Living wills often stipulate that a person doesn't want "extraordinary" measures taken to sustain life if there is no chance of recovery.
You may have thought about having to say, "Don't charge the paddles," in the event your father's heart stops for the fifth time, or mulled over whether you could agree to turn off life-sustaining machines if MRI scans reveal there is no hope of recovery from a profound brain trauma.
But when it comes to end-of-life medical care, treatments most of us think of as ordinary can be deemed extraordinary. Blood transfusions. Dialysis. Intravenous fluids for people who can no longer swallow.
Instead of, "Should we resuscitate?" you may face the question, "Should we give her antibiotics for this urinary tract infection?"
Questions like these will elicit different answers in different households. And in some, the discussion will be heated.
But experts in end-of-life care say these scenarios should be explored early with substitute decision makers — and the broader circles of family and friends.
"Sometimes people say 'I don't want heroic measures' and everyone nods their heads and says 'Yeah, OK, sounds good,'" says Dr. James Downar, a palliative care specialist at the University Health Network in Toronto.
"(But) if that hasn't translated into an actual medical plan, then all you've got is just a general vague notion of what you should be doing. And that's a problem."
It's also common, Downar and others suggest.
"If any given advance directive was read by 100 doctors, there would be a range of interpretation because of the vague terminology," says Dr. Vincent Maida, a palliative medicine specialist at Toronto's William Osler Health Centre.
"What is an extraordinary measure? It's all relative."
Working through potential scenarios and overarching goals of care should help respect the wishes of patients who can no longer voice them. It can also help family members with their agonizing decisions and alleviate some stress and anxiety.
"I'm not saying it's easy, when the time comes, to make decisions. For sure it's not easy. But if people have had conversations in advance, it helps," says Louise Hanvey, project director for Advance Care Planning in Canada.
Hanvey's program, which operates under the auspices of the Canadian Hospice Palliative Care Association, runs Speak Up, a campaign designed to promote discussion of end-of-life care. Information about the campaign can be found at www.advancecareplanning.ca.
One of the first steps involves spending time figuring out what makes life meaningful for the person in question.
"And that might be: Being able to recognize my family. Being able to have conversations with them. Being able to be physically active. Being able to garden. Being able to whatever," Hanvey says.
"What would make it unacceptable — or acceptable — to prolong my life if I was in a coma and there was little chance that I was going to have the quality of life that ... (is) important to me?"
Maida says some people will opt to fight death with all the medical tools available.
But others will decide that if, for example, Alzheimer's disease turns family and friends into strangers, that they would want comfort care — which eases the dying process — if they become sick with something like a pneumonia.
Some people may be startled to learn that treating pneumonia under such a circumstance might not be automatic. But in frail elderly people, especially those with swallowing problems who regularly inhale small bits of food or droplets of fluids, treating pneumonia may be seen as futile.
"I would submit that even though we're treating that pneumonia we're unlikely to clear it completely," Maida says.
The ultimate goal in considering end of life, Downar says, is to be as prepared as possible for making choices that reflect a person's values and wishes.
"It doesn't tell you everything that you're going to do. But it means that your team is ready."