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Arterial Blood Gas

Arterial blood gas analysis is ordered to precisely determine blood oxygen level, oxygen saturation, carbon dioxide levels, and pH. The test is obtained by puncturing an artery - frequently the radial artery in the wrist area. Information from this test is helpful in determining the adequacy of the lungs in transferring oxygen from the air to the bloodstream as well as transferring carbon dioxide from the blood stream to the air during exhalation.

The blood oxygen level (known as oxygen tension) shows the amount of oxygen freely dissolved in the blood. The normal value is usually greater than approximately 70 mm Hg.

The blood oxygen saturation shows the percentage of the hemoglobin in the blood cells occupied by oxygen. The normal value is usually greater than approximately 92%.

The blood carbon dioxide level shows the amount of carbon dioxide freely dissolved in the blood. Carbon dioxide is a waste product of human metabolism and may accumulate in the blood stream in patients with poor lung function. The normal value is usually between 36 and 44 mm Hg.

The blood pH is a global measurement of the balance of blood acids and bases. The healthy human body usually regulates this value tightly with a normal range between 7.36 and 7.44. Pulmonary and metabolic disorders may create abnormalities in blood pH.

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