Final answer:
The most appropriate action for the nurse is to continue following the healthcare directions documented for the client, respecting the patient's wishes through the son's legal authority.
Step-by-step explanation:
In the case of the nurse caring for a client with terminal cancer who is in excruciating pain, the most appropriate action is to continue to follow the documented healthcare directions for the client. It is critical to respect the wishes of the patient as represented by the son who has durable power of attorney. In situations of ethical controversy, such as end-of-life decisions, healthcare providers must navigate the complexities of patient autonomy, family wishes, and legal mandates while adhering to professional ethical standards.
Although the nurse may disagree with the family member's decision, it is not within their professional scope to confront the family, share personal feelings with the client, or refuse care based on the situation presented. The role of hospice care can also come into the conversation if the focus shifts to palliative measures that prioritize the quality of life over the extension of life.