Skill List > Oxygen Therapy: Simple Face 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
Updated by: Sue Faulds BSc (Hons) MA(ed) RN
Last updated: April 20

Hudson mask. (From Nicol M, Bavin C, Cronin P, et al. 2012 Essential Nursing Skills, 4th edn. Mosby Elsevier, Edinburgh.)
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 the Hudson mask.


Oxygen may be required by a patient when the level of oxygen they have in their blood is insufficient for normal functioning.  At the same time, they may be experiencing shortness of breath but it is the low level of oxygen rather than the breathlessness that is the reason for oxygen administration.  The aim of administering oxygen is to achieve a normal or near normal oxygen saturation.  What is normal will depend on the individual but for those without chronic respiratory conditions such as Chronic Obstructive Pulmonary Disease (COPD) it may be as low as 88–92% when monitored with an oxygen saturation probe. For those without chronic respiratory conditions the normal oxygen saturation level is 94–98% (BTS 2011). Pulse oximetry must be available in all settings where emergency oxygen is used (Olive 2016).

The simple face mask is a variable performance oxygen delivery device, which is sometimes referred to as a Hudson mask intended for short-term use, such as post-op recovery (Olive 2016). The simple face mask is made of plastic and shaped to fit over the mouth and nose with a port at the bottom for the connection of oxygen tubing (Figure 1). Oxygen is delivered into the mask and air entrained from the atmosphere through side ports, so that the concentration of delivered oxygen depends on the amount of air drawn in through the mask by the patient. It has been noted, therefore, that there can be unpredictable levels of actual oxygenation depending on the patient’s respiratory pattern, and how much mouth breathing occurs (Olive 2016). Due to the unpredictable levels of actual oxygenation, this mask is not suitable where the patient requires accurate low dose oxygen therapy owing to respiratory disease or where there is a risk of carbon dioxide retention, but it may be appropriate at times where high levels of oxygen are required.

McGloin (2008) states that there are differences in various manufacturers’ guidelines for using variable performance simple face masks, therefore making it essential to refer to individual guidelines. Simple masks deliver oxygen concentrations of between 40% and 60%. Flow rates for simple masks should not be below 5 L/min as the patient could easily breathe in air that has not been flushed from the mask. McGloin (2008), however, identifies that some manufacturers indicate that 24% and 28% oxygen can be delivered at rates below 5 L/min, while Dougherty and Lister (2011) argue that between 21% and 60% can be delivered through a variable simple semi-rigid face mask at oxygen flow rates of 2–15 L/min. The British Thoracic Society (BTS) has also identified that different brands of simple face mask can deliver different oxygen concentrations at a given flow rate. Considering all the above points, it is essential when applying a simple face mask that every nurse is fully aware of equipment used and follows the manufacturer’s instructions.
Simple face masks are used and are effective when patients require a high percentage of oxygen. They can be used for hours or several days, but should be used in conjunction with a humidifier if used for more than 12 h and/or the patient has a dry or productive cough (Perry et al. 2016). The BTS concluded in its review of oxygen delivery methods that many patients prefer not to use a simple face mask and are more likely to tolerate nasal cannulae for medium dose range oxygen delivery (BTS 2011). Eastwood et al. (2009) found that patients stated that it was easier to comply with oxygen therapy when they could maintain activities of daily living. It must be noted that nasal cannulae are better for the patient than a face mask in respect of facilitating communication and enabling the patient to eat and drink uninhibited. These factors may be leading to a decline in use of the simple face mask. 

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 inflammable.
  • 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 need to be read in conjunction with the latest advice from PHECC

  1. Perform hand hygiene, introduce yourself and explain the need for oxygen to gain consent and cooperation. Check the patient’s identity and the prescription. 
    Rationale – To safeguard the patient and aid in reducing any worries and fears the patient may have. The National Patient Safety Agency (2010) emphasises that oxygen therapy is a medication and therefore must be prescribed, except in emergency situations (BTS 2008).
  2. Turn on the oxygen flow meter and set the flow meter to the prescribed rate before putting the mask on the patient. 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.
  3. 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 the length of the strap to ensure the mask fits securely.
    Rationale – To ensure the system is correctly fitted and is as comfortable as is possible, thus ensuring the patient receives the oxygen as prescribed.
  4. Document oxygen administration according to local policy.
    Rationale – Patient records should contain precise descriptions of treatments given.
  5. Assess the patient and continue to monitor vital signs and oxygen saturations in accordance with the patient’s condition and local policy.
    Rationale – To ensure that the treatment is having the desired effect. Pulse oximetry must be available in all settings where emergency oxygen is used (Olive 2016).

Ongoing care, monitoring and support

  • Observe the patient’s colour and perfusion, oxygen saturations and respiratory pattern.
  • Offer drinks or mouth washes. Oxygen therapy dries the mucous membranes of the mouth. Frequent drinks as appropriate to the patient's condition should be provided if the oxygen is not being humidified.
  • 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.

Documentation and reporting

  • Document the method of oxygen delivery, the percentage that is being delivered, and monitoring and assessment of the patient that will be carried out.
  • Report any abnormalities or complications so that appropriate interventions can be initiated.
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