Oxygen therapy in a hospital setting

Oxygen therapy, also referred to as supplementary oxygen, may be required for patients who need treatment for, or are at risk of, hypoxaemia, thereby preventing the occurrence of a hypoxic injury (O'Driscoll et al, 2017). However, although the administration of oxygen will improve the oxygenation of the patient, it does not treat the initial cause of hypoxaemia, which should be investigated as a matter of urgency.

Oxygen saturation levels (SpO2) are used to monitor the level of haemoglobin carrying oxygen in the blood, relative to the amount of haemoglobin that is not carrying oxygen. These levels can be obtained with the use of a pulse oximetry device, which can be attached to a patient's finger, toe, earlobe or nose to retrieve an accurate reading (O'Driscoll et al, 2017). The monitor displays a reading of how well saturated the patient's haemoglobin is with oxygen, and this number is presented as a percentage.

Target saturations for a healthy individual should be in the range 95-100% (indicating that the haemoglobin in the blood is almost fully saturated with oxygen). If a SpO2 reading is under 95%, this could indicate early stages of hypoxaemia; however, lower SpO2 readings can be expected in patients with chronic lung disease, such as chronic obstructive pulmonary disease (COPD), chronic bronchitis and emphysema. For patients

A range of devices can be used to deliver oxygen to patients, ranging from those that enable the delivery of high percentages of oxygen to devices that facilitate lower and medium levels of oxygen concentration. The exact percentages and associated flow rates for these devices may vary slightly between manufacturers, therefore it is important to work within manufacturers guidelines.

For many of the devices, the actual percentage of oxygen delivered will also be variable depending on the flow rate that is set, how well the device conforms to the patient's face and the depth and rate of the patient's respirations (ie fast and shallow breathing often result in lower levels whereas deeper and longer breathing may influence higher oxygen concentration levels) (Moore, 2017). These devices are therefore referred to as variable performance devices.

Oxygen cylinder procedure

• Remove plastic coverings on the cylinder to reveal the on/off wheel and the oxygen outlet
• To commence cylinder use, first switch the HX or CD cylinder on, by turning the on/off hand-wheel slowly anticlockwise two revolutions
• Attach the oxygen tubing and required oxygen administration device to the oxygen flow outlet
• Turn the oxygen flow controller clockwise to set the required flow rate; the correct flow rate setting must be fully visible in the window. Check for the flow of oxygen gas prior to use
• After cylinder use, return the oxygen flow controller to ‘0’ and remove and dispose of any used oxygen tubing and oxygen administration device
• Switch the device off by turning the on/off hand-wheel clockwise. Check the ‘live’ gauge to ensure adequate supply for the next administration

Monitoring of patients receiving oxygen therapy

As with every administered drug or treatment, the effects of oxygen therapy

Nursing and Midwifery Council: standards of proficiency for registered nurses

Part 1: Procedures for assessing people’s needs for person-centred care

2.13 identify and respond to signs of deterioration and sepsis

Part 2: Procedures for the planning, provision and management of person-centred nursing care

8. Use evidence-based, best practice approaches for meeting needs for respiratory care and support, accurately assessing the person’s capacity for independence and self-care and initiating appropriate interventions

8.2 manage the administration of oxygen using a range of routes and best practice approaches

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Dudley LS, DiCorpo JE, Merlin MA. Capnography provides bigger physiological picture to maximize patient care. JEMS. 2015. https://www.jems.com/patient-care/capnography-provides-bigger-physiological-picture-to-maximize-patient-care/ (accessed 2 November 2023)

Health and Safety Executive. Oxygen use in the workplace. 2013. https://www.hse.gov.uk/pubns/indg459.htm (accessed 2 November 2023)

Healthcare Safety Investigation Branch. Piped supply of medical air and oxygen. 2019. https://www.hsib.org.uk/investigations-and-reports/piped-supply-of-medical-air-and-oxygen/ (accessed 2 November 2023)

Joint Formulary Committee. Treatment summary: oxygen. 2023. https://bnf.nice.org.uk/treatment-summary/oxygen.html (accessed 2 November 2023)

Kasuya Y, Akça O, Sessler DI et al. Accuracy of postoperative end-tidal Pco2 measurements with mainstream and sidestream capnography in non-obese patients and in obese patients with and without obstructive sleep apnea. Anesthesiology. 2009;111(3):609–615. https://doi.org/10.1097/ALN.0b013e3181b060b6 

Kodali BS. Capnography outside the operating rooms. Anesthesiology. 2013;118(1):192–201. https://doi.org/10.1097/ALN.0b013e318278c8b6 

Medicines and Healthcare products Regulatory Agency. Top tips on care and handling of oxygen cylinders and their regulators. 2013. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/428425/O2_cylinders_top_tips_2013.pdf