A living will shall have no force or effect if the declarant is a patient in a hospital or skilled nursing facility at the time the living will is executed unless the living will is signed in the presence of the two witnesses as provided in Code Section 31-32-3 and, additionally, is signed in the presence of either the chief of the hospital medical staff, any physician on the medical staff who is not participating in the care of the patient, or a person on the hospital staff who is not participating in the care of the patient designated by the chief of staff and the hospital administrator, if witnessed in a hospital, or the medical director or any physician on the medical staff who is not participating in the care of the patient, if witnessed in a skilled nursing facility.