Physiologic Effects of Acidosis


Respiratory Effects
  • Hyperventilation ( Kussmaul respirations)
  • Shift of oxyhaemoglobin dissociation curve to the right
  • Decreases 2,3 DPG levels in red cells, which opposes the effect above. (shifts the ODC back to the left) This effect occurs after 6 hours of acidemia.
Cardiovascular Effects
  • Depression of myocardial contractility (this effect predominates at pH < 7.2 )
  • Sympathetic over-activity ( tachycardia, vasoconstriction, decreased arrhythmia threshold)
  • Resistance to the effects of catecholamines (occur when acidemia very severe)
  • Peripheral arteriolar vasodilatation
  • Venoconstriction of peripheral veins
  • Vasoconstriction of pulmonary arteries
  • Effects of hyperkalemia on heart
Central Nervous System Effects
  • Cerebral vasodilation leads to an increase in cerebral blood flow and intracranial pressure (occur in acute respiratory acidosis)
  • Very high pCo2 levels will cause central depression
Other Effects
  • Increased bone resorption (chronic metabolic acidosis only)
  • Shift of K+ out of cells causing hyperkalemia (an effect seen particularly in metabolic acidosis and only when caused by non organic acids)
  • Increase in extracellular phosphate concentration