PF Ratio Calculator
Calculate the PaO2/FIO2 ratio (PF ratio) to assess lung function and oxygenation, based on arterial oxygen partial pressure (PaO2) and fraction of inspired oxygen (FIO2).
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Detailed Steps
Visual Representation
Formula
PF Ratio Calculation
The PF ratio is calculated by dividing the arterial oxygen partial pressure (PaO2) by the fraction of inspired oxygen (FIO2):
Clinical Thresholds
| PF Ratio | Interpretation |
|---|---|
| ≥ 400 | Normal (equivalent to PaO2 ≥ 80 mmHg on room air) |
| 300–399 | Mild hypoxemia |
| 200–299 | Moderate ARDS |
| 100–199 | Severe ARDS |
| < 100 | Critical ARDS |
The PF ratio is used to diagnose and assess the severity of acute respiratory distress syndrome (ARDS). Consult a healthcare provider for interpretation and management.
How to Use the PF Ratio Calculator
- Enter the PaO2 value in mmHg (e.g., 80) from an arterial blood gas (ABG) test.
- Enter the FIO2 value as a decimal (e.g., 0.40 for 40% oxygen).
- Choose your preferred display mode (Standard, Step by Step, or Chart).
- Click the “Calculate” button to view the PF ratio.
- Review the results to assess lung function, with clinical thresholds (e.g., ≥400 for normal).
Frequently Asked Questions (FAQs)
What is the PF ratio?
The PF ratio (PaO2/FIO2) measures lung oxygenation by dividing arterial oxygen partial pressure (PaO2) by the fraction of inspired oxygen (FIO2). It’s used to assess acute respiratory distress syndrome (ARDS).
What is a normal PF ratio?
A PF ratio ≥400 is considered normal, equivalent to a PaO2 ≥80 mmHg on room air (FIO2 = 0.21).
How is the PF ratio used in ARDS?
The PF ratio helps diagnose ARDS severity: 200–299 (moderate), 100–199 (severe), <100 (critical). Lower ratios indicate worse lung function.
Where do I get PaO2 and FIO2 values?
PaO2 is obtained from an arterial blood gas (ABG) test. FIO2 is the oxygen concentration delivered to the patient, expressed as a decimal (e.g., 40% = 0.40).
Can I use this calculator for home monitoring?
No, this calculator is for educational purposes and requires clinical data (ABG results). Consult a healthcare provider for accurate diagnosis and treatment.