Question

A female patient in her late fifties with widely metastatic ovarian cancer is admitted to the inpatient palliative care unit for management of intractable pain. She is somnolent, intermittently delirious, and has been explicitly determined to lack the capacity to make medical decisions. She is visibly grimacing, tachypneic, and moaning continuously despite receiving scheduled doses of intravenous morphine. The medical team concludes that initiating a continuous intravenous fentanyl infusion is required to provide adequate analgesia.

The patient's legally appointed healthcare proxy is her adult son. Her estranged husband, from whom she has been separated for five years but not legally divorced, is also present at the bedside. Upon discussing the pain management plan, the son refuses to provide consent for the fentanyl infusion. He states, "I know these continuous opioid drips can suppress respiratory drive and hasten death. Our religion strictly forbids any action that might shorten a person's life. You must use something else."

The physician explains that while respiratory depression is a known risk, the exclusive medical intent is to relieve her severe suffering, and non-opioid medications are entirely insufficient for this level of pain. The son remains steadfast in his refusal. The estranged husband approaches the physician privately and says, "She is in agony. I give you permission to start the fentanyl."

Which of the following is the most appropriate next step in management?