Pulmonary Function Testing

Pulmonary Function Testing: Understanding Your Lung Health

Pulmonary Function Testing (PFT) is a group of diagnostic tests used to assess how well your lungs work. Also known as lung function testing, these tests measure how much air you can breathe in and out, how quickly you can exhale, and, when indicated, how effectively your lungs transfer oxygen into the bloodstream.

If you experience persistent coughing, shortness of breath, wheezing, or difficulty breathing during everyday activities, a pulmonary function test may help your doctor understand what is happening. These tests are commonly used to evaluate respiratory conditions such as asthma, chronic obstructive pulmonary disease (COPD) and other disorders that affect breathing.

At Siris Healthcare, patients can explore respiratory diagnostic services and learn about the investigations that may be recommended as part of an individual care plan. The choice of test depends on your symptoms, medical history and your doctor's assessment.

To understand related services, explore our Diagnostics page and Respiratory Health Screening resources.

What Is a Pulmonary Function Test (PFT)?

A Pulmonary Function Test (PFT) measures different aspects of lung performance, including airflow, lung volume and the exchange of gases. Your doctor may recommend one or more tests depending on whether the concern involves narrowed airways, reduced lung capacity or another respiratory problem.

A lung function test can provide objective information that supports clinical assessment. It may help doctors investigate unexplained breathlessness, assess known lung conditions, monitor changes over time, or evaluate respiratory function before certain medical procedures.

A PFT does not diagnose every lung condition on its own. Your doctor interprets the results alongside your symptoms, examination findings and other investigations when needed.

Types of Pulmonary Function Tests

Different tests measure different aspects of respiratory function.

1. Spirometry Test

Spirometry is one of the most commonly used lung function tests. It measures how much air you can exhale and how quickly you can blow air out after taking a deep breath. It can help evaluate airflow obstruction and support the assessment of conditions such as asthma and COPD.

2. Lung Volume Testing

Lung volume tests measure the amount of air your lungs can hold, including air that remains after you breathe out. These measurements can help doctors investigate conditions associated with reduced lung capacity or restricted lung expansion.

3. Diffusion Capacity Test

A diffusion test, often called DLCO testing, assesses how effectively gases move from the lungs into the bloodstream. It may be recommended when a doctor needs additional information about gas exchange or certain lung tissue disorders.

4. Bronchodilator Response Testing

In some cases, spirometry is performed before and after administering a bronchodilator medication. Comparing the results can help assess whether airflow changes after the medicine, which may contribute to the evaluation of asthma and other airway conditions.

5. Exercise-Related Breathing Assessment

When breathlessness occurs during physical activity, a doctor may recommend exercise-based testing or other assessments to understand how the respiratory system responds to exertion. The appropriate test depends on the suspected cause of the symptoms.

Not every patient needs all these investigations. Your doctor will select the tests that best address your clinical needs.

When Should You Consider a Lung Function Test?

A lung function test may be recommended if you have symptoms that suggest a problem with your breathing or if your doctor needs to monitor an existing respiratory condition.

Common reasons for pulmonary function testing include:

• Persistent or unexplained shortness of breath
• A cough that continues or repeatedly returns
• Wheezing or chest tightness
• Reduced exercise tolerance or breathlessness during routine activities
• Suspected asthma or COPD
• Monitoring of an already diagnosed lung condition
• Assessment of possible occupational or environmental exposure-related lung problems
• Evaluation of respiratory function before selected surgeries or treatments
• Follow-up to assess changes in lung function over time

Breathing difficulties can have several causes, so a PFT may be only one part of the diagnostic process. If symptoms are sudden or severe, seek urgent medical care rather than waiting for a routine test appointment.

Patients looking for additional information about respiratory conditions can explore our Pulmonology specialty page.

Conditions That May Require Pulmonary Function Testing

Pulmonary function tests can support the evaluation and monitoring of several respiratory conditions. The results must be interpreted in the context of the patient's medical history and other clinical findings.

Asthma

Asthma can cause recurring wheezing, coughing, chest tightness and difficulty breathing. Spirometry and bronchodilator response testing may help assess airflow and support asthma evaluation when clinically appropriate.

Learn more about Asthma Treatment.

Chronic Obstructive Pulmonary Disease (COPD)

COPD is a long-term lung condition associated with persistent airflow limitation. Symptoms may include breathlessness, chronic cough and mucus production. Spirometry is an important test used to assess airflow obstruction when COPD is suspected and to support ongoing disease management.

Explore COPD Treatment for more information about the condition and its management.

Interstitial Lung Disease

Interstitial lung diseases affect the tissues surrounding the air sacs in the lungs. Some of these conditions can reduce lung volumes or affect the transfer of oxygen into the bloodstream. Depending on the suspected condition, doctors may recommend lung volume measurements, diffusion capacity testing and chest imaging.

Occupational and Environmental Lung Conditions

Long-term exposure to dust, fumes, chemicals or other airborne irritants can affect respiratory health. When symptoms or exposure history raise concerns, pulmonary function testing may help assess lung function and guide further evaluation.

Other Respiratory Conditions

PFTs may also be considered when doctors investigate unexplained breathlessness or monitor selected chronic respiratory disorders. The test results alone may not establish the underlying cause, and additional investigations may be necessary.

How to Prepare for a Pulmonary Function Test

Following the instructions provided by your healthcare team can help ensure that your PFT test is performed appropriately.

Before your appointment, consider the following:

• Wear comfortable clothing: Choose clothes that allow you to breathe and move comfortably.
• Follow medication instructions: Some inhalers and other medicines may affect test results. Your doctor or testing team will tell you whether any medication needs to be adjusted before the test. Do not stop prescribed medication without medical guidance.
• Avoid smoking before the test: Your healthcare provider may advise you to avoid smoking for a specified period before testing.
• Follow food and drink guidance: You may be asked to avoid a heavy meal shortly before your appointment.
• Mention recent illnesses: Inform the testing team if you have recently had a respiratory infection or if your breathing symptoms have worsened.
• Share your medical history: Tell the healthcare professional about your current medicines, respiratory conditions and any relevant medical or surgical history.

Preparation requirements vary according to the type of pulmonary function test. Always follow the specific instructions given when booking your test.

What Happens During a Pulmonary Function Test?

Most routine pulmonary function tests are performed in a clinical testing area under the guidance of trained personnel.

Step 1: Initial Assessment

The healthcare team may review your symptoms, medical history, current medicines and the reason for the test. They may also explain the procedure and check whether any additional precautions are needed.

Step 2: Breathing Through a Mouthpiece

For spirometry, you generally sit upright and breathe through a mouthpiece connected to a testing device called a spirometer. A nose clip may be used to help ensure that air passes through the mouthpiece.

Step 3: Following Breathing Instructions

You may be asked to take a deep breath and blow out as forcefully and completely as possible. The manoeuvre may be repeated to obtain reliable measurements. Other PFT procedures use different breathing instructions or equipment.

Step 4: Additional Measurements, If Required

Depending on the reason for testing, you may undergo additional assessments, such as lung volume measurements, diffusion capacity testing or spirometry after a bronchodilator.

Step 5: Review of Results

The measurements are interpreted by a qualified healthcare professional in relation to your symptoms, medical history and other findings. Your doctor will explain what the results mean and whether any further evaluation is required.

The duration of a pulmonary function test varies with the type and number of measurements performed.

Benefits of Pulmonary Function Testing

A pulmonary function test provides measurable information about how the lungs are working. When used appropriately, it can support several aspects of respiratory care.

• Assessment of breathing problems: Helps doctors investigate symptoms such as breathlessness, persistent cough and wheezing.
• Evaluation of airflow: Spirometry can identify patterns of airflow limitation that may be associated with obstructive lung conditions.
• Measurement of lung capacity: Selected tests help assess lung volumes and identify patterns that may require further investigation.
• Monitoring of respiratory conditions: Repeat testing may help doctors assess changes in lung function over time.
• Treatment assessment: In appropriate cases, measurements can help evaluate respiratory function before and after certain treatments.
• Support for clinical decisions: Results can contribute to decisions about further investigations, treatment planning and follow-up.

The usefulness of the test depends on the clinical question being investigated. Results should always be interpreted by a qualified healthcare professional.

Is Pulmonary Function Testing Safe?

Routine pulmonary function tests are generally well tolerated and do not require surgery or injections. However, the forceful breathing manoeuvres involved can temporarily cause coughing, dizziness, fatigue or shortness of breath in some people.

Certain medical conditions may require postponing the test or taking additional precautions. Inform your healthcare provider if you have recently undergone surgery, experienced a significant cardiovascular event, or have another condition that could make forceful breathing difficult.

Your doctor or testing team will determine whether the test is appropriate for you and explain any relevant precautions.

Understanding Your Pulmonary Function Test Results

PFT reports contain several measurements. Their interpretation depends on the test performed, the patient's age, height, sex-related reference parameters, clinical history and the laboratory's reference standards.

Common spirometry measurements include:

• Forced Vital Capacity (FVC): The total amount of air a person can forcibly exhale after taking a full breath.
• Forced Expiratory Volume in One Second (FEV1): The amount of air exhaled during the first second of a forced breath.
• FEV1/FVC Ratio: The proportion of the forced vital capacity exhaled in the first second, which can help assess airflow obstruction.
• Diffusion Capacity (DLCO): A measurement of how effectively gas transfers from the lungs into the bloodstream, when this test is performed.

A result outside the expected reference range does not automatically confirm a particular disease. Similarly, normal results do not rule out every respiratory condition. Your doctor may recommend further tests, repeat measurements or specialist assessment depending on the findings.

Pulmonary Function Testing and Respiratory Care at Siris Healthcare

Understanding your breathing symptoms starts with appropriate medical evaluation. Siris Healthcare provides information about diagnostic services, respiratory screening and specialist care to help patients explore available healthcare options.

You can learn more through our related resources:

• Diagnostics and Medical Tests - Explore diagnostic testing and imaging services.
• Respiratory Health Screening - Understand lung health assessment and screening considerations.
• Pulmonology and Lung Care - Learn about specialist evaluation for respiratory conditions.
• Pulmonary Function Test (PFT) Package - Explore information about the listed PFT package.
• Medicover Hospitals, Chandanagar - Pulmonology - View respiratory specialty information for this Hyderabad location.
• Medicover Hospitals, Financial District - Pulmonology - Explore published pulmonology services at the Financial District location.
• Medicover Hospitals, Secunderabad - Pulmonology - Find information about respiratory specialist care.
• Medicover Hospital, Whitefield - Pulmonology - Explore published pulmonology services in Bengaluru.
• Persistent Cough and Breathlessness: When to See a Pulmonologist - Learn when persistent respiratory symptoms may require medical evaluation.
• Lung Health Screening - Read about lung screening and commonly used respiratory assessments.

If you are experiencing ongoing breathing difficulties or have been advised to undergo a lung function test, speak with a qualified healthcare professional to understand which investigations are appropriate for your situation.

Frequently Asked Questions About Pulmonary Function Testing

What is a pulmonary function test used for?

A pulmonary function test measures how well your lungs move air and, depending on the test, how effectively they transfer gases. It can help evaluate symptoms such as breathlessness, persistent cough and wheezing, and support the assessment or monitoring of conditions such as asthma and COPD.

Is a PFT the same as a spirometry test?

Not exactly. Spirometry is one type of pulmonary function test. Comprehensive pulmonary function testing may include additional measurements, such as lung volumes and diffusion capacity, depending on the clinical need.

How long does a pulmonary function test take?

The duration depends on the tests required. A basic spirometry assessment may take around 15–30 minutes, while a more comprehensive pulmonary function evaluation can take longer. Your testing centre can confirm the expected appointment duration.

Do I need to fast before a PFT test?

Fasting is not routinely required for every pulmonary function test. You may be advised to avoid a heavy meal shortly before testing. Follow the instructions provided by your healthcare team.

Can I take my inhaler before a lung function test?

It depends on the purpose of the test and the inhaler you use. Your doctor may ask you to withhold certain bronchodilators temporarily when it is safe and clinically appropriate. Never stop or change prescribed medication without specific medical instructions.

Is pulmonary function testing painful?

Routine PFTs are non-invasive and are not usually painful. Forceful breathing can sometimes cause temporary coughing, dizziness or breathlessness. Inform the testing team if you feel uncomfortable during the procedure.

Can a PFT diagnose asthma or COPD?

Pulmonary function testing, particularly spirometry, can provide important evidence when evaluating asthma and COPD. However, diagnosis requires interpretation of the test results alongside symptoms, medical history and other relevant clinical information.

What happens if my PFT results are abnormal?

Your doctor will review the measurements and determine whether further investigation, repeat testing or specialist consultation is necessary. An abnormal result does not automatically indicate a specific disease.

How often should pulmonary function tests be repeated?

There is no single testing schedule for everyone. Repeat testing depends on the respiratory condition, symptom changes, treatment plan and your doctor's recommendations.

Where can I learn more about pulmonary diagnostics?

You can explore the Siris Healthcare Diagnostics page and the Pulmonology specialty page for more information about diagnostic services and respiratory care.

Medical disclaimer: This content is intended for general educational purposes and does not replace a consultation with a qualified healthcare professional. Test selection, preparation and interpretation should be guided by your treating clinician.