Continuous Renal Replacement Therapy in Neonates and Young Infants

Abstract

After completing this article, readers should be able to: 1. Compare and contrast hemodialysis and hemofiltration. 2. Compare and contrast continuous arteriovenous and venovenous hemofiltration. 3. List the primary indications for continuous renal replacement therapy (CRRT). 4. Describe the consequences of blood flow rates that are too low or too high in CRRT. 5. List the potential complications of CRRT. Continuous renal replacement therapy (CRRT) consists of a group of hemofiltration-based dialytic modalities that are used to manage acute renal failure, fulminant hepatic failure, sepsis, and certain inborn errors of metabolism. Although most of these treatments initially were developed for adults, adaptations have expanded their use to children and neonates. During the last decade, use of CRRT in neonatal intensive care has increased dramatically. The primary advantages of this form of therapy include slow continuous fluid removal, minimal hemodynamic instability, and excellent dialytic efficacy. The dialytic efficiency of CRRT often exceeds that of both peritoneal and conventional hemodialysis. CRRT would be used even more commonly in the neonatal setting if circuit volumes could be decreased and if anticoagulation could be employed safely in all children, even those who have a high risk of bleeding. Unlike hemodialysis, which removes solute primarily by the process of diffusion, hemofiltration purifies blood by convective transport, with the fluid crossing a semipermeable membrane under the influence of hydrostatic pressure. Solutes are removed from the blood by solvent drag at a rate equal to their blood concentration times the fluid filtration rate. Middle- and larger-molecular weight solutes are cleared at an excellent rate because the semipermeable hemofilter membrane has a higher molecular weight cutoff (∼20,000 daltons) than a traditional dialyzer. However, without counter-current dialysate flow, clearance of low-molecular weight solutes, including urea and creatinine, is less than with standard hemodialysis. Hemofilters are used with both traditional hemodialysis machines, which can generate …