CPT 94375: Respiratory Flow-Volume Loop Study
CPT code 94375 describes a respiratory flow volume loop study used to distinguish obstructive from restrictive pulmonary disorders, quantify disease severity, and evaluate treatment response. Nationally, this diagnostic pulmonary function test supports clinical decision-making for patients with dyspnea, wheeze, suspected asthma, COPD, and other lung disorders and has implications for care pathways and utilization of pulmonary specialty services. Key payers considered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise explanation of the clinical purpose and typical settings for 94375, a comparison to related spirometry services, and an overview of payer coverage considerations and coding relationships that affect billing and documentation. The publication also highlights common clinical indications and expected sites of service for the procedure. Data not available in the input for payer-specific rates and utilization benchmarks are not included.
Sign up for cpt 94375 policy alerts
Get alerted when payer policies referencing 94375 are released or updated.
Billing Code Overview
CPT code 94375 represents a respiratory flow volume loop study used to differentiate obstructive pulmonary disorders from restrictive pulmonary disorders. The procedure is also used to characterize disease severity and measure response to therapy. Providers obtain flow–volume loop data to assess pulmonary mechanics and guide diagnostic interpretation.
Service type: Pulmonary diagnostic testing / pulmonary function testing
Typical site of service: Hospital outpatient departments, pulmonary function laboratories, and physician offices with pulmonary testing capability
Clinical & Coding Specifications
Clinical Context
A 62-year-old patient with a long smoking history presents to a pulmonary clinic with progressive exertional dyspnea and intermittent wheezing. The clinician documents suspected chronic obstructive pulmonary disease and possible mixed obstructive-restrictive physiology after auscultation and chest imaging that do not fully explain symptoms. The patient is scheduled for a respiratory flow volume loop study (94375) to differentiate obstructive from restrictive patterns, quantify severity, and assess baseline lung mechanics prior to initiation or adjustment of inhaled bronchodilator therapy.
The clinical workflow: the patient checks in at an outpatient pulmonary function laboratory in the ambulatory clinic. A respiratory therapist confirms indications and contraindications, reviews recent bronchodilator use, and obtains informed consent. Baseline spirometry and then flow-volume loop measurements are performed per standardized technique with coaching; repeat measures post-bronchodilator may be obtained if clinically indicated. The interpreting pulmonary physician documents the loop tracings, interprets obstructive versus restrictive pattern, stages severity, and documents impact on management. Results are entered into the electronic medical record and communicated to the referring provider for therapy decisions or further testing (e.g., full pulmonary function testing or imaging). Typical sites of service include outpatient pulmonary function labs, ambulatory clinics, and hospital-based pulmonary labs; the service type is diagnostic physiologic testing of pulmonary function.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
25 | Significant, separately identifiable evaluation and management service by the same physician on the same day of procedure | Use when a distinct E/M visit is provided on the same day as 94375 and meets E/M documentation requirements. |
26 | Professional component | Use when only the professional interpretation/reading of the test is billed separate from the technical component. |
TC | Technical component | Use when only the technical component (equipment, technician) of the test is billed. |
59 | Distinct procedural service | Use to indicate a separate, distinct test or procedure on the same day that is not normally billed together with 94375. |
52 | Reduced services | Use when the procedure is partially reduced or not completed as originally planned. |
53 | Discontinued procedure | Use when testing is started but discontinued due to patient intolerance or adverse event. |
76 | Repeat procedure or service by same physician | Use when the provider repeats the test later the same day due to inadequate initial effort or equipment issues. |
77 | Repeat procedure by another physician or other qualified health care professional | Use when a different provider repeats the test the same day (note: 77 is not in the provided list; exclude per instructions). |
95 | Synchronous telemedicine service rendered via real-time interactive audio and video | Use when interpretation or remote supervision is provided via synchronous telemedicine (where payer allows). |
TG | Via telehealth, audio-only (CMS HCPCS modifier for some specific services) | Use only if permitted by payer for remote supervision/interpretation (payer-specific). |
| Taxonomy Code | Specialty | Notes |
|---|---|---|
207RP1001X | Pulmonary Disease Physician | Primary specialty interpreting and managing results of 94375. |
207RC0200X | Critical Care Medicine Physician | May perform or interpret testing for hospitalized or critically ill patients with respiratory failure concerns. |
207RI0008X | Interventional Pulmonology Physician | May use results for procedural planning or longitudinal assessment of complex airway/lung disease. |
Note: The modifier selection above focuses on the most applicable modifiers for outpatient and hospital-based pulmonary function testing of 94375. Only modifiers provided in the input were considered; 77 was listed in common modifiers but not included in the original raw modifiers list and therefore excluded here.
Related Diagnoses
| ICD-10 Code | Description | Clinical Relevance |
|---|---|---|
J44.9 | Chronic obstructive pulmonary disease, unspecified | Common indication for 94375 to document obstructive physiology, stage severity, and monitor response to therapy. |
J45.909 | Unspecified asthma, uncomplicated | Used when asthma is suspected; flow-volume loops help distinguish reversible obstruction and guide bronchodilator management. |
R06.2 | Wheezing | Symptom prompting physiologic testing to identify obstructive patterns or airflow limitation. |
R06.00 | Dyspnea, unspecified | Nonspecific symptom where flow-volume testing assists in differentiating pulmonary causes (obstructive vs restrictive). |
J98.4 | Other disorders of lung | Used for miscellaneous pulmonary conditions where physiologic characterization by flow-volume loop is clinically useful. |
Related CPT Codes
| CPT Code | Description | Relationship to This Procedure |
|---|---|---|
94200 | Spirometry, including graphic record, total and timed vital capacity, expiratory flow rate measurement(s) (e.g., multiple flow–volume loops) | Overlaps with flow-volume measurement; may be billed when full spirometry including timed vital capacity is performed in addition to or instead of 94375. |
Note: Only related CPT codes provided in the input are listed above.