Nonresuscitation Fluid Accumulation and Outcomes After Pediatric Cardiac Surgery: Single-Center Retrospective Cohort Study

OBJECTIVES: Postoperative patients after congenital cardiac surgery are at high risk of fluid overload (FO), which is known to be associated with poor outcomes. “Fluid creep,” or nonresuscitation IV fluid in excess of maintenance requirement, is recognized as a modifiable factor associated with FO in the general PICU population, but has not been studied in congenital cardiac surgery patients. Our objective was to characterize fluid administration after congenital cardiac surgery, quantify fluid creep, and the association between fluid creep, FO, and outcome. DESIGN: Retrospective, observational cohort study. SETTING: Single-center urban mixed-medical and cardiac PICU. PATIENTS: Patients admitted to the PICU after cardiac surgery between January 2010 and December 2020. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: There were 1,459 postoperative encounters with 1,224 unique patients. Total fluid intake was greater than maintenance requirements on 3,103 of 4,661 patient days (67%), with fluid creep present on 2,624 patient days (56%). Total nonresuscitation intake was higher in patients with FO (defined as cumulative fluid balance 10% above body weight) versus those without. Fluid creep was higher among patients with FO than those without for each of the first 5 days postoperatively. Each 10mL/kg of fluid creep in the first 24 hours postoperatively was associated with 26% greater odds of developing FO (odds ratio [OR] 1.26; 95% CI, 1.17–1.35) and 17% greater odds of mortality (OR 1.17; 95% CI, 1.05–1.30) after adjusting for risk of mortality based on surgical procedure, age, and day 1 resuscitation volume. Increasing fluid creep in the first 24 hours postoperatively was associated with increased postoperative duration of mechanical ventilation and PICU length of stay. CONCLUSIONS: Fluid creep is present on most postoperative days for pediatric congenital cardiac surgery patients, and fluid creep is associated with higher-risk procedures. Fluid creep early in the postoperative PICU stay is associated with greater odds of FO, mortality, length of mechanical ventilation, and PICU length of stay. Fluid creep may be under-recognized in this population and thus present a modifiable target for intervention.