1340: Fluid Balance Trajectory in Pediatric Hematopoietic Cell Transplant

Introduction: Fluid overload (FO) is common in pediatric hematopoietic cell transplant (HCT) patients and is associated with increased morbidity and mortality. IV fluid intake, endothelial dysfunction, HCT-related complications, and acute kidney injury all contribute to FO. Greater than 10% FO is recognized as a clinically significant threshold and is associated with increased ICU admissions, decreased survival, and multiorgan dysfunction. Changes in fluid balance (FB) over the initial transplant course have not been described in detail. We aimed to explore point prevalence and timing of critical FO and FB in the first 30 days following HCT. Methods: We included patients 10% using the equation (fluid input–fluid output)/weight (kg)*100. Primary outcomes were cumulative net FB per kilogram (mL/kg) and point prevalence of critical FO, stratified by mortality. Results: 747 patients were included. Median age was 11 years old (IQR 2-13), 57% were female, 68% underwent an allogeneic HCT, and the most common indication was malignancy (70%). All-time mortality was 26%. The cumulative median net FB was 7 mL/kg (IQR -3-32) by day 30 post-HCT. Peak point prevalence of critical FO was 40% and was observed during week 4 (day 22-30). Cumulative net FB median was significantly higher on days 4-9 in survivors (2-4 mL/kg) compared to non-survivors (1-2 mL/kg)(p< 0.05). Cumulative net FB median was 8 mL/kg (IQR -1-31) in survivors and 5 mL/kg (IQR -3-33) in non-survivors at 30 days(p=0.5). 45% of survivors had critical FO at day 30 compared to 39% of non-survivors(p=0.4). There was no significant association with presence of critical FO and all-time mortality at any time point. Conclusions: FO is complex and common in pediatric HCT patients. There was no association with critical FO and mortality at any time point. This finding warrants evaluation to assess different thresholds for %FO to help guide fluid management strategies. Further analysis should be directed to uncover drivers of cumulative FB and impact on other patient-important outcomes.