Early restrictive fluid balance is associated with lower hospital mortality independent of acute disease severity in critically ill patients on CRRT

Abstract

Fluid overload (FO) with coincident acute kidney injury has been associated with increased mortality. However, it is unclear whether FO is an independent determinant of mortality for disease severity. We aimed to explore whether the development of fluid balance (FB) during the first 72 h of continuous renal replacement therapy (CRRT) is independently associated with hospital mortality. All patients admitted to a single centre ICU requiring CRRT for at least 24 h between years 2010–2019 were included. Extracted data included patient demographics and clinical parameters including daily cumulative fluid balance (FBcum), lactate, SOFA score and vasoactive requirement at the initiation and during the first 72 h of CRRT. 399 patients were included in the analysis. Hospital survivors had a significantly lower FBcum at CRRT initiation compared to non-survivors (median 1382 versus 3265 ml; p = 0.003). Hourly fluid balance per bodyweight (FBnet) was lower in survivors at 0–24, 24–48 and 48–72 h after initiation of CRRT (p < 0.008 for all comparisons). In the survival analysis (analyzed with counting process model) significant time-dependent explanatory variables for hospital mortality were FBnet (per ml/kg/h: HR: 1.319, 95% CI 1.038–1.677, p = 0.02), lactate (HR: 1.086, 95% CI 1.030–1.145, p = 0.002) and SOFA score (per ml/kg/h: HR: 1.084, 95% CI 1.025–1.146, p = 0.005) during the first 72 h of CRRT. Even after careful adjustment for repeated measures of disease severity, FBnet during the first 72 h of CRRT remains independently associated with hospital mortality, in critically ill patients with AKI.

Early fluid management affects short-term mortality in patients with end-stage kidney disease undergoing chronic hemodialysis and requiring continuous renal replacement therapy

“…In the comparisons of mortality risk, in which patients were stratified into low and high cumulative input/output groups on day 3, the group with high input and low output tended to have higher 7- and 14-day mortality risks compared to the reference group (i.e., low input/output) (Table 8 ). These observations suggested that fluid balance of cumulative high input and cumulative low output, referred to as positive fluid balance, was related to the increased mortality risk seen in ESKD patients undergoing CRRT, similar to previous studies [ 13 – 15 ]. However, our study lacked information on volume status at CRRT initiation in ESKD patients and the actual amount of fluid overload over the period when CRRT was required, which limited our ability to compare of mortality risk with previous studies.…”

“…The authors of that study suggested that the impact of cumulative fluid balance on mortality may be more dependent on cumulative output [ 14 ]. Although their study population consisted of patients with sepsis requiring CRRT, Uusalo et al showed that higher fluid balance during first 72 h of CRRT was independently associated with hospital mortality in patients with AKI, even after adjustment for repeated measures of disease severity over the period when CRRT was required [ 15 ]. Among the patients with AKI, hospital survivors had a significantly lower cumulative fluid balance at CRRT initiation compared to non-survivors.…”

Chloride, Sodium and Calcium Intake Are Associated with Mortality and Follow-Up Kidney Function in Critically Ill Patients Receiving Continuous Veno-Venous Hemodialysis—A Retrospective Study

“…Indeed, fluid overload has been associated with poor patient outcomes in critically ill AKI patients in prior reports [ 18 ]. However, our earlier work has shown that a lower cumulative fluid net balance resulting from fluid administration minus fluid removal during dialysis, diuresis and other losses in critically ill CRRT patients is associated with improved survival, suggesting that effective fluid removal may outweigh the prognostic significance of fluid intake during the course of ICU care in patients receiving RRT [ 19 ]. Intuitively, fluid balance is what matters, not the volume of fluids administered.…”

Early Net Ultrafiltration during Continuous Renal Replacement Therapy: Impact of Admission Diagnosis and Association with Mortality

“…Intensity of CRRT has been studied in detail with randomized trials showing no benefit with increased intensity [2], and timing of RRT trials have suggested that delayed intervention may be safest [3]. However, other aspects of CRRT beyond intensity and timing may impact outcomes, such as those related to fluid management [4][5][6][7]. Beyond overall fluid balance, a particularly important aspect of CRRT may relate to the rate of fluid removal with the CRRT machine, the so-called net ultrafiltration rate (UF NET ).…”