Arterial Blood Gas Calculator
The Arterial Blood Gas Calculator estimates acid-base diagnosis and oxygenation status based on pH, PaCO₂, and PaO₂ values. This tool helps healthcare professionals quickly interpret complex blood gas results to identify respiratory or metabolic disorders. Whether you are assessing compensation levels or screening for ARDS severity, this calculator provides instant, reliable clinical insights for faster decision-making.
How Acid-Base Diagnosis and Oxygenation Status Is Calculated
Acid-base diagnosis and oxygenation status determine if a patient has respiratory or metabolic imbalances. This tool uses established clinical equations to verify how the body is responding to illness. First, it compares the pH against normal ranges to identify acidity or alkalinity. Next, it analyzes PaCO₂ and HCO₃⁻ levels to pinpoint the primary cause of the imbalance.
Expected PaCO₂ = (1.5 × HCO₃⁻) + 8 ± 2
A-a Gradient = (FiO₂ × 713) - (PaCO₂ / 0.8) - PaO₂
Where:
- PaCO₂ = Partial pressure of carbon dioxide
- HCO₃⁻ = Bicarbonate
- A-a Gradient = Difference between alveolar and arterial oxygen
- FiO₂ = Fraction of inspired oxygen
- PaO₂ = Partial pressure of oxygen
Then, it applies Winter's Formula to check if compensation is adequate. Finally, it calculates the A-a Gradient to assess oxygen transfer efficiency. This structured approach ensures accurate interpretation for critical care.
What Your Acid-Base Diagnosis and Oxygenation Status Means
Your results reveal the specific type of acid-base imbalance and how well the lungs are oxygenating blood.
Respiratory Acidosis: If the pH is low (under 7.35) and PaCO₂ is high (over 45 mmHg), the lungs are not removing enough CO2. Consider increasing ventilation support to help the patient breathe out excess acid.
Metabolic Acidosis: If the pH is low and HCO₃⁻ is low (under 22 mEq/L), the body has too much acid. You should investigate underlying causes like sepsis or diabetic ketoacidosis.
ARDS Indication: A P/F ratio below 300 suggests acute lung injury, while a ratio under 200 usually indicates ARDS. These patients often need positive pressure ventilation.
Important Note: Always compare the actual values against the expected compensation range. If the numbers do not match, the patient likely has a mixed disorder requiring complex management.
This tool is for educational purposes only and does not replace professional medical advice. Always consult with a qualified healthcare provider before making treatment decisions based on these calculations.
Monitor trends by repeating the ABG test after any clinical intervention to confirm the treatment is working.