Pulmonary Function Tests

What are pulmonary function tests (PFT)?
Pulmonary function tests measure how well your lungs are functioning and how well oxygen gets into your blood from lungs.

What are the important PFT’S?
Spirometry, Diffusion capacity of the lung for carbon monoxide (DLCO), Six-minute walk test (6MWT) are some important PFT’S.

What is Spirometry?
“Spirometry” (Lung function test)  is a simple non-invasive tool to diagnose certain lung diseases.  During this test you will be asked to take a deep breath and then blow out as fast, as long and as hard as you can into a tube. A spirometer machine attached to the tube measures how much and how fast you can breathe in and breathe out of your lungs.

What are the indications for spirometry?
Spirometry is used for the evaluation of undiagnosed chronic symptoms or when there is a suspicion of asthma, COPD (Chronic Obstructive Pulmonary Disease caused most often because of smoking tobacco ) or pulmonary fibrosis.  In asymptomatic individuals, it may be done

  • Prior to surgery- to look at how well the lungs are functioning
  • In chronic smokers to detect early COPD
  • Patients in certain occupations (e.g-miners) to detect pulmonary fibrosis in an early stage so that an appropriate action is taken.

What is Diffusion capacity of the lung for carbon monoxide (DLCO) and what are the common indications?
This is a special test to measure how well oxygen is getting into the blood from the lungs.  This is done after asking the patient to inhale a special gas mixture from DLCO machine and exhale it back into the machine.  This is commonly done as a part of an evaluation for pulmonary fibrosis (diagnosing and following up) and pulmonary arterial hypertension.

What is 6MWT?
6MWT measures the total distance walked by a person for six minutes time.  This is a simple non-invasive test which measures the global function of cardiac and respiratory systems.  An arterial blood gas analysis (ABG) is done before and after the procedure to check for any decrease in arterial blood oxygen levels.  Blood oxygen level is checked before, during and after the procedure with the help of a tiny sensor attached to the finger.  This tester is used for monitoring the condition of the patient during follow-up visits.

What are the possible problems during Pulmonary function testing?
During the testing patients can sometimes have a cough, feeling of light-headedness or dizziness.  Rarely an attack can be precipitated in patients with asthma or COPD after pulmonary function testing.

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