What is lung function test / Pulmonary function test / spirometry?

PFT is a simple breathing test to assess your lung capacity

It is ordered by a chest/lung specialist if you are suspected to have obstruction/restriction in your lungs and also differentiate between breathlessness due to lung or heart conditions

This simple test helps in grading the severity and assists in monitoring the improvement/deterioration of the lung disease

When should you undergo this test?

Visit lung/chest specialist if you have complaints of

  • Breathlessness which is increasing in severity
  • If you have ever smoked cigarettes/bidis/hukkahs etc
  • If you have persistent cough
  • If you are exposed to fumes in a factory
  • If your chest produces whistling sound especially with changes in weather

What is your role  in  spirometry / PFT?

Patient plays the most important role in spirometry. The procedure is divided into four stages

Stage 1:

Patient is instructed to take a deep breath in order to completely fill his lungs with air

Stage 2:

Patient is instructed to blast the inhaled air out like blowing 100 candles at one time


Stage 3:

Patient is instructed to blast the inhaled air out like blowing 100 candles at one time

Stage 4:

Here, patient is instructed to take a deep breath

  • The machine records the patient’s speed and the amount of the air that he/she blows into the device
  • The report is generated as per the patient’s performance
  • You may also be administered a inhaler in order to see your response to the medicine and lay a good probability of your diagnosis

What does the report signify?

The report quantifies the speed of the air blown/amount of the air blown in the form of numbers and graphs

The physician carefully analysis your report

He is now able to confirm his diagnosis of airway disease after interpreting the report

Sample  PFT report

Important parameters in the report

  • FVC(forced vital capacity)
  • FEV1(forced expiratory volume in 1sec)
  • FEV1/FVC
  • FEF 25-75%(forced expiratory volume from small air sacs)