Pulmonary Function Testing: (Spirometry, Lung Volumes and Diffusion Capacity) This is often the first step in the evaluation of lung function for defining the cause of shortness of breath. Unlike a chest x-ray which just gives a picture of lungs, Pulmonary Function Tests (PFTs):

-tell how well lungs function.
-are used to follow the progression of a disease and its response to treatment.
-assess if there is adequate respiratory function to withstand surgery.

Spirometry: (Pre and post bronchodilator available) An abbreviated lung function test used to evaluate the status of patients with asthma and COPD. It gives an assessment of how well treatment is working.