P/F Ratio

Calculate PaO2/FiO2 ratio for oxygenation assessment and ARDS classification.

Oxygenation Parameters

mmHg
Partial pressure of arterial oxygen from ABG. Normal: 80-100 mmHg on room air.
%
Fraction of inspired O2 as percentage. Room air = 21%, Nasal cannula ~24-44%, Face mask 35-60%.

Quick FiO2 Reference:

  • • Room air: 21%
  • • NC 1-6L: 24-44%
  • • Simple mask: 35-50%
  • • Non-rebreather: 60-80%
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P/F Ratio

0

ARDS Berlin Criteria

P/F > 400Normal
P/F 300-400Mild Hypoxemia
P/F 200-300Mild ARDS
P/F 100-200Moderate ARDS
P/F < 100Severe ARDS
ARDS Diagnosis Requires: Bilateral infiltrates on CXR, not fully explained by cardiac failure, with PEEP ≥5 cmH2O.

Formula

P/F Ratio = PaO2 / FiO2

= 80 / 0.40 = 0

Frequently Asked Questions
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