At what point does persuasion challenge voluntariness?

_{Ash is physically weak and ill. His doctor recommends a procedure that is in Ash’s best medical interests. Ash is fully informed about the procedure and the consequences of saying no. He refuses the procedure. Knowing that Ash trusts her, his doctor repeatedly explains the treatment's benefits to encourage him to agree to the procedure. Because of his weak condition, Ash lacks the motivation to continue to refuse. Ash consents to the procedure. Is Ash’s consent voluntary?}

How would you describe what the doctor does?