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Arterial Blood Gas (ABG) Interpreter
An Arterial Blood Gas (ABG) analysis measures the acidity (pH) and the levels of oxygen and carbon dioxide in the blood. It is essential for assessing gas exchange efficiency and the body’s acid-base balance.
This calculator helps identify the primary acid-base disorder (Metabolic vs. Respiratory) and determines if the body has compensated for the imbalance.
Blood Gas Values
InputsNormal: 7.35 – 7.45
mmHg (Normal: 35 – 45)
mEq/L (Normal: 22 – 26)
Interpretation
Logic Overview
Step 1: Look at the pH
• pH < 7.35 = Acidemia
• pH > 7.45 = Alkalemia
Step 2: Check the PaCO₂ (Respiratory)
• High PaCO₂ (>45) is Acidic.
• Low PaCO₂ (<35) is Basic (Alkaline).
Step 3: Check the HCO₃⁻ (Metabolic)
• Low HCO₃⁻ (<22) is Acidic.
• High HCO₃⁻ (>26) is Basic (Alkaline).
Step 4: Determine Compensation
The primary disorder matches the pH direction. Compensation occurs when the opposing system moves outside the normal range to normalize the pH.
Clinical References
How to Use This Calculator
Follow these steps to interpret ABG values.
Input pH
Enter the arterial pH (e.g., 7.25).
Input PaCO₂
Enter the partial pressure of carbon dioxide in mmHg.
Input HCO₃⁻
Enter the bicarbonate level in mEq/L.
Frequently Asked Questions
ROME is a mnemonic for the relationship between pH and CO₂: Respiratory Opposite, Metabolic Equal.
No, this calculator provides a basic interpretation of primary disorders and simple compensation. For metabolic acidosis, Winter’s formula should be used separately to check for mixed respiratory disorders.