"Normally, an attorney-in-fact can exercise power only if you are capable of exercising the same power. Therefore, the agent would not be able to act when you are incapacitated. A durable POA overcomes this problem. By including specific language, the POA is made durable and your agent will be able to exercise the powers you have granted after you become disabled.
A DPA usually must be signed, notarized and must state that it shall be “durable” (meaning it will continue in effect after you become incapacitated). It terminates upon your death, at a time you specify, or if you cancel it while you are still competent.
A DPA for healthcare decisions generally gives the agent the following powers:
HG.org Worldwide Legal Directories
"A medical power of attorney (or healthcare proxy) gives someone else the legal right to make healthcare decisions for you. The person you appoint is usually referred to as your agent or attorney-in-fact. You can give your agent as much or as little authority as you choose, and in most states, you can include the same kind of instructions that you would implement in a Living Will. You can also set up the POA to begin only when specific criteria are met, if you prefer.