Pulmonary function tests

The Pulmonary Function Lab does many types of lung function tests. Some of the most common tests are:

Spirometry

This test measures how much air a person can blow out of his or her lungs and how fast the air can be blown. This is the most common test for breathing problems. The patient will be asked to take a deep breath and then quickly blow all the air out. This test lasts about 20 minutes.

Medicine to open up the airways may be given, depending on the values measured during the test.

Lung volumes

This test measures the amount of air in the lungs. This test can help the doctor better diagnose some lung problems. This test may help find out if there is a smaller than normal amount of air in the lungs or if the lungs are overinflated. This test takes about 20 minutes.

Pre- and post-bronchodilator spirometry

Spirometry is measured before and after taking an inhaled bronchodilator medicine. This test checks to see if there is improvement in breathing after the inhaled medicine. This test lasts about 40 minutes.

To prepare for pre- and post-bronchodilator spirometry test:

  • Fast-acting bronchodilators such as albuterol (Proair®, Ventolin®, Proventil®) and levalbuterol (Xopenex®) should not be used for at least four hours before this test.
  • If the patient is having trouble breathing, use the inhaler and then call the Pulmonary Function Lab for advice on rescheduling the breathing test.

Positional spirometry

Spirometry is measured while a patient is in a standing or sitting position, and again while he or she is lying down. This test lasts about 40 minutes.

A medicine to open up the airways may be given, depending on the values measured during the test.

Exhaled nitric oxide analysis

Nitric oxide gas is present in the airways. The levels may increase when the airways are inflamed.During this test, the patient will exhale into a specific measuring device. The results of this test can help the doctor decide on the best treatment plan for asthma and other conditions. This test takes about 20 minutes.

To prepare for a FENO test:

  • Nothing to eat or drink for one hour before the test.
  • Avoid high nitrate foods for 24 hours before the test. These foods include processed meats like bacon, lunchmeat, hotdogs, ham, and other cold cuts.

Not all insurance providers will pay for this test. Please check with your insurance provider to see if they will pay for testing.

Diffusion capacity

This breathing test measures how well air moves from the lungs into the blood. During this test, the patient must be able to hold his or her breath for 10 seconds. This test takes about 20 minutes.

To prepare for a DLCO test:

  • No smoking on the day of the test.
  • No alcohol for four hours before the test.
  • Do not eat a large meal for two hours prior to the test.

Maximal respiratory pressures

This test measures the strength of the breathing muscles. This test takes about 20 minutes.

Six-minute walk test

This test measures the distance a person can quickly walk in the hallway for six minutes. Oxygen levels, heart rate and blood pressure are compared before and after the test. This test takes about 20 minutes.

Bronchial challenges

These tests help diagnose asthma or reactive airways disease. A patient can have only one bronchial challenge test per day. If two challenge tests are ordered, they will be scheduled on different days. The patient will be asked to do numerous spirometry blows during the test. After the bronchial challenge test, an inhaled bronchodilator medicine will be given. A challenge test takes about two hours.

Some medications need to be withheld before a challenge test (see chart below).

Methacholine challenges

In this test, the patient breathes in a medicine called methacholine. Spirometry measurements are made. The results of this test show if the airways are more sensitive than normal.

This test will not be done if the patient has:

  • Had a heart attack or stroke within the past three months.
  • A known aortic aneurysm.
  • Very high blood pressure.

We will discuss the need for this test with your doctor if the patient is:

  • Using beta-blocker medication.
  • Using cholinesterase inhibitor medication.
  • Pregnant.
  • Breastfeeding.

Exercise challenge

In this test, the patient will exercise on a treadmill to see if it causes trouble breathing. Comfortable shoes and clothing should be worn. Numerous spirometry measurements will be made after exercise.

This test will not be done if the patient has:

  • Had a heart attack or stroke within the past three months.
  • Severe aortic stenosis or aortic aneurysm.
  • Very high blood pressure.

Patients over the age of 30 should schedule this test in an adult Pulmonary Function Lab.

We will discuss the need for this test with your doctor if you have:

  • Known electrolyte abnormality.
  • Uncontrolled diabetes.
  • Limitations to exercise.

Medications

Some medicines need to be withheld before the exercise challenge or methacholine challenge tests. They include:

Medication or activity Time to withhold 
Albuterol, Xopenex 8 hours
Advair, Symbicort 48 hours
Atrovent, Combivent, Duoneb 24 hours
Spiriva  72 hours
Singulair, Accolate, Zyflo  24 hours
Theophylline, Liquid   12 hours
Theophylline, twice daily 24 hours
Theophylline, once daily 48 hours
Antihistamines, short acting Methacholine: Not usually withheld;
Exercise Challenge: 48 hours 
Antihistamines, long acting  Methacholine: Not usually withheld;
Exercise Challenge: 72 hours 
Caffeine  Methacholine: Day of test;
Exercise Challenge: 3 hours 
Inhaled or oral steroids  Not usually withheld. If withheld, only on day of test. 
Heavy exercise or cold air exposure  4 hours
Avoid eating a heavy meal, smoking cigarettes or consuming alcohol 3 hours 

Exercise physiology

This test is used to assess heart and lung function during exercise. The patient must be able to exercise to their maximum ability, usually on a treadmill. Comfortable shoes and clothing should be worn. The patient will exercise wearing a mouthpiece. This test lasts about two hours.

This test will not be done if the patient has:

  • Had a heart attack or stroke within the past three months.
  • Severe aortic stenosis or aortic aneurysm.
  • Very high blood pressure.
  • Certain other heart conditions.
  • Fever.

Patients older than 30 should schedule this test in an adult Pulmonary Function Lab. We will discuss the need for this test with your doctor if the patient has:

  • Very high blood pressure.
  • Uncontrolled diabetes.
  • Orthopedic limitations to exercise.
  • Certain conditions that are worsened by exercise.
  • Advanced or complicated pregnancy.
  • Cardiomyopathy.

Infant and toddler pulmonary function test

You need to have an appointment with a pediatric pulmonary doctor before this test can be scheduled. Your child must be younger than 3 years old and less than 36 inches tall for this test. Your child will be sedated. We will talk to you about the preparation for this test during your visit with the pulmonary doctor. This test takes three to four hours.

Metabolic study (resting energy expenditure)

A metabolic study measures the calorie needs of the patient. Exhaled breath is measured while the patient rests under a clear plastic bubble. Because this is a resting measurement, the patient needs to be as relaxed as possible during the test. This test lasts one hour.

To prepare for a metabolic study, do not eat or drink anything for at least two to four hours before the test. 

Test results

A pediatric pulmonary specialist reads the results of your test, and test results usually are faxed to your doctor within four business days of testing.