Apheresis is a medical technology in which the blood of a donor or patient is passed through an apparatus that separates out one particular constituent and returns the remainder to the circulation. While being related to it, it is distinct from dialysis, which does not separate directly but rather uses osmosis.

Method

Depending on the substance that is being removed, different processes are employed in apheresis. If separation by weight is required, centrifugation would be the method of choice. Other methods involve absorbation onto beads coated with an absorbent material.

Types of apheresis

There are numerous types of apheresis:

• Plasmapheresis - blood plasma.
• Plateletpheresis - blood platelets.
• Leukapheresis - leukocytes (white blood cells).
• Stem cell harvesting - circulating bone marrow cells are harvested to use in bone marrow transplantation
• LDL apheresis - removal of low density lipoprotein in patients with familial hypercholesterolemia

Uses

Donation

Blood componenents can be separated from a collected bag of whole blood or from a donor's blood flow before collected to a blood bag.

Various blood componenents are obtained by apheresis from donors. This includes platelets and blood plasma.

Therapy

Please refer to the individual apheresis methods for use in diseases

The various apheresis techniques may be used whenever the removed constituent is causing severe symptoms of disease. Generally, apheresis has to be performed fairly often, and is an invasive process. It is therefore only employed if other means to control a particular disease have failed, or the symptoms are of such a nature that waiting for medication to become effective would cause suffering or risk of complications.

See also

• Leukoreduction

External links

• WebPath Apheresis page.
• WebPath Blood Donation and Processing
• Donating Platelet Apheresis: Facts and the FAQ
• Baxter: Automated Component Collection
• Haemonetics: PCS2 System
• Haemonetics: MCS+ 9000 Dystem
• Gambro BCT: Trima Automated Blood Collection System