This is the most practical book I know of on the ethics of end-of-life decision-making:
Bill Davis. Departing in Peace: Biblical Decision-Making at the End of Life. Phillipsburg, NJ: P&R Publishing, 2017.
You can read a 48-page sample PDF here.
Four excerpts:
- Declining treatment is not a form of suicide. (p. 51)
- Letting die is not the same as killing. (p. 59)
- We are not biblically required to start or continue to use medical treatment that is excessively burdensome. We may choose to start or continue its use when we believe that doing so is part of faithful stewardship of our resources, but we are not obligated to bear excessive medical burdens in order to stay alive. (p. 78)
- God’s Word does not require us to force food or water on our loved ones by mechanical means if the burdens of those means greatly exceed the benefits involved. (p. 105)