Stewart’s approach for acid-base disorders: Does the strong ion difference and effects have an impact on intensive care unit mortality?

• Published in: Turk Yogun bakim Dernegi Dergisi Vol. 21; no. 1; pp. 25 - 32
• Main Authors: Tontu,Furkan, Aşar,Sinan, Ören Bilgin,Beyza, Yıldız,Güneş Özlem
• Format: Journal Article
• Language: English
• Published: Türk Yoğun Bakım Derneği 01-03-2023; Galenos Yayinevi
• Subjects: acid-base; base excess; chloride; intensive care unit; mortality; sodium; strong ion difference; Tıp; İstanbul; strong ion difference; sodyum; baz açığı; klorür; mortalite; sodium; Asit-baz; mortality; chloride; yoğun bakım ünitesi; intensive care unit; base excess; güçlü iyon farkı; base
• ISSN: 2146-6416; 2147-267X
• DOI: 10.4274/tybd.galenos.2022.83007

Objective: The diagnosis and treatment of electrolyte and acid-base imbalances
in intensive care unit (ICU) patients have critical importance. The value of Stewart’s approach
in revealing acid-base disorders is known. There are parameters defined according to this
approach. This study investigates the impact of the chloride effect (ClEffect), sodium effect
(NaEffect), sodium-chloride effect (Na-ClEffect), strong ion difference (SIDnl) and Cl/Na ratio values
calculated according to Stewart’s approach on ICU mortality.
Materials and Methods: Two thousand patients whose Na, Cl, K, standard base excess (SBE),
pH values were recorded and SIDnl, ClEffect, NaEffect, Na-ClEffect, Acute Physiology Assessment
and Chronic Health Evaluation-II (APACHE-II) and Sequential Organ Failure Assessment (SOFA)
scores calculated are included in this study. ClEffect, NaEffect, Na-ClEffect, SIDnl, Cl/Na ratio values were
evaluated with a multivariable logistic regression model in terms of ICU mortality.
Results: Abnormal ranges of SIDnl (SIDnl <30 or SIDnl ≥43) were significantly increased in nonsurvivors
than survivors (p=0.026). ClEffect, NaEffect, Na-ClEffect, Cl/Na ratio and their percentages of
abnormal ranges were similar between survivor and non-survivor patients.In the multivariate logistic
regression model, the likelihood of mortality was 3.5-fold (2.9-4.3), 1.7-fold (1.4-2.1) and 1.2-fold
(1.0-1.5) increased by APACHE-II ≥26, SOFA >7, and SIDnl <30 or SIDnl ≥43 (p<0.001, p<0.001,
p=0.041, respectively).
Conclusion: SIDnl is associated with ICU mortality, but pH, SBE, ClEffect, NaEffect, Na-ClEffect and Cl/
Na ratio is not. SIDnl is one of the independent variables of Stewart’s approach and is a valuable
parameter in blood gas evaluations.