title: Admission high serum sodium is not associated with increased intensive care unit mortality risk in respiratory patients.
abstract: BACKGROUND
  Because increased serum osmolarity may be lung protective, we hypothesized that increased mortality associated with increased serum sodium would be ameliorated in critically ill patients with an acute respiratory diagnosis.
  
  
  METHODS
  Data collected within the first 24 hours of intensive care unit (ICU) admission were accessed using ANZICS CORE database. From January 2000 to December 2010, 436,209 patients were assessed. Predefined subgroups including patients with acute respiratory diagnoses were examined. The effect of serum sodium on ICU mortality was assessed with analysis adjusted for illness severity and year of admission. Results are presented as odds ratio (95% confidence interval) referenced against a serum sodium range of 135 to 144.9 mmol/L.
  
  
  RESULTS
  Overall ICU mortality was increased at each extreme of dysnatremia (U-shaped relationship). A similar trend was found in various subgroups, with the exception of patients with respiratory diagnoses where ICU mortality was not influenced by high serum sodium (odds ratio, 1.3 [0.7-1.2]) and was different from other patient groups (P<.01). Any adverse associations with hypernatremia in respiratory patients were confined to those with arterial pressure of oxygen (PaO2)/fraction of inspired oxygen (Fio2) ratios of greater than 200.
  
  
  CONCLUSIONS
  High admission serum sodium is associated with increased odds for ICU death, except in respiratory patients.
authors.affiliation: Department of Critical Care Medicine, Flinders University, Bedford Park, South Australia, Australia; Department of Intensive Care Medicine, Flinders Medical Centre, Bedford Park, South Australia, Australia. Electronic address: biharishailesh@gmail.com.
authors.forename: Shailesh
authors.initials: S
authors.lastname: Bihari
authors.affiliation: School of Medicine, University of Adelaide, Adelaide, South Australia, Australia; ANZIC Research Centre, Monash University, Melbourne, Australia; Department of Intensive Care Medicine, The Queen Elizabeth Hospital, Adelaide, Australia. Electronic address: Sandra.Peake@health.sa.gov.au.
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Peake
authors.affiliation: Australian and New Zealand Intensive Care Research Centre, Department of Epidemiology & Preventive Medicine, Monash University, Melbourne, Australia. Electronic address: michael.bailey@monash.edu.
authors.forename: Michael
authors.initials: M
authors.lastname: Bailey
authors.affiliation: ANZIC Research Centre, Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia; The Alfred Hospital, Melbourne, Australia; Australia New Zealand Intensive Care Society (ANZICS), Clinical Outcomes and Resource Evaluation (CORE) Centre, Melbourne, Australia. Electronic address: D.Pilcher@alfred.org.au.
authors.forename: David
authors.initials: D
authors.lastname: Pilcher
authors.affiliation: Department of Intensive Care Medicine, Flinders Medical Centre, Bedford Park, South Australia, Australia. Electronic address: shivesh.prakash@health.sa.gov.au.
authors.forename: Shivesh
authors.initials: S
authors.lastname: Prakash
authors.affiliation: Department of Critical Care Medicine, Flinders University, Bedford Park, South Australia, Australia; Department of Intensive Care Medicine, Flinders Medical Centre, Bedford Park, South Australia, Australia. Electronic address: bers0002@flinders.edu.au.
authors.forename: Andrew
authors.initials: A
authors.lastname: Bersten
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D016001:Confidence Intervals; D016638:Critical Illness; D005260:Female; D017052:Hospital Mortality; D006760:Hospitalization; D006801:Humans; D006955:Hypernatremia / Q000401:mortality*; D007362:Intensive Care Units / Q000706:statistics & numerical data*; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D012120:Respiration Disorders / Q000097:blood / Q000401:mortality*; D012189:Retrospective Studies; D012306:Risk; D012720:Severity of Illness Index; D012964:Sodium / Q000097:blood*
chemical_list: D015415:Biomarkers; D012964:Sodium; D010100:Oxygen
keywords: Hypernatremia; Hyperosmolarity; Hyponatremia; ICU mortality; PaO(2)/FiO(2) ratio; Serum sodium