My source is that we live our lives, every aspect of our lives, according to Torah. The way we know what the Torah wants is through our rabbanim.
If you're explaining vrapeh to mean that the doctors opinion supersedes the rabbanims in medical cases, you need the source not me.
So if a doctor who is a Baki tells you a patient is in sakana and needs fluid immediately on Yom Kippur and a Rosh Yeshiva standing there tells you he feels that it’s not proper for Yom Kippur , besides, maybe the zechus of Yom Kippur will protect him, and if the patient dies at least he died doing a dvar mitzvah (it would never happen but hypothetically) do you a) listen to the Rosh Yeshiva because he’s Daas Torah or b)physically remove the Rosh Yeshiva from in front of the sink to obtain water if need be, since the doctor is calling it a sakana and the Rosh Yeshiva is not disputing the facts as the doctor stated them?