Pulmonary Function Test

What is Pulmonary Function Test?

Pulmonary Function Tests (PFTs) are noninvasive tests. These are aimed at demonstrating the functioning of the lungs. The tests help measure the following:

• Lung volume
• Capacity of lungs
• Rates of flow
• Gas exchange

The above-listed information helps diagnose the infection and decide on the best treatment for lung disorders.

Types of Pulmonary Function Tests

Pulmonary function tests assess an individual’s lung function or capacity. These tests are performed at rest or during exercise. These types of tests include the following:

Lung Volumes

It is conducted using a plethysmograph (a machine) to measure air volume in the lungs at different stages of the breathing cycle. The patient is seated during the test and asked to breathe in and out and even pant. Lung volumes distinguish between restrictive lung diseases (pulmonary fibrosis) and obstructive lung diseases (asthma).

Spirometry

The most basic test is used to analyze the amount of air inhaled and exhaled as a function of time. Spirometry calculates the speed (flow) of air inhaled or exhaled. It involves normal and deep breaths and breathing out as hard as the patient can into a tube with a sensor for measurement.

Gas Exchange Testing (DLCO)

It measures how much oxygen passes from the air sacs of the lungs to the blood. Doctors use it for assessing lung diseases. The patient is asked to do normal and deep breathing while holding their breath briefly.

Maximal Voluntary Ventilation (MVV)

The test lasts over 15 seconds, measuring the maximum amount of air one can inhale and exhale in sixty seconds. The patient needs to breathe in and out as forcefully as possible. This test is aimed at assessing the overall function of the respiratory system.

Six-Minute Walk Test

The test checks how far an individual can walk in 6 minutes. It accurately assesses one’s functional status or aptitude to perform day-to-day activities.

Inspiratory and Expiratory Muscle Pressures (PI and PE max)

These tests are prescribed for the assessment of pressures generated by the respiratory muscles. Doctors can evaluate possible neuromuscular disease using PI and PE max.

Oxygen Titration Test

The test determines the requirement for oxygen. It helps check if patients already on oxygen at home are receiving the accurate amount. An oximeter measures oxygen saturation and heart rate.

Cardiopulmonary Exercise Testing

This is a test that assesses your exercise capacity. In most cases, you will be asked to ride a stationary bicycle. We will monitor your heart and lung function at rest, during a warm-up phase, during a short period of exercise, and during “recovery” when you are no longer peddling. The test is beneficial in evaluating the causes of shortness of breath or decreased exercise tolerance. Exercise testing can also be conducted on a treadmill.

Methacholine Challenge Test

This test helps with the diagnosis of asthma. The patient requires breathing in a mist of a solution of Methacholine resulting in “twitchiness” of the airways at low doses among individuals with asthma or asthma-like conditions. The patient must breathe out after each dose is inhaled and then breathe out forcefully into a tube with a sensor. The doctor will monitor changes in lung functioning after each dose. If lung function falls by 20%, the test will stop.

High Altitude Simulation Testing

The test facilitates medical professionals to estimate levels of blood oxygen in high altitudes, especially among patients with lung disease and dependent on oxygen at sea level. The test results will help a doctor prescribe the accurate flow of oxygen during a flight or a visit to an area at a high altitude.

The medical professional will ask the patient to breathe into a mask during this test. This mask simulates the lower oxygen levels found at high altitudes. Symptoms and oxygen levels are monitored closely during this test.

Fractional Exhaled Nitric Oxide (FeNO)

This test lasts for about 60 seconds and is prescribed for diagnosing and managing lung diseases (mainly allergic asthma). The Nitric Oxide produced in the breathing passages is a marker of allergic inflammation. It involves breathing out, taking a deep breath, and exhaling at a slower, continuous rate.

Impulse Oscillation or Forced Oscillation Testing (IOS)

The test is new. It is used to measure airway resistance to assess the narrowness of airways. IOS helps a medical professional distinguish between the resistance of the large and small airways while measuring the stiffness of your lungs. It involves a patient breathing in and out quietly for 30 seconds at a time.

Compliance Testing

The test is used to measure the stiffness or elasticity of the lungs. It diagnoses a wide range of lung conditions. It involves inserting a tiny catheter into the nasal passage of a patient with a soft un-inflated balloon into the esophagus to estimate the pressure around the lung.

Symptoms that Suggest You Need a PFT

There are numerous reasons pulmonary function tests (PFTs) may be recommended by medical professionals. In some cases, healthy individuals may be prescribed this test as part of a routine physical. Some individuals who work in a specific environment (coal mines and graphite factories) are also recommended these tests to ensure they are in good health.

The most common reason for PFTs recommendation is the diagnosis of any of these or more conditions:

• Scleroderma (a condition characterized by the thickening and hardening of connective tissue)
• Allergies
• Respiratory infections
• Sarcoidosis (a condition characterized by lumps of inflammatory cells around organs, including the spleen, lungs, and liver)
• Chronic lung conditions (bronchiectasis, chronic bronchitis, asthma, or emphysema)
• Trouble breathing from injury to the chest or a recent surgery
• Asbestosis (condition of the lung caused by inhaling asbestos fibers)
• Restrictive airway issues such as tumors, problems from scoliosis, inflammation of the lungs, and scarring of the lungs)

PFTs may be used to check lung function before surgery or other procedures in patients who have lung or heart problems, are smokers or have other health conditions. Another use of PFTs is to assess treatment for asthma, emphysema, and other chronic lung problems. Your healthcare provider may also have other reasons to advise PFTs.

Reasons Pulmonary Function Test Done

Doctors may suggest getting a PFT to diagnose a variety of conditions. These may include:

• Allergies
• Asthma
• Chronic bronchitis
• Chronic obstructive pulmonary disease (COPD)
• Disease caused by breathing in asbestos fibers
• Damaged or scarred lung tissue
• Sarcoidosis, a collection of inflammatory cells around organs
• Lung cancer
• Thickening or hardening of your connective tissues (scleroderma)
• Infections
• Weakness of the muscles in the wall of the chest
• Thickened, stretched, or enlarged airways

Benefits and Risks

Risks Pulmonary Function Test

Pulmonary function tests are usually safe. However, as with all medical procedures, PFTs also have risks. These include the following listed below:

• Coughing
• Dizziness
• An asthma attack
• Shortness of breath

Doctors may ask patients to avoid PFT under the following circumstances:

• Had eye surgery in the recent past
• Had surgery on chest or belly in the recent past
• Experiencing symptoms such as chest pain
• Had a heart attack in the recent past
• Suffering from heart conditions
• Detection of a bulging blood vessel (aneurysm) in the brain, belly, or chest
• Active tuberculosis or respiratory infection

PFT is important. If you are short of breath, speak to your doctor if you need a lung function test soon. The test can be the first important step toward breathing easier and leading an everyday happy life.

Frequently Asked Questions