There are many ways in which cancer can cause fatigue. The growth of a tumor, in general, can be taxing for your body. Other symptoms of cancer such as shortness of breath, anemia, pain, or a decreased level of oxygen in your blood (hypoxia) can cause fatigue.
A pulmonary function test may take 30 to 60 minutes to complete. This will vary according to the amount of trials necessary for you to get repeatable test results.
Spirometry Testing. Pulmonary function testing measures how well you are breathing. There are different types of pulmonary function tests that can be done. Spirometry is one type of pulmonary function test. Spirometry is a simple test to measure how much (volume) and how fast (flow) you can move air into and out of your lungs.