How to Interpret Blood Gas Results
An arterial blood gas (ABG) is a blood test that involves drawing blood from an artery. It normally uses the radial artery near the wrist but it may also use the femoral artery near the groin. An ABG measures the concentration of various gases that are dissolved in the blood such as oxygen, carbon dioxide, hydrogen and bicarbonate.
Instructions
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Examine the partial pressure of oxygen (PaO2) in the blood. The normal PaO2 range is between 80 and 100 mm of mercury (mmHg). A PaO2 below this range indicates the patient isn't breathing properly and will require supplemental oxygen at a level below 60 mmHg. A patient with a level below 26 mmHg is in danger of dying and requires immediate oxygen.
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2
Look at the partial pressure of carbon dioxide (PaCO2) in the blood. The normal range for the PaCO2 level is from 35 to 45 mmHg and indicates the patient's degree of ventilation. A high PaCO2 value is known as respiratory acidosis and indicates underventilation. A low PaCO2 is called respiratory alkalosis and indicates overventilation.
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3
Interpret the concentration of hydrogen ions (H+). This value ranges between 35 and 45 nanomoles per liter (nmol/l), and corresponds to a pH range of 7.35 to 7.45. A pH below this range is defined as acidosis and a pH above this range is defined as alkalemic.
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Inspect the bicarbonate (HCO3-) value. The HC03- level should remain between 22 and 26 millimoles per liter (mmol/l). A high value indicates metabolic alkalosis and a low value indicates metabolic acidosis. These conditions are typically caused by a metabolic problem. An abnormal pH level can also indicate a respiratory problem where the kidneys are attempting to normalize the pH.
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