In Canada, we have something called MOST, which stands for Medical Scope of Treatment. This form outlines the levels of care and the focus of the care you would like your loved one to have. It is broken down into sections, based on the interventions that you would like to be given.
Being a nurse myself, I know first-hand that CPR (chest compressions) on a very elderly person are going to do more harm than good, so that's a big NO for us. After that, we have decided we don't want mechanical ventilation (basic life support to breathe for her if she can't herself)
It gets a bit harder when you think of the next stage, such as: do you want antibiotics to fight off a serious infection like pnuemonia? Pnuemonia is nicknamed the friend of the elderly for a reason. It's often what takes someone who is frail. I'm not sure I'd want to fight off something that could take her more kindly than Alzheimer's disease, you know?
My main focus is that I want my mom to be as comfortable as possible. No feeding tubes, no breathing tubes, no intravenous hydration. If her body cannot sustain itself, then in my opinion it is her time to go. I'm sure it will be more difficult to decide these things when the time comes, but this is how I feel right now.
YES to pain medications and sedatives.
YES to all comfort measures.