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.
How long does it take? A brief examination in an uncomplicated case may be done within 15 to 20 minutes. The additional use of Doppler may add an additional 10 to 20 minutes. However, it may take up to an hour when there are multiple problems or when there are technical problems (for example, patients with lung disease, obesity, restlessness, and significant shortness of breath may be more difficult to image).