Overview Introduction Simple acid-base disorders have changes in pH PCO2 HCO3− The acid-base nomogram depicts these associated changes for example, in metabolic acidosis there is a decreased pH and HCO3− level, along with a decreased PCO2 (due to respiratory compensation) General principles simple metabolic disorders (e.g., acidosis or alkalosis) have one set of expected values this is because respiratory compensation is immediate simple respiratory disorders (e.g., acidosis or alkalosis) have two set of expected values renal compensation has not occured in acute respiratory disorders renal compensation takes time to occur renal compensation has occured in chronic respiratory disorders blood pH would be expected to be close to normal or normal Acid-Base Disorders Acid-Base Disorder pH PCO2 [HCO3-] Compensatory Response Metabolic acidosis ↓ ↓ ↓ (primary disturbance) Hyperventilation Metabolic alkalosis ↑ ↑ ↑ (primary disturbance) Hypoventilation Respiratory acidosis ↓ ↑ (primary disturbance) ↑ ↑ renal HCO3- reabsorption Respiratory alkalosis ↑ ↓ (primary disturbance) ↓ ↓ renal HCO3- reabsorption