Recently I've assisted in placing defibrillators in people who cannot walk, eat, use the bathroom, or get out of bed unassisted. And never will again. Because they're not only so elderly that they are incredibly frail, and weakened, but mainly because most of who they were isn't there any more.
Nobody wants to think about a loved one having dementia so severely that they no longer recognize their family, can't care for themselves, or communicate. It's something I personally consider worse than death. Day after day, sitting in a chair or lying in a bed, not knowing anyone, developing bed sores, totally dependent on others to feed, dress, and clean you. Think about it: nothing to look forward to, no comprehension of what's happening, just a steady degeneration into a shell of what used to be a vital, active person.
Why, if you love that person, would you choose to ensure that someone will have to endure this for another one, two, or ten years? Why do you want to have a device in them that will deliver a substantial unexpected shock, or series of shocks, to them when you have decided to list them as DNR in the medical record? Do you really think that's the caring thing to do? Is it what you would want for yourself?
Someday, perhaps that won't even be an option. Many of these devices are well over $10,000. If we get to the point where we're looking at cost/benefit models for getting a procedure, I'd guess a lot of these defibrillators won't be going to people we do them for now. I don't particularly like that approach. But I do recognize none of us are supposed to be here indefinitely. And at some point, if we last long enough, quality of life will reach the point where most of us would rather not be here. Work in a hospital long enough, and you'll see people in conditions you'll never see on TV drama. Their quality of life is almost zero. Feeding tubes, IVs, bruising, bleeding, and opportunistic infections; blood clots, bed sores, poor circulation. Sooner or later, everyone goes. The lucky ones go fast, and sometimes even in their sleep. For most of us, it will be a long, slow decline.
Think long and hard before making that decline harder and longer for someone you care about.