A 60-year-old man complains of chest pain and difficulty breathing. He is pale, diaphoretic, and in severe pain. As your partner applies supplemental oxygen, you assess his vital signs. His blood pressure is 180/90 mm Hg, pulse is 110 beats/min and irregular, respirations are 24 breaths/min and labored, and oxygen saturation is 93%. You ask him if has taken any nitroglycerin and he tells you that he does not have any but his wife does. You should: