ECMO and Continuous Renal Replacement Therapy - PPAG

What happened to.….• SCUF – Slow Continuous UltraFiltration• Convective removal, no replacement fluid• CAVH – Continuous ArterioVenous Hemofiltration• Convective removal, patient blood pressure determinesflow, 2 vessels, replacement fluid• CVVHD – Continuous VenoVenous HemoDialysis• Diffusive removal, pump driven, usually no replacementfluid, dialysate delivered countercurrent to blood• CVVH – Continuous VenoVenous Hemofiltration• Convective removal, pump driven, replacement fluid• CVVHDF – Continuous VenoVenousHemoDiaFiltration• Diffusive + Convective Removal, pump driven,replacement fluid, dialysate delivered countercurrent tobloodCRRT - Principles• Blood flows through a semipermeablemembrane driven either by patient bloodpressure (AV mode) or by a peristalticpump (VV mode)• Semipermeable membrane of the filter istypically synthetic and high-flux• Solute clearance can be achieved bydiffusion, convection, or a combinationDiffusion• Solutes such as urea, phosphate, and uremictoxins are driven by their electrochemicalgradient to move across the membrane into thesterile dialysate, which is runningcountercurrent to blood on the other side of themembrane capillaries• Different than IHD• CRRT – dialysate flow is slow• Typically 0.6 - 2 L/hr• IHD – dialysate flow is fast• Typically 500 mL/min or 30 L/hr