Fluid balance, intradialytic hypotension, and outcomes in critically ill patients undergoing renal replacement therapy: a cohort study

Abstract

IntroductionIn this cohort study, we explored the relationship between fluid balance, intradialytic hypotension and outcomes in critically ill patients with acute kidney injury (AKI) who received renal replacement therapy (RRT).MethodsWe analysed prospectively collected registry data on patients older than 16 years who received RRT for at least two days in an intensive care unit at two university-affiliated hospitals. We used multivariable logistic regression to determine the relationship between mean daily fluid balance and intradialytic hypotension, both over seven days following RRT initiation, and the outcomes of hospital mortality and RRT dependence in survivors.ResultsIn total, 492 patients were included (299 male (60.8%), mean (standard deviation (SD)) age 62.9 (16.3) years); 251 (51.0%) died in hospital. Independent risk factors for mortality were mean daily fluid balance (odds ratio (OR) 1.36 per 1000 mL positive (95% confidence interval (CI) 1.18 to 1.57), intradialytic hypotension (OR 1.14 per 10% increase in days with intradialytic hypotension (95% CI 1.06 to 1.23)), age (OR 1.15 per five-year increase (95% CI 1.07 to 1.25)), maximum sequential organ failure assessment score on days 1 to 7 (OR 1.21 (95% CI 1.13 to 1.29)), and Charlson comorbidity index (OR 1.28 (95% CI 1.14 to 1.44)); higher baseline creatinine (OR 0.98 per 10 μmol/L (95% CI 0.97 to 0.996)) was associated with lower risk of death. Of 241 hospital survivors, 61 (25.3%) were RRT dependent at discharge. The only independent risk factor for RRT dependence was pre-existing heart failure (OR 3.13 (95% CI 1.46 to 6.74)). Neither mean daily fluid balance nor intradialytic hypotension was associated with RRT dependence in survivors. Associations between these exposures and mortality were similar in sensitivity analyses accounting for immortal time bias and dichotomising mean daily fluid balance as positive or negative. In the subgroup of patients with data on pre-RRT fluid balance, fluid overload at RRT initiation did not modify the association of mean daily fluid balance with mortality.ConclusionsIn this cohort of patients with AKI requiring RRT, a more positive mean daily fluid balance and intradialytic hypotension were associated with hospital mortality but not with RRT dependence at hospital discharge in survivors.Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-014-0624-8) contains supplementary material, which is available to authorized users.

Sustained low-efficiency dialysis in septic shock: Hemodynamic tolerability and efficacy

“…Silversides et al . [18] demonstrated fluid balance during dialysis as a predictor of mortality in AKI. Our results also show a correlation of fluid balance during dialysis with mortality.…”

Associations of fluid overload with mortality and kidney recovery in patients with acute kidney injury: A systematic review and meta-analysis

“…In addition, another study [19] showed that there was no significant association of fluid overload with dialysis dependence (OR, 0.72; 95% CI, 0.38 to 1.35).…”

“…ventilation-free days, and another study [19] presented the relationship between fluid overload and RRT dependence.…”

“…Fluid overload is a common complication in critically ill patients with AKI, with a high incidence ranging from 30% to 70% [9,10,12,19,22,24,25]. AKI patients might be more likely to receive RRT when suffering fluid overload.…”

“…Eight studies presented risk estimates for associations between fluid overload and mortality (OR calculated on dichotomous variables) [12,15,19,[21][22][23][24][25], but adjusted ORs were obtained in six studies [12,15,19,22,24,25].…”