<unk>  <unk> , corrected denoted with a capital "I", is the molar or volumetric<unk>  of<unk>  in the inhaled gas. Medical patients experiencing difficulty breathing are provided with<unk> -enriched air, which means a higher-than-atmospheric<unk> . Natural air includes 21%<unk> , which is equivalent to<unk>  of 0.21.<unk> -enriched air has a higher<unk>  than 0.21; up to 1.00 which means 100%<unk> .<unk>  is typically maintained below 0.5 even with mechanical ventilation, to avoid<unk>  toxicity, but there are applications when up to 100% is routinely used. Often used in medicine, the<unk>  is used to represent the percentage of<unk>  participating in gas-exchange. If the barometric pressure changes, the<unk>  may remain constant while the partial pressure of<unk>  changes with the change in barometric pressure.
Fraction of inspired oxygen
Oxygen saturation 
Oxygen saturation
Minute ventilation
Oxygenation index
Pulse oximetry
Mandatory minute ventilation
Respiratory rate