ABG analysis provides critical information about lung function and the body’s acid–base balance.

It evaluates how well oxygen is being transferred into blood and how effectively carbon dioxide is being removed.

Clinical uses include:

Diagnosing respiratory disorders (e.g., COPD, asthma, pneumonia).

Assessing metabolic conditions (e.g., diabetic ketoacidosis, renal failure).

Monitoring patients on ventilators or oxygen therapy.

Evaluating severity of critical illness (shock, sepsis).

The test is performed using a sample of arterial blood, usually from the radial artery.

Analytes:

pH: Indicates acid–base status.

PaO₂ (Partial pressure of oxygen): Reflects oxygenation.

PaCO₂ (Partial pressure of carbon dioxide): Reflects ventilation.

HCO₃⁻ (Bicarbonate): Indicates metabolic component of acid–base balance.

O₂ Saturation: Percentage of hemoglobin saturated with oxygen.

Normal Ranges:

pH: 7.35 – 7.45

PaO₂: 75 – 100 mmHg

PaCO₂: 35 – 45 mmHg

HCO₃⁻: 22 – 26 mmol/L

O₂ Saturation: 95 – 100%

Abnormal Findings:

Respiratory acidosis/alkalosis: Caused by abnormal PaCO₂.

Metabolic acidosis/alkalosis: Caused by abnormal HCO₃⁻.

Hypoxemia: Low PaO₂ or O₂ saturation.

Clinical Use:

Provides rapid assessment of respiratory and metabolic status.

Guides treatment in critical care and emergency settings.

Helps monitor response to oxygen therapy or mechanical ventilation.