventilation distribution abnormalities) | Gas dilution/washout techniques assess ventilation distribution and closing volumes
| Z95.1 | Presence of aortocoronary bypass graft (example comorbidity) | Included as a representative comorbidity that may affect test safety and interpretation
| R53.1 | Weakness | Symptom that may limit ability to perform maneuvers; influences test selection and interpretation
Related CPT Codes
| CPT Code | Description | Relationship to This Procedure |
|---|
94010 | Breathing capacity test before and after bronchodilator administration; spirometry, including graphic record, total and timed vital capacity, expiratory flow rate measurement(s), with or without maximal voluntary ventilation | Often performed immediately before gas dilution lung volume testing to assess baseline and bronchodilator responsiveness |
| 94620 | Pulmonary stress testing (eg, bronchospasm provocation); spirometry post-bronchial challenge | Used when bronchoprovocation testing is indicated to evaluate airway hyperresponsiveness in conjunction with lung volumes
| 94726 | Measurement of diffusing capacity (Dl, CO), single breath method | Commonly performed alongside lung volumes to assess gas transfer and differentiate parenchymal from airway disease
| 94729 | Carbon monoxide diffusing capacity, single breath, interpretation and report (when billed separately) | Interpretation/reporting component that complements the technical DLCO measurement
| 94060 | Bronchospasm evaluation, spirometry as part of pre- and post-bronchodilator testing with interpretation | Used in assessment of reversible obstruction prior to or after lung volume measurement
| 94640 | Inhalation treatment for acute airway obstruction; nebulizer administration of a bronchodilator | Therapeutic intervention that may be performed in the lab if bronchospasm occurs during testing