Fluid balance and fluid overload in pediatric critical illness: a state-of-the-art review

Abstract For nearly 40 years, pediatricians have been leaders in recognizing the detrimental effect of fluid overload on outcomes in critical care. This state-of-the-art narrative review provides a detailed description of fluid balance including its terminology, diagnosis and measurement, pathophysiology, epidemiology, management, and future directions. Percent cumulative fluid balance is anchored to a patient’s weight, and the threshold of fluid balance that is associated with worse outcomes, and thus progression to fluid overload, varies by age, acuity, case-mix, and phase of illness, with temporality of fluid accumulation likely being critical. Despite technological advances and improvements in care delivery, our ability to measure intravascular volume and fluid responsiveness is poor and merits further research. Fluid accumulation is often precipitated by disease states that cause endothelial dysfunction, activation of the renin angiotensin pathway, and anti-diuretic hormone production. Inadequate circulation of blood, insufficient oncotic pressure, and poor excretion of fluid all contribute to fluid accumulation. Management of fluid balance begins with fluid stewardship, focusing on precise and thoughtful timing, amount, and reasons for fluid delivery. The nuanced timing of deresuscitation is critical to fluid balance optimization. The R.O.S.E.—resuscitation, optimization, stabilization, and evacuation—framework describes a patient’s dynamic fluid needs over the course of critical illness and is one model that conceptualizes when to start fluid restriction and removal. Future directions involve prognostically enriched interventional fluid management trials focused on pediatric-specific outcomes, creation of tools and biomarkers to detect fluid phase transition, and formation of multicenter collaboratives utilizing informatics to facilitate data extraction and analysis capturing data necessary to inform new initiatives.