Today's the 1st anniversary of the legal murder of Terri Schiavo. May her soul and all the souls of the faithful departed, through the mercy of God, rest in peace.
But don't rely on a living will. No document can possible accout for every situation you may find yourself in. Get a Durable Power of Attorney instead. This a document that gives someone you trust the power (spouse, friend, child, parent, etc.) the final say in end of life issues in the event you're incapacitated or otherwise unable to make your won decisions.