A 66-year-old female with a history of hypertension and diabetes presents with substernal chest pressure of 2 hours' duration. Her blood pressure is 140/90 mm Hg, her pulse is 100 beats/min and irregular, her respirations are 22 breaths/min, and her oxygen saturation is 92%. The patient does not have prescribed nitroglycerin, but her husband does. You should:

Administering oxygen, giving 324 mg of aspirin, and assessing further are appropriate actions for this patient's presentation. The patient is exhibiting symptoms consistent with a possible myocardial infarction (heart attack), indicated by her history and the substernal chest pressure lasting two hours.

Aspirin serves an important role in this situation as it helps to inhibit platelet aggregation, which can prevent further clotting in the case of a blockage in the coronary arteries. Oxygen administration is also critical given her low oxygen saturation level of 92%. By improving oxygen delivery, you can help manage potential ischemia to the heart muscle.

Following these interventions, a thorough assessment can provide additional insight into her condition, including monitoring her vital signs, further evaluating her symptoms, and determining the next steps for treatment or transport, based on the findings. Thus, taking these actions prioritizes the patient's immediate needs and follows established protocols for managing possible cardiac emergencies.