can a large plural effusion cause diminished breath sounds with possible crackles on in spiration

Anon,

In short, yes, a pleural effusion (too much fluid in the lung) can indeed cause diminished breath sounds on the side of the body where the lung is affected, as well as the crackling sounds you describe.

Have you or someone close to you been diagnosed with pleural effusion? Was there a chest X-ray to confirm?

Was the cause of the effusion determined?

Does the person have other contributing health conditions?

Please let us know a little more. In the meantime, though, please call the doctor if you or this person is having difficulty breathing.

Here is the Merck Manual entry on pleural effusion:

http://www.merck.com/mmpe/sec05/ch060/ch060d.html