Principles of Hemodialysis

When a patient's kidneys cease to function, waste products build up in the patient's blood, and extra fluid builds up in the cells and vascular system. The patients may also often have electrolyte imbalances. Dialysis is designed to do the job that the kidneys can no longer do: remove the waste products and excess fluid from the blood and maintain the patient's electrolyte balance.

This resource covers the basic principles of dialysis, including the way fluids are compartmentalized in the body; how diffusion works, and the factors that impact the rate of diffusion; how diffusion works in dialysis to clean the blood and the factors that impact the transfer rate of solutes from the blood to the dialysate; and finally, how pressure is used to control diffusion in dialysis, or ultrafiltration.

After completing this resource, learners will be able to:

• List the fluid compartments in the body
• Describe how fluids move among body compartments
• Explain the role of diffusion in dialysis
• Explain the role of filtration in dialysis
• Differentiate between diffusion and convection
• Discuss fluid dynamics in relation to dialysis
• Explain the role of osmosis in dialysis
• Describe how kidneys use diffusion and filtration to clean the blood
• Describe how dialysis uses diffusion and filtration to mimic the kidneys