Blood Gases

From Health Facts
Jump to: navigation, search
Latest Edit: Hector 2014-03-24 (EDT)

See Also Lab Tests

The Blood Gases test, also known as arterial blood gases, PO2, PCO2 or oxygen saturation test, is used to determine if your lungs are functioning sufficiently to exchange oxygen and carbon dioxide when presenting with symptoms of a respiratory problem. It is also used to determine whether there is an imbalance in the amount of oxygen gas (O2) or carbon dioxide gas (CO2) in the blood, or an acid-base imbalance which may indicate a respiratory, metabolic, or kidney disorder.[1], [2]


  • Blood gases are a group of tests that are performed together to measure the pH and the amount of oxygen (O2) and carbon dioxide (CO2) present in a sample of blood.
  • This test is typically ordered if a patient presents with worsening symptoms of an acid/base imbalance, difficulty breathing, or shortness of breath.
  • Blood pH is maintained by the body within a range of 7.35-7.45.
  • Metabolism and the kidneys play an important role in the body's regulation of acids and bases.
  • The process of converting one substance to another for energy produces large amounts of acid, which the kidneys help to eliminate.

Patient Preparation

No preparation is required. However, if a person is on oxygen therapy there may be special instructions prior to the test.

Clinical Implications

High levels indicate:

Low levels indicate:

Associated Tests


  1. Pagana Kathleen D, Pagana Timothy J (2006) Mosby's Manual of Diagnostic and Laboratory Tests, Mosby.
  2. Weatherby Dicken, Ferguson Scott (2002) Blood Chemistry and CBC Analysis: Clinical Laboratory Testing from a Functional Perspective, Bear Mountain.