Chest X-Ray came back Pleural after Triple Bypass. What next?

Hello, my Mother of  82 years of age had emergency Triple Bypass on January 1st 2011. She is still in the hospital 19 days later. She has been making steady progress, but slow.  All the tubes have been removed, she has not asked for any Pain medications for 12 days, up walking a bit and her surgery entries have healed nicely. I expected them to send her home in  just a few days.

She started coughing more the last 2 days, her breathing is short and somewhat fast, her Blood Pressure dropped to 93 over 40 and her pulse is bouncing from 90 to 110 to 109. They discontinued her blood pressure medicine and that seemed to help with the low BP. Yesterday they did a Chest X-Ray and said the X-Ray came back Pleural? Is this common after Triple Bypass surgery? Is this condition usually easy to treat? Is it possible they removed the chest drain tube to early? I was so happy with her recovery.   I know I just asked a bazillion questions, as you can see, I am becoming extremely concerned about her recovery now. Does this Pleural thing ever remedy itself? What should I expect next?