• NORMAL ABG Values 
    • pH: 7.35 – 7.45
    • CO2: 35 – 45 mEq/L
    • HCO3: 24 – 26 mEq/L
    • PaO2: 80– 100
    • SaO2: >95%
  Compensated Partially Compensated Uncompensated
pH Normal Abnormal Abnormal
PaCO2 Abnormal Abnormal One Normal

One Abnormal

HCO3 Abnormal Abnormal

ABG Interpretation Examples:

The patient’s ABG values are as follows:

  1. pH – 7.32 [abnormal – acidosis]

PaCO2 – 41 mmHg [normal value]

HCO3 – 20 mEq/L [abnormal – low]

         Answer: Uncompensated Metabolic Acidosis

  1. pH – 7.26 [abnormal – acidosis]

PaCO2 – 15 mmHg [abnormal – low – alkalosis]

HCO3 – 7 mEq/L [abnormal – low]

        Answer: Partially Compensated Metabolic Acidosis


*** When all 3 are abnormal values (or partially compensated)
Remember that CO2 is an acid and is HCO3 a base:
Low CO2 = Alkalosis
High HCO3 = Acidosis