A "Constitutional Right to Refuse Medical Treatment"

A clip of MICHAEL Schiavo's attorney, George Felos, shows him talking about a "Constitutional right to refuse medical treatment" (Michael Schiavo claims these are Terri's wishes). I must be blind because I don't see anything about that in the U.S. Constitution. And while someone is looking for that right, perhaps they could find the right to abortion, which I'm told is also in the Constitution.