A 6-year-old patient with anaphylaxis is receiving oxygen via nasal cannula at 2 L/min with an order to titrate oxygen saturations of greater than 94%. Fifteen minutes later, the nurse notes that the patient is sleepy, breathing with the mouth open at a rate of 32 breaths per minute, and has oxygen saturations of 89%. What would be the best method of delivering oxygen delivery for the patient at this time?