If you’re on medications that open your airways, such as those used for asthma or chronic bronchitis, your doctor may ask you to stop taking them before the test. If it isn’t clear whether or not you should take your medication, make sure to ask your doctor. Pain medications may also affect the results of the test. You should tell your doctor about any over-the-counter and prescription pain medications you’re taking.
It’s important that you don’t eat a large meal before testing. A full stomach can prevent your lungs from inhaling fully. You should also avoid food and drinks that contain caffeine, such as chocolate, coffee, and tea, before your test. Caffeine can cause your airways to be more open which could affect the results of your test. You should also avoid smoking at least an hour before the test, as well as strenuous exercise before the test.
Be sure to wear loose-fitting clothing to the test. Tighter clothing may restrict your breathing. You should also avoid wearing jewelry that might affect your breathing. If you wear dentures, wear them to the test to ensure that your mouth can fit tightly around the mouthpiece used for the test.
If you have had recent eye, chest, or abdominal surgery or a recent heart attack, you will likely need to delay the test until you have fully recovered.