Pulmonary function tests (PFTs) are a group of tests that measure and assess the lungs’ functioning. Aids in monitoring the quality and quantity of air used in respiration. Determines how a patient is responding to the treatment or how well his or her lungs are working before undergoing any surgery.

WHY IS THE PFT (PULMONARY FUNCTION TEST) DONE?

The  doctor may order PFT  in the following circumstances: 

1. visible symptoms of lung problems
2. regular exposure to adverse substances in the workplace or environment
3. to monitor the course of chronic lung disease like asthma or COPD (chronic obstructive pulmonary disease), allergies , bronchitis, respiratory infections, lung fibrosis, bronchiectasis, pulmonary tumours, lung cancers, etc 
4. to capture  inflammation of lungs, liver, lymph nodes, eyes, skin, or other tissues
5. weakness of the chest wall muscles

HOW TO PREPARE FOR PULMONARY FUNCTION TESTS (PFT)?

•  smoking needs to be avoided 4-6 hrs before 
•  a small meal advised before the test 
• doctor will advise if any medicines to be stopped that a patient is taking
• avoid food and drinks containing caffeine (chocolate, coffee, and tea, etc) before the test
• wear loose-fitting clothing and no jewelry to the test for uninterrupted breathing
• In case using dentures, do wear them to the test to enable mouth fit tightly around the mouthpiece used for the test
• If underwent any recent chest, eye or abdominal surgery or had a recent heart attack, the patient might need to postpone the procedure until recovery

WHAT HAPPENS DURING THE PFT (PULMONARY FUNCTION TEST)?

1. Spirometry measures the amount of air one breathes. Patient sits in front of the machine and is fitted with a mouthpiece.The respiratory technologist guides his or her  breathing pattern. The patient could also be asked to breathe in a medication to open the airways. The patient repeats breathing into the machine under observation. 

2. Plethysmography measures the volume of gas in the lungs (lung volume). Patient sits or stands in a small booth and breathes into the mouthpiece. The doctor can work out the lung volume through measuring pressure in the booth.

3. Diffusion Capacity Test evaluates how well the lungs are able to transfer oxygen and carbon dioxide to and fro from the bloodstream. Patient is asked to breathe in certain gases like  oxygen, helium, carbon dioxide or the tracer gas. 

AFTER THE TEST

• Patient may feel tired and require rest
• Results are shared with the doctor

IMPORTANT INFORMATION 

This  test is approx 1 hour long and mostly safe. However, as it may require one to breathe in and out quickly, a patient might  feel dizzy and there’s a chance of fainting. 

Being an asthma patient, PFT may induce an asthma attack or result in lightheadedness. While  In very rare cases, it might result in a collapsed lung.