Oxygen therapy is the clinical use of supplemental oxygen for patients with hypoxia. As discussed in the breathing section, if untreated, low oxygen levels can lead to organ failure and cardiac arrest. 

Starting oxygen therapy can be life-saving and is often time critical. If your patient is hypoxic you should start oxygen therapy straight away, you do not need to wait for it to be prescribed. 

Oxygen should be titrated to achieve the patients set oxygen saturation target. Every patient needs an oxygen saturation target prescribed on admission. This will determine whether they are scale 1 or scale 2 on their NEWS chart. If using supplemental oxygen this should also be prescribed. 

Patients with hypercapnic respiratory failure rely on their hypoxic drive to breathe, so too much supplemental oxygen can inhibit this and reduce respiration. This is why they have a lower target saturation set (NEWS scale 2).

This section will talk through the various oxygen therapies available on the ward. When we describe the amount of oxygen delivered some devices use L/minute and some describe a fraction of inspired oxygen (FiO2) or both. Be aware the L/ minute and FiO2 are not necessarily comparable between devices. For example if you have a patient desaturating on 4L nasal cannula, and you changed them to humidified system 5L (28% FiO2), you would actually be giving them less oxygen. As 4L/min nasal cannula is about 34% FiO2. It is important to have an understanding of this when switching between devices.