Conditions Involving the Pleural Cavity. The presence of an excess of fluid, or of air or gas in the pleural cavity can interfere with its function in respiration. Some conditions affecting the pleural space may include: Pleural effusion - A pleural effusion refers to a build-up of fluid in the pleural cavity. When too much fluid accumulates in this space it can interfere with the expansion of the lungs with inspiration. There are many causes, with the most common being viral infections and congestive heart failure.