Skill List > Oxygen Therapy: Non-rebreathe Mask
Clinical Alert

Elsevier Clinical Skills covers the principles of this procedure. You must follow local policies and procedures regarding technique, equipment used and documentation.
Based on Nicol: Essential Nursing Skills 4E
Adapted by: James Mulkerrins MSc RNT
Updated by: Sue J. Faulds BSc (Hons) MA(ed) RN
Last updated: April 20

Non-rebreathe oxygen mask. (From Perry A G, Potter P A 2002 Clinical Nursing Skills and Techniques, 5th edn. Mosby, St Louis.)
Learning Objective
After reading the skill overview, watching the video, following up some of the references/web sites and completing the self-test quiz you should be ready to be assessed in practice in the skill of giving oxygen therapy using a non-rebreathe mask.


The non-rebreathe oxygen mask can deliver very high concentrations of oxygen and is commonly used in acute care situations where the patient's demand for oxygen is higher than they are able to achieve on room air;  for example, shock states, loss of blood and respiratory conditions such as asthma (Singh et al. 2011). This is usually established using pulse oximetry or arterial blood gases. The non-rebreathe mask consists of a mask that has several one-way valves and a reservoir bag (Figure 1). The valves on the mask prevent air from entering the mask and reducing the amount of oxygen but also allow expired breath to exit the mask, therefore preventing rebreathing of expired air. The reservoir bag at the bottom of the mask provides a reservoir of oxygen for the patient to inhale, but also has a valve which prevents exhaled air from entering the reservoir. The non-rebreathe mask is a variable performance device and is generally only used for short-term therapy for acutely ill patients who require higher levels of oxygen than room air (room air is approximately 21% oxygen). There is some variation between authors about the concentration of oxygen that can be delivered with a non-rebreathe mask. Cooper et al. (2006) state that a face mask with a reservoir bag can deliver 70–80% oxygen at 15 l/min but this depends on the fit of the mask and the way that the patient is breathing. The BTS (2017) states that the concentration of oxygen delivered is not exactly accurate and will depend on the flow of oxygen and the patient’s breathing pattern but concentrations of up to 90% can be achieved. The non-rebreathe mask has, in the past, been referred to as a 100% oxygen mask but this is an incorrect term. Cooper et al. (2006) state that it is impossible for a patient to receive 100% oxygen via these masks for the simple reason that there is no air-tight seal between mask and patient. It is therefore imperative that when fitting these masks the practitioner ensures a comfortable and well fitting seal is created in order for the patient to receive the prescribed high level concentration of oxygen.

There are a number of other checks that are essential to carry out when using a non-rebreathe mask. Jevon (2007) stresses that the patency of the valve between mask and reservoir bag should be checked. After setting the flow rate of oxygen, occlude the valve between mask and reservoir bag to make the reservoir bag fill with oxygen. Then squeeze the reservoir bag; if it empties, the valve is working correctly. Then reinflate the reservoir bag before fitting the mask onto the patient to ensure that the appropriate concentration of oxygen will be delivered to the patient. The nurse also needs to ensure the reservoir bag does not collapse fully during use. This may require the adjustment of the flow rate. Humidification is not required when using a mask with a reservoir device (Timby 2009).

Eastwood et al. (2009) investigated patients’ perceptions of oxygen therapy. They found that patients identified device comfort as a major factor in helping them comply with oxygen therapy. Non-rebreathe masks can be very uncomfortable, difficult to keep on, claustrophobic, and can cause pressure ulcers around the ears. They must also be removed for many activities of daily living including eating and drinking, communicating, and expectorating. It is therefore essential that adequate support, assurance, and education are given to the patient to reduce any anxieties and concerns they may have and to aid them in complying with oxygen therapy.

The BTS guidelines on oxygen delivery stress that high concentration oxygen should be given to critically ill patients immediately and this should be recorded in the patient’s notes (BTS 2017). They also state that the ‘fifth vital sign’, oxygen saturation, should be monitored as well as pulse, respiratory rate, blood pressure, and temperature and pulse oximetry (oxygen saturations) must be available in all settings where oxygen is used (Olive 2016). Acutely ill patients being treated with high concentration oxygen via non-rebreathe masks require continuous observation of vital signs, colour and perfusion, and response to treatment, and any abnormalities must be reported so that appropriate interventions are initiated promptly (Woodrow 2016). Caution must exercised with patients with a history of respiratory disease such as Chronic Obstructive Pulmonary Disease (COPD) because a higher concentration of oxygen may lead to an increase in carbon dioxide level, leading to respiratory distress and even coma in these patients (BTS 2017).

Preparation and safety

  • Explain the procedure, to gain consent and cooperation.
  • Prepare the patient preoperatively, if oxygen therapy is planned postoperatively.
  • Patients and visitors must be made aware of the dangers of smoking when oxygen is being administered, because it is highly flammable.
  • The hands should be clean and an apron should be worn.
  • Additional protective clothing may be necessary if indicated by the patient’s condition.


If you are in the Republic of Ireland this skill must be read in conjunction with advice from PHECC

  1. Check the patient’s identity and the prescription. Explain the need for a higher concentration of oxygen.
    Rationale – These measures will safeguard the patient, and ensure the patient understands and is able to give informed consent. It will also aid in reducing any worries and fears they may have. The National Patient Safety Agency (2010) emphasises that oxygen therapy is a medication and therefore must be prescribed, except in emergency situations.
  2. Attach the oxygen tubing to the mask.
    Rationale – To ensure that there is a closed circuit and no leaks are present.
  3. Turn on the oxygen flow meter and set the centre of the ball to the prescribed rate. Ensure the centre of the ball in the flow meter sits at the level of the flow rate prescribed.
    Rationale – To make certain that the system is working correctly and that the correct oxygen level is given.
  4. Allow the reservoir bag to inflate by occluding the valve and test that the valves on the mask will open freely by squeezing the reservoir bag.
    Rationale – To ensure that the valve on the mask is working and that the reservoir bag which contains oxygen is available for the patient to inspire but prevents expired air entering the reservoir bag.
  5. Place the mask over the patient’s nose and mouth, with the elastic strap over the ears to the back of the head. Adjust the nose section and length of the strap to ensure the mask fits snugly but is not tight.
    Rationale – To ensure the system is correctly fitted and is as comfortable as possible, thus the ensuring the patient receives oxygen as prescribed.
  6. Ensure that the flaps of the valves on the mask will open as the patient exhales and that the bag does not collapse down; this indicates that the flow rate of oxygen needs increasing.
    Rationale – To ensure that when the patient exhales, expired air exits the mask via the open mask flap and side holes and not into the reservoir bag, thus preventing rebreathing of air.
  7. Document oxygen administration according to local policy.
    Rationale – Patient records should contain precise description of treatments given, including the administration of a medicine such as oxygen. All primary care trusts, ambulance trusts, and hospital trusts should take specific measures to institute safe and effective administration and documentation of oxygen therapy (BTS 2011).
  8. Assess and observe the patient in accordance with their condition and local policy.
    Rationale – The use of high flow oxygen is reserved for unwell patients whose condition may deteriorate rapidly.  Continuous assessment ensures that the patient’s condition is monitored and any deterioration quickly spotted and acted upon.

Ongoing care, monitoring and support

  • Observe the patient’s oxygen saturation, colour, perfusion, respiratory rate and pattern as a minimum. Local policy may dictate additional observations.
  • Offer drinks or mouth washes. Oxygen therapy dries the mucous membranes of the mouth. Frequent drinks should be provided if the patient's condition allows it.
  • Tubing and masks may be reused several times for the same patient, as long as they are kept dry and free from dust. They should be disposed of in the clinical waste when no longer required.
  • If using an oxygen cylinder, ensure that a replacement cylinder is available when the volume indicator gauge shows only one quarter full.
  • Document oxygen therapy according to local policy.
  • Observe the patient’s skin under the mask and strap to ensure there are no pressure ulcers developing.

Documentation and reporting

  • Document the method of oxygen delivery, the percentage that is being delivered (or flow rate), and monitoring that will be carried out.
  • Document continuous monitoring and observation and report any abnormalities or complications to the appropriate person so that appropriate interventions can be initiated.
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