Fluid accumulation has an adverse effect on outcome of ICU patients with acute kidney injury

Introduction

Management of acute kidney injury (AKI) is heterogeneous with little consensus about fluid therapy, vasopressors and diuretics. The aim was to analyse whether fluid management influences outcome in critically ill patients with AKI.

Methods

Retrospective analysis of the data for 4,645 patients admitted to the multidisciplinary ICU at Guy's and St Thomas' Foundation Hospital between April 2004 and June 2009. AKI was defined according to the AKI network criteria, which distinguish between three different grades of AKI. Maximum degree of AKI and total cumulative fluid balance between ICU admission and the day of AKI were recorded.

Results

A total of 1,225 patients (26.4%) had AKI I, 29 patients (0.6%) had AKI II and 1,183 patients (25.5%) had AKI III of whom 89% were treated with renal replacement therapy. Two hundred and thirty-seven (5.1%) patients had end-stage dialysis-dependent renal failure and 1,971 patients (42.4%) had no AKI during their stay in the ICU. The ICU mortality was 15.6% in AKI I, 17.2% in AKI II and 34.9% in patients with AKI III (AKI I vs AKI III: P < 0.0001). Cumulative fluid balance at diagnosis of AKI was significantly higher in patients who later died (Table 1).

Table 1 Mean cumulative fluid balance (SD) in ICU survivors and nonsurvivors

Conclusions

There is a correlation between fluid accumulation on the day of AKI and subsequent ICU outcome. Among patients with any degree of AKI, nonsurvivors had a higher cumulative fluid balance compared with ICU survivors. Future analysis needs to determine whether fluid accumulation was the cause of worse outcome, the result of more aggressive resuscitation or a marker of more severe AKI.