Indications for pediatric RRT

  • Fluid Overload (hypervolemia with pulmonary edema/respiratory failure) and/or electrolyte imbalance
  • Uremia with bleeding and/or encephalopathy
  • Acuity/degree of kidney injury: Reduction of GFR/elevated cratinine; reduction in urine output
  • Intoxications
  • Inborn errors of metabolism
  • Nutritional support

Important concepts

Diffusion: solute transport across a semi-permeable membrane

  • Molecules move from an area of higher concentration to lower concentration
  • Effective for small molecule clearance

Convection: process where solutes pass across the semi-permeable membrane along with the solvent in response to a positive transmembrane pressure

  • Effectiveness is less dependent on molecular size

RRT options

Hemodialysis, Peritoneal Dialysis, or Continuous RRT - each has advantages and disadvantages

Choice is guided by:

  • Patient characteristics (disease/symptoms, hemodynamic stability)
  • Goals of therapy (fluid removal, electrolyte correction)
  • Availability, expertise, and cost

Continuous veno-venous hemofiltration (CVVH)

  • Provides solute removal by convection
  • Uses replacement fluid

Continuous veno-venous hemodialysis (CVVHD)

  • Provides solute clearance by diffusion
  • Uses dialysate fluid

Continuous veno-venous hemodiafiltration (CVVHDF)

  • Provides solute removal by both convection and diffusion
  • Uses both replacement fluids and dialysate fluids

*Proposed benefits of above three methods:

  • Reduces hemodynamic instability
  • Effective control of uremia, hyperphosphatemia, and hyperkalemia
  • Rapid control of acid-base imbalance
  • Allows for improved nutritional support
  • Management of sepsis/plasma cytokine filter

Peritoneal dialysis (PD)

  • Fluid removal follows an osmotic gradient, therefore more dependent on concentration of dialysis solution
  • Clearance achieved by PD depends on size of molecule, dialysis fluid osmolality, dwell time, and volume of dialysis fluid
  • Contraindications: defect in peritoneal membrane, abdominal problems

Intermittent hemodialysis

  • Extracorporeal exchange of fluid and solute that occurs across an artificial semipermeable membrane between blood and dialysis fluid moving in opposite directions
  • Children have to be hemodynamically stable and be able to tolerate interval between dialysis runs