What is pulmonary function testing?

Pulmonary or lung function testing includes various tests that measure how well your lungs are working. Doctors use pulmonary function testing to diagnose and manage many diseases that affect your lungs and breathing. These diseases commonly include asthma, cystic fibrosis, blood clot in the lung (pulmonary embolism), and COPD (chronic obstructive pulmonary disease).

Pulmonary function testing is only one method of diagnosing and managing respiratory diseases. Discuss all the testing and monitoring methods with your doctor to understand which options are right for you.

Types of pulmonary function testing

Common types of pulmonary function testing include:

  • Arterial blood gas test to measure oxygen and carbon dioxide levels and other factors in the blood 
  • Body plethysmography to measure how much air is in your lungs when you take a deep breath and how much air remains in your lungs after you exhale as much as you can
  • Bronchoprovocation tests to measure lung function after exposure to factors that commonly trigger asthma. This includes a methacholine challenge test to help diagnose asthma.
  • Lung diffusion capacity to measure how well oxygen moves into your blood from your lungs
  • Peak expiratory flow to measure the speed of exhaling and lung constriction. People with asthma often use this test routinely to monitor their asthma control.
  • Pulse oximetry to measure oxygen levels in the blood
  • Spirometry to measure the amount of air and the rate that you inhale and exhale

Pulmonary function tests are sometimes done at the same time using the same equipment. Body plethysmography, spirometry, bronchoprovocation tests, and lung diffusion capacity are often performed at the same time.

Why is pulmonary function testing used? 

Your doctor may recommend pulmonary function testing to diagnose and determine the severity of diseases that affect breathing and to determine how well treatments are working. These diseases, disorders and conditions include:

  • Allergic conditions that affect the lungs including asthma, anaphylaxis, and allergic alveolitis
  • Blood clots including pulmonary embolism (blood clot in a blood vessel of the lungs)
  • Cardiac diseases including congestive heart failure, congenital (present at birth) heart disease, and pulmonary hypertension
  • COPD (chronic obstructive pulmonary disease) including emphysema and chronic bronchitis
  • Congenital (present at birth) and genetic lung and chest conditions including cystic fibrosis, chest deformities, scoliosis, cystic adenomatoid malformations, pulmonary sequestrations, and congenital lobular emphysema
  • Inflammatory conditions including sarcoidosis and systemic lupus erythematosus, which can affect the lungs and other organs
  • Lung infections including pneumonia, acute bronchitis, and fungal and viral infections
  • Lung scarring and damage including damage due to pulmonary fibrosis and asbestosis
  • Neuromuscular diseases including multiple sclerosis, myasthenia gravis, and Guillain-Barré syndrome

Your doctor may also use pulmonary function testing in the following situations: 

  • You are a current or former smoker. 
  • You are having surgery including abdominal, heart and lung surgery.
  • You have abnormal test results including abnormal arterial blood gases and chest X-ray.
  • You have symptoms of respiratory disease including chest tightness, cough, phlegm, wheezing, and shortness of breath.

Who performs pulmonary function testing?

A pulmonary function technologist or a specially trained respiratory therapist or nurse usually performs pulmonary function testing. A pulmonary function technologist is a healthcare provider who specializes in performing lung function tests to diagnose and treat lung diseases. Common lung diseases include asthma, chronic obstructive pulmonary disease (COPD), and other breathing problems. 

The following types of doctors are likely to supervise your pulmonary function testing:

  • Allergist-immunologists specialize in caring for people with allergies, asthma, and other diseases of the immune system.
  • Pediatric allergist-immunologists specialize in caring for children from infancy through adolescence with allergies, asthma, and other diseases of the immune system.
  • Pulmonologists specialize in the medical care of people with breathing problems and diseases and conditions of the lungs.
  • Pediatric pulmonologists specialize in the medical care of infants, children and adolescents with diseases and conditions of the lungs.