OBJECTIVES: To characterize current practice in fluid administration and deresuscitation (removal of fluid using diuretics or renal replacement therapy), the relationship between fluid balance, deresuscitative measures, and outcomes and to identify risk factors for positive fluid balance in critical illness.
DESIGN: Retrospective cohort study.
SETTING: Ten ICUs in the United Kingdom and Canada.
PATIENTS: Adults receiving invasive mechanical ventilation for a minimum of 24 hours.
MEASUREMENTS AND MAIN RESULTS: Four-hundred patients were included. Positive cumulative fluid balance (fluid input greater than output) occurred in 87.3%: the largest contributions to fluid input were from medications and maintenance fluids rather than resuscitative IV fluids. In a multivariate logistic regression model, fluid balance on day 3 was an independent risk factor for 30-day mortality (odds ratio 1.26/L [95% CI, 1.07-1.46]), whereas negative fluid balance achieved in the context of deresuscitative measures was associated with lower mortality. Independent predictors of greater fluid balance included treatment in a Canadian site.
CONCLUSIONS: Fluid balance is a practice-dependent and potentially modifiable risk factor for adverse outcomes in critical illness. Negative fluid balance achieved with deresuscitation on day 3 of ICU stay is associated with improved patient outcomes. Minimization of day 3 fluid balance by limiting maintenance fluid intake and drug diluents, and using deresuscitative measures, represents a potentially beneficial therapeutic strategy which merits investigation in randomized trials.