Non-Rebreather Mask

What Is It, When Is It Used, and More

Author:Lily Guo

Editors:Alyssa Haag,Emily Miao, PharmD,Kelsey LaFayette, DNP, ARNP, FNP-C

Illustrator:Jessica Reynolds, MS

Copyeditor:Stacy M. Johnson, LMSW

What is a non-rebreather mask?

A non-rebreather mask (NRM) is a non-invasive oxygen supplementation device that is used to provide continuous oxygen flow, typically in a hospital setting. Non-rebreather masks are used for individuals who are still able to breathe on their own but require additional oxygen (e.g., traumatic injury to the lungs; smoke inhalation; carbon monoxide poisoning; any chronic disorder of the airways that limits the amount of oxygen reaching the lungs, such as chronic obstructive pulmonary disease [COPD], cystic fibrosis, pulmonary fibrosis, and sarcoidosis). High-flow oxygen through a non-rebreather mask is also specifically used for a type of headache called cluster headaches

The mask consists of a reservoir bag, multiple one-way valves, and a tube to connect the mask to an oxygen tank. When the individual inhales, they are inhaling oxygen directly from the reservoir bag. On exhalation, gasses, such as carbon dioxide, leave via the one-way valve(s) on the mask. The one-way valves prevent exhaled air from entering the reservoir bag and diluting the oxygen. Non-rebreather masks are able to greatly increase the amount of inspired oxygen compared to normal breathing. For example, the normal fraction of inspired oxygen (FiO2), or concentration of oxygen in the air, is approximately 21%. A non-rebreather mask can increase the FiO2 to 60-91%. 

Non-rebreather mask on a patient.

What oxygen flow rate is needed for a non-rebreather mask?

A non-rebreather mask requires a sufficient oxygen flow rate to ensure that the oxygen reservoir bag does not collapse when the individual inspires. Therefore, a flow rate of 12-15 liters per minute is generally recommended. 

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What is the difference between a non-rebreather mask and a rebreather mask?

A non-rebreather mask differs from a rebreather mask, also known as a simple face mask, in that the former prevents mixing of inhaled and exhaled air and allows for greater oxygen administration, while the latter does not. To use a non-rebreather mask, one first attaches the oxygen tubing to the oxygen tank and sets the oxygen flow rate to approximately 12-15 liters per minute. The individual administering oxygen via the mask may first occlude the valve between the mask and the oxygen reservoir bag to check that the reservoir bag is properly filling. It is also advantageous to squeeze the oxygen reservoir bag to check the patency of the valve located between the mask and the reservoir bag. The bag should be able to deflate if the valve is working properly. The administrator can also occlude the valve between the mask and the oxygen reservoir bag to fill the reservoir bag before placing it on the individual’s face. The oxygen flow rate can be adjusted until the reservoir bag deflates by approximately one-third with each breath. The individual might need some time to become accustomed to the mask. Their vital signs, including respiratory rate, oxygen saturation, and levels of consciousness may be consistently monitored throughout the course of their oxygen therapy

In contrast, a simple rebreather oxygen mask provides a smaller amount of supplemental oxygen. Like the non-rebreather mask, a simple mask fits over the nose and mouth and is connected via tubes to an oxygen tank. Unlike a non-rebreather, a simple mask has exhalation ports, which are holes on the sides of the mask through which carbon dioxide is exhaled. There are no one-way valves, so ambient air can enter the mask and exhaled air can mix with the oxygen being delivered. This eliminates the danger of suffocation should a mask with one-way valves become disconnected from oxygen. Additionally, the simple face mask lacks a reservoir bag. The simple face mask delivers lower flow rates (about 6–10 liters per minute) and has an FiO2 of 40 to 60% oxygen. Simple oxygen masks are used when a small amount of additional oxygen is required and is commonly preferred by support personnel trained in basic first aid, such as firefighters, lifeguards, and other non-medical rescue personnel. 

Both non-rebreather masks and simple face masks are non-invasive methods of oxygen delivery that do not provide positive pressure to help support the patient to breathe mechanically or reduce lung collapse, or atelectasis.

In addition to non-rebreather masks and simple masks, there are partial rebreather masks. Partial rebreather masks allow some air to be recycled instead of completely preventing one from rebreathing air. They resemble a non-rebreather mask and consist of similar components; however, they use two-way instead of one-way valves. This allows some exhaled carbon dioxide to return to the reservoir bag. Like a simple mask, partial rebreather masks provide high concentrations of oxygen without the risk of suffocation.

What are the most important facts to know about non-rebreather masks?

Non-rebreather masks are used to provide continuous oxygen therapy to an individual who is capable of breathing on their own. They are particularly useful in cases of lung damage from smoke inhalation, carbon monoxide poisoning, or for cluster headaches (where high flow oxygen can rapidly and effectively reduce the headache). The mask consists of three to four one-way valves, which prevent oxygen from entering the reservoir bag; therefore, the individual is only inhaling oxygen and not the exhaled carbon dioxide. The mask is connected to an oxygen tank via tubes, similar to a rebreather mask (more commonly known as a simple mask). Unlike the non-rebreather mask which allows for a FiO2 of up to 91%, the simple mask has an FiO2 of up to 60% oxygen. The minimal flow rate of non-rebreather masks is typically 12 liters per minute to prevent collapse of the bag upon inhalation. 

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Related links

Respiratory: Oxygen therapy (for nursing assistant training)
Chronic obstructive pulmonary disease (COPD): Clinical practice
Chronic bronchitis

Resources for research and reference

AARC clinical practice guideline. Oxygen therapy in the home or extended care facility. American Association for Respiratory Care. (1992). Respiratory Care, 37(8): 37:918-922. Retrieved from

Kallstrom, T. J. (2002). AARC clinical practice guideline: Oxygen therapy for adults in the acute care facility – 2002 revision & update. Respiratory Care, 47(6): 717-720. Retrieved from

Kramer, D., & Baram, M. (2021). Non-rebreather mask: A bridge worth crossing? The American Journal of the Medical Sciences, 361(4): 409–410. DOI: 10.1016/j.amjms.2021.01.011 

MacPherson, S. P. (1995). Respiratory care equipment (5th ed.). Mosby.

Nagler, J. (2021). Continuous oxygen delivery systems for the acute care of infants, children, and adults. In UpToDate. Retrieved July 10, 2022, from

Non-rebreather mask. In ScienceDirect. Retrieved July 10, 2022, from 

Weekley, M. S., & Bland, L. E. (2022). Oxygen administration. In StatPearls. Retrieved from: