A living will is one form of advance medical directive. Advance medical directives preserve the person's right to accept or reject a course of medical treatment even after that person becomes mentally or physically incapacitated to the point of being unable to communicate those wishes. There are two basic types of advance directives: (1) a living will, in which the person outlines specific treatment guidelines that are to be followed by health care providers; (2) a health care proxy (also called a
power of attorney for health-care decision-making) in which the person designates a trusted individual to make medical decisions in the event that he or she becomes too incapacitated to make such decisions.

Patienten-Testament

Darunter versteht man eine schriftliche Willenserklärung, mit welcher die künftige Patientin/der künftige Patient
ersucht, im Fall einer an sich zum Tod führenden Erkrankung, Verletzung oder Bewusstlosigkeit auf künstliche
lebensverlängernde Maßnahmen zu verzichten und alle Möglichkeiten der Schmerzlinderung zu nutzen.

sounds dramatic and, at the given moment, may or will be. This is a paper in which e.g. I willfully and voluntarily make known my desire that my dying shall not be artificially prolonged under the circumstances set forth below:
If at any time I should have a terminal condition and if my attending physician has determined that there can be no recovery from such condition and that my death is imminent, I direct that life-prolonging procedures be withheld or withdrawn when the application of such procedures would serve only to prolonge artificially the process of dying, and that I be permitted to die naturally with only the administration of medication or the performance of any medical procedure deemed necessary to provide me with comfort care or to alleviate pain. I do desire that nutrition and hydration (food and water) be withheld or withdrawn when the application of such procedures would serve only to prolong artificially the process of dying.
etc. etc.
quoted in part from my own Living Will.