The inspired oxygen concentration (FIO2) for patients receiving oxygen therapy can be calculated from the ventilatory minute volume and the flow rate of pure oxygen.


ventilatory minute volume in liters per minute =

= (respiratory rate in breaths per minute) * (tidal volume in liters per breath)


amount of air breathed =

= (ventilatory minute volume) - (100% oxygen flow rate)


inspired oxygen concentration FIO2 =

= (((amount of air breathed) * 0.21) + (100% oxygen flow rate)) / (ventilatory minute volume)


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