Hello @lindalee, and welcome to Mayo Clinic Connect.
I am so happy that you found this site before your upcoming surgery and I hope that you were able to find information that is helpful on here.
I posted my little open heart surgery story with the hopeful intent that by sharing with others who have not yet had their surgery, they would find a bit more information from those of us who have gone through this.
I do not blame you for being scared! I was too! But I also had worked myself into almost a freak out frenzy over it...without the need to do that! I over thought everything. I think it is normal to do that so you must be normal!
I also don't blame your concern for having COPD going into this. The surgical staff doing this will be well aware of all that, and your care will be guided by their amazing talent at treating patients with all sorts of pre-existing co-morbid conditions.

@walkinggirl shared great thoughts. She has gone through this surgery too, and has some wonderful sage advice. I like that she encouraged you to talk to the surgical team about any of your concerns. I would encourage you to do that same thing. Write a list of all your questions and do not be afraid to ask. You need to know as much as you can about what to expect, and here on Connect, many have shared their stories in order to help others.

I only had Tylenol for pain. I think if I had been a little more assertive, they would have given it to me...but I have never been an assertive person. That's on me! I'm learning as I go along here on the planet.

There is a protocol for open heart surgery at every hospital. They are very similar I imagine and have many things in common. The bypass machine is used to perform the intended surgery while the heart and lungs are at rest, and the machine does the work for them.
It's really common to have fluid in the lungs after this, but your team will be very much aware of your COPD and follow the protocol which is best for you. These teams are amazing and know what they are doing. I know how easy it is to say "don't worry" because any sane person would worry...but I also hope that you have an outlet for your anxiousness.
A hobby you love.
A place you love to visit.
Meditation.
God.
Somewhere to go to find some balance and peace for your weary mind. You have Mayo Connect now...and we are here to help and virtually hold your hand and listen without judgement.

May I ask the name of the hospital where your surgery is scheduled?