....how old is he? did they harvest mammary arteries? if so, then this is a normal event and needs to be montoried very closely; they might drain the pleural fluids (if that's what the trouble is) if the problem doesn;t clear itself up on it's own. One very helpful thing that he should be doing is "huff" deep breathing exercises...sit up straight, inhale as deeply as possible, hold it for a beat, then open the mouth and say the word "huff", pushing hard out from the diaphram...do it deeply and do it hard...do it for a half hour 3-4 times a day and he'll see results in a day or so...he will nbeed to keep at it until he is cleared up...I had this condition and no one told me about huff breathing; I discovered it on the net and it worked...took 90 days, but it worked and it's a lot better than having a hole punctured in the lung and avoiding the potential side effects of that kind of therapy...good luck
This happened to my wife after lung surgery. She had a small leak in her lung that caused the pressure in her pleura to become higher than the pressure inside of her lungs. This will cause the lung to collapse.
The pleura is a sac within a sac that holds the lungs, and maintains some amount of fluid so we can move without pain. It is like the pericardium that surrounds the heart. It is also a sac within a sac that maintains fluid for movement.
Just guessing, I would say the surgeon nicked a small hole in a lung. He will need a tube to drain or depressurize his pleura until the tiny hole heals. My wife had a tube for almost 3 weeks.
Remember that this is just a guess. I did not major in anatomy.
Good luck,
Jack