Metabolic Acidosis and Respiratory Acidosis

Occurs in:

  • Respiratory compromise with hypoxia (producing lactic acid from cellular anaerobic glycolysis)

ABG hallmark: the pCO2 will be raised and the HCO3 reduced

For example, in acute hypoxaemia, secondary to pulmonary embolus with poor tissue perfusion:

  • pH   7.22
  • pCO2   8.4 kPa
  • pO2   8.0 kPa
  • bicarbonate  14.1 mmol/L
  • lactate   3.3 mmol/L


In a simple disorder, it would be expected that the CO2 and bicarbonate would move in the same direction, but in this case, the bicarbonate is low from the metabolic disorder and the CO2 is high from the respiratory component.