The normal values of blood gases are partial pressure of 75 to 100 millimeters of mercury for oxygen and 38 to 42 millimeters of mercury for carbon dioxide. The normal arterial blood pH is 7.38 to 7.42, and oxygen saturation is 94 to 100 percent, as stated by MedlinePlus.
Blood gases measure the levels of oxygen and carbon dioxide in the blood and also the acidity of the blood, according to MedlinePlus. During the test, a health care provider usually draws blood from an artery in the patient's arm, wrist or groin. In some cases, the provider may choose to draw blood from a vein.