No special preparation is required for this examination. You can eat and drink before the test. You can also use any medication as usual, unless the laboratory technician or doctor gives you other indications.
itting in a chair or lying down on a bed you will first have to fill out a questionnaire with the help of the laboratory technician. It takes about five minutes to complete. A mouthpiece connected to a measuring device is taken in the mouth. Then the lab technician places a clip on the nose to prevent breathing through the nose. Through the mouthpiece you can breathe freely. The lab technician will ask you to breathe faster and deeper than usual for a while. The device measures how fast and how often you breathe per minute and how much carbon dioxide you exhale. The exam lasts about half an hour. It carries no risks and is not painful but is somewhat exhausting.
It is possible that the doctor will ask for additional blood gas measurement.