Pulmonary Function Test (PFT) is a non-invasive test and used to get the complete evaluation of the lungs. It evaluates how well the lungs are working and measure how much the lungs can hold the air, capacity, rates of flow and gas exchange. With all these pieces of information and patient’s medical history, if they have, doctor will diagnose and decide the treatment of respiratory disorder.

Why is it done?

If you are already suffering or to get to know about the diseases, your doctor may order the test to see how well you are responding to the treatment or to diagnose the problem respectively. Your doctor may order this test if you have symptoms of lung diseases, to monitor the treatment of chronic lung diseases, to evaluate the lung’s working before surgery and many more.

This test helps to make a diagnosis of lung diseases such as -

• Asthma
• Allergies
• Chronic bronchitis
• COPD
• Damaged lung tissue
• Sarcoidosis
• Lung cancer
• Thickened, or enlarged airways
• Pulmonary tumor
• Weakness of chest wall muscles

How is it done?

Different tests are done for evaluating different conditions:
Spirometry: This test is done to measure the amount of air you inhale and exhale. Your doctor may ask you to sit in front of the machine and fit the mouthpiece. You may also wear the nose clip so that the patient can’t breathe out from the nose. Your doctor may ask you to breathe in and out quickly for several seconds. It helps the doctor to see how well the medication works.
Plethysmography test: This test is done to measure the volume of gas in the lungs. Your doctor may ask you to stand or sit in a small booth with a mouthpiece and breathe in and out and measure the volume by measuring the pressure in the booth.
Diffusion capacity test: This test is done to evaluate how well the small air sacks inside the lungs work. Your doctor may ask you to breathe oxygen, helium or carbon dioxide and when you breathe out; the machine detects how well the lungs are able to transfer gases to and from the bloodstream.

Tips to remember:

• Do not eat large meals.
• Inform your doctor about your prescribed medications.
• Do not take any medications that open the airways or any pain medication.
• Avoid coffee, chocolate or tea.
• Do not smoke at least an hour before.
• Wear loose-fitting clothes.
• Do not go for the test or inform your doctor if you had a recent heart attack, chest, eye or abdominal surgery.