The Brophy Kit™: An in vivo Experimental Model of Ultrafiltration for Extremely Low Birthweight Neonates.

INTRODUCTION: Neonatal acute kidney injury disproportionately affects extremely low birthweight (ELBW) infants (<1,000 g), who are especially vulnerable to fluid imbalance and its consequences. Current renal replacement therapy options are not optimized for patients under 2.5 kg. The Brophy Kit™, a cost-conscious, manual single-lumen dialysis device, may address this gap. METHODS: A preclinical feasibility study was conducted using eight healthy male Sprague Dawley rats (600-800 g), approximating the weight and blood volume of ELBW neonates. Each rat underwent 3-French catheter placement and sequential ultrafiltration (UF) cycles with the Brophy Kit™, targeting 5% and 10% blood volume removal. Respiratory rate was monitored as a surrogate for procedural tolerance. RESULTS: All eight animals tolerated the procedure and survived to UF completion. One rat was excluded due to catheter clotting before UF initiation. Respiratory rates remained stable throughout. Observed UF volumes deviated from prescribed volumes at the end of each experiment day by 11-12%. CONCLUSION: This proof-of-concept study demonstrates the feasibility of using the Brophy Kit™ for manual UF in a preclinical model approximating ELBW neonates. The device shows potential as an accessible solution for fluid management in resource-limited settings.