An Arterial Blood gas (ABG) is a test that measures the oxygen tension (PaO2), carbon dioxide tension (PaCO2), acidity (pH), oxyhaemoglobin saturation (SaO2) and bicarbonate concentration (HCO3) in arterial blood .
The methods for and importance of blood gas testing for pO2 and pCO2 were first described by Van Slyke in the early 1900’s (1)
The term “Blood gas testing” traditionally refers to determining the partial pressures of the physiologically active gases in blood (pO2, pCO2), the blood pH, and the oxygen saturation of haemoglobin (SaO2) (2)
However, current commercially-available instruments are capable of performing haemoglobin quantitation and co-oximetry, as well as measuring electrolytes (sodium, potassium, chloride, ionized calcium and magnesium), glucose, lactate, and creatinine, usually simultaneously (3,4)
The process of analysis and monitoring of arterial blood gas (ABG) is an essential part of diagnosing and managing the oxygenation status and acid–base balance of the high-risk patients intra-operatively, as well as in the care of critically ill patients in the Intensive Care Unit. Disorders of acid–base balance can lead to severe complications in many disease states, and occasionally the abnormality may be so severe as to become a life-threatening risk factor.
Thus, what is commonly referred to as a “blood gas” analysis may include a few or many tests, and may be performed in a central laboratory, at the point of care.
Measurements of blood gas analysis are most accurate when the sample is analyzed immediately. For a variety of reasons, immediate analysis is not always possible.
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