Oxygenation Index Calculator
Calculate oxygenation index (OI) and assess lung function in critically ill patients
Calculate Oxygenation Index
Reference: Room air = 21%, Pure oxygen = 100%
Definition: Average pressure throughout the respiratory cycle during mechanical ventilation
Normal Range: 75-100 mmHg on room air (measured via arterial blood gas)
Oxygenation Assessment Results
Formula: OI = (FiO₂ × MAP) / PaO₂
Calculation: (0.000 × 0.0) / 0.0 = 0.00
PaO₂/FiO₂ Ratio: 0.0 / 0.000 = 0
Clinical Interpretation Guide
Oxygenation Index Values:
ARDS Classification:
⚠️ Medical Disclaimer: This calculator is for educational purposes only. Always consult with qualified healthcare professionals for medical decisions. Clinical interpretation should consider the complete clinical picture, not just calculated values.
Example Calculation
ICU Patient Example
Patient: 65-year-old with severe pneumonia on mechanical ventilation
FiO₂: 80% (0.80)
Mean Airway Pressure: 25 cmH₂O
PaO₂: 70 mmHg
Calculation
OI = (FiO₂ × MAP) / PaO₂
OI = (0.80 × 25) / 70
OI = 20 / 70
OI = 0.29
Interpretation: Normal oxygenation (OI < 5)
Parameter Definitions
FiO₂
Fraction of inspired oxygen - percentage or decimal of oxygen in breathed air
MAP
Mean Airway Pressure - average pressure in airways throughout breathing cycle
PaO₂
Partial pressure of oxygen in arterial blood - measured via arterial blood gas
Normal Reference Values
Clinical Tips
Lower OI values indicate better lung function
OI is especially useful in neonatal critical care
High MAP or low PaO₂ increases OI
Trending OI values is more valuable than single measurements
Understanding the Oxygenation Index
What is the Oxygenation Index?
The Oxygenation Index (OI) is a critical care parameter that assesses the lung's ability to transfer oxygen from inhaled air into the blood. It provides a comprehensive measure of oxygenation efficiency by considering three key factors: oxygen concentration, ventilator pressure, and blood oxygen levels.
Clinical Applications
- •Assessment of acute lung injury severity
- •Decision-making for ECMO initiation
- •Monitoring treatment response in ARDS
- •Prognostic indicator in critically ill patients
Formula Explanation
OI = (FiO₂ × MAP) / PaO₂
- Higher OI values indicate worse lung function
- Lower PaO₂ increases OI (worse oxygenation)
- Higher FiO₂ increases OI (more oxygen needed)
- Higher MAP increases OI (more pressure needed)
Critical Values: OI > 40 typically indicates the need for ECMO consideration in appropriate candidates, as conventional mechanical ventilation may be insufficient.
ECMO Decision Making
Extracorporeal Membrane Oxygenation (ECMO) is considered when conventional mechanical ventilation fails to provide adequate oxygenation. The OI helps clinicians make this critical decision:
OI 25-40
Consider ECMO evaluation. Increased monitoring and aggressive management required.
OI 40-60
Strong ECMO candidacy. High mortality risk without intervention.
OI > 60
Urgent ECMO consideration. Conventional ventilation often inadequate.