BACKGROUND: To determine the association between fluid balance metrics and mortality and other postoperative outcomes after neonatal cardiac surgery in a contemporary multi-center cohort. METHODS: Observational cohort study across 22 hospitals in neonates (≤30 days) undergoing cardiac surgery. We explored overall % fluid overload, postoperative day 1 % fluid overload, peak % fluid overload, and time to first negative daily fluid balance. The primary outcome was in-hospital mortality. Secondary outcomes included postoperative duration of mechanical ventilation, and intensive care unit (ICU) and hospital length of stay. Multivariable logistic or negative binomial regression was used to determine independent associations between fluid overload variables and each outcome. RESULTS: The cohort included 2223 patients. In-hospital mortality was 3.9% (n=87). Overall median peak % fluid overload was 4.9%, (interquartile range 0.4–10.5%). Peak % fluid overload and postoperative day 1 % fluid overload were not associated with primary or secondary outcomes. Hospital resource utilization increased on each successive day of not achieving a first negative daily fluid balance and was characterized by longer duration of mechanical ventilation (incidence rate ratio 1.11, 95% confidence interval 1.08–1.14, ICU length of stay (incidence rate ratio 1.08, 95% confidence interval 1.03–1.12), and hospital length of stay (incidence rate ratio 1.09, 95% confidence interval 1.05–1.13). CONCLUSIONS: Time to first negative daily fluid balance, but not % fluid overload is associated with improved postoperative outcomes in neonates after cardiac surgery. Specific treatments to achieve an early negative fluid balance may decrease postoperative care durations.

Although <2% of coronavirus disease 2019 (COVID-19) infections are reported in the pediatric population, children with comorbidities such as congenital heart disease and those at a younger age are more likely to become critically ill.1-3 Remdesivir has been reported to be efficacious in adults with COVID-194; however, there are no studies in children. Convalescent plasma (CP) can contain neutralizing antibodies to viruses,5 and has been used during previous viral epidemics with clinical improvement.6-11 COVID-19 CP (C19-CP) may be useful in critically ill adults, resulting in improvement in inflammatory markers, pulmonary lesions, and mortality.12 However, the impact of C19-CP in pediatric patients, particularly infants with developing immune systems and significant comorbidities, is completely unknown. We present an infant with cardiopulmonary failure secondary to unrepaired congenital heart disease exacerbated by COVID-19. Given postsurgical complications of children with viral respiratory infection,13-17 the patient required clearance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) for surgical candidacy. We hypothesized that C19-CP administration may clear SARS-CoV-2 following failure of remdesivir.