One of the most common pulmonary disorders is the accumulation of fluid in the pleural cavity or pleural effusion. The pleural cavity is a space around the lungs which normally contains only a thin layer of fluid. However, in many diseases this cavity gets filled with fluid, which can cause certain problems such as breathlessness, chest pain, fever and heaviness in the chest. Some of the common diseases which are associated with the development of pleural effusions include pneumonia, tuberculosis, lung cancer, etc.