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Pulmonary function tests are quick procedures performed by a pulmonary function technician and include the following steps.
Pulmonary function tests (PFTs) are tests done on an outpatient basis (takes only 15 to 30 minutes) to determine lung function.
The procedure is quick and safe and performed by a pulmonary function technician.
- The technician asks the individual to wear loose clothing and remove jewelry or any other thing that might hinder the examination.
- They give a sterile mouthpiece to the individual that is attached to a spirometer.
- They instruct the individual to inhale (breath in) and exhale (breath out) several times and in different ways (gentle breathing, breath in a quick and deep breath, holding the breath for a few seconds, and then breathing out forcefully).
- To get an accurate result, the technician repeats the test at least three times.
- The technician watches the individual closely to look out for any dizziness or difficulty breathing.
- In some cases, the technician administers a bronchodilator medication. After a few minutes, they repeat the test to provide accurate results.
Normal values of PFTs vary from person to person. Results are compared with those of the average of people of the same age, height, sex, and race.
What are pulmonary function tests?
Pulmonary function tests (PFTs) or lung function tests are breathing tests that evaluate the movement of air back and forth from the lungs and the amount of oxygen entering the bloodstream.
Three types of PFTs include:
- Spirometry: Performed using a spirometer, which is a device with a mouthpiece connected through a tube to an electronic machine.
- Diffusion studies: Measure how efficiently the exchange of carbon dioxide and oxygen occurs through the lungs.
- Body plethysmography: The person is made to stand inside an air-tight short square box, made to wear a nose clip, and asked to breathe through a special mouthpiece.
The most commonly performed PFT is spirometry although in some cases, all the three types of PFTs are scheduled on the same day.
Two types of lung disorders that can cause problems in the movement of air through the lungs include:
- Obstructive: A decreased flow of air is caused by airway resistance (air cannot flow out of the lungs)
- Restrictive: A decreased lung volume leads to airflow issues due to incomplete expansion of lungs or chest muscles
What do pulmonary function tests measure?
A pulmonary function test measures how well the lungs are working through parameters such as lung volume, capacity, rates of flow, and gas exchange.
- Tidal volume: The amount of air inhaled or exhaled during normal breathing
- Minute volume: The total amount of air exhaled or inhaled per minute
- Vital capacity: The total volume of air that can be exhaled after inhaling
- Functional residual capacity: The amount of air left in the lungs after exhaling normally
- Residual volume: The amount of air left in the lungs after maximum exhalation
- Total lung capacity: Maximum volume of air that the lungs can hold
- Forced vital capacity: The amount of air exhaled forcefully and quickly after inhaling as much as possible
- Forced expiratory volume: The amount of air exhaled during a forced breath
- Forced expiratory flow: The average rate of flow during the middle portion of forced expiration
- Peak expiratory flow rate: The fastest rate that a person can force air out of the lungs
Why would I need a pulmonary function test?
There are several reasons to perform pulmonary function tests (PFTs). PFTs may be performed in healthy individuals as a part of routine physical screenings or health checkups or as a mandate in a certain type of work environment to ensure the employee’s health such as coal mines or factories.
PFTs may be recommended by a healthcare professional to diagnose problems such as:
- Allergies
- Respiratory infections
- Trouble breathing from an injury to the chest
- Difficulty breathing after a recent surgery
- Asbestosis (a lung disease caused by inhaling asbestos fiber)
- Restrictive airway problems such as:
- Scoliosis
- Tumors (lung cancer)
- Scarring of the lungs
- Sarcoidosis (a disease that causes lumps of inflammatory cells in organs such as the liver, lungs, and spleen)
- Scleroderma (a disease characterized by the thickening and hardening of connective tissues)
- Chronic lung conditions such as:
- Lung function before surgery in individuals
- Who smoke
- Have lung and heart problems
How to prepare for pulmonary function tests
There are no specific preparations for the procedure although for the best results:
- Avoid smoking at least an hour before the test.
- Take your regular medications unless you have been told not to take them by your doctor.
- Do not drink alcohol at least four hours before the test.
- Avoid eating a large meal at least two hours before the test.
- Avoid any intense exercise at least 30 minutes before the test.
- Do not wear tight clothing that might hinder deep breathing.
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8 benefits of pulmonary function test
Pulmonary functions tests are:
- Noninvasive
- Painless
- Less time-consuming
- Quick and accurate results
- Safe
- Helpful in diagnosing various obstructive and restrictive lung disorders
- Helpful in predicting the way medications and bronchodilator inhalers work
- Helpful in figuring out if surgery is needed
Are there any risks involved in PFT?
Pulmonary function tests (PFTs) are quick and safe for most people, but all of the procedures have a minimal risk involved if not done properly or clear instructions are not followed.
Risks involved in PFT include:
- Excessive coughing
- Shortness of breath
- Feeling dizzy during the test
- An asthmatic episode during or immediately after the test (due to deep inhalations)
PFT is contraindicated in conditions such as:
- Chest pain
- Recent history of
- Heart attack
- Chest surgery
- Abdominal surgery
- Eye surgery
- Active pulmonary tuberculosis
- Respiratory infections such as cold or flu
- Aneurysm (a bulging blood vessel in the chest, abdomen, or brain)