Pulmonary Function Tests (PFT)

Prior to Procedure

• Review your medications with your doctor; there may be some that you should stop taking before testing.
• Don't eat, smoke, or exercise 4-8 hours before testing.
• Wear loose-fitting clothing.

During Procedure

You'll be asked to exhale and inhale in different patterns and speeds into pulmonary testing devices (ie, spirometer, peak flow meter). You will be able to rest between tests.

Anesthesia

None

Description of the Procedure

Immediately before each PFT, the technician will explain how each test is performed and how the PFT device being used works. You may be asked to sit in an atmosphere-controlled booth and/or put on a nose clip. In some cases, one or more of these tests may be done during or immediately following exercise (on a treadmill or stationary bike). If you have breathing problems, pain, or dizziness during testing, tell the technician right away.

The pulmonary function tests consist of:

• Spirometry—the main measurements include: forced expiratory volume in one second (FEV1) and forced vital capacity (FVC)
• Lung volumes—include total lung capacity (TLC), functional residual capacity (FRC), and residual volume (RV)
• Quantification of diffusing capacity—measures gas exchange

Other tests may include flow-volume loops (can identify upper airway obstruction) and measurements of maximal respiratory pressures (detects respiratory muscle weakness).

Additional pulmonary function tests that are used in certain situations include:

• Oxygen saturation test—A small probe is painlessly strapped or clipped to one of your fingers or toes to measure the amount of oxygen being carried in the blood.
• Allergen challenge tests—You are exposed to specific allergens during pulmonary function testing. This is only done in limited situations, under close and careful supervision.
• Bronchoprovocation testing:
  
  • Methacholine provocation test—People with asthma will experience a mild constriction of the airways when the drug methacholine is inhaled. This test may be done in situations where asthma is suspected but other pulmonary function tests have not shown a clear diagnosis of asthma.

After Procedure

Rest until you feel able to leave. If testing causes symptoms of a lung condition or disease, you'll be given a bronchodilator or other medication.

How Long Will It Take?

20-45 minutes

Will It Hurt?

The testing is not painful. However, you may experience symptoms of your lung condition or disease (wheezing, coughing, shortness of breath) during or immediately following testing. Symptoms usually can be cleared with the use of a bronchodilator.

Possible Complications

• There may be a slight risk of collapsed lung in some patients with lung disease.
• Allergen challenge tests can pose dangers, since side effects may occur hours after testing. Such tests should only be done in limited, specific circumstances, and under close and careful supervision by a doctor or specially trained technician.

Average Hospital Stay

None

Postoperative Care

Medications may be adjusted if a new lung condition is diagnosed.