AG = Na - (Cl  +  HCO3)
Normal Anion<unk>  = 12+/-4 (8-16)
12-20 mEq/L when including K+
Primary acidosis if pH <7.38
HCO3 <24 = metabolic acidosis
Always determine if there is another acid/base process occurring
Primary respiratory acidosis if pCO2 > pCO2expected
Primary respiratory alkalosis if pCO2 < pCO2expected
use Winter's formula: PCO2 (expected) = (1.5 x [HCO3–] + 8) ± 2
In acute setting PCO2 should fall by 1 mmHg for every 1 mEq fall in HCO3
Concurrent metabolic alkalosis if delta-delta > 28
Delta-Delta = (AG - 12) + HCO3
Primary respiratory acidosis if pCO2 > pCO2expected
Primary respiratory alkalosis if pCO2 < pCO2expected
use Winter's formula: PCO2 (expected) = (1.5 x [HCO3–] + 8) ± 2
In acute setting PCO2 should fall by 1 mmHg for every 1 mEq fall in HCO3
Concurrent metabolic alkalosis if delta-delta > 28
Delta-Delta = (AG - 12) + HCO3
use Winter's formula: PCO2 (expected) = (1.5 x [HCO3–] + 8) ± 2
In acute setting PCO2 should fall by 1 mmHg for every 1 mEq fall in HCO3
Anion gap acidosis
Lactic acidosis
Non anion gap acidosis
Sepsis, shock, liver disease, CO, CN, metformin, methemoglobin
Metabolic alkalosis
Short bowel syndrome
Metabolic acidosis
Propylene glycol infusions for lorazepam and phenobarbital