Influence of Daily Fluid Balance prior to Continuous Renal Replacement Therapy on Outcomes in Critically Ill Patients

Positive fluid balance is a risk factor for mortality in critically ill patients, especially those requiring continuous renal replacement therapy (CRRT). However, the association between daily fluid balance and various organ impairments remains unclear. This study investigated the impacts of daily fluid balance prior to CRRT on organ dysfunction, as well as mortality in critically ill patients. We identified daily fluid balance between intensive care unit (ICU) admission and CRRT initiation. According to daily fluid balance, the time to CRRT initiation and the rate of organ failure based on the sequential organ failure assessment (SOFA) score were assessed. We recruited 100 patients who experienced CRRT for acute kidney injury. CRRT was initiated within 2 [0, 4] days. The time to CRRT initiation was shortened in proportion to daily fluid balance, even after the adjustment for the renal SOFA score at ICU admission (HR 1.14, P = 0.007). Based on the SOFA score, positive daily fluid balance was associated with respiratory, cardiovascular, nervous, and coagulation failure, independent of each initial SOFA score at ICU admission (HR 1.36, 1.26, 1.24 and 2.26, all P < 0.05). Ultimately, we found that positive fluid balance was related with an increase in the rate of 28-day mortality (HR 1.14, P = 0.012). Positive daily fluid balance may accelerate the requirement for CRRT, moreover, it can be associated with an increased risk of multiple organ failure in critically ill patients.