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.
The two most common pulmonary function tests for asthma are spirometry and methacholine challenge tests. 1  Spirometry: This pulmonary function test for asthma is a simple breathing test that measures how much air you can blow out of your lungs and how quickly. Spirometry: This pulmonary function test for asthma is a simple breathing test that measures how much air you can blow out of your lungs and how quickly.