When should pulmonary function test be done in asthma?

Q: I developed asthma in 1979 and during 1979 to 1989, I used to take medicines like Asthalin-2 mg or Ventorlin or Terbutaline or Hetrazan. From 1989 to 1999 there were no asthamatic bouts. But now when I am 49, I get mild occasional breathlessness while walking or when I talk and laugh slightly. I develop slight breathlessness and wheezing. In winter, moisture, dust smoke or entering a closed room leads to a feeling of suffocation and cough with wheeze, but these subside quickly and the next dat the doctor may find nothing. My doctor gave me the following medicines recently: Hetrazan thrice a day, Levobact 500 mg once, Deriphylin Retard 300 twice daily, Levocetrizine once. Within 5 days it was controlled. After one month again symptoms started and doctor advised me to take UNICNTIN 400 once daily and suggested Pulmonary Function test. I want to know if PFT is to be performed only during symptoms or anytime ? Some call it allergic bronchitis or esonophilia. Actually what is this called? Please guide me.

A:As per description given, the problem is obviously of asthma. In asthma, the eosinophil count goes up to some extent. In order to prescribe diethylcarbamazine (Hetrazan), the diagnosis ought to be Tropical Eosinophilia where the eosinophil count goes up very high (25 to 90%) and there are other symptoms (coughing worse at night, breathlesseness resembling asthma). On X-ray there is often mottling. Since levocetirizine can dry up secretions, its use in asthma is not in vogue. Interestingly, one of the side effects of levocetirizine is breathlessness. The use of long acting theophylline (Unicontin 400 Continus) is quite appropriate in your case. Pulmonary Function Tests should be performed when there is no acute attack. In asthma patients, even when the patient is normal, the tests show underlying problem.