Thanks Canuck,

Just to clarify.

With healthy lungs, full chest expansion acts to facilitate mucous transport to the lymph system. With a pleural effusion, decreased chest expansion (from the mechanical effects of fluid in the pleura) results in mucous retention in the alveoli/airways as normal mucous transport is impeded. This mucous retention is the actual cause of crackles (not the fluid in the pleural space).

Am I correct in saying this?

Kevin