Design and Validation of a Novel Fluid Management System for Pediatric Continuous Renal

Design and validation of a novel fluid management system for pediatric continuous renal replacement therapy

Arvind Santhanakrishnan, T. Nestle, B. L. Moore, A. P. Yoganathan and M. L. Paden

Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University Division of Pediatric Critical Care, Children’s Healthcare of Atlanta at Egleston Department of Pediatrics, Emory University School of Medicine

Nearly 3,600 critically ill children per year with acute kidney injury receive life-saving continuous renal replacement therapy (CRRT) in the United States. However, there is currently no CRRT device approved by the Food and Drug Administration for use in pediatric patients. Several complications in using adult- adapted CRRT devices have been described in the literature, primarily originating from the inaccurate fluid balance between the ultrafiltrate (UF) and replacement fluid (RF) volumes. Departing from conventional scale-based methods, we designed and developed a prototype of a novel system that relies on fluid incompressibility to provide accurate fluid balance. Fluid transport is realized via miniature diaphragm pumps that function similar to a cardiac ventricle to achieve highly accurate and controlled pumping, and this reduced the extracorporeal circuit volume to a pediatric-safe level of 34 mL. The UF and RF pumps were mechanically linked using a crankshaft mechanism and driven out-of-phase relative to each other using a common actuator. Accuracy testing was conducted in vitro for 8-hour long continuous operation of the coupled UF and RF pumps. Flow rate and fluid balance accuracy of the prototype was experimentally evaluated over driving pressures of 50-120 mm Hg and flow rates of 300-3000 mL/hour. Device flow rate error was calculated as the difference between the prescribed and delivered flow rates. Fluid balance accuracy was calculated as the difference between the UF and RF flow rates. Individual flow rate errors of the pumps were under 2% of the programmed flow rate. The mean cumulative fluid balance error was <1% across filtration flows from 300 mL/hour to 3000 mL/hour. This approach of fluid balance control in a pediatric specific CRRT device provides a significant accuracy improvement over currently used clinical implementations.

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