# Blood Gas Acid-Base Interpretation (AG / ΔAG)

Complete ABG analysis: pH, primary disorder, compensation (Winter's formula), anion gap ± albumin correction, delta ratio for mixed disorder detection. Derived from Emmett 2016, Kraut 2007, Rastegar 2007, LITFL, MDCalc, and Adrogué 1998. Not medical advice.

> Canonical page: https://elysiatools.com/en/tools/blood-gas-anion-gap

- **Category:** Health

- **Keywords:** blood gas, abg, acid base, anion gap, delta delta, delta ratio, winters formula, metabolic acidosis, mixed acid base disorder, hagma, lactic acidosis, dka, critical care, nephrology

## Overview

Blood Gas Acid-Base Interpretation analyzes arterial pH, PaCO₂, HCO₃⁻, sodium, and chloride to identify the primary acid-base disorder, assess compensation with Winter’s formula, calculate the anion gap, and use the delta ratio to flag possible mixed disorders. Albumin can be added for anion gap correction. This tool is not medical advice.

## Inputs

- **pH** (number): Arterial blood pH.
- **PaCO₂ (mmHg)** (number): Arterial CO₂ partial pressure (mmHg).
- **HCO₃⁻ (mmol/L)** (number): Bicarbonate (mmol/L) from ABG or serum.
- **Sodium Na⁺ (mmol/L)** (number): Serum sodium (mmol/L).
- **Chloride Cl⁻ (mmol/L)** (number): Serum chloride (mmol/L).
- **Albumin (g/dL, optional)** (number): Serum albumin (g/dL) for AG correction. Leave blank if unavailable.
- **Decimal Places** (number)

## When to use

- Interpret an arterial blood gas together with basic electrolyte values.
- Check whether respiratory compensation is appropriate for metabolic acidosis.
- Assess for high anion gap metabolic acidosis and possible mixed acid-base disorders.

## How it works

- Enter pH, PaCO₂, HCO₃⁻, sodium, and chloride; optionally enter albumin for anion gap correction.
- The tool classifies pH and identifies the primary metabolic or respiratory disorder.
- For metabolic acidosis, it compares measured PaCO₂ with the expected value from Winter’s formula.
- It calculates the anion gap and delta ratio, then returns a structured JSON interpretation.

## Use cases

- Bedside review of acid-base status in critical care and emergency settings.
- Evaluation of suspected lactic acidosis or diabetic ketoacidosis alongside clinical findings.
- Nephrology teaching and case review involving anion gap and mixed acid-base disorders.

## Frequently asked questions

### What inputs are required?

Enter pH, PaCO₂, HCO₃⁻, sodium, and chloride. Albumin is optional.

### What is the anion gap formula?

The tool calculates anion gap as Na⁺ − Cl⁻ − HCO₃⁻.

### What does Winter’s formula assess?

It estimates the expected PaCO₂ during metabolic acidosis to assess respiratory compensation.

### What does the delta ratio indicate?

The delta ratio helps distinguish a relatively pure high anion gap metabolic acidosis from possible mixed metabolic disorders.

### Can albumin be left blank?

Yes. Albumin is optional and can be omitted when it is unavailable.

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