Calculated PaCO2

• Calculated PaCO2 in Respiratory Conditions
      A    Increase PaCO2 by 10 mmHg
              1    Acute Respiratory Acidosis: decreases pH 0.08
              2    Chronic Respiratory Acidosis: decreases pH 0.03
      B    Decrease PaCO2 by 10 mmHg
              1    Acute Respiratory Alkalosis: increases pH 0.08
              2    Chronic Respiratory Alkalosis: increases pH 0.03
  

   

   

• Calculated PaCO2 in Metabolic Conditions
      A    Metabolic Acidosis with expected compensation
                  1    PaCO2 = 1.5 x HCO3 + 8 (+/- 2)
      B    Metabolic Alkalosis with expected compensation
                  1    PaCO2 = 0.7 x HCO3 + 20 (+/- 1.5)
  

   

   

• Interpretation: Elevated Anion Gap Metabolic Acidosis
          A    Measured PaCO2 > Calculated PaCO2
                  1    Metabolic Acidosis with Respiratory Acidosis
          B    Measured PaCO2 < Calculated PaCO2
                  1    Metabolic Acidosis with Respiratory Alkalosis