Skill List > Oxygen Therapy: Humidified Oxygen
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: Professor Maggie Nicol BSc(Hons) MSc(Nursing) PGDipEd RN
Updated by: Sue Faulds BSc(Hons) MA(Ed) DipHE RN
Last updated: April 20
Humidified oxygen system. (From Esmond G 2001 Respiratory Nursing. Baillière Tindall, 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 administering humidified oxygen.


Oxygen therapy is used for patients who are hypoxaemic (low levels of oxygen in the blood) due to illness or injury. The aim of treatment is to correct hypoxaemia and prevent hypoxia (low levels of oxygen in the tissues) by increasing the amount of oxygen in the air that the patient breathes. At the same time, the patient may be experiencing shortness of breath but it is the low level of oxygen rather than the breahlessness that is the reason for oxygen administration (Vates 2011). Oxygen therapy can therefore be life-saving when used correctly but has many important dangerous complications (British Thoracic Society (BTS) 2008, Woodrow 2016).

One of these complications is drying of the respiratory tract. In normal breathing, room air is warmed and moistened as it passes through the upper airway (Marieb & Hoehn 2015). This may be prevented when high flow oxygen is used, in prolonged oxygen therapy, and patients who have a tracheostomy.

Drying of the oral mucosa causes patient discomfort, which may prevent compliance with this important therapy. It can also cause drying of secretions, which makes it more difficult for the patient to expectorate sputum. Prolonged therapy may also cause collapse of the smaller airways or atelectasis causing more severe infection or hypoxia (McGloin 2008). Humidified oxygen can be used to prevent these complications (Jindal 2008). The British Thoracic Society (2008)  states that humidification is unnecessary in short-term oxygen use or in flow rates of 1–4 l/min but suggests that it is always used for patients with tracheostomy except in emergencies only. Duck (2009) agrees but also supports the use of humidified oxygen for patients who complain of discomfort including mucosal drying. She emphasises the importance of adequate systemic hydration as patients on oxygen therapy are at risk of reduced oral intake. If the patient is unable to take oral fluids then appropriate mouth care must be given. 

Oxygen can be humidified in several ways: nebulisation, heat and moisture exchange (HME) filters (often used in intubated patients or those with a tracheostomy), or through the use of humidified circuits. Some of these can also warm inspired air, which improves gas exchange at the alveolar level (Cuquemelle et al. 2012).

Cold water humidified circuits are commonly used in ward and community settings (Figure 1). They contain an air entrainment (also known as venturi) system that will draw in specific proportions of room air to gain a selected concentration of oxygen, which is set using a dial (Figure 1). The flow of oxygen is set according to the value given. The selected concentration of gas then bubbles through a water reservoir in order to humidify the air before it reaches the patient.

Oxygen should be considered like any other drug and should be prescribed (except in an emergency) and administered accordingly. The required flow rate or concentration as well as the device required should be clearly prescribed (McGloin 2008, BTS 2008).

The water reservoir provides an environment for micro-organisms to grow; this risk increases when warmed circuits are used. It is important that an aseptic non-touch technique is used when assembling circuits and they are changed according to manufacturer guidelines. Circuits must never be shared with other patients.

Preparation and safety

  • Explain the procedure to the patient, to gain consent and cooperation.
  • Assemble the necessary equipment.
  • The hands should be clean and an apron worn.
  • Asepsis must be maintained when handling the water reservoir of the humidifier.


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

  1. Perform hand hygiene and put on an apron. Wear personal protective equipment where necessary. 
  2. Introduce yourself and explain the procedure.
  3. Check the patient’s identity and the prescription regarding the percentage of oxygen to be administered.
    Rationale – Oxygen is a drug and the percentage of oxygen and type of device should be clearly stated.
  4. Using an aseptic non-touch technique attach the humidifier to the oxygen flow meter according to the manufacturer’s instructions.
    Rationale – Failure to assemble correctly may mean the humidification system does not work properly.
  5. Adjust the percentage by turning the valve to the prescribed setting and adjust the flow of oxygen until the centre of the ball is at the prescribed rate. Humidification produces a fine mist that is visible inside the mask.
    Rationale – This will ensure that the correct volume of air is mixed with the oxygen to achieve the prescribed concentration (or percentage).
  6. Ask/assist the patient to put on the mask and adjust the retaining strap to ensure a snug fit without pressure on the ears. Adjust the nose section of the mask to prevent the mist going into the patient’s eyes.
    Rationale – To improve patient comfort and compliance and prevent pressure ulcers developing where the strap rests on the ears.
  7. Document the percentage of oxygen according to local policy.
    Rationale – The administration of oxygen should be treated like any other drug and should be recorded on the prescription chart as well as the observation chart.

Care, monitoring and support

  • Ensure the patient is comfortable and make sure they have a drink if their clinical condition allows. If not appropriate, mouth care should be available.
  • The humidified oxygen may encourage the patient to cough so a sputum pot and tissues should be provided.
  • Regular monitoring is required for all patients receiving oxygen therapy. This should include respiratory rate and effort, oxygen saturation levels, and conscious level (Royal College of Physicians 2012).
  • If using an oxygen cylinder, monitor the amount remaining and order a replacement when it is down to one quarter full.
  • Check regularly to see if water is collecting in the tubing. The wide bore tubing should be emptied or the tubing changed according to local policy.
  • The water reservoir should be monitored and should be replaced when empty.
  • The tubing and mask should be changed every 24 h.

Documentation and reporting

  • Document humidified oxygen administration and the prescribed percentage of oxygen according to local policy.
  • Report any abnormalities or complications so that appropriate interventions can be initiated.
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