Plateletpheresis
Plateletpheresis | |
---|---|
ICD-10-PCS | 6A550Z2, 6A551Z2 |
ICD-9-CM | 99.05 |
MeSH | D010983 |
Plateletpheresis (more accurately called thrombocytapheresis or thrombapheresis, though these names are rarely used) is the process of collecting
Platelet transfusion
In adults, platelets are recommended in those who have levels less than 10,000/µL, or less than 20,000/µL if a central venous catheter is being placed, or less than 50,000/µL if a lumbar puncture or major surgery is required.[1]
Whole blood platelets
Not all platelet transfusions use platelets collected by automated apheresis. The platelets can also be separated from donations of
Collecting the platelets from a single donor also simplifies human leukocyte antigen (HLA) matching, which improves the chance of a successful transfusion. Since it is time-consuming to find compatible donors for HLA-matched transfusions, collecting a full dose from a single donor is more practical than finding multiple compatible donors.[citation needed]
Plateletpheresis products are also easier to test for bacterial contamination, a leading cause of transfusion-associated deaths.[citation needed] Pooling of whole blood platelets is often done in an "open" system where the platelet containers are connected in a way that could expose the platelets to air, and pooled platelets must be transfused promptly so that any contamination does not have time to grow.[citation needed]
Problems with apheresis include the expense of the equipment used for collection. Whole blood platelets also do not require any additional donor recruitment, as they can be made from blood donations that are also used for packed red blood cells and plasma components.[citation needed]
Thrombocytopenia due to underproduction
Recipients in this category include those undergoing chemotherapy, those with
Immune thrombocytopenia
Recipients in this category include those with idiopathic thrombocytopenic purpura or drug-induced thrombocytopenia. Platelet transfusions are generally not recommended for this group of patients because the underlying cause involves antibodies that destroy platelets, therefore any newly transfused platelets will also be destroyed. Platelet transfusion may be used in emergency bleeding situations where the platelets could be used by the body before the immune system destroys them.
Altered platelet functions
Disorders of platelet function can be congenital or acquired. Most of these disorders are mild and may respond to therapy with
Cardiopulmonary bypass surgery
Drug-induced platelet dysfunction
The most common of these is
Expected platelet increase after transfusion
Platelet count increase as well as platelet survival after transfusion is related to the dose of platelets infused and to the patient's body surface area (BSA). Usually these values are less than what would be expected.
- Corrected platelet count increment (CCI) = platelet increment at one hr x BSA (m2) / # platelets infused x 1011
- Expected platelet increase (per μL) = platelets infused x CCI / BSA (m2)
The theoretical value of the CCI is 20,000/μL but clinically, the value is closer to 10,000/μL. If the CCI is less than 5,000/μL, patients are said to have "refractoriness" to platelet transfusion.
Platelet collection
The separation of individual
Modern automatic thrombapheresis allows blood donors to give a portion of their platelets, while keeping their
Because platelets have a shelf life of just five days, more platelet donors are always needed. Some centers are experimenting with seven-day platelets, but this requires additional testing and the lack of any preservative solutions means that the product is far more effective when fresh.
Even though red blood cells can also be collected in the process, many blood donation organizations do not do so because it takes much longer for the human body to replenish their loss. In addition, some (though not all) centers defer further platelet donations until the red blood cells can be replenished.
In most cases, blood plasma is returned to the donor as well. However, in locations that have plasma processing facilities, a part of the donor's plasma can also be collected in a separate blood bag (see plasmapheresis). For example, in Australia around 5.9×1011 platelets and 580 mL of plasma might be collected from an 88 kg donor.
Leukoreduction
Due to their higher relative density, white blood cells are collected as an unwanted component with the platelets. Since it takes up to 3 liters of whole blood (the amount of a dozen blood bags) to generate a dose of platelets, white blood cells from one or several donors will also be collected along with the platelets. A 70 kg (154 lb) man has only about 6 liters of blood. If all of the incidentally collected white blood cells are transfused with the platelets, substantial rejection problems can occur. Therefore, it is standard practice to filter out white blood cells before transfusion by the process of leukoreduction.
Early platelet transfusions used a filter to remove white blood cells at the time of transfusion. It takes a trained person about 10 minutes to assemble the equipment, and this is not the safest or most efficient means of filtration because living white blood cells can release cytokines during storage and dead white blood cells can break up into smaller fragments that can still stimulate a dangerous response from the immune system. In addition, simple filtration can lead to increased risks of infection and loss of valuable platelets. Newer, more advanced thrombapheresis machines can filter white blood cells during separation.[citation needed]
For example, with marginally acceptable whole blood (white blood cells: < 10,000/mm³; platelets: > 150,000/mm³), a dose (3×1011) of platelets comes with about 2×1010 white blood cells. This can seriously damage the patient's health. A dose of single-donor platelets prepared using latest filters can contain as little as 5×106 white blood cells.
Apheresis
There are two types of manual platelet apheresis. Platelet-rich plasma (PRP) is widely used in North America and buffy coat (BC) is more widely used in Europe.
The basic principles of automatic platelet apheresis are the same as in the manual procedure, but the whole procedure is performed by a computer-controlled machine. Since the donor's blood is processed in a sterile single-use centrifuge, the unwanted components can be returned to the donor safely. This allows the apheresis machine to repeat the draw-centrifuge-return cycle to obtain more platelets. The bulk of the machine and the length of the donation process means most platelet donations are done in blood centers instead of mobile blood drives.
Each country has its own rules to protect the safety of both donor and recipient. In a typical set of rules, a platelet donor must weigh at least 50 kg (110 lb) and have a platelet count of at least 150 x 109/L (150,000 platelets per mm³).[2]
One unit has greater than 3×1011 platelets. Therefore, it takes 2 liters of blood having a platelet count of 150,000/mm³ to produce one unit of platelets. Some regular donors have higher platelet counts (over 300,000/mm³); for those donors, it only takes about one liter of their blood to produce a unit. Since the machine used to perform the procedure uses suction to draw blood out of a donor's body, some people who can give whole blood may have veins too small for platelet donation.
Blood accounts for about 8% of body weight, so a 50 kg (110 lb) donor has about four liters of blood. No more than 50% of a donor's platelets are ever extracted in one sitting, and they can be replenished by the body in about three days.
Most newer apheresis machines can separate a maximum donation of platelets in about 60 to 120 minutes depending on the donor's health condition.
Platelet donation
After a short
Side effects of the donation of platelets generally fall into three categories: blood pressure changes, problems with vein access, and effects of the anticoagulant on the donor's calcium level. Blood pressure changes can sometimes cause nausea, fatigue, and dizziness. Venous access problems can cause bruising, referred to as a
Aside from the procedure, donating platelets is different from donating blood in a few ways.
Firstly, the donor must not take aspirin or other anti-platelet medications such as clopidogrel (Plavix) for anywhere from 36 to 72 hours prior to donation (guidelines vary by blood center). (Aspirin can prevent platelets from adhering to clot bleeding.) Some blood centers also prohibit the taking of any non-steroidal anti-inflammatory drug (NSAID) for 36 hours prior.
Secondly, platelet donations are allowed anywhere from every 3 to 28 days. This is in contrast to whole-blood donation, which has an eight-week (or longer) waiting period. Along those lines, since platelet donation temporarily removes whole blood from the body, it may be necessary to wait eight weeks after a whole blood donation to donate platelets, although two weeks is more common. In the US, a donor is allowed to donate platelets every seven days, but not more than 24 times during any 365-day period and may not lose more red blood cells or plasma during that period than they would from the maximum allowable number of whole blood donations.[3] In India, as per Ministry of Health, the blood donation interval criteria for apheresis requires at least 48 hours interval after platelet- or plasma-apheresis. Any donation should not be done more than two times a week and should be limited to 24 times in one year.[4][5]
Thirdly, additional tests may be required before becoming a donor for the first time. These tests may establish a platelet count. Newer automated platelet pheresis machines do that as the donation begins, and adjust accordingly the quantity of platelets to be drawn. Tests may also determine the donor's compatibility with particular recipients through a
Adverse events
Adverse conditions that can happen during a plateletpheresis donation are
Vein scarring
Repeated platelet donations at short intervals will cause the venipuncture site to scar. While cosmetically it is virtually invisible, the scarring also occurs on the vein itself, making it harder to insert a needle on future occasions. Anecdotal reports have said that rubbing vitamin E oil (or the insides of a vitamin E capsule) on the venipuncture site may reduce scarring. [citation needed] However, a study conducted by the University of Miami Department of Dermatology and Cutaneous Surgery in 1999 demonstrated no positive effect from the application of topical vitamin E.[7]
See also
References
- S2CID 13276003.
- ^ "Criteria for acceptance of donors". Retrieved 2008-02-25.
- ^ "Guidance for Industry and FDA Review Staff-Collection of Platelets by Automated Methods". US Food and Drug Administration. December 2007. p. 6. Retrieved 3 July 2023.
- ^ "Everything you need to know before donating blood". The Times of India. 13 June 2019. Retrieved 2020-05-16.
- ^ "Guidelines for Blood Donor Selection and Blood Donor Referral" (PDF). Govt. of India, Ministry of Health & Family Welfare, National Blood Transfusion Services. Oct 11, 2017.
- PMID 23830186. Retrieved 2013-09-19.
- PMID 10417589.
Further reading
- Stroncek DF, Rebulla P (2007). "Platelet transfusions". Lancet. 370 (9585): 427–38. S2CID 27840543.
- Circular of Information for Blood Products, page 32 (page 35 of the PDF)