Spirometry measures the ratio of the forced expiratory volume in the first second to the forced vital capacity (FEV1/FVC) and this measurement is the most sensitive and specific test for detecting obstruction of airflow in the lungs. The confirmation of airway obstruction in a patient with significant history of exposure to cigarette smoke or pollution helps the doctor to confirm the diagnosis and assess the severity of the condition. Using spirometry, some pulmonary diseases including Chronic Obstructive Pulmonary Disease (COPD) can also be easily detected in its preclinical phase, ie before symptoms of the illness (such as cough or breathlessness) arise in a smoker or ex-smoker
REASON FOR THE TEST
Spirometry is a basic test of pulmonary (lung) function. Pulmonary function tests are used to detect lung diseases or to monitor the progression of a particular disease, such as COPD. Regular testing can detect lung disease in its early stages and allow for timely treatment. The most common pulmonary function test is done with a machine called a Spirometer. Spirometry testing is quick, non-invasive and painless. If you regularly experience breathlessness, have difficulty breathing, or otherwise suspect you have a lung disease, the COPD Association encourages you to ask your doctor for spirometry testing.
DESCRIPTION OF THE TEST
Spirometry is performed under various conditions with the patient breathing into a tube attached to the machine, which calculates the amount of air the lungs can hold and the rate that air can be inhaled and exhaled. The results of the test are compared with those of healthy individuals of similar height and age, and of the same sex and race. You will be required to provide basic information about yourself (height, weight, age and sex) will be recorded. You will have to breathe into a Spirometer - a machine that measures how much air you are able to breathe in and out. Several breathing tasks may be required, such as :
Taking in a deep breath, holding the breath and breathing out as forcefully as possible.
Breathing rapidly into the tube.
WHAT TO EXPECT
Before the test:
Follow your doctor's orders to stop taking some or all of your medication.
Get a good night's sleep as tiredness can affect the accuracy of the test.
Do not smoke or eat a heavy meal.
Do not carry out strenuous activity. Wear loose, non-restrictive clothes that keep your chest area as free as possible when you come for the test.
During the test: The test is painless. Remain calm because fear or anxiety can make the test results less reliable. After the Test: You may feel light-headed because of the deep breathing you have been doing. You should remain seated until the feeling passes. The doctor will have a report of your test results. He/she will review these results with you. A number of different terms will arise during the discussion including lung volumes and how you are compare with people of the same height, weight, age and sex as you. A common spirometry measurement is FEV1 (Forced Expiratory Volume in One Second), the volume of air exhaled in the first second after a deep inhalation. For COPD patients, FEV1 is used to determine the severity of obstruction, with less than 80% considered mild and less than 50% severe.
HOW LONG WILL IT TAKE
The entire test takes approximately 20 to 45 minutes
Measured values are your results in comparison with normal or predicted values. For example, if you only blow out half the amount of air that would normally be predicted, the measured value of your vital capacity (VC) would be 50 percent. If your total lung capacity (TLC) is exactly what would be predicted, the measured value is 100 percent. A common spirometry measurement is FEV1 (Forced Expiratory Volume in One Second), the volume of air exhaled in the first second after a deep inhalation. For COPD patients, FEV1 is used to determine the severity of obstruction, with less than 80% considered mild and less than 50% severe.