NCLEX-PN

Setting

Reason for ordering an ABG test

Emergency medicine

To assess the respiratory status of critically ill or injured clients

Anesthesiology

To monitor the respiratory status of clients during and after surgery

Pulmonology

To diagnose and manage lung diseases

Cardiology

To assess the heart's ability to pump oxygen-rich blood to the body

Critical care

To monitor the respiratory status and overall health of critically ill client

Interpreting ABG Results The normal value ranges may vary slightly from lab to lab. In general, normal values at sea level include: ●​ pH: 7.35-7.45. ●​ Partial pressure of oxygen (PaO 2 ): 75 to 100 millimeters of mercury (mmHg).

●​ Partial pressure of carbon dioxide (PaCO 2 ): 35 to 45 mmHg. ●​ Bicarbonate (HCO 3 ): 22 to 26 milliequivalents per liter (mEq/L). ●​ Oxygen saturation (O 2 Sat or SaO 2 ): 95 to 100%.

The first step in interpreting an arterial blood gas (ABG) test is to assess the client's pH level . A normal pH level is between 7.35 and 7.45. If a client's pH is below 7.35, they are said to be in acidosis. Acidosis means that there is too much acid in the blood. If a client's pH is above 7.45, they are said to be in alkalosis. Alkalosis means that there is too much base in the blood. Even if a client's pH level is within the normal range, they may still have acidosis or alkalosis because the body can compensate for changes in pH by adjusting the levels of carbon dioxide and bicarbonate in the blood. The next step is to examine the PaCO 2 level that represents the amount of carbon dioxide dissolved in the blood. When the lungs are working properly, they remove carbon dioxide from the blood. If the lungs are not working properly, the PaCO 2 level will rise. This is called respiratory acidosis. However, PaCO 2 levels can also be affected by the metabolic system . For example, if the kidneys are not working properly, they may not be able to remove excess acid from the blood leading to metabolic acidosis, which can also cause the PaCO 2 level to rise. In combination with the HCO 3 level , the nurse can fully comprehend the blood gas. HCO 3 is a measure of the bicarbonate level in the blood that helps to neutralize acid in the blood. HCO 3 levels are primarily influenced by the metabolic system. When the kidneys and other metabolic processes are not working properly, the HCO 3 level may rise or fall. By examining both the PaCO 2 and HCO 3 levels, the nurse can determine whether the changes in the blood gas are due to the respiratory system or metabolically driven. This information is essential for diagnosing and treating acid-base balance disorders.

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