Acid-base disturbance analysis: Comparison of the traditional and Stewart approaches

Hari Kushartono, Antonius H. Pudjiadi, Susetyo Harry Purwanto, Imral Chair, Darlan Darwis, Abdul Latief

Research output: Contribution to journalReview articlepeer-review


Introduction: The new approach to acid-base balance which initially proposed by Stewart in 1978 was success to provide a new insight which more easy to understand what is the cause, the mechanism and the degree of acid-base disturbance. The purpose of the present study was to compare two different methods of analysis acid-base disturbance in patients admitted to Pediatric Intensive Care Unit (PICU). Methods: The study was performed in 43 patients admitted to the pediatric intensive care unit of Cipto Mangunkusumo Hospital, Jakarta. Sodium, potassium, chloride, albumin, lactate and arterial blood gases were measured. All samples were taken from artery in every patient. The anion gap (AG) was calculated using the Narins method (1977), the corrected anion gap (AGcorr) using the Moviat method (2003), the strong ion gap (SIG) using Kellum method (1995) and the base excess unmeasured anions (BEUA) using the Fencl-Stewart method simplified by Story (2003). Results: The presence of unmeasured ions identified by significantly abnormal BEUA was poorly identified by SBE. Of the 43 patients included in the study, 18 (41.9%) had a different interpretation of acid-base balance when the Fencl-Stewart method was used compared to using SBE. There was good correlation between SIG and AG (r = 0.831), and there was excellent correlation between SIG and AGcorr (r = 0.991). Conclusions: In the condition of electrolyte unbalance and hypoalbuminemia the Stewart approach is better than the traditional approach. Nevertheless, the calculation of SIG is more time-consuming, therefore the corrected anion gap (AGcorr) was suggested to use in clinical practice as a combination with SBE.

Original languageEnglish
Pages (from-to)67-76
Number of pages10
JournalCritical Care and Shock
Issue number3
Publication statusPublished - Aug 2007


  • Acid-base
  • Acidosis
  • Anion gap corrected
  • Henderson-Hasselbalch
  • Stewart
  • Strong ion gap


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