This article explains Pulmonary function test, how it is done, general tips for preparing for the test lung functions and much more.
Pulmonary function test
Before you can diagnose bronchial asthma, your doctor will carefully examine your symptoms, your medical history, your hereditary predisposition to various diseases, and conduct lung function tests (also called lung performance tests). The doctor will be interested in any breathing problems that bother you, as well as a hereditary predisposition to asthma and other pulmonary or skin diseases, for example, eczema. It is very important that you describe in detail your symptoms (coughing, wheezing, shortness of breath, squeezing in the chest area), including when and how often they manifest.
The doctor also conducts a physical examination and listens to how the lungs and heart work.
In addition to the test of pulmonary functions, the doctor can advise you to undergo an allergic reaction test, take a blood test and make an x-ray of the chest and nasal cavity. The results of these tests will help the doctor determine if your symptoms are caused by asthma or some other illness.
What is a test of pulmonary function?
The pulmonary function test includes several procedures for diagnosing lung function problems. The two most common pulmonary function tests are spirometry and a test with methacholine load.
Spirometry: a test of pulmonary functions, during which the volume of lungs and the maximum velocity of exhaled air are measured. It is often used to determine if the airways are blocked. Spirometry is performed before and after taking a fast-acting medication, bronchodilator, for example, albuterol. The bronchodilator causes the airways to expand, allowing air to circulate freely around them. In the future, this test is necessary to monitor the effectiveness of treatment and helps the doctor choose the right treatment program.
Methacholine load test: The lung function test is used for both adults and children. It is used if the symptoms and results of spirometry do not provide an opportunity to put an accurate diagnosis. Methacholine is a substance that, during inhalation, causes spasm (non-insulating compression) and constriction of the airways. During the test, you inhale the increasing amount of methacholine through the inhaler before and after spirometry. The results of the test with methacholine are considered positive (which means the presence of asthma) if the lung capacity drops by 20%. Always after the test, you need to use a bronchodilator, which neutralizes the effect of methacholine.
How should you prepare for a test of pulmonary function?
Ask your doctor if any special preparations are necessary before spirometry.
Before the methacholine load test, be sure to notify your doctor if you recently had a viral infection, such as a cold, or you underwent immunotherapy, as this may affect test results.
A few more general tips for preparing for the test lung functions:
Do not smoke the day before the test.
Do not drink coffee, tea, cola, chocolate the day before the test
Avoid exercise or prolonged exposure to cold air the day before the test
Can I take medications to treat asthma before a test of pulmonary function?
Be ready to adjust the medication. Some medications that apply asthma treatments can affect test results. The intake of certain drugs must be stopped within a certain time interval. For example, the intake of inhaled bronchodilators of fast action should be stopped eight hours before the test, and inhalation of long-acting bronchodilators in 48 hours. Your doctor will tell you when to stop taking medication. Do not make a decision to stop taking medication yourself, without the permission of a doctor.