PF Ratio Calculator
Calculate the PaO2/FiO2 ratio to assess the severity of lung injury or Acute Respiratory Distress Syndrome (ARDS).
Complete User Guide
Step 1: Enter the arterial partial pressure of oxygen (PaO2) from an ABG report in mmHg.
Step 2: Enter the fraction of inspired oxygen (FiO2) as a percentage (e.g., 21 for room air).
Step 3: Click 'Calculate' to see the P/F ratio and the ARDS severity classification based on the Berlin criteria.
The Mathematical Formula
P/F Ratio = PaO2 (mmHg) / FiO2 (Decimal)
The P/F ratio is calculated as: PaO2 / (FiO2 / 100).
A normal ratio is >400. According to the Berlin criteria (with PEEP ≥5 cmH2O): - Mild ARDS: 201 – 300 - Moderate ARDS: 101 – 200 - Severe ARDS: ≤ 100
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