There is no requirement in Texas state law or by the BON for a physician co-signature on orders written by a CRNA in the perioperative period. Board Rule 221.15(a) establishes the legal basis for the ordering of drugs and devices by a CRNA in a licensed hospital or ambulatory surgical center. Board Rule 221.16(b)(3) establishes the legal basis for the ordering of drugs and devices by a CRNA in an outpatient setting.