Apheresis is a medical technology in which a person's blood is passed through an apparatus that separates one particular constituent and returns the rest to the circulation. Blood is filtered to remove stem cells. Thus it is an extracorporeal therapy.
Video Apheresis
Method
Depending on the substance being removed, different processes are used in apheresis. If separation by density is required, centrifugation is the most common method. Other methods involve absorption into beads coated with absorbent and filtration materials.
The centrifugation method can be divided into two basic categories:
Continuous flow centrifugation
Continuous flow centrifugation (CFC) historically requires two venipunctures because "continuous" means blood is collected, spun, and returned simultaneously. The newer system can use one venipuncture. The main advantage of this system is the low extracorporeal volume (calculated on the basis of apheresis space volume, donor hematocrit, and total donor blood volume) used in the procedure, which may be beneficial to parents and children.
Intermittent flow centrifugation
Intermittent flow centrifugation works in cycles, draws blood, spins/processes it and then returns unused portions to donors in boluses. The main advantage is the single venipuncture site. To stop the blood from coagulation, anticoagulants are automatically mixed with blood when pumped from the body into the apheresis machine.
Centrifugation variable
The centrifugation process itself has four controllable variables to selectively remove the desired components. The first is the rotational speed and the diameter of the bowl, the second is the "sitting time" in the centrifuge, the third is the added solute, and the fourth is not easily controlled: the plasma volume and the donor cellular content. The final product in most cases is a classical blood sample deposited with RBC at the bottom, platelet spreader layer and WBC (lymphocytes/granulocytes, PMN, basophils, eosinophils/monocytes) in the middle and plasma above.
Maps Apheresis
Type
There are many types of apheresis.
Donations
Blood taken from a healthy donor can be separated into its component parts during a blood donor, in which the required components are collected and the "unused" component is returned to the donor. Fluid replacement is not usually required in this type of collection. There are many categories of component collections:
- Plasmapheresis - blood plasma. Plasmapheresis is useful in collecting FFP (fresh frozen plasma) from certain ABO groups. Commercial uses other than FFP for this procedure include immunoglobulin products, plasma derivatives, and rare WBC and RBC antibody collections.
- Erythrocytapheresis - red blood cells. Erythrocytapheresis is the separation of erythrocytes from whole blood. This is most often done using centrifugal sedimentation methods. This process is used for red blood cell disease such as sickle cell crisis or severe malaria. The procedure for collecting red blood cells automatically to donate erythrocytes is referred to as 'Double Reds' or 'Double Red Cell Apheresis.'
- Plateletpheresis (thrombapheresis, thrombocytapheresis) - blood platelets. Plateletpheresis is a platelet collection by apheresis when restoring red blood cells, leukocytes, and plasma components. Results are usually equivalent to between six and ten random platelet concentrations. Quality control requires platelets of apheresis equal to or greater than 3.0 ÃÆ'â € "10 11 in quantities and has a pH equal to or greater than 6.2 in 90% of the product tested and must used in five days.
- Leukapheresis - leukocytes (white blood cells). Leukopheresis is the removal of PMN, basophils, eosinophils for transfusion to patients whose PMN is ineffective or when traditional therapy has failed. There is limited data to suggest the benefits of granulocyte infusion. Complications of this procedure are difficulty in collection and short shelf life (24 hours at 20 to 24 ° C). Because the "buffy coat" layer is directly above the RBC layer, HES, the sedimentary agent, is used to improve yield and minimize RBC collection. Quality control requires the concentrate produced to be 1.0 ÃÆ'â € "10 10 granulocytes in 75% of the units tested and that the product is irradiated to avoid graft-versus-host disease (debilitating lymphocytes). Irradiation does not affect PMN function. Because there is usually a small amount of red blood cells collected, ABO compatibility should be used when feasible.
- Stem cell removal - circulating bone marrow cells are harvested for use in bone marrow transplantation.
Donor security
- Single use device - Apheresis is performed using a disposable device, so there is no risk of infection from blood-contaminated tubing or centrifuges.
- Immune system effects - "an immediate decrease in the number of blood lymphocytes and serum immunoglobulin concentrations are mild to moderate and with no known side effects • Lack of available information on long-term changes of the immune system"
Troubleshooter
The two apheresis kits are:
- Baxter Healthcare Corporation (2005), where "pinhole leakage is observed at the omega-two ends of the umbilicus (multilange tubing), causing blood leakage."
- Included Filenames (2007), where there are "two examples where the anticoagulant citrate dextrose (ACD) and inverted copy lines are in assembly process.Inverse line connections may not be visually obvious in the monitor box, and may produce an ACD infusion excessive and severe injuries, including death, to donors. "
Plasticizer exposure
Apheresis uses plastic and tubing, which come into contact with blood. Plastic is made of PVC in addition to additives such as plasticizer, often DEHP. DEHP dissolves from the plastic into the blood, and people begin to study the possible effects of this washed DEHP on donors and transfusion recipients.
- "current risk or prevention limit values ​​for DEHP such as RfD from US EPA (20 μg/kg/day) and EU TDI (20-48 μg/kg/day) may be exceeded on plateletpheresis day... Especially women in their reproductive age need to be protected from the exposure of DEHP beyond the above mentioned preventive limits. "
- "Disposable commercial plateletpheresis releases large amounts of DEHP during the apheresis procedure, but the total dose of DEHP stored by the donor is within the normal range of exposure to DEHP from the general population."
- The Baxter Company produces blood bags without DEHP, but there is little demand for products on the market
- "Means DEHP dose for both plateletpheresis techniques (18.1 and 32.3 g/kg/day) approach or exceed the reference dose (RfD) of US EPA and the tolerable daily intake value (TDI) of the EU days of apheresis. Therefore, safety margins may not be sufficient to protect especially young men and women in their reproductive age from the effects on reproductivity. Currently, intermittent flow devices should be preferred to avoid possible health risks from platelet pheresis donors. avoid exposure to donor DEHP during apheresis needs to be developed. "
Therapy
Various apheresis techniques can be used when the released constituents cause severe disease symptoms. In general, apheresis should be done quite frequently, and is an invasive process. It is therefore only used if other ways to control certain diseases have failed, or symptoms that are such that waiting for the drug to be effective will cause the suffering or risk of complications.
- Plasma exchange - removal of fluid portion of blood to remove harmful substances. Plasma replaced with replacement solution.
- apheresis LDL - removal of low density lipoproteins in patients with familial hypercholesterolaemia.
- Photopheresis - used to treat graft-versus-host disease, cutaneous T-cell lymphoma, and rejection in a heart transplant.
- Immunoadsorbtion with Staphylococcal A-agarose protein - removal of allo- and autoantibodies (in autoimmune diseases, transplant rejection, hemophilia) by directing plasma through the A-agarose protein column. Protein A is a cell wall component produced by several Staphylococcus aureus strains binding to the Fc region of IgG.
- Leukocytapheresis - removal of malignant white blood cells in people with leukemia and very high white blood cell counts that cause symptoms. Erythrocytapheresis - removal of erythrocytes (red blood cells) in people with iron overload as a result of hereditary haemochromatosis or transfusional iron surplus
- Thrombocytapheresis - the removal of platelets in people with symptoms of extreme increases in platelet counts such as those with essential thrombocythemia or polycythemia vera.
Evidence-based guidelines for therapeutic apheresis
In 2010, the American Society for Apheresis published the 5th Special Edition (1) evidence-based guidelines for the practice of Apheresis Medicine. These guidelines are based on a systematic review of available scientific literature. The clinical utility for a particular disease is denoted by the assignment of ASFA Categories (I - IV). The quality and strength of the evidence is represented by a standard GRADE recommendation. The ASFA category is defined as follows:
- Category I for the disorder in which apheresis therapy is accepted as first-line treatment,
- Category II for the disorder in which apheresis therapy is accepted as second-line treatment,
- Category III for the disorder in which the optimal role of apheresis therapy is not clearly defined and
- Category IV for the disorder in which apheresis therapy is considered ineffective or dangerous.
Liquid replacement during apheresis
When the apheresis system is used for therapy, this system removes a small amount of liquid (not more than 10.5 mL/kg body weight). The fluid must be replaced to keep the intravascular volume correct. The different fluids are replaced at different institutions. If crystalloids such as normal saline (NS) are used, the amount of infusion should triple what is removed because a 3: 1 ratio of normal salt for plasma is needed to keep the oncotic pressure. Some institutions use normal serum albumin, but they are expensive and hard to find. Some supporters use fresh frozen plasma (FFP) or similar blood products, but there are dangers including citrate toxicity (from anticoagulants), ABO incompatibilities, infections, and cellular antigens.
See also
- Leukoreduction
- Plasmapheresis
- Venipuncture
References
External links
- NIH
- American Society for Apheresis
- Apheresis in Platelet Blood Donor
- WebPath Apertment page.
- WebPath Blood Donor and Processing
- Donate Plather Apheresis: Facts and FAQs
Source of the article : Wikipedia
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