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  • Selecting the optimal oxygen delivery system will depend on both individual patient factors such as oxygen requirements, patient physiology, and device tolerance and structural factors such as the location of care, device availability, and patient monitoring capabilities.

  • Given the consequences of both hypoxemia and hyperoxemia, oxygen should be prescribed to achieve a target saturation such as oxygen saturation of 94% to 98% for most acutely ill patients, with a lower goal of 88% to 92% being preferred in patients with chronic hypoxemia, chronic obstructive pulmonary disease, or other risk factors for hypercapnia.

  • Low-flow oxygen devices deliver oxygen at a flow rate below that of the patient’s inspiratory demand, resulting in the precise delivered FiO2 being dependent on the oxygen flow rate, patient inspiratory effort, device fitment, and amount of entrained room air.

  • High-flow oxygen devices deliver total gas flow rates exceeding the patient’s inspiratory demand, delivering a mixture of oxygen and air in a specified ratio at a precise FiO2 independent of external factors.

  • High-flow oxygen devices, in addition to systems that bypass the upper airway, require humidification, which is most frequently accomplished with heated humidifiers or heat and moisture exchangers.


Oxygen therapy is an effective treatment for hypoxemia and its use is ubiquitous in intensive care units. Like any other drug, however, the administration of oxygen should be deliberate, with conscientious selection of dose and route of administration along with careful patient monitoring and titration. Fundamentally, oxygen therapy increases the alveolar partial pressure of oxygen (PAO2) and is therefore only effective in increasing the arterial partial pressure of oxygen (PaO2 PaO2) while functional alveolar ventilation is maintained. While oxygen therapy can be a rapid method of improving oxygen delivery in cases of tissue hypoxia, it is not a curative treatment, but rather supportive therapy for the prevention of end-organ damage while measures are taken to identify and correct the underlying cause of hypoxia.

The primary indication for oxygen therapy is hypoxemia, a low blood oxygen content, which is generally defined as a PaO2<60 mm Hg or SaO2<90%.1 The goal of oxygen therapy in the case of hypoxemia is to prevent hypoxia, the tissue injury that occurs as a result of insufficient oxygen delivery. As the exact tissue oxygen requirements vary by patient and physiologic state, there is no lower limit of PaO2 or SaO2 that can be universally regarded as safe, and many patients with chronic lung disease are able to tolerate a PaO2<60 mm Hg or SaO2<90% without evidence of tissue hypoxia.2 In addition to hypoxemia, oxygen therapy is indicated for the treatment of a select few indications even in the absence of hypoxemia, such as carbon monoxide ...

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