This brings back bad memories. My mother had fluid accumulating in the sac around the lungs. She was drained several times.
The next winter, we made her sleep under an electric blanket, and she was fine. No fluid problems.
However, she developed adhesions that restricted the ability of her lungs to expand and contract. They formed at the spots where the drainage tube had been inserted.
She was operated upon to remove the adhesions, but died soon afterward. Her death certificate said that she had congestive heart failure. That was the first time we had heard she had a heart problem.
Sometimes I think doctors don't tell you everything, especially if there is no remedy to the problem.
Also, remember the whole process is driven by insurance companies, and they are out to make money. They limit what tests and procedures can be used.
Go to a different doctor and don't mention insurance, but offer to pay out of your own pocket. When your wallet comes out, so does the truth.
Good Luck,
Rufus