FiOværdier

FiOværdier is a Danish term that refers to the fraction or level of oxygen delivered to and inspired by a person, commonly denoted as FiO2. In clinical contexts, FiO2 represents the amount of oxygen in the inhaled air mixture, and it is used to describe and manage a patient’s oxygenation.

Under normal conditions at sea level, room air contains about 21 percent oxygen, corresponding to FiO2 around 0.21. When a patient receives supplemental oxygen, the FiO2 increases above this baseline. The exact FiO2 depends on the delivery method, the device, and the patient’s breathing pattern.

Various oxygen delivery devices provide different FiO2 ranges. A nasal cannula typically delivers approximately 24–40% FiO2, increasing with higher flow rates up to about 6 liters per minute. A simple or short-sleeve face mask can deliver roughly 40–60% FiO2. A non-rebreather mask may provide higher FiO2, commonly up to about 85–95% with a good seal and reservoir. High-flow nasal oxygen systems and Venturi masks can deliver more precise and sometimes higher FiO2, sometimes approaching 100% with appropriate settings. In mechanical ventilation, the ventilator can be set to deliver a wide range of FiO2, from just above ambient to near 1.0 (100%).

FiO2 is used together with arterial oxygen measurements (PaO2) to assess oxygenation, often via the PaO2/FiO2 ratio in conditions such as respiratory failure and ARDS. Clinically, FiO2 targets are guided by oxygen saturation (SpO2) goals, with emphasis on using the lowest FiO2 that maintains safe and adequate oxygenation to minimize risks associated with prolonged high oxygen levels.

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