What was the calculated anion gap in the ABG case?

What was the calculated anion gap in the ABG case?

• A. 8
• B. 14
• C. 20
• D. 28

Answer: (B)

Anion gap is a quick way to assess metabolic acidosis by identifying unmeasured anions. It is calculated as the difference between measured cations and measured anions: Na minus (Cl plus HCO3). In this ABG case, the values are sodium 140 mEq/L, chloride 100 mEq/L, and bicarbonate 26 mEq/L. So the gap is 140 − (100 + 26) = 14 mEq/L. Therefore, the calculated anion gap is 14 mEq/L. This is mildly elevated above the typical normal range of about 8–12 mEq/L, pointing to a high anion gap metabolic acidosis. In the perioperative setting, causes often include lactate accumulation from tissue hypoperfusion or hypoxia, among others, which would raise the unmeasured anions contributing to the gap.

Anion gap is a quick way to assess metabolic acidosis by identifying unmeasured anions. It is calculated as the difference between measured cations and measured anions: Na minus (Cl plus HCO3).

In this ABG case, the values are sodium 140 mEq/L, chloride 100 mEq/L, and bicarbonate 26 mEq/L. So the gap is 140 − (100 + 26) = 14 mEq/L.

Therefore, the calculated anion gap is 14 mEq/L. This is mildly elevated above the typical normal range of about 8–12 mEq/L, pointing to a high anion gap metabolic acidosis. In the perioperative setting, causes often include lactate accumulation from tissue hypoperfusion or hypoxia, among others, which would raise the unmeasured anions contributing to the gap.