Pulmonary Function Test

What is a pulmonary function test?

Pulmonary function tests, also known as lung function tests, are a group of tests that measure how well the lungs are working. These tests assess various aspects of lung function, including the capacity to inhale and exhale air, the efficiency of oxygen exchange, and the strength of respiratory muscles.

Pulmonary function tests are safe and do not require a doctor to put any tools or instruments inside the body (non-invasive).

Who performs pulmonary function test?

Pulmonologists (chest physicians), respiratory therapists, technicians, and trained nurses conduct pulmonary function tests.

What are the types of lung function tests?

There are several types of lung function tests (pulmonary function tests) that provide different information about lung function.

  • Spirometry: This is the most common type of pulmonary function test, and it measures how much air the patient can breathe in and out. It also estimates the amount of air in the lungs.
  • Lung volumes or body plethysmography: It is more precise than spirometry. It measures the air volume in the lungs at different stages of breathing, including after inhaling and exhaling.
  • Gas diffusion study: This test measures how well oxygen and other gases transfer from the lungs into blood.
  • The cardiopulmonary exercise test (CPET) measures how effectively the heart, lungs, and muscles work together during exercise.

How is the test performed?

Spirometry is a lung function test that measures airflow. To prepare for the test, the technician will place soft clips on the patient’s nose to ensure that the patient breathes through the mouth rather than the nose. Next, the patient will place lips around a mouthpiece, which is connected to a spirometer, a device that measures lung function. The technician will provide instructions on how to breathe during the test. During the test, the patient may be instructed to take deep breaths in and out and also may be asked to take deep breaths in and exhale forcefully and rapidly. These breathing maneuvers help assess lung capacity and function.

Body plethysmography is a more precise method where once the nose clips are placed on the patient by a technician, the patient will be seated inside a clear (see-through) box. The technician will close the door, which typically remains shut for approximately five minutes. If the patient experiences discomfort in confined spaces or has claustrophobia, it is important to inform the technician. They can assist in making the patient feel more comfortable during the test. The patient will then place the lips around the mouthpiece, and the technician will provide instructions on how to breathe in and out. During the test, a spirometer will monitor pressure or volume changes within the box, enabling the measurement of lung volume. This helps assess lung function and capacity.

Diffusion capacity is measured by having the patient breathe in a harmless gas for a brief moment, usually just one breath, and exhale into a tube. The concentration of the gas in exhaled breath is measured to assess how efficiently gases travel from the lungs into the bloodstream. This test helps estimate the lung’s ability to transfer oxygen into the blood.

During a cardiopulmonary exercise test, a technician will connect the patient to machines that monitor heartbeat, blood pressure, and blood oxygen levels. The patient will be asked to walk on a treadmill or pedal a stationary bicycle. These machines will track different aspects of the heart, lungs, and muscles as the patient exercises. This test helps show how well the lungs perform during exercise.

A PFT may take between 15 and 45 minutes to complete.

The doctor will compare the patient’s test results with the average scores of people similar to the patient in terms of age, height, and sex. This comparison will help them determine whether the patient’s scores are within the expected range.

Pulmonary function testing is generally safe, but the patient may experience some temporary effects. Deep breathing during the test might make the patient feel dizzy, lightheaded, or tired. Blowing into the mouthpiece may cause coughing, and exercising during the test can tire the patient. These symptoms should go away shortly after completing the test.

It is important to note that a pulmonary function test can temporarily increase heart rate. If the patient has recently had a heart attack or has any heart conditions, he needs to inform the doctor before undergoing the test.


Select your Location

Please select your nearest location from the list below