A. It is a procedure in which a particular component of blood is collected and the remainder of the blood is returned to the donor with the help of an automated machine.
Q. How does Apheresis works?
A. Blood is separated into various components based on their specific gravity by centrifugal force.
In a closed system, blood flows from the donor’s arm into the centrifuge bowl, where a specific component is removed and the remaining blood is returned to the donor.
It can be a continous or intermittent flow. In intermittent flow blood is removed through a venepuncture, centrifuged and returned in alternating steps to the same venepuncture.
In continous flow, blood is removed by one venepuncture in one arm and returned through another venepuncture in the other arm.
Q. How long does it take for the procedure to take place?
A. It might take 30 minutes to 2 hours depending on the requirements and donor’s status.
Q. Why Apheresis is preferred over routine transfusions?
A. This procedure allows collection of larger volume a specific component and decreases the exposure of patient to multiple numbers of donors.
Q. What are the different types of apheresis ?
A. Plasmapheresis and cytapheresis.
Q. What is plasmapheresis?
A. Plasma is harvested from the donors and cellular components are returned to the body.
For occasional plasmapheresis (once every 12 weeks) donor criteria is same as for whole blood donors.
For frequent plasmapheresis (more than once every 12 weeks) donor must fulfill the following criteria along with the regular whole blood donation requirements-
- Haemoglobin ≥12g/dl
- Serum proteins ≥6.0 g/dl
- Volume of plasma for a donor weighing ≥55 kgs should not exceed 500 ml during one procedure.
Plasmapheresis can be used for the removal of abnormal plasma proteins (eg. Guillain-barre syndrome, myasthenia gravis, thrombotic thrombocytopenic purpura, monoclonal gammopathies)
Q. What is cytapheresis ?
A. Individual cellular components are harvested from whole blood by cell separator machine.
Q. Which cellular components can be collected through apheresis?
- Red cells (red cell apheresis) - red blood cells can be collected in acid citrate dextrose solution.
- Plateletpheresis- also called as single donor platelets (SDP). Platelets are separated from the whole blood and rest of the components is returned to the donor. The advantage of this procedure is HLA- matched platelets can be collected for patients who are refractory in random donor platelets due to development of anti-HLA antibodies. For frequent plateletpheresis platelet count should be ≥150x 109 per liter and donor should not have taken aspirin for atleast 36 hours before donation. Apheresis platelets can be leucoreduced (removal of white blood cells) during the procedure. One unit of SDP is equivalent to 5-6 units of Random donor platelets (RDP).
- Leucapheresis-collection of white blood cells by apheresis. This procedure is not widely used.
- Stem cell collection- haematopoietic stem cells can be collected from peripheral blood of the donor by apheresis for reconstitution of bone marrow in patients with blood cancers, aplastic anemia and haemoglobinopathies.
also read the original article on Plateletpheresis co-authored by me by clicking here
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