Fluid overload may increase risk for major adverse kidney events in critically ill patients who require continuous renal replacement therapy (CRRT) for acute kidney injury (AKI), a new study found.
Researchers conducted a retrospective cohort study at a single ICU at a tertiary medical center in Kentucky to determine how fluid overload affected adverse event risk in this patient population. They assessed fluid overload as fluid balance from admission to initiation of CRRT, adjusted for body weight, and defined major adverse kidney events as a composite of death, dependence on renal replacement therapy, or, in patients not on renal replacement therapy, inability to recover 50% of baseline estimated glomerular filtration rate up to 90 days after discharge. The study results were published June 3 by Critical Care Medicine.
Four hundred eighty-one patients were included in the study. The mean age was 56 years, and most (64.4%) were men. Two hundred forty-three patients (50.5%) had fluid overload less than or equal to 10% when CRRT was initiated, and 238 patients (49.5%) had fluid overload above 10%. Those with fluid overload less than or equal to 10% were less likely to have major adverse kidney events than those with fluid overload greater than 10% (71.6% vs. 79.4%; P=0.047). In multivariable logistic regression analysis, fluid overload above 10% was seen to be associated with 58% higher odds of major adverse kidney events. This finding continued to be seen after adjustment for timing of CRRT initiation. Every one-day increase in time from ICU admission to initiation of CRRT was associated with a 2.7% increased odds of major adverse kidney events. Fluid overload greater than 10% was independently associated with 82% increased odds of hospital mortality (P=0.004) and 2.5 fewer ventilator-free days (P=0.044) versus fluid overload of 10% or lower.
The researchers noted that their results were vulnerable to selection bias and may not be generalizable to other critically ill populations, among other limitations. They concluded that in critically ill patients with AKI who require CRRT, fluid overload above 10% was independently associated with increased risk of major adverse kidney events. Clinicians should routinely calculate fluid overload in the critical care setting to prevent it and its potential consequences, the authors recommended. They also noted that an association was seen between major adverse kidney outcomes and increased time from ICU admission to CRRT initiation. “Further randomized controlled trials are needed to determine how conservative fluid management strategies, including diuretic use and early initiation of CRRT for volume removal, will affect short- and long-term renal outcomes,” they wrote.