1. What is the SpO2/FiO2 Ratio?

The SpO2/FiO2 ratio is a simple calculation used to estimate the oxygenation status of a patient. It provides an approximation of the PaO2/FiO2 ratio, which is a key indicator in assessing respiratory function and severity of lung disease.

2. How Does the Calculator Work?

The calculator uses the SpO2/FiO2 ratio formula:

Where:

• \( SpO_2 \) — Peripheral oxygen saturation (%)
• \( FiO_2 \) — Fraction of inspired oxygen (unitless)

Explanation: This ratio provides a non-invasive estimate of oxygenation status, particularly useful in clinical settings where arterial blood gas measurements are not readily available.

3. Importance of SpO2/FiO2 Ratio

Details: The SpO2/FiO2 ratio is valuable for quickly assessing respiratory function, monitoring patients with respiratory conditions, and helping to guide treatment decisions in critical care settings.

4. Using the Calculator

Tips: Enter SpO2 as a percentage (0-100%) and FiO2 as a decimal between 0.21 (room air) and 1.0 (100% oxygen). Both values must be valid positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: How does SpO2/FiO2 ratio relate to PaO2/FiO2 ratio?
A: The SpO2/FiO2 ratio provides a non-invasive estimate of the PaO2/FiO2 ratio, which is a more direct measure of oxygenation but requires arterial blood sampling.

Q2: What are typical SpO2/FiO2 ratio values?
A: Normal values are typically above 400, while values below 300 may indicate mild hypoxemia, and values below 200 suggest severe respiratory impairment.

Q3: When is this ratio most useful?
A: This ratio is particularly valuable in emergency departments, ICUs, and other settings where rapid assessment of oxygenation status is needed without arterial blood gas analysis.

Q4: Are there limitations to this calculation?
A: The ratio may be less accurate in patients with poor peripheral perfusion, anemia, or carbon monoxide poisoning, as these can affect SpO2 readings.

Q5: Can this ratio be used for all patients?
A: While useful for many patients, clinical judgment should always be used, and arterial blood gas measurements should be obtained when precise oxygenation assessment is critical.