A living will is much more cut and dry than the attorneys would like you to believe. The biggest decision is what you choose to quantify as "hopeless" and "extraordinary measures."
You have a basic DNR...Do Not Resuscitate. In the event your heart were to stop, responders would not perform CPR (chest compressions) or defibrillate (shock) your heart if appropriate. You also have a DNI (Do Not Intubate) which means that if you were to become respiratory compromised that responders would not place a tube into your airway to assist your breathing.
You can specify if you want tube feedings, IV medications to allow your heart to continue perusing the organs (pressors), or other conditionals.
Keep in mind however, that in the event of an accident where your living will/advance directive is not immediately available that responders will do everything--all extraordinary measures--to save your life until the contents of the advanced directive are revealed.
Your decisions involve the following: non-oral feeding, surgery, ventilator breathing, tracheostomy, chest compressions, additional medications in the Advanced Cardiovascular Life Support algorithms, and medications to prolong cardiac perfusion.
Basically, if you enter a hospital, they will assist you (if conscious on admission) in the preparation of an advanced directive. If you choose to execute an advanced directive outside of a hospital setting, your discussion is in what you feel are hopeless medical conditions and what you would define as extraordinary or heroic measures. A living will is designed to allow you to guide your own medical care in the event you are incapable of consenting or not consenting for yourself. This isn't to be confused with a last will and testament, which is definitely a "lawyer thing."
Hope this helps.
