Statistical & Clinical Analysis
Fencl-Stewart Base Excess Partition Formula: Na-Cl Effect & Hypoalbuminemia Alkalosis
Uncover hidden hyperchloremic acidosis masked by hypoalbuminemic alkalosis in ICU patients using Story, Morimatsu & Bellomo’s simplified Fencl-Stewart Base Excess partition: BE_NaCl = Na - Cl - 38 and BE_Alb = 0.25 * (42 - Albumin_gL).
How severe ICU hypoalbuminemia (+5 mEq/L alkalosis) masks saline-induced hyperchloremic acidosis!
Critically ill ICU patients infused with 0.9% normal saline frequently exhibit a seemingly mild arterial Base Excess (e.g., SBE = -9 mEq/L) that hides TWO opposing acid-base derangements! Building on Vladimir Fencl and Peter Stewart’s physicochemical framework, David A. Story, Hiroshi Morimatsu, and Rinaldo Bellomo (2004, British Journal of Anaesthesia) validated two bedside Base Excess partitions: Sodium-Chloride Effect BE_NaCl = [Na+] - [Cl-] - 38 (mEq/L, normal ≈ 0) and Albumin Weak-Acid Effect BE_Alb = 0.25 * (42 - Albumin_g/L)!
Subtracting BE_NaCl + BE_Alb from measured arterial Standard Base Excess SBE isolates Unmeasured Anions BE_UMA = SBE - BE_NaCl - BE_Alb (lactate, ketones, uremic/toxic anions)! At Na+ = 130 mEq/L, Cl- = 106 mEq/L, and Albumin = 22 g/L (2.2 g/dL), severe hyperchloremic/dilutional acidosis BE_NaCl = 130 - 106 - 38 = -14.0 mEq/L is partially masked by hypoalbuminemic alkalosis BE_Alb = 0.25 * (42 - 22) = +5.00 mEq/L (net explained BE = -9.00 mEq/L)!
| ICU Electrolyte & Albumin Panel | BE_NaCl = Na - Cl - 38 | BE_Alb = 0.25*(42 - Alb_gL) | Combined Na-Cl + Albumin BE |
|---|---|---|---|
| Na=130, Cl=106 mEq/L; Alb=22 g/L | -14.0 mEq/L (Acidifying) | +5.00 mEq/L (Alkalinizing!) | -9.00 mEq/L |
| Balanced Crystalloid: Na=140, Cl=102; Alb=42 | 0.0 mEq/L (Neutral) | 0.00 mEq/L (Normal Albumin) | 0.00 mEq/L |
| Invalid Electrolyte <= 0 | Error Guard | "Invalid ICU Electrolyte Panel" | Physiological Bounds Check |
Fencl-Story Sodium-Chloride Base Excess Effect BE_NaCl = Na - Cl - 38 (mEq/L)
Evaluates strong-ion free-water + chloride acid-base contribution from serum Na+ (B2, mEq/L) and Cl- (B3, mEq/L).
=IF(OR(B2 < 100, B2 > 190, B3 < 60, B3 > 160, B4 <= 0, B4 > 65), "Invalid ICU Electrolyte Panel", ROUND(B2 - B3 - 38, 2))Hypoalbuminemic Weak-Acid Base Excess Effect BE_Alb = 0.25 * (42 - Albumin_gL) & Combined Sum
Computes alkalinizing base-excess offset from serum albumin in g/L (B4; multiply g/dL by 10).
=IF(OR(B2 < 100, B2 > 190, B3 < 60, B3 > 160, B4 <= 0, B4 > 65), "Invalid ICU Electrolyte Panel", ROUND(0.25 * (42 - B4), 2))Try the example
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