Which device delivers the highest FiO2 commonly available in EMS?

Which device delivers the highest FiO2 commonly available in EMS?

• A. Nasal Cannula
• B. Nonrebreather Mask
• C. Simple Face Mask
• D. Bag-Valve Mask with Reservoir

Answer: (B)

The main idea is understanding how much oxygen concentration a device can deliver to a patient who is breathing on their own. A nonrebreather mask achieves this by using a reservoir and one-way valves that minimize mixing of exhaled air with incoming oxygen. When you supply high-flow oxygen (typically 10–15 L/min) and seal the mask well, the patient inhales a very high fraction of inspired oxygen—greatly higher than a nasal cannula or a simple face mask, usually around 80–90% and sometimes approaching 95% with an excellent seal. While a bag-valve mask with a reservoir can also provide very high FiO2 (nearly 100%) when actively ventilating, it is used for assisted ventilation rather than simply delivering oxygen to a spontaneously breathing patient. In the context of a patient who is breathing on their own, the nonrebreather mask is the device that reliably delivers the highest FiO2 among the listed options, making it the best choice in this scenario.

The main idea is understanding how much oxygen concentration a device can deliver to a patient who is breathing on their own. A nonrebreather mask achieves this by using a reservoir and one-way valves that minimize mixing of exhaled air with incoming oxygen. When you supply high-flow oxygen (typically 10–15 L/min) and seal the mask well, the patient inhales a very high fraction of inspired oxygen—greatly higher than a nasal cannula or a simple face mask, usually around 80–90% and sometimes approaching 95% with an excellent seal.

While a bag-valve mask with a reservoir can also provide very high FiO2 (nearly 100%) when actively ventilating, it is used for assisted ventilation rather than simply delivering oxygen to a spontaneously breathing patient. In the context of a patient who is breathing on their own, the nonrebreather mask is the device that reliably delivers the highest FiO2 among the listed options, making it the best choice in this scenario.