The pulmonary function test is also known as spirometry or lung function tests. This test is administered for a complete evaluation of the respiratory system including the physical examinations, chest x-ray examinations, arterial blood gas analysis, etc. This includes testing how well the person is able to breathe and how effective the working of the lungs is to be able to bring oxygen to the rest of the body. This could be ordered as a routine test or if the person exhibits symptoms of lung problems.