II. Labs: Excess Anion Gap

  1. Calculation: Excess Anion Gap (EAG)
    1. EAG = Anion Gap - 12 meq/L + serum bicarbonate
  2. Interpretation
    1. EAG > 30 mEq/L: Metabolic Alkalosis present
    2. EAG < 23 mEq/L: Non-Anion Gap Metabolic Acidosis

III. Labs: Delta Gap (Bicarbonate Gap)

  1. Calculation: Delta Gap (dG)
    1. dG = dAG/dBicarb
    2. Where delta Anion Gap (dAG) = AG - 12 mEq/L
    3. Where delta bicarb (dBicarb) = Bicarb - 24 mEq/L
  2. Interpretation
    1. dG 1 to 2
      1. Anion Gap Metabolic Acidosis
    2. dG <1 (negative Bicarbonate Gap)
      1. Non-Anion Gap Metabolic Acidosis
      2. Other process responsible for decreased bicarbonate
    3. dG >2 (positive Bicarbonate Gap)
      1. Metabolic Alkalosis is contributing to the acid base status
  3. Further interpretation: dG + bicarbonate
    1. dG + bicarbonate >24 mEq/L: Associated Metabolic Alkalosis
    2. dG + bicarbonate <24 mEq/L: Non-Anion Gap Metabolic Acidosis

IV. References

  1. Yavorsky and Glauser (2023) Crit Dec Emerg Med 37(9): 24-9

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