Lecture Code : PG04-S1
Session Name : PG Education 4 - Acute Kidney Injury
Session Topic : PG Education 4 - Acute Kidney Injury
Date & Time, Place : June 11 (Thu) / 13:00-14:30 / Room 2 (GBR 102), 1F
Patient Fluid Balance and Net Ultrafiltration: Impacts on Survival in CKRT Patients
Jin Hyuk Paek
Keimyung University Dongsan Medical Center, Republic of Korea
Fluid overload is one of the most common complications in critically ill patients with acute kidney injury (AKI), affecting up to two-thirds of those receiving continuous kidney replacement therapy (CKRT). Accumulating evidence demonstrates that both the degree of fluid accumulation and the strategy employed for fluid removal significantly influence patient outcomes, including mortality, duration of mechanical ventilation, and length of ICU stay.
Net ultrafiltration (NUF) represents the rate of circuit-level fluid removal during CKRT, while patient fluid balance (FB) reflects the net result of all fluid inputs and outputs, encompassing both machine and non-machine components. Although higher NUF rates are intended to correct fluid overload, observational studies from the RENAL trial and other large cohorts have shown that aggressive NUF is paradoxically associated with increased mortality and delayed renal recovery, likely through mechanisms of intravascular volume depletion, hemodynamic instability, and ischemic organ injury. Conversely, persistent positive FB—indicating inadequate fluid removal or excessive fluid administration—is itself an independent predictor of poor outcomes.
This apparent paradox underscores the complexity of fluid management during CKRT. Importantly, NUF and FB capture fundamentally different dimensions: NUF reflects only circuit-level fluid removal, whereas FB integrates all sources of fluid gain and loss, providing a more comprehensive measure of a patient's volume status. Furthermore, the concept of the fluid balance gap—the discrepancy between prescribed and achieved FB—has emerged as a quality indicator, with studies demonstrating that failure to meet FB targets is independently associated with higher mortality.
This lecture will review the current evidence on the independent and interrelated effects of NUF and patient FB on survival, discuss the physiological rationale for prioritizing FB-targeted strategies, and explore contemporary frameworks for precision fluid management in CKRT, including individualized goal-directed approaches integrating hemodynamic monitoring and real-time fluid assessment.
Keywords: AKI, CRRT, fluid