Hourly Fluid Balance in Patients Receiving Continuous Renal Replacement Therapy

Introduction: Little is known about early (first 48 h) hourly and cumulative fluid balance (FB) during continuous renal replacement therapy (CRRT). Objectives: To study the characteristics and outcome associations of early hourly and cumulative FB. Methods: We studied FB in CRRT patients (2016-2018). Results: Among 350 patients, mean hourly FB became negative after 20 CRRT hours, but within 6 CRRT hours in patients with baseline fluid overload. A negative early FB was never achieved in patients receiving vasopressor therapy (p < 0.001). Mortality was 31%. The percentage of hourly negative FB was independently associated with decreased ICU mortality. A time-weighted hourly FB between 18.5 and -33 mL/h was also significantly and independently associated with decreased mortality. Conclusions: In CRRT patients, an early FB conservative approach is possible, modulated by patient characteristics, and associated with a low mortality. Moreover, avoidance of an early positive FB is associated with decreased mortality.