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ABG Interpretation

PiO₂ / FiO₂ Ratio

March 4th, 2023


The PaO₂ on an arterial blood is only relevant for assessing for hypoxia when the patient is on room air.  If they are receiving supplemental oxygen this will artificially increase the PaO₂ which may appear normal.
The PF ratio is an assessment of PaO2₂ taking into account the FiO₂ - correcting for this discrepancy.
PF Ratio =
    • Normal Range

    • >400
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