Positive fluid balance as a prognostic factor for mortality and acute kidney injury in severe sepsis and septic shock.

Purpose: The purpose of this study is to assess whether late positive fluid balances are associated with acute kidney injury and mortality in severe sepsis and septic shock.

Methods: In this retrospective study, fluid balances were calculated at 3 different time points: the onset of organ dysfunction attributed to sepsis, sepsis diagnosis, and vasopressors initiation. Data were analyzed in logistic regression models for mortality and acute kidney injury as outcomes.

Results: We included 116 patients. A RIFLE score F, diuresis less than 0.9 L from the second day after the first organ dysfunction, and fluid balance more than 3 L between the 24th and the 48th hour after diagnosis were independently associated with higher mortality, whereas in the subgroup with shock, only the latter parameter and diuresis less than 0.85 L on the first day of shock were independent risk factors. After adjusting for age, creatinine more than 1.2 mg/dL, a nonrenal Sequential Organ Failure Assessment greater than or equal to 7.5 on the first day and urine output less than 1.3 L on the first day after organ dysfunction were independent risk factors for RIFLE F. No relationship was found between fluid balance and acute kidney injury.

Conclusion: Late positive fluid balance is an independent risk factor for mortality in severe sepsis. Positive fluid balances are not associated with either protection against or risk for acute kidney injury.