Mixed primary acid-base disorders

HCO₃⁻

PaCO₂

pH

Example

Metabolic acidosis +
respiratory acidosis

↓

↑

Very low

Sepsis (lactic acidosis)
with respiratory failure

Metabolic alkalosis +
respiratory alkalosis

↑

↓

Very high

Hyperemesis gravidarum &
hyperventilation of pregnancy

Metabolic acidosis +
respiratory alkalosis

↓

↓

Near normal

Salicylate toxicity

Metabolic alkalosis +
respiratory acidosis

↑

↑

Near normal

Overdiuresed heart failure
& underlying COPD

Metabolic acidosis +

metabolic alkalosis

↔

↔

Near normal

Diabetic ketoacidosis
with severe vomiting

COPD = chronic obstructive pulmonary disease.