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Table 3.1

Steps to ABG Interpretation

1. Check the pH>7.45 = Alkalosis
<7.35 = Acidosis
Normal = no imbalance or compensated
2. Check the PaCO2>45 = CO2 retention related to
  • Hypoventilation
  • Increased CO2 productivity
  • Increased physiologic dead space
<35 = CO2 blown off related to
  • Hyperventilation
  • Respiratory alkalosis
  • Compensation for metabolic acidosis
Normal = No imbalance of respiratory component
3. Check the HCO3>26 = Nonvolatile acid lost (HCO3 gained). Indicates
  • Metabolic alkalosis
  • Compensation for respiratory acidosis
<22 = Nonvolatile acid is added (HCO3 lost). Indicates
  • Metabolic acidosis
  • Compensation for respiratory alkalosis
Normal = No imbalance of metabolic component
4. Determine the imbalance
5. Determine if compensation exists