Year-old male with an extensive cardiac history presents with 2 hours of crushing chest pain and shortness of breath. he is pale and diaphoretic and tells you that he feels like he is going to die. his medications include nitroglycerin, sildenafil (viagra), and enalapril (vasotec). his blood pressure is 140/90 mm hg and his heart rate is 110 beats/min. in addition to administering supplemental oxygen if needed, you should: