Pulmonary Diagnostic Testing

Pulmonary Function Tests (PFTs) are a group of breathing tests that help doctors see how well your lungs are working. The test is preformed with the patient seated in a booth.

This test determines the amount of oxygen and carbon dioxide dissolved in the blood, as well as the acid/base status. Oxygen and carbon dioxide levels are indicators of lung function. The acid/base status provides information on how well the lungs and kidneys are functioning. It can also give information as to whether there is a problem in the body, like an infection, that is throwing off the acid/base balance in the body. If you are undergoing oxygen therapy, this test can help to see if the therapy is effective.

Diseases that affect the heart, lungs, circulation, or blood, will cause an abnormal response to exercise. Exercise testing is helps evaluate the cause of shortness of breath that otherwise cannot be determined at rest (heart vs. lungs). For this test, patients exercise on a stationary bike (ergometer) to their maximum capacity to duplicate the symptoms that limit their exercise.

During the test, EKG, blood pressure and oxygen saturation is monitored and composition of inhaled and exhaled gases are measured and analyzed to estimate gas exchange, oxygen consumption, carbon dioxide output and ventilatory efficiency. This enables identification of whether the limiting factor is heart disease, lung disease, obesity or deconditioning.

Spirometry is the first and most commonly done lung function test. It measures how much and how quickly you can move air out of your lungs. For this test, you breathe into a mouthpiece attached to a recording device (spirometer). The information collected by the spirometer may be printed out on a chart called a spirogram. Watch the video below for a demonstration.

The six-minute walk test is a performance-based measure of functional exercise capacity. The test is most commonly used to measure exercise tolerance in chronic respiratory disease and heart failure.

The six-minute walk test measures the distance an individual is able to walk over a total of six minutes on a hard, flat surface. The goal is for the individual to walk as far as possible in six minutes. The individual is allowed to self-pace and rest as needed as they walk back and forth along a marked walkway.

This independent exercise assessment is used to qualify a person for home oxygen support for patients whose blood levels of oxygen at rest do not qualify them to receive home oxygen. During the test, a patient is walked while they use both air and oxygen. Oxygen saturation (amount of oxygen in your blood) is measured throughout the test using pulse oximetry. If it can be shown that the administration of oxygen enhances the patient’s exercise challenge, he or she will qualify for home oxygen support.

You can visit the Ontario Ministry of Health Home Oxygen Program web page for more information.