How is PFT Performed ?


This is a short, simple breathing test requiring you to take a deep breath and blow out hard into a mouthpiece. The spirometer records how much and how fast you blow air out of your lungs. You usually have to do this at least three times to get your best effort. The test takes about 15 minutes and the results are immediately available for your visit with the lung specialist. If your doctor wants you to do the test before and after a bronchodilator, an inhaled medication that relaxes the muscles around your breathing tubes in your lungs, the test will take a total of about 30-40 minutes.

Body Plethysmography

In this the patient is asked to sit in a transparent, sealed box and to breathe into a mouthpiece. The lung volume is determined with the help of the variation of PFT pressure inside the chamber. Another procedure for this lung function test involves the patient’s breathing helium or nitrogen gas through a tube. This tube is attached to a chamber and in which the concentration of the helium or nitrogen gas is measured to determine the volume of the lungs.

Lung Diffusion Capacity

In this patient is asked to breathe in a harmless gas, also called a tracer gas, mostly for just a single breath. The amount of gas that the patient breathes out is measured and the difference between the amount of gas inhaled and exhaled is determined. This difference allows the doctors to determine how effectively oxygen is passed from the lungs to the bloodstream.

Who performs the test ?

A pulmonary function test procedure is usually carried out by a PFT technician or a Respiratory Therapist. In some cases a Lung Specialist supervises the test.