The most important documents in your estate plan are the Powers of Attorney. In a Healthcare Power of Attorney, the maker names someone to be their "Patient Advocate" to make medical decisions for them if they are determined to be incompetent by two doctors. This document is much broader than stating whether or not the maker wants heroic medical care if they are in the dying process. If the maker is suffering from dementia, then the Patient Advocate will be making all medical decisions such as having an MRI, drawing blood, getting an X-ray, having surgery, or taking chemotherapy.
Additionally, the document should also name the family and friend the maker wants to be their HIPAA Representative. The HIPAA Representative is entitled to receive medical information about the maker. Otherwise, doctors, nurses, and others cannot disclose medical information — even to a family member. This document will generally replace the need to go to court and have a Guardian named for an incompetent person.