Vital signs
Inspired Oxygen (FiO₂)
For education. Check every result.
Anatium is a study resource, not medical advice. Nothing here is a diagnosis, a prescription or a substitute for a clinician who has seen the patient. Check every number against a current local protocol before it touches anyone, and never act on a result you cannot reproduce yourself.
Reference range
| Range | 21 to 100 % |
About
The fraction of oxygen being breathed in, from 0.21 in room air upward. A saturation figure is meaningless without knowing this.
When it is low
21% is room air - the baseline against which every saturation must be read
When it is high
High FiO₂ means the patient is sick, however good the saturation looks. A rising oxygen requirement is deterioration even when SpO₂ stays constant
How it is measured
always record SpO₂ with the oxygen delivered - a saturation without an FiO₂ is uninterpretable. Target 94-98% for most, and 88-92% where there is CO₂ retention risk.
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