[Speaking to anyone reading this, not just the person that I am replying to.]  If you want to donate your organs, you can always leave instructions with trusted family members to authorize the donation in lieu of being a designated organ donor on your license.  I recommend that they not discuss donation with the hospital staff until right after everyone is confident that no recovery is possible.  If you are listed as an organ donor, then the family does not have the authority to demand that more be done to save you.