S.C. Code Ann. § 62-5-509: Duty of agent.

An agent acting pursuant to a health care power of attorney shall make decisions concerning the principal's health care in accordance with the principal's directives in the health care power of attorney and with any other statements of intent by the principal that are known to the agent and are not inconsistent with the directives in the health care power of attorney. If a principal has a valid Declaration of a Desire for a Natural Death pursuant to Chapter 77, Title 44, then the declaration must be given effect in any situation to which it is applicable. The agent named in the health care power of attorney has authority to make decisions only in situations to which the declaration does not apply. However, nothing in this section prevents the principal or a person designated by the principal in the declaration from revoking the declaration pursuant to Section 44-77-80.