title: Association between fluid balance and survival in critically ill patients.
abstract: OBJECTIVE
  Although the consequences of chronic fluid retention are well known, those of iatrogenic fluid retention that occurs during critical illness have not been fully determined. Therefore, we investigated the association between fluid balance and survival in a cohort of almost 16,000 individuals who survived an intensive care unit (ICU) stay in a large, urban, tertiary medical centre.
  
  
  METHODS
  Longitudinal analysis of fluid balance at ICU discharge and 90-day post-ICU survival.
  
  
  METHODS
  Associations between fluid balance during the ICU stay, determined from the electronic bedside record, and survival were tested using Cox proportional hazard models adjusted for severity of critical illness.
  
  
  RESULTS
  There were 1827 deaths in the first 90 days after ICU discharge. Compared with the lowest quartile of discharge fluid balance [median (interquartile range) -1.5 (-3.1, -0.7) L], the highest quartile [7.6 (5.7, 10.8) L] was associated with a 35% [95% confidence interval (CI) 1.13-1.61)] higher adjusted risk of death. Fluid balance was not associated with outcome amongst individuals without congestive heart failure or renal dysfunction. Amongst patients with either comorbidity, however, fluid balance was strongly associated with outcome, with the highest quartile having a 55% (95% CI 1.24-1.95) higher adjusted risk of death than the lowest quartile. Isotonic fluid balance, defined as the difference between intravenous isotonic fluid administration and urine output, was similarly associated with 90-day outcomes.
  
  
  CONCLUSIONS
  Positive fluid balance at the time of ICU discharge is associated with increased risk of death, after adjusting for markers of illness severity and chronic medical conditions, particularly in patients with underlying heart or kidney disease. Restoration of euvolaemia prior to discharge may improve survival after acute illness.
authors.affiliation: Lab of Computational Physiology, Division of Health, Sciences and Technology, Harvard-Massachusetts Institute of Technology, Cambridge, MA, USA; School of Public Health and Health Systems, University of Waterloo, Waterloo, ON, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Lee
authors.forename: E
authors.initials: E
authors.lastname: de Louw
authors.forename: M
authors.initials: M
authors.lastname: Niemi
authors.forename: R
authors.initials: R
authors.lastname: Nelson
authors.forename: R G
authors.initials: RG
authors.lastname: Mark
authors.forename: L A
authors.initials: LA
authors.lastname: Celi
authors.forename: K J
authors.initials: KJ
authors.lastname: Mukamal
authors.forename: J
authors.initials: J
authors.lastname: Danziger
mesh_terms: D058186:Acute Kidney Injury / Q000401:mortality; D015897:Comorbidity; D016638:Critical Illness / Q000453:epidemiology / Q000401:mortality*; D006333:Heart Failure / Q000401:mortality; D006801:Humans; D016016:Proportional Hazards Models; D014882:Water-Electrolyte Balance
keywords: diuresis; fluid balance; heart failure; oedema; survival; weight