Table 4.1-2. Diagnosis of acid-base disorders based on blood gas analysis

Diagnosis

pH

PaCO2

HCO3

Simple acid-base disorders

Respiratory acidosis

  Uncompensateda

N

Partially compensateda

Completely compensated respiratory acidosis or completely compensated metabolic alkalosisb

N

Metabolic acidosis

  Uncompensated

N

Partially compensated

Completely compensated metabolic acidosis or completely compensated respiratory alkalosisb

N

Respiratory alkalosis

  Uncompensateda

N

 

Partially compensateda

Metabolic alkalosis

  Uncompensated

N

 

Partially compensated

Mixed acid-base disordersc

Metabolic and respiratory acidosis

Metabolic and respiratory alkalosis

a In patients with respiratory disturbances, changes in pH and in PaCO2 develop in opposite directions.

b These entities may be differentiated only on the basis of a complete clinical presentation.

c In mixed acid-base disorders, changes in PaCO2 and in [HCO3] develop in opposite directions.

↑, increased; ↓, decreased; N, normal; PaCO2, partial pressure of carbon dioxide in arterial blood.