The use of sodium-chloride difference and chloride-sodium ratio as strong ion difference surrogates in the evaluation of metabolic acidosis in critically ill patients.

Purpose: Inorganic apparent strong ion difference (SIDai) improves chloride-associated acidosis recognition in dysnatremic patients. We investigated whether the difference between sodium and chloride (Na(+)-Cl(-)) or the ratio between chloride and sodium (Cl(-)/Na(+)) could be used as SIDai surrogates in mixed and dysnatremic patients.

Patients And Methods: Two arterial blood samples were collected from 128 patients.