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.
Pulmonary function testing and arterial blood gas analysis. Measuring the vital capacity in the upright and supine positions is the most important part of the pulmonary function test. Diaphragmatic paralysis reduces the measured compliance of the lungs and a restrictive pattern can develop. Normally, vital capacity in recumbency decreases by 10%.