Specimen Name Result Units Range

ABG pH 7.09 (7.36-7.44)
PaO2 85 mmHg (70-100)
PaCO2 21 mmHg (35-45)
HCO3- 6 mmol/L (21-26)

No History

What is the acid-base disorder?


Metabolic Acidosis - Partially Compensated
  • pH : acidaemia
  • HCO3- : metabolic
  • PCO2 : should be 10-15 mmHg, therefore respiratory component
  • PO2 + 1.25*PCO2 ≈ 110 : A-a gradient > 40 mmHg

 

ABG Correction Factors

  1. Metabolic Acidosis:
    • PCO2 : last 2 digits of pH ≥ 7.10
    • HCO3- : for each 10 mmHg fall → ↓ PCO212 mmHg
  2. Metabolic Alkalosis:
    • PCO2 : last 2 digits of pH ≤ 7.60
    • HCO3- : for each 10 mmHg rise → ↑ PCO27 mmHg
    • *least well compensated due to hypoxaemia 2° hypoventilation
  3. Respiratory Acidosis:
    • Acute : for each 10 mmHg PCO2 rise → ↑ HCO3-1-2 mmol/L
    • Chronic : for each 10 mmHg PCO2 rise → ↑ HCO3-4 mmol/L
  4. Respiratory Alkalosis:
    • PCO2 : for each 10 mmHg fall → ↓ HCO3-2.5 mmol/L