Pulmonary Function Testing: What It Is and Where to Get It Fast

Introduction: When Breathing Becomes a Question Mark

Persistent shortness of breath. A nagging cough that won’t quit. Feeling winded climbing a single flight of stairs. For many people, these symptoms trigger a doctor’s visit, a referral for a lung test, and then a frustrating discovery: the earliest available appointment at a hospital-based pulmonary lab is weeks, sometimes months, away.

This article addresses two problems at once. First, many people don’t fully understand what pulmonary function testing (PFT) actually is. Second, even those who do often don’t know where to get tested quickly. PFTs are a noninvasive, comprehensive evaluation of how well the lungs move air, hold volume, and transfer oxygen into the blood. They are a critical diagnostic tool, not a frightening procedure.

The stakes are real. Roughly 16 million Americans have diagnosed COPD, and about 25 million live with asthma, yet millions more remain undiagnosed. This guide covers what PFTs are, why they’re ordered, the four core test types, what to expect, and how to access testing without a months-long wait.

What Is Pulmonary Function Testing?

Pulmonary function testing is a complete, noninvasive evaluation of the respiratory system that quantitatively measures airflow, lung volumes, and gas exchange to identify the presence and severity of pulmonary impairment. The Merck Manual describes PFTs as tools that measure airflow, lung volumes, gas exchange, and response to bronchodilators.

The process is straightforward: patients breathe into a mouthpiece connected to a machine. There are no needles, no radiation, and no pain. Results are compared against personalized predicted values based on the patient’s age, height, sex, and ethnicity, not a universal standard. The 2022 ERS/ATS interpretive standards now use z-scores and Global Lung Function Initiative (GLI) reference equations rather than simple percent-predicted values, improving accuracy and equity across diverse populations.

An important reassurance: PFT results cannot be “failed.” If results fall outside the expected range, the provider simply recommends further evaluation or treatment. A full PFT order typically includes spirometry, body plethysmography, and diffusion capacity (DLCO) for the most comprehensive picture.

The Four Core Types of Pulmonary Function Tests

Not every patient needs all four tests. The ordering provider determines the appropriate combination based on clinical presentation.

Spirometry: The Most Common Starting Point

Spirometry is the most widely used and foundational PFT. It measures how much air a patient can inhale and exhale, and how quickly. Key metrics include FEV1 (forced expiratory volume in one second), FVC (forced vital capacity), and the FEV1/FVC ratio, the primary indicators for distinguishing obstructive from restrictive lung patterns.

Spirometry diagnoses asthma and COPD, monitors disease progression, and assesses response to bronchodilator therapy. Unfortunately, it is underused: only about 29% of patients diagnosed with COPD in primary care settings had confirmatory spirometry performed. Spirometers represent the largest segment of the PFT market at a 45% share as of 2025.

Lung Volume Testing (Body Plethysmography): Measuring Total Capacity

Lung volume testing measures the total amount of air the lungs can hold, including air that cannot be voluntarily exhaled (residual volume). Body plethysmography, commonly called the “body box,” is the gold standard. The patient sits inside a sealed, phone-booth-sized chamber and breathes against a closed shutter while pressure changes are measured.

Key metrics include Total Lung Capacity (TLC), Residual Volume (RV), and Functional Residual Capacity (FRC). This test helps distinguish obstructive from restrictive disease and evaluates conditions such as pulmonary fibrosis, emphysema, and neuromuscular disorders.

Diffusion Capacity Testing (DLCO): How Well Oxygen Crosses Into the Blood

DLCO (Diffusing Capacity of the Lungs for Carbon Monoxide) measures how efficiently oxygen transfers from the air sacs into the bloodstream. The patient inhales a small, safe amount of carbon monoxide tracer gas, holds their breath briefly, then exhales while the machine calculates absorption.

A reduced DLCO can indicate pulmonary fibrosis, emphysema, pulmonary hypertension, or anemia. Two patients can have identical FEV1 values but very different DLCO results, which is why DLCO adds critical diagnostic information that spirometry alone cannot provide.

Cardiopulmonary Exercise Testing (CPET): Evaluating Lungs and Heart Under Stress

CPET is the most comprehensive PFT type, evaluating how the lungs, heart, and muscles work together during controlled exertion on a treadmill or stationary bike. It measures oxygen consumption (VO2), carbon dioxide production, ventilation, heart rate, and blood pressure simultaneously in real time.

CPET diagnoses unexplained shortness of breath, distinguishes cardiac from pulmonary causes of exercise limitation, and supports preoperative risk stratification. It is also used for exercise prescription and athletic VO2 Max assessment. While more involved than other PFT types, it remains safe and well-monitored, with staff present throughout.

Why Is Pulmonary Function Testing Ordered? Common Clinical Indications

PFTs provide objective, quantifiable data that guides clinical decisions. According to Johns Hopkins Medicine, common indications include:

• Diagnosing respiratory conditions: asthma, COPD, pulmonary fibrosis, interstitial lung disease, sarcoidosis, and bronchiectasis.
• Monitoring disease progression: tracking how a known condition changes over time.
• Assessing treatment response: determining whether medications or pulmonary rehabilitation are working.
• Preoperative surgical clearance: postoperative respiratory failure is the most frequent complication in postsurgical patients, especially those aged 75 and older, smokers, or those with cardiopulmonary disease.
• Occupational exposure screening: for workers exposed to asbestos, coal dust, silica, or chemicals.
• Medication toxicity monitoring: drugs like amiodarone and certain chemotherapy agents can damage lung tissue.
• Post-COVID evaluation: persistent dyspnea and impaired gas exchange after infection.
• Symptom-driven evaluation: unexplained shortness of breath, chronic cough, or wheezing.

What to Expect: Before, During, and After a PFT

Before the Test: How to Prepare

Preparation is straightforward. Patients should avoid bronchodilator medications for 4 to 24 hours beforehand (the window depends on the medication type), refrain from smoking on test day, and avoid vigorous exercise. Wearing loose, comfortable clothing, eating only a light meal, and informing the facility of all current medications and recent illnesses are also recommended.

During the Test: What Actually Happens

Patients sit upright, a nose clip prevents air from escaping, and they breathe through a mouthpiece. For spirometry, they take a deep breath and exhale forcefully, repeated several times. For body plethysmography, they sit in a sealed chamber and pant gently. For DLCO, they hold their breath for approximately 10 seconds after inhaling tracer gas. For CPET, they exercise while being monitored.

Per the Cleveland Clinic, some patients feel briefly lightheaded after maximal effort, which resolves quickly. A trained clinician is present throughout. Total testing time typically ranges from 30 to 60 minutes.

After the Test: Understanding Results

Results are compared to personalized predicted values. PFTs identify two primary patterns: obstructive (limited airflow, as in asthma or COPD) and restrictive (reduced volume, as in fibrosis). Abnormal findings simply guide the next clinical step. New 2025 ATS reporting guidance makes results clearer and more consistent across providers. Follow-up may include medication adjustments, pulmonary rehabilitation, or specialist referral.

The Underdiagnosis Crisis: Millions of Americans Don’t Know Their Lungs Are at Risk

The scale of the problem is striking. While 16 million Americans have diagnosed COPD, studies suggest up to 70% of adults with COPD remain undiagnosed globally; a 27-country study found 81.4% of cases undiagnosed. Roughly 25 million Americans have asthma, and misdiagnosis is common when spirometry isn’t used to confirm it.

COPD prevalence rises sharply with age, from 0.4% in adults aged 18 to 24 to 10.5% in those 75 and older. COPD costs the U.S. an estimated $50 billion annually, and chronic lower respiratory diseases are the fifth-leading cause of death. The core issue is access: when testing is delayed or simply not ordered, patients go undiagnosed and untreated.

The Access Problem: Why Hospital Wait Times Are Delaying Diagnoses

Hospital-based pulmonary labs are often backlogged, with waits stretching weeks or months. Contributing factors include increased infection-control protocols following COVID-19, staffing shortages, high patient volumes, and limited scheduling flexibility. The downstream consequences are serious: delayed diagnoses, delayed treatment, and disease progression during the wait.

A structural response is underway. Decentralized, outpatient PFT solutions are expanding access and closing care gaps. The home care segment is the fastest-growing PFT market category at 8.2% CAGR, reflecting a broader shift toward accessible, patient-centered diagnostics.

A Faster Path to Answers: How Belmar Cardiopulmonary Diagnostic Center Bridges the Gap

Belmar Cardiopulmonary Diagnostic Center (BCDC) is a dedicated outpatient cardiopulmonary diagnostic center serving the Bellevue, WA area, purpose-built to deliver focused, accessible, high-quality PFT services. Its key differentiators for PFT access include:

• Reduced wait times: BCDC positions itself directly as a solution to regional diagnostic backlogs.
• Flexible scheduling: weekend appointments and direct referral availability for patients who cannot take time off work.
• Comprehensive services under one roof: spirometry, full pulmonary function panels, CPET/VO2 testing, methacholine challenge, exercise challenge, FeNO testing, HAST, and arterial blood gas sampling, all performed, overseen, and interpreted by licensed, credentialed staff and board-certified physicians.
• Patient-centered environment: a quality-over-quantity philosophy with individualized attention.
• 21+ years of experience and a Minority and Veteran Owned foundation.

Patients and referring physicians in the Bellevue area can learn more about available services and scheduling options at bcdctesting.com. For primary care providers and specialists, BCDC offers a streamlined referral pathway that delivers timely, reliable results without subjecting patients to extended hospital waits.

A Note on Technology: How AI Is Improving PFT Accuracy in 2026

Artificial intelligence is transforming PFT interpretation. Algorithms can now detect technical errors in spirometry maneuvers, classify spirometric patterns, and support clinical decisions with greater consistency. In one recent study, an AI system outperformed both senior and junior pulmonologists when interpreting PFT and clinical data for 50 patients.

The broader context is significant: the global PFT systems market is projected to grow from $5.3 billion in 2025 to $10.23 billion by 2035, driven partly by AI-powered tools. For patients, better technology means more accurate results, fewer inconclusive tests, and faster, more confident diagnoses.

Who Should Consider Getting a Pulmonary Function Test?

A conversation with a primary care provider about a PFT is reasonable for anyone who:

• Experiences persistent shortness of breath, chronic cough, wheezing, or reduced exercise tolerance.
• Is a current or former smoker, especially over age 40.
• Is aged 75 or older, given COPD prevalence of 10.5% in that age group.
• Has known asthma or COPD without recent confirmatory testing.
• Has occupational exposure to asbestos, coal dust, silica, or chemicals.
• Takes medications known to cause pulmonary toxicity.
• Is preparing for major thoracic, abdominal, or cardiac surgery.
• Has persistent respiratory symptoms after COVID-19.
• Is planning high-altitude travel or wants objective cardiopulmonary performance data.

Conclusion: Don’t Let a Backlog Stand Between You and a Diagnosis

Pulmonary function testing is a safe, noninvasive, and clinically powerful tool that detects lung disease early, guides treatment, and prevents unnecessary progression. However, it delivers these benefits only when patients can actually access it. Millions of Americans live with undiagnosed COPD or asthma, not because testing doesn’t exist, but because access barriers get in the way.

PFTs are nothing to fear. They are painless, relatively brief, and the results do not pass or fail anyone. Whether the goal is finding answers after a long wait or identifying a reliable referral option, a dedicated outpatient PFT center offers a meaningful alternative to the hospital backlog. Knowing how the lungs are functioning is one of the most actionable steps toward long-term respiratory health.

Ready to Schedule a Pulmonary Function Test?

For patients experiencing respiratory symptoms, carrying risk factors for lung disease, or waiting on a hospital referral, Belmar Cardiopulmonary Diagnostic Center offers a faster, more accessible path to answers.

For referring physicians, BCDC provides a streamlined referral option with flexible scheduling, board-certified physician interpretation, and a patient-centered environment that supports compliance and follow-through.

Getting started is simple. Reach out today:

• Phone: 206-730-9364
• Email: hello@belmarcardio.org
• Online: Use the contact or appointment booking form at bcdctesting.com to schedule a visit.

The BCDC team will guide patients and providers through the entire scheduling process.