Home » Medical Staff » Emergency Medicine » Pater, Erika K. PA Erika Pater, Physician Assistant Erika Pater, PA Emergency Medicine is on staff atCHOC Hospital Orange Erika Pater is a physician assistant who specializes in emergency medicine at CHOC Hospital. Location EMSOC 1310 W. Stewart Drive, Suite 212 Orange, CA 92868 Education Chapman University, Orange, CA