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    Pulmonary Function Testing

    Pulmonary function tests are a group of procedures that measure the function of the lungs, revealing problems in the way a patient breathes. The tests can determine the cause of shortness of breath, and may help confirm lung disease such as asthma, bronchitis, or emphysema. Some tests may be repeated after you inhale medicine that temporarily enlarges your airways to see if there is a positive change in breathing.

    Pulmonary function labs are located on two campuses:
    St. Luke's
    3555 Cesar Chavez
    4th floor, Room 401
    San Francisco, CA
    Convenient scheduling
    (415) 641-6565

    2351 Clay Street, 5th Floor
    San Francisco, CA
    Directions to the pulmonary function lab on our Pacific Campus

    There are several tests that may be performed but the most common are spirometry, gas diffusion, and plethysmography. Here are basic definitions to help explain the most common tests.

    Spirometry – this test is usually done first. It measures how quickly your lungs can move air in and out and how much air they can move in and out.

    Gas diffusion – this test measures the amount of oxygen and other gases that cross the lung air sacs per minute. These tests evaluate how well gases are being absorbed into your blood from your lungs. For this test a small finger prick is done to collect a few samples of blood to help calculate the test. Blood collection is usually not done for children.

    Plethysmography – airway resistance can be directly measured, which determines the pressure required to produce a given flow. For this test, you sit in a “booth” and breathe through a mouthpiece while pressure and airflow measurements are collected.

    Other common tests include:

    Exercise testing – This test evaluates the effect of exercise on the lung function. If you are scheduled for this test, we recommend that you wear comfortable clothing or bring a change of clothes such as sweat pants or shorts. Walking or jogging shoes will also be needed.

    Arterial Blood Gases (ABG) – ABG’s can show how well your lungs are getting oxygen into your blood. For this test a sample of blood is drawn from your artery, usually drawn from the wrist area.

    Please print and complete this pulmonary diagnostic services questionnaire (PDF, 24KB) and bring it with you the day of your scheduled test.

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