When an acid (AH) accumulates in the blood, the hydrogen ion [H+] is buffered by HCO3- and the retained acid anion [A-] contributes to unmeasured anions
, raising the AG.
Strong ion gap: a methodology for exploring unmeasured anions.
Estimating unmeasured anions in critically ill patients: anion gap, base deficit and strong ion gap.
Unmeasured anions identified by the Fencl-Stewart method predict mortality better than base excess, anion gap and lactate in patients in the pediatric intensive care unit.
The anion gap is commonly used in clinical practice, especially in critically ill patients, as an approximation of the difference between the concentration of unmeasured anions
and unmeasured cations in plasma.
The SIG is superior to the anion gap for this purpose, since it retains sensitivity to unmeasured anions
despite fluctuating albumin and phosphate concentrations, simply because the [A.
An increase in the mean strong ion gap of > 10 mEq/l at bypass initiation (T2) signalled a surge of unmeasured anions.
In other words, unmeasured anions were still present but at reduced concentration.
It is noteworthy that Liskaser and colleagues also detected surges of unmeasured anions during bypass on Plasma-Lyte 148 prime (2).