Final answer:
The nurse should advise the patient to prepare a living will, which is a legal document specifying their medical care preferences and may include a health care proxy to appoint someone to make decisions on their behalf.
Step-by-step explanation:
If a patient has no one they trust to make healthcare decisions on their behalf should they become incapacitated, the nurse should suggest they prepare a living will. A living will is a legal document that details specific medical interventions the patient wants or does not want, such as life-extending treatments or a Do Not Resuscitate (DNR) Order. Additionally, it can include a health care proxy, appointing a specific person to make medical decisions if the patient is unable to speak for themselves. This safeguards the patient's wishes regarding their medical care and end-of-life decisions aligning with their values, religion, and upbringing.