Pulmonary function tests (spirometry tests) measure how well your lungs take in and release air. Your lung function will be compared to the normal lung function for someone of your age, height, ethnicity and sex. If your lung function is less than 80 percent of the norm, your lungs may be abnormal, indicating lung disease such as asthma, emphysema or chronic bronchitis.
How to Compare Your Lung Function
Ask your doctor for a spirometry test where you breathe into a mouthpiece connected to an instrument called a spirometer. It records the amount and the rate of air that you breathe in and out over a period of time, so you can compare your lung function to that of someone with your same characteristics (height, age, ethnicity and sex) who breathes normally.
Follow your doctor’s or nurse’s instructions for doing a lung function test with a spirometer. This will be done in your doctor’s office. Don’t eat a heavy meal before the spirometry test; don’t smoke for four to six hours before the test; ask your doctor for specific instructions and if you need to stop using inhaler medicines if you use them. Empty your bladder before the test.
Place a nose clip on your nose to pinch your nostrils if your doctor advises. Take a deep breath through your mouth. Put your mouth tightly around the mouthpiece on the tube connected to the spirometer. Exhale through the tubing as hard and fast as you can.
Do the test three times. Your doctor or nurse will take your measurements. The results will be analyzed and compared to lung function values that are norms for your age, height, ethnicity and sex. You may feel dizzy after the lung function tests since it requires you to forcefully exhale.
Ask your doctor what your test results mean. The Forced Vital Capacity (FVC) is the maximum amount of air that you can exhale. The Forced Expiratory Volume (FEV1) is the volume of air you can exhale in the first second you are exhaling.