A 71-year-old female awoke with sudden shortness of breath. She has a history of myocardial infarction. What is the first action you should take given SpO2 of 91% on room air?

• A. Administer oxygen by NRB
• B. Ask if she takes nitroglycerin
• C. Lay her flat and elevate legs
• D. Listen to her lungs for wheezes

Answer: (A)

The main action here is to treat potential hypoxemia right away by delivering high-concentration oxygen. A SpO2 of 91% on room air indicates the patient isn’t getting enough oxygen, and in an older patient with a history of myocardial infarction and sudden shortness of breath, securing oxygen delivery supports tissue perfusion and buys time for further assessment and treatment.

Administering oxygen by a non-rebreather mask is the best choice because it provides a high fraction of inspired oxygen quickly, helping raise the SpO2 toward normal levels despite the patient’s acute dyspnea. This immediate step addresses the airway–breathing problem first, which is the priority in EMS care.

Other steps, while important in their own right, don’t address the urgent hypoxemia as directly. Nitroglycerin can be considered for suspected ischemia or chest pain, but it’s not the first move when breathing is compromised and oxygen is needed, and it has contraindications (like hypotension or certain meds). Laying the patient flat with legs elevated is not ideal in acute dyspnea from possible cardiac or pulmonary causes; a more upright or slightly elevated position typically eases breathing. Listening to lung sounds is helpful for assessment, but it doesn't correct the low oxygen saturation by itself.