PFT is a complete evaluation of the respiratory system including patient history, physical examinations and tests of pulmonary function. The primary purpose of the PFT is to identify severity of pulmonary impairment. This test is designed to measure how well the lungs are working, how the lungs are expanding and contracting (when a person inhales and exhales) and measures the efficiency of the exchange of oxygen and carbon dioxide between the blood and the air within the lungs. It is used to detect early lung problems which can be treated in the early phase and also is used to measure how a lung disease is progressing.