Supplemental oxygen therapy can be crucial in a patient’s care, but nurses must have a solid foundation of understanding of how it works, when to use it, and how to perform ongoing assessment of the patient’s response to treatment in order for oxygen to be administered appropriately and safely.
When Is Oxygen Therapy Indicated?
Low tissue oxygenation (hypoxia, hypoxemia) is an indication to begin oxygen therapy.1Hypoxia may be acute or chronic and vary in severity. Common acute symptoms include:2
- Shortness of breath, breathlessness (dyspnea)
- Increased respiratory rate
- Increased heart rate (tachycardia)
An important distinction to make is that breathlessness (dyspnea) alone does not indicate hypoxia, and oxygen therapy will not resolve breathlessness if hypoxia is not also present.1Hypoxia is typically diagnosed by a physical examination, which may include the use of pulse oximetry, blood gas samples, and/or pulmonary function tests to determine oxygen levels in the blood and tissues.1,3The normal ranges for pulse oximetry and blood gas samples are 95-100% and 75-100 mmHg respectively.3Values below these ranges may indicate hypoxia and a need for oxygen supplementation even if the patient is not currently demonstrating outward physical symptoms such as shortness of breath or other deteriorating vital signs.1
When used as a medical treatment, oxygen is treated as a drug and requires a prescription unless emergency circumstances are present.1In the prescription, a target oxygen saturation range should be specified to guide treatment. The target saturation range varies according to the patient’s individual needs, demographics, and their degree of risk for hypercapnic respiratory failure. A target saturation range of 94-98% is appropriate for most patients, but a target of 88-92% may be indicated for patients at risk for hypercapnia to reduce the risk for respiratory acidosis.1,4Patients who may be at risk are patients with:1
- Chronic obstructive pulmonary diseasea (emphysema)
- Neuromuscular or chest wall disorders
- Cystic fibrosis
- Morbid obesity
Oxygen Delivery Devices
Once a target oxygen saturation range has been prescribed the oxygen can be delivered via a variable-performance or fixed-performance device. In variable-performance devices the actual amount of oxygen delivered is influenced by the oxygen flow rate, patient’s inspiratory volumes, respiratory rate, and the proportion of room air added during breathing. Nasal cannulas, reservoir masks, and simple face masks are all examples of variable-performance devices.1,5
Fixed-performance devices, also referred to as controlled oxygen delivery systems, deliver a set fixed proportion of oxygen ensuring a more precise concentration of oxygen is delivered regardless of inspiratory volumes and respiratory rate. The oxygen is delivered via color-coded Venturi valves with each color signifying a specific minimum oxygen flow rate being provided by the device. This type of oxygen delivery is recommended for use in patients who are acutely ill and are at risk for carbon dioxide retention.1,5
Monitoring Oxygen Therapy
Nursing assessment and documentation of oxygen therapy should be done at the end of each shift and with any changes in the patient’s condition. All adjustments to inspired oxygen should be recorded. In addition to this, hourly checks should be made for each of the following:4
- Oxygen flow rate
- Oxygen saturation—via blood gas samples or pulse oximetry
- Respiratory rate and effort
- Heart rate and blood pressure
- Patency of tubing
- Humidifier settings (if applicable)
- Fill level of the oxygen cylinder/tank (if applicable)
Oxygen supplementation can be a lifesaving technique if prescribed and administered appropriately. Nurses and doctors alike need to be aware of the indications and various methods for oxygen delivery, as well the guidelines for proper evaluation of a patient’s response to oxygen delivery in order for this treatment to be safe and effective.
- Olive S. Practical procedures: oxygen therapy. Nursingtimes.net. https://www.nursingtimes.net/clinical-archive/respiratory/practical-procedures-oxygen-therapy/7001482.article/. Published January 11, 2016. Accessed April 8, 2019.
- Cafaro RP. Hypoxia: Its causes and symptoms. J Am Dent Soc Anesthesiol. 1960;7(4):4–8.
- Mayo clinic staff. Symptoms: Hypoxemia. Mayoclinic.org. https://www.mayoclinic.org/symptoms/hypoxemia/basics/definition/sym-20050930. Reviewed December 1, 2018. Accessed April 8, 2019.