title: Impact of chloride and strong ion difference on ICU and hospital mortality in a mixed intensive care population.
abstract: BACKGROUND
  Abnormal chloride levels are commonly observed in critically ill patients, but their clinical relevance remains a matter of debate. We examined the association between abnormal chloremia and ICU and hospital mortality. To further refine findings and integrate them into the ongoing discussion on the detrimental effects of chloride-rich solutions, the impact of strong ion difference (SID) on the same end points was assessed.
  
  
  METHODS
  Retrospective cohort study in an academic tertiary intensive care unit on 8830 adult patients who stayed at least 24 h in the ICU was carried out. Patients admitted after elective cardiac surgery were treated as a separate subgroup (n = 2350). Analyses were performed using multivariable logistic regression. All statistical models were extensively adjusted for confounders, including comorbidity, admission diagnosis, other electrolytes and acid-base parameters.
  
  
  RESULTS
  Severe hyperchloremia (>110 mmol/L), but not low (SID) was significantly associated with increased mortality in the ICU (odds ratio vs. normochloremia 1.81; 95 % CI 1.32-2.50; p < 0.001) and the hospital (odds ratio 1.49; 95 % CI 1.14-1.96; p = 0.003). Hyperchloremia and low (SID) were encountered in the majority of patients admitted after cardiac surgery (in 86.9 and 47.2 %, respectively), but were not negatively associated with mortality.
  
  
  CONCLUSIONS
  In the ICU, hyperchloremia at admission was associated with negative outcome. On the other hand, decreased strong ion difference did not have an impact on mortality, precluding a simple extrapolation of these findings to the ongoing discussion on the detrimental effects of chloride-rich solutions. This notion is fueled by the finding that hyperchloremia after cardiac surgery, frequently encountered and probably fluid-induced, did not seem to be deleterious.
authors.affiliation: Department of Intensive Care Medicine, Antwerp University Hospital, Wilrijkstraat 10, 2650, Edegem, Antwerp, Belgium. niels.vanregenmortel@uza.be.|Department of Intensive Care Medicine, Ziekenhuis Netwerk Antwerpen Campus Stuivenberg, Lange Beeldekensstraat 267, 2060, Antwerp, Belgium. niels.vanregenmortel@uza.be.
authors.forename: Niels
authors.identifier: http://orcid.org/0000-0002-8746-2325
authors.initials: N
authors.lastname: Van Regenmortel
authors.affiliation: Department of Intensive Care Medicine, Antwerp University Hospital, Wilrijkstraat 10, 2650, Edegem, Antwerp, Belgium.
authors.forename: Walter
authors.initials: W
authors.lastname: Verbrugghe
authors.affiliation: Department of Nuclear Medicine, Antwerp University Hospital, Wilrijkstraat 10, 2650, Edegem, Antwerp, Belgium.|Faculty of Medicine and Health Sciences, University of Antwerp, Universiteitsplein 1, 2610, Antwerp, Belgium.
authors.forename: Tim
authors.initials: T
authors.lastname: Van den Wyngaert
authors.affiliation: Department of Intensive Care Medicine, Antwerp University Hospital, Wilrijkstraat 10, 2650, Edegem, Antwerp, Belgium.|Faculty of Medicine and Health Sciences, University of Antwerp, Universiteitsplein 1, 2610, Antwerp, Belgium.
authors.forename: Philippe G
authors.initials: PG
authors.lastname: Jorens
keywords: Balanced solutions; Chloride; Hyperchloremia; Mortality; NaCl 0.9 %; Saline; Strong ion difference