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Medical Policy

Policy Num:      02.005.001
Policy Name:    Pulmonary Function Test
Policy ID        [02.005.001][Ar/L /M+ /P+ ][0.00.00]

Last Review:    October 16, 2025
Next Review:    Archived

Pulmonary Function Test

Summary

Chronic Obstructive Pulmonary Disease, or COPD, is a condition caused by damage to the airways or other parts of the lung. This damage leads to inflammation  and other problems that block airflow and make it hard to breathe. COPD refers to wo main conditions: Emphysema and Chronic (long term) bronchitis. The main test to diagnose COPD is spirometry.

Pulmonary function tests allow physicians to evaluate the respiratory function of their patients in many clinical situations and when there are risk factors for lung disease, occupational exposures, and pulmonary toxicity. These are done with the patient breathing normally, in inspiration and forced expiration and trying to keep as much air as possible in the lung. The results of the PFTs are affected by the effort of the patient. PFTs do not provide a specific diagnosis; the results should be combined with relevant history, physical exam, and laboratory data to help reach a diagnosis. PFTs also allow physicians to quantify the severity of the pulmonary disease, follow it up over time, and assess its response to treatment. 

Objective

The objective of this evidence review is to determine which of the pulmonary function tests is the most appropriate for managing chronic obstructive pulmonary disease in different clinical scenarios. 

Policy Statement

Pulmonary function tests are considered medically necessary for evaluating obstructive pulmonary diseases when they measure: 

1. FEV1: The volume of air forcefully expired during the first second after taking a full breath. 
2. Forced vital capacity (FVC): The total volume of air expired with maximal force. 
3. Flow-volume loops: Simultaneous spirometric recordings of airflow and volume during forced maximal expiration and inspiration.

Other applications of pulmonary function tests not used for the above indicated is considered investigational. 

Policy Guidelines

Coding

See the Codes table for details.

Benefit Application

BlueCard/National Account Issues

State or federal mandates (eg, Federal Employee Program) may dictate that certain U.S. Food and Drug Administration-approved devices, drugs, or biologics may not be considered investigational, and thus these devices may be assessed only by their medical necessity.

Benefits are determined by the group contract, member benefit booklet, and/or individual subscriber certificate in effect at the time services were rendered. Benefit products or negotiated coverages may have all or some of the services discussed in this medical policy excluded from their coverage.

Background

The major types of pulmonary function tests (PFTs) are spirometry, lung volume, diffusing capacity, respiratory muscle pressure, bronchoprovocation testing, and the six-minute walk test. The most commonly used test for pulmonary evaluation is spirometry. It measures the ability to inhale and exhale air relative to time, and it serves as a diagnostic test for several common respiratory diseases such as asthma and COPD. In preparation for PFTs, bronchodilator medications are typically held so that bronchodilator response can be assessed after baseline spirometry.

The main results of spirometry are forced vital capacity (FVC), forced expiratory volume exhaled in the first second (FEV1), and the FEV1/FVC ratio. The procedure of spirometry has 3 phases: 1) maximal inspiration; 2) a “blast” of exhalation; 3) continued complete exhalation to the end of the test. There are within-maneuver acceptability and between-maneuver reproducibility criteria for spirometry.⁷

Spirometry is a key diagnostic test for asthma and chronic obstructive pulmonary disease (COPD) (when performed before and after bronchodilator) and is useful to assess for asthma or other causes of airflow obstruction in the evaluation of chronic cough. It is also used to monitor the progression of a broad spectrum of respiratory diseases, including asthma, COPD, interstitial lung disease, and neuromuscular diseases affecting respiratory muscles. This procedure includes the measurement of flow volume loops. The maximal flow-volume curves are a great asset for detecting mild airflow obstruction. In each flow-volume loop, there is an inspiratory and expiratory segment. The flow-volume loops (FVL) allow assessment of upper airway obstruction, both variable (e.g., vocal fold paralysis) and fixed types (e.g., tracheal stenosis), and intra- and extrathoracic locations. When the plateau of the FVL occurs in the inspiratory limb, the obstruction is variable and extrathoracic, while when it only occurs in the expiratory FVL limb, the obstruction is variable and intrathoracic. When both limbs are plateaued, then the obstruction is fixed, such as in tracheal stenosis.⁶

Reductions of FEV1, FVC, and the ratio of FEV1/FVC are the hallmark of airflow limitation. Flow-volume loops show a concave pattern in the expiratory tracing ⁶.

There are 2 basic pathways by which COPD can develop and manifest with symptoms in later life:

• In the first pathway, patients may have normal lung function in early adulthood, which is followed by a more rapid decline in FEV1 (≥ 60 mL/year).

• With the second pathway, patients have impaired lung function in early adulthood, often associated with asthma or other childhood respiratory disease. In these patients, COPD may present with a normal age-related decline in FEV1 (approximately 30 mL/year).

FEV1 and FVC are easily measured with office spirometry. Normal reference values are determined by patient age, sex, and height. It is recommended that race not be used for calculating predicted reference values. Airflow limitation severity in patients with COPD and FEV1/FVC < 0.70 can be classified based on post-bronchodilator FEV1:

• Mild: ≥ 80% of predicted

• Moderate: 50% to 79% of predicted

• Severe: 30% to 49% of predicted

• Very severe: < 30% of predicted

Additional pulmonary function testing is necessary only in specific circumstances, such as before lung volume reduction procedures. Other test abnormalities may include:

• Increased total lung capacity

• Increased functional residual capacity

• Increased residual volume

• Decreased vital capacity

• Decreased single-breath diffusing capacity for carbon monoxide (DLCO)

Findings of increased total lung capacity, functional residual capacity, and residual volume can help distinguish COPD from restrictive pulmonary disease, in which these measures are diminished.

Measurements of total lung capacity (TLC) using the chest radiograph or high-resolution computed tomography (HRCT) correlate within 15 percent of those obtained by body plethysmography.

Rationale

This evidence review was created in April 2009 and has been updated regularly with searches of the PubMed database. The most recent literature update was performed through October 16, 2025.

Evidence reviews assess the clinical evidence to determine whether the use of a technology improves the net health outcome. Broadly defined, health outcomes are length of life, quality of life (QOL), and ability to function-including benefits and harms. Every clinical condition has specific outcomes that are important to patients and to managing the course of that condition. Validated outcome measures are necessary to ascertain whether a condition improves or worsens; and whether the magnitude of that change is clinically significant. The net health outcome is a balance of benefits and harms.

Population Reference No. 1 Policy Statement

In patients with pulmonary obstructive disease, most pulmonary problems can be grouped in those conditions that affect the expansion of the lung (restrictive) and those where there is increased resistance to the passage of air (obstructive). Both conditions can affect the exchange of gases, the main physiological function of the respiratory system. In addition to classifying pulmonary diseases as restrictive, obstructive or mixed, pulmonary function studies are useful in determining the severity of the lung condition in a certain disease, monitoring its progress, and evaluating the effect of its treatment.

Suplemental Information

As per the Global Initiative for Chronic Obstructive Lung Disease 2025 (GOLD) ¹:

• A diagnosis of COPD should be considered in any patient who has dyspnea, chronic cough or sputum production, a history of recurrent lower respiratory tract infections and/or a history of exposure to risk factors for the disease, but spirometry showing the presence of a post-
• bronchodilator FEV1/FVC < 0.7 is mandatory to establish the diagnosis of COPD.
• The goals of the initial COPD assessment are to determine the severity of airflow obstruction, the impact of disease on the patient's health status, and the risk of future events (such as exacerbations, hospital admissions, or death), to guide therapy.
• Additional clinical assessment, including the measurement of lung volumes, diffusion capacity, exercise testing and/or lung imaging may be considered in COPD patients with persistent symptoms after initial treatment.
• Concomitant chronic diseases (multimorbidity) occur frequently in COPD patients, including cardiovascular disease, skeletal muscle dysfunction, metabolic syndrome, osteoporosis, depression, anxiety, and lung cancer. These comorbidities should be actively sought, and treated appropriately when present, because they influence health status, hospitalizations and mortality independently of the severity of airflow obstruction due to COPD.

The USPSTF (2022) recommends against screening for chronic obstructive pulmonary disease in asymptomatic adults².

References

1. Global Initiative for Chronic Obstructive Lung Disease. Goldcopd.Org. Retrieved October 16, 2025, from https://goldcopd.org/wp-content/uploads/2024/11/Pocket-Guide-2025-v1.0-New-Format-15Nov2024_WMV.pdf
2. Chronic Obstructive Pulmonary Disease: screening. (2022, May 10). https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/chronic-obstructive-pulmonary-disease-screening 
3. COPD resources for health professionals. (2024, May 15). Chronic Obstructive Pulmonary Disease (COPD). https://www.cdc.gov/copd/php/key-resources/index.html
4. What is COPD? Diagnosis | NHLBI, NIH. (2024, October 4). NHLBI, NIH. https://www.nhlbi.nih.gov/health/copd/diagnosis
5. COPD resources for health professionals. (2024, May 15). Chronic Obstructive Pulmonary Disease (COPD). https://www.cdc.gov/copd/php/key-resources/index.html
6. Wise, R. A. (2024, September 9). Chronic Obstructive pulmonary Disease (COPD). Merck Manual Professional Edition. https://www.merckmanuals.com/professional/pulmonary-disorders/chronic-obstructive-pulmonary-disease-and-related-disorders/chronic-obstructive-pulmonary-disease-copd#Diagnosis_v914664
7. Ponce, M. C., Sankari, A., & Sharma, S. (2023, August 28). Pulmonary function tests. StatPearls - NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK482339/
8. Medicare Coverage Database: LCD for  Pulmonary Diagnostic Services (L33705)
9. Donald F. Dexter,MD Diplomate to the American Board of Pulmonary Diseases; Personal Communication
10. Miller MR, Hankinson J, Brusasco V, et al. Standardisation of spirometry. Eur Respir J 2005; 26:319.
11. Aaron SD, Dales RE, Cardinal P. How accurate is spirometry at predicting restrictive pulmonary impairment? Chest 1999; 115:869.
12. Tashkin DP, Celli B, Decramer M, et al. Bronchodilator responsiveness in patients with COPD. Eur Respir J 2008; 31:742.
13. Modrykamien AM, Gudavalli R, McCarthy K, et al. Detection of upper airway obstruction with spirometry results and the flow-volume loop: a comparison of quantitative and visual inspection criteria. Respir Care 2009; 54:474.
14. Washko GR, Hunninghake GM, Fernandez IE, et al. Lung volumes and emphysema in smokers with interstitial lung abnormalities. N Engl J Med 2011; 364:897.
15. Crapo RO. Pulmonary-function testing. N Engl J Med 1994; 331:25.
16. Pellegrino R, Viegi G, Brusasco V, et al. Interpretative strategies for lung function tests. Eur Respir J 2005; 26:948.
17. Holland AE, Spruit MA, Troosters T, et al. An official European Respiratory Society/American Thoracic Society technical standard: field walking tests in chronic respiratory disease. Eur Respir J 2014; 44:1428.
18. Crapo RO. Pulmonary-function testing. N Engl J Med 1994; 331:25.
19. Pellegrino R, Viegi G, Brusasco V, et al. Interpretative strategies for lung function tests. Eur Respir J 2005; 26:948.
20. Holland AE, Spruit MA, Troosters T, et al. An official European Respiratory Society/American Thoracic Society technical standard: field walking tests in chronic respiratory disease. Eur Respir J 2014; 44:1428.
21. Wise RA, Brown CD. Minimal clinically important differences in the six-minute walk test and the incremental shuttle walking test. COPD 2005; 2:125.
22. Parreira VF, Janaudis-Ferreira T, Evans RA, et al. Measurement properties of the incremental shuttle walk test. a systematic review. Chest 2014; 145:1357.
23. Probst VS, Hernandes NA, Teixeira DC, et al. Reference values for the incremental shuttle walking test. Respir Med 2012; 106:243.
24. Harrison SL, Greening NJ, Houchen-Wolloff L, et al. Age-specific normal values for the incremental shuttle walk test in a healthy British population. J Cardiopulm Rehabil Prev 2013; 33:309.
25. Singh SJ, Morgan MD, Scott S, et al. Development of a shuttle walking test of disability in patients with chronic airways obstruction. Thorax 1992; 47:1019.
26. Singh SJ, Jones PW, Evans R, Morgan MD. Minimum clinically important improvement for the incremental shuttle walking test. Thorax 2008; 63:775.
27. Win T, Jackson A, Groves AM, et al. Comparison of shuttle walk with measured peak oxygen consumption in patients with operable lung cancer. Thorax 2006; 61:57.
28. Revill SM, Morgan MD, Singh SJ, et al. The endurance shuttle walk: a new field test for the assessment of endurance capacity in chronic obstructive pulmonary disease. Thorax 1999; 54:213.
29. Singh SJ, Morgan MD, Hardman AE, et al. Comparison of oxygen uptake during a conventional treadmill test and the shuttle walking test in chronic airflow limitation. Eur Respir J 1994; 7:2016.
30. Feiner JR, Severinghaus JW, Bickler PE. Dark skin decreases the accuracy of pulse oximeters at low oxygen saturation: the effects of oximeter probe type and gender. Anesth Analg 2007; 105:S18.
31. Van der Molen T, Østrem A, Stallberg B, et al. International Primary Care Respiratory Group (IPCRG) Guidelines: management of asthma. Prim Care Respir J 2006; 15:35.

Codes

Policy History