An ABG test is used to help check your acid-base balance, diagnose serious problems with your lungs and breathing, diagnose kidney disorders and find out if a treatment is working for the conditions mentioned or any other condition that may affect your acid-base balance.
An arterial blood gas (ABG) test is a blood test that takes a sample from an artery to measure the levels of oxygen and carbon dioxide in the blood. ABG also checks the balance of acids and bases, known as the pH balances, in the blood.
The pH is the concentration of hydrogen ions and determines the acidity or alkalinity of body fluids.
Also known as PaCO2 (partial pressure of carbon dioxide), it shows the adequacy of the gas exchange between the alveoli and the external environment (alveolar ventilation).
HCO3 or bicarbonate ion is an alkaline substance that comprises over half of the total buffer base in the blood.
Interpreting arterial blood gases is useful to understand the degree or severity of abnormalities, whether they are acute or chronic, and if the primary disorder is metabolic or respiratory in origin. Frequently, an ABG test alone can't provide a final diagnosis but will play a part in your diagnosis and treatment. In case your results are not normal, your doctor will likely order more tests to make a diagnosis. Your arterial blood gas test results may show if you're getting enough oxygen, your lungs are exhaling enough carbon dioxide, your kidneys are working properly and if you have a serious infection effecting perfusion to your organs.
The normal ABG values are the following:
| Normal Value | |
|---|---|
| pH | 7.35 - 7.45 |
| PaCO2 | 35 - 45 mmHg |
| PaO2 | 75 - 100 mmHg |
| HCO3 | 22 - 26 mEq/L |
| SaO2 | 94 - 99 % |
| Base Excess | -2 to +2 mmol/L |