A few years ago my 90 year old grandma had a stroke in her sleep and the doctors told us she'd never really have any more quality of life and what's usually done is just pull out the sugar drip and basically wait for her to (for lack of better word) starve to death.

After a day or two with no food or water she'd drift in and out of consciousness. It was amazing how she would even refuse my offer of wetting her lips with a sponge.

During a time I was alone with her, her breathing became so heavy, this rattling sound. I asked a nurse "can't you give her something" and he gave her a shot of morphine and a few min later the breathing stopped and that was that. It was quite a humbling experience.

Another thing that comes to mind is the "Brompton cocktail", a mix of morphine/heroin, cocaine, alcohol and thorazine against the nausea: https://en.wikipedia.org/wiki/Brompton_cocktail