Which of the following patients requires a non-rebreather mask (NRB)?

• A. Trauma pt in cardiac arrest
• B. COPD pt in respiratory distress
• C. Diabetic pt with blood sugar of 3.6 mmol/l
• D. Obstetrical pt with contractions less than 2 min apart

Answer: (B)

Non-rebreather masks are used when a patient needs a high concentration of oxygen delivered quickly due to significant hypoxemia or severe respiratory distress. In a COPD patient with respiratory distress, oxygenation can deteriorate rapidly because gas exchange is impaired, so providing a high, readily available oxygen concentration helps raise arterial oxygen levels promptly. The non-rebreather design delivers a large portion of the inhaled oxygen with a reservoir and one-way valves, minimizing rebreathing of exhaled air and maximizing the oxygen fraction the patient inhales.

The other scenarios don’t center on needing a rapid, high-oxygen delivery: a trauma patient in cardiac arrest is managed first with CPR and airway support that often uses a bag-valve mask or advanced airway with high FiO2; a diabetic patient with severe hypoglycemia has a problem of low glucose, not oxygenation; and an obstetrical patient with very close contractions is not an oxygenation crisis. In COPD, while oxygen must be used carefully to avoid CO2 retention, the immediate need in this case is to boost oxygen delivery, making a non-rebreather the best choice in the moment.