Restrictive lung disease is either intrinsic or extrinsic within the lungs. Intrinsic means that the lungs themselves are causing the restrictive defect, usually from scarring that is preventing the lung from expanding properly with each breath. Some disorders that cause intrinsic restrictive disease are pulmonary fibrosis, sarcoidosis,etc....Extrinsic disease involves external factors necessary to breath such as weakened respiratory muscles (especially the diaphragm) or obesity which crowds the lungs, not allowing them to inflate properly thus restricting them.
Her doctor will do more testing to figure out what type of restrictive disease she has as there are many that fall under this category. If she hasn't had a CT scan of her chest, she will probably get one to get a better picture of what is going on inside her lungs. Sometimes a lung biopsy is done depending on what other tests show.
I wish I could be of more help...I am not a doctor, just a former nurse so please take what I say for face value. The best person to talk to would be your wife's doctor with her permission of course.
Sunny
Does your wife smoke? Sometimes that is the reason for it and other times even none smokers can get this. I'm thinking it is like having COPD - Chronic, Obstructive Pulmonary Disorder.........basically means you airways are restricted and it's hard to breath. In my case it's due to smoking. I don't know her circumstances but I would image it is similiar reasons. Tightness in chest, shortness of breath. They will give her meds to help breathing easier.