An adult client is being admitted to the coronary care unit with a possible myocardial infarction (MI). The client reports feeling like they are going to "pass out." The cardiac monitor displays the rhythm shown. The client's respiratory rate is 12 to 16 breaths/minute and blood pressure is 78/52 mm Hg. The nurse auscultates clear breath sounds bilaterally and the skin is pale and diaphoretic. After administering oxygen, which action should the nurse prepare to perform?