DR. R. NARASIMHAN
Pulmonary function test gives information about the extent of lung disease.
Twenty years ago, when I started my practice and decided to do pulmonary function tests to assess lung function, my colleagues ridiculed me. Everybody knows about a blood test, a sugar test, a ECG but a test to diagnose lung disease was not known.
This is understandable, as in India, any cough is TB unless proved otherwise. All asthmatics in that period would have had anti-TB medication at some point in their life.
Twenty-five years later, the situation remains the same in non-metropolitan areas. Lung Function test is an important component in screening for chest disease but, to my surprise, many have not even seen a spirometer. So here is the basic information on pulmonary function test.
What is Pulmonary function test?
Pulmonary function tests are done to assess one’s lung function. It requires simple equipment like Peal flow gauge or a spirometer.
When are they ordered?
Pulmonary function tests are ordered when one is suffering from asthma, or COPD or is undergoing a surgery — whether cardiac, pulmonary or abdominal. It is important to know lung function before the surgery because the lung plays a major role during anaesthesia and in the post-operative period. If the lung function is not assessed preoperatively, recovery will be delayed in the post-operative period causing anxious moments to patient, physicians and attendants.
Is it possible to diagnose diseases?
No. But it will tell you that the function of the lung is not normal and that this needs some care either as medications or some further tests like CT scan or bronchoscopy.
What is a spirometry?
It is a technical word used for pulmonary function tests. A person is asked to breathe through the mouth piece into the spirometer. The machine calculates the values based on the speed at which he blows and the volume that he has blown and a print-out is obtained.
Though it is effort-dependent and children may find it difficult, when done properly in appropriate circumstances the information can be mind blowing and decisions with regards to the type of anaesthesia and management in post-operative period will be altered.
Is it useful in smokers?
Yes. It is possible to diagnose smoking-induced lung disease by doing special tests. Routine spirometry tests do not detect defects in lung function as nicotine gets deposited in small airways to start with. Only after the majority of the small airways are affected does the nicotine get deposited in the large airways. This is when they start experiencing the symptoms. By this time the damage to small airways is permanent and nothing can be done. Many smokers live in the false belief that if they stop smoking their lungs will come back to normal.
But smoking-induced lung damage takes long to manifest and hence there is great reluctance to seek advice in contrast to cardiac events, which are sudden and shake the whole fabric of the family.
Pulmonary function tests can be used to diagnose illnesses like asthma or COPD and also to screen people on a mass scale. It should be compared to a BP apparatus. With a spirometer one can assess a person’s lung function with ease.
The writer Senior Respiratory Physician based in Chennai. E-mail firstname.lastname@example.org