title: Effectiveness of the Stewart Method in the Evaluation of Blood Gas Parameters.
abstract: OBJECTIVE
  In 1981, Peter A. Stewart published a paper describing his concept for employing Strong Ion Difference. In this study we compared the HCO3 levels and Anion Gap (AG) calculated using the classic method and the Stewart method.
  
  
  METHODS
  Four hundred nine (409) arterial blood gases of 90 patients were collected retrospectively. Some were obtained from the same patients in different times and conditions. All blood samples were evaluated using the same device (ABL 800 Blood Gas Analyzer). HCO3 level and AG were calculated using the Stewart method via the website AcidBase.org. HCO3 levels, AG and strong ion difference (SID) were calculated using the Stewart method, incorporating the parameters of age, serum lactate, glucose, sodium, and pH, etc.
  
  
  RESULTS
  According to classic method, the levels of HCO3 and AG were 22.4±7.2 mEq/L and 20.1±4.1 mEq/L respectively. According to Stewart method, the levels of HCO3 and AG were 22.6±7.4 and 19.9±4.5 mEq/L respectively.
  
  
  CONCLUSIONS
  There was strong correlation between the classic method and the Stewart method for calculating HCO3 and AG. The Stewart method may be more effective in the evaluation of complex metabolic acidosis.
authors.affiliation: Department of Internal Medicine, Mevki Military Hospital, Ankara, Turkey.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Gezer
authors.affiliation: Department of Internal Medicine, Gulhane Military Medical Academy, Ankara, Turkey.
authors.forename: Fatih
authors.initials: F
authors.lastname: Bulucu
authors.affiliation: Department of Gastroenterology, Gulhane Military Medical Academy, Ankara, Turkey.
authors.forename: Kadir
authors.initials: K
authors.lastname: Ozturk
authors.affiliation: Department of Public Health, Gulhane Military Medical Academy, Ankara, Turkey.
authors.forename: Selim
authors.initials: S
authors.lastname: Kilic
authors.affiliation: Department of Emergency Medicine, Gulhane Military Medical Academy, Ankara, Turkey.
authors.forename: Umit
authors.initials: U
authors.lastname: Kaldirim
authors.affiliation: Department of Emergency Medicine, Gulhane Military Medical Academy, Ankara, Turkey.
authors.forename: Yusuf Emrah
authors.initials: YE
authors.lastname: Eyi
keywords: Blood gases; Stewart method