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

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.