ABG ANALYSIS TOOL

Enter ABG values

Normal Reference Range :
• pH 7.35–7.45 • PaCO₂ 35–45 mmHg • HCO₃⁻ 22–26 mmol/L

PaCO₂ (mmHg)

HCO₃⁻ (mmol/L)

PaO₂ (mmHg)

FiO₂ (as decimal) 0.21 in room air

Age (yrs)

Na⁺ (mmol/L)

Cl⁻ (mmol/L)

Disclaimer : The ABG Interpret Tool is a decision support tool for healthcare professionals. It should never replace overall comprehensive patient assessment or the clinical judgment of a doctor anyplace and anytime.

Result

of ABG

pH Status

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Primary Disorder

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Compensation

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Anion Gap & Δ-gap

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Oxygenation & A–a

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P/F ratio (PaO₂/FiO₂)

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Final ABG Interpretation

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HOW TO INTERPRET ABG

1) pH -> direction (acidemia/alkalemia).
2) Use ROME to identify primary disorder.
3) Use Winter's formula for metabolic acidosis.
4) For respiratory disorders compare acute vs chronic HCO₃ change.
5) Calculate AG & Δ-gap to identify mixed metabolic processes.
6) Assess oxygenation A–a gradient and
7) P/F ratio for ARDS classification.
8) FiO₂ defaults to 0.21 (in room air) FiO2 varies if patients are on O₂, NRBM, HFNC or in Ventilator.So put Fio2 accordingly

➟ BICARBONATE low = ACIDOSIS
➟ BICARBONATE high = ALKALOSIS

➟ PaCo2 High = ACIDOSIS : Hypoventilation
➟ PaCo2 Low = ALKALOSIS : Hyperventilation

Parameter	Interpretation
HCO₃⁻ Low ↓	Metabolic Acidosis Examples: DKA, Renal Failure, Lactic Acidosis, Diarrhea.
HCO₃⁻ High ↑	Metabolic Alkalosis Examples: Severe Vomiting, Gastric Suction, Diuretic use.
PaCO₂ High ↑	Respiratory Acidosis Examples: COPD, Opioid Overdose, Hypoventilation.
PaCO₂ Low ↓	Respiratory Alkalosis Examples: Anxiety, Hyperventilation, Fever, High Altitude.

Parameter	Level	Interpretation
HCO₃⁻	Low ↓	Metabolic Acidosis
HCO₃⁻	High ↑	Metabolic Alkalosis
PaCO₂	High ↑	Respiratory Acidosis
PaCO₂	Low ↓	Respiratory Alkalosis

Acid-Base Compensation Summary

If Primary is...	Body Will...
Met. Acidosis (↓HCO₃)	Blow off CO₂ Hyperventilate (Minutes)
Met. Alkalosis (↑HCO₃)	Retain CO₂ Hypoventilate (Minutes)
Resp. Acidosis (↑CO₂)	Retain HCO₃ Renal Buffer (SLOW)
Resp. Alkalosis (↓CO₂)	Excrete HCO₃ Renal Buffer (SLOW)

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Please correlate clinically.* Remember, the calculator is for education and quick decision support only; it must always be used alongside professional medical advice from a qualified healthcare provider. This tool is for Doctors use only