How to interpret arterial blood gases?

 How to interpret arterial blood gases?
• "6 Easy Steps" to Accurately interpret arterial blood gases

1. The first step look at PH. Normal blood PH range (7.35_7.45) if PH falls below 7.35 it is acidic. If blood pH rises above 7.45, it is alkalotic.

2. The second step is to examine the PCO2 Normal pCO2 levels are 35-45mmHg. Below 35 is alkalotic, above 45 is acidic.


3. The third step is to look at the HCO3 level. A normal HCO3 level is 22-26 mEq/L. If the HCO3 is below 22 is acidotic. If the HCO3 is above 26, is alkalotic.

4. Next Match either the PCO2 or the HCO3 with the PH to determine the acid –base disorder.
For example if the pH is acidotic, and the CO2 is acidotic, then the acid-base disturbance is being caused by the respiratory system. . However, if the pH is acidotic, and the HCO3 is acidotic then the acid-base disturbance is being caused by the metabolic (or renal) system.

5. Fifth, Dose either the CO2 or HCO3 go in opposite direction of the PH? If so, there is compensation by that system.
For example, the pH is acidotic, the CO2 is acidotic, and the HCO3 is alkalotic. The CO2 matches the pH making the primary acid-base disorder respiratory acidosis. The HCO3 is opposite of the pH and would be evidence of compensation from the metabolic system.

6. Finally, evaluate the PaO2 and O2 sat. pO2 (80-100 ),O2 Sat. (95-100% )If they are below limits there is evidence of hypoxemia