What percentage of oxygen is delivered by a non-rebreather mask?

A non-rebreather mask is designed to deliver a high concentration of oxygen to patients suffering from conditions that require immediate intervention, such as respiratory distress or hypoxia. When properly fitted and functioning, it can provide an oxygen concentration ranging from 90% to 100%.

The mask includes a reservoir bag filled with pure oxygen, and one-way valves prevent exhaled air from entering the bag. This design allows the patient to inhale the oxygen directly from the reservoir, minimizing the dilution with room air. This results in the high concentration of oxygen that is critical for rapidly stabilizing the patient's condition.

Lower percentages of oxygen delivery from other devices, such as nasal cannulas or simple face masks, reflect less effective methods for treating severe oxygenation issues, as they cannot deliver the same volume of oxygen. That’s why the values in the other choices—such as 65-75%, 80-90%, and 24-44%—do not accurately represent the capabilities of a non-rebreather mask. The ability of the non-rebreather mask to provide near-total oxygen concentration is essential in emergency medical scenarios.