you are treating a patient with severe crushing chest pain. she has had two heart attacks in the​ past, and you believe that she is currently in cardiogenic shock. blood pressure is​ 86/66 mmhg, respirations are 20​ breaths/min, heart rate is 102​ beats/min, and​ room-air pulse oximetry reading is​ 91%. which intervention is the most appropriate next action in this​ case?