, Volume 35, Issue 8, pp 1377-1382
Date: 15 Apr 2009

Acid–base disorders evaluation in critically ill patients: we can improve our diagnostic ability

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To determine whether Stewart’s approach can improve our ability to diagnose acid–base disorders compared to the traditional model.


This prospective cohort study took place in a university-affiliated hospital during the period of February–May 2007. We recorded clinical data and acid–base variables from one hundred seventy-five patients at intensive care unit admission.


Of the 68 patients with normal standard base excess (SBE) (SBE between −4.9 and +4.9), most (n = 59; 86.8%) had a lower effective strong ion difference (SIDe), and of these, 15 (25.4%) had SIDe < 30 mEq/L. Thus, the evaluation according to Stewart’s method would allow an additional diagnosis of metabolic disorder in 33.7% patients.


The Stewart approach, compared to the traditional evaluation, results in identification of more patients with major acid–base disturbances.