In this article, Mark Handelman of Whaley Estate Litigation does a great job of talking about Powers of Attorney for Personal Care (also called Personal Directives or Health-care Directives). I recommend that you read it if you are wondering how to communicate your end-of-life decisions.
When you see an estate planning lawyer, you will of course talk about your wills and how your property is going to be distributed after your death. You should also expect to discuss your plans for mental incapacity. You should name someone to look after health care decisions and someone (perhaps the same person but it doesn't have to be) to look after financial decisions. Most lawyers who specialize in estate planning will ensure that you have this whole package in place.
Best of all, Mr. Handelman includes some sample wording, and some legal humour as well. Click here to read this very good article.