Blood gases

Arterial blood gas test
Medical diagnostics
MeSH	D001784
MedlinePlus	003855
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An arterial blood gas test (ABG) is a blood gas test of blood taken from an artery that measures the amounts of certain gases (such as oxygen and carbon dioxide) dissolved in arterial blood. An ABG test usually involves a radial artery puncture using a thin needle and syringe and drawing a small volume of blood, but sometimes the femoral artery in the groin or another site is used. The blood can also be drawn from an arterial catheter. An ABG test measures the blood gas tension values of the arterial partial pressure of oxygen, and the arterial partial pressure of carbon dioxide, and the blood's pH. In addition, the arterial oxygen saturation can be determined. Such information is vital when caring for patients with critical illness or respiratory disease. Therefore, the ABG test is one of the most common tests performed on patients in intensive care units. In other levels of care, pulse oximetry plus transcutaneous carbon dioxide measurement is an alternative method of obtaining similar information less invasively.

A blood gas test can also measure the level of bicarbonate in the blood. Many blood gas analyzers will also report concentrations of lactate, hemoglobin, several electrolytes, oxyhemoglobin, carboxyhemoglobin and methemoglobin. ABG testing is mainly used in pulmonology and critical care medicine to determine gas exchange which reflect gas exchange across the alveolar-capillary membrane. ABG testing also has a variety of applications in other areas of medicine. Combinations of disorders can be complex and difficult to interpret, so calculators,nomograms, and rules of thumb are commonly used.

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