What is a blood gas analysis and how is it performed? What is the purpose of this test?

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The blood gas analysis is a low risk test since the sample of blood required is not large. Usually most tests use samples of blood collected from veins. For the ABG (arterial blood gases) test, the sample of blood is collected from an artery. Through this test several parameters are measured: partial pressure of CO2, partial pressure of oxygen, the pH levels, oxygen levels and saturation, the content of bicarbonate.

The test is performed in order to examine if there exists a problem of lungs or kidneys, such as asthma, chronic obstructive pulmonary disease, or kidney failure. The test is also performed to check the response to the treatment of lung diseases, or to identify an uncontrolled diabetes or a severe infection. The test could also pinpoint the troubles of sleeping or drug overdoses.

The collection of a blood sample from an artery produces more pain than the collection of blood sample from veins, since arteries are protected by nerves and they are located much deeper.

The ABG test itself cannot establish the diagnostic, hence, it is useful when it is accompanied with other tests or examinations. Usually, the ABG test can be relevant when the breathing rate is altered or when the glucose levels high, or in case of a infection, or to monitor the kidneys and lungs of an injured hospitalized patient.

The results of an ABG test can indicate several diseases, such as

- low levels of bicarbonate, partial pressure of CO2 and a pH level less than 7.4 could indicate metabolic acidosis (kidney failure), while a pH level less than 7.4 accompanied by the increased levels of bicarbonate and the partial pressure of CO2 could indicate respiratory acidosis (pneumonia or COPD).

- high levels of bicarbonate, partial pressure of CO2 and a pH level more than 7.4 could indicate a metabolic alkalosis (low blood potassium), while a pH level more than 7.4 accompanied by decreased levels of bicarbonate and a partial pressure of CO2 could indicate respiratory alkalosis (pain, anxiety).


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