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Background Information and justification

Platelet apheresis is a method of collecting platelets performed by a device which separate platelets and return the rest of blood to the donor in a safely manner. Donor should be connected to the apheresis machine through the sterile tubing system with the help of a large bore needle.  After removing blood from the donor using a large bore needle, a measured amount of anticoagulant (Citrate) is mixed to prevent the coagulation. Then it is transferred to the place where the separation is taken place, either the centrifugation bowl, chamber or belt. The same principle is applied in apheresis as for the blood component preparation by the whole blood. Based on specific gravity and the weight of the constituents’ separation of blood components is done. While the platelets are diverted to the temporary storage remaining elements are returned to the donor by intermittent or continuous flow. (Modern332)

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Although platelet aphaeresis procedures are well tolerated than whole blood donations significant level of adverse events (AEs) occur during and after the procedure. Those AEs can be severe in apheresis procedures but are less often with comparison to the whole blood donations. AEs to apheresis procedures can be categorized as systemic or local.

Citrate toxicity is known to be the most frequent systemic reaction in apheresis occurs as a result of the anticoagulant acid- citrate-dextrose. Citrate chelates ionized calcium in the blood which is an essential factor for coagulation, platelets aggregation. Usually infused citrate is metabolized by the liver, kidneys and muscles and also diluted in intra cellular and extra cellular fluid allowing the release of bound calcium to the blood stream. In addition to that para thyroid hormone is released in response to decreased calcium levels. Despite these compensatory mechanisms certain individuals experience hypocalcaemic symptoms like perioral tingling and parasthesia, chills, nausea, twitching, tremors or severe symptoms such as  carpopedal spasms, seizures, tetany and cardiac arrhythmias.

Vaso vagal reaction can be triggered by the anxiety and tension for the undergoing procedure or due to the pain causes by the venepuncture. It is characterized by the pallor, sweating, dizziness, nausea, hypotension and syncope. 

 Local reactions include hematomas, brusing and phlebitis as a result of defective venepuncture and irritation or allergy to needles. 

Adverse effects due to platelet apheresis are mostly under reported. Most of the platelet apheresis donors are regular donors and they frequently experience mild hypocalcaemic symptoms like perioral tingling, paresthesia due to citrate toxicity. These symptoms tend to be a normal phenomenon for them with regular donations and ultimately they don’t complain as adverse effects, therefore those adverse effects are under reported. This will put healthy donors in great danger as these mild reactions can lead in to severe reactions like arrhythmias. And importantly there is evidence in reducing bone marrow density in recurrent exposure to citrate as an anticoagulant. Therefore detecting each and every reaction values safety of donors.

No study has yet been carried out in Sri Lanka relevant to adverse effects in platelet apheresis. The scarcity of studies done elsewhere in the world, demands for more research as to improve the donor safety and to promote apheresis procedures. Addressing and reporting of each and every adverse event lies a greater importance in ensuring the donor safety and stabilizing the donor pool.

 

Objectives

General Objective

To assess the occurrence and probable risk factors of acute adverse effects in platelet apheresis donations in National Blood Center and identify corrective measures

Specific objectives

·         To assess the frequency of adverse events due to platelet apheresis donations

·         To evaluate donor variables as potential risk factors for different types adverse events (AEs) during apheresis collections

·         To assess the knowledge and attitude on adverse effects of apheresis procedures in platelet apheresis donors

·         To identify the frequency of underreported adverse events as a result of the tolerance by the donors

·         To identify corrective measures for better detection and minimize the donor adverse effects

 

Methods

 

This will be a prospective, descriptive cross sectional study of all adverse reactions related to platelet apheresis donations in the National Blood Center in Sri Lanka. The ethical clearance will be taken from the ethical committee in the National Blood Center and if the data is published in the future the permission will be taken from the Director, National Blood transfusion Service Sri Lanka.  

 

All platelet apheresis donations will be assessed in three separate apheresis instruments. Those are single needle intermittent flow type of cell separators namely Amicus, Heamonitics MCS+ and the Spectra Optia. All donations will be collected using 16 gauze needle inserted into a vein in the antecubital fossa, with all aseptic precautions. Donors were selected as per the set criteria for single donor platelet preparation according to A to Z guidelines:

•        Weight 50 kg or more

•        Age between 18 to 55 years (60 if it is a regular donor)

•        Hb more than 12.5 g/dl

•        Donors who have taken aspirin containing medication within 36 hours are usually deferred

•        Interval between procedures should be at least 48 hours. A donor shall not undergo the procedure more than 2 times in a week or 24 times in a year.

•        Platelet count >200*10*6

•        Absence of any illness.

•        Negative test for HIV, hep. B, HCV, syphilis, malaria

 

 

 

After each procedure every donor will be given a questionnaire as to question about the experience of adverse effects during and after the procedure if any and to assess the knowledge about the adverse effects of the procedure.  The questionnaire will be evaluated by a pilot study.  

The questionnaires are analyzed and wil

 

Winters, Jeffrey. (2006). Complications of Donor apheresis. Journal of clinical apheresis. 21. 132-41. 10.1002/jca.20039.

Mehran Monchi, Citrate pathophysiology and metabolism, In Transfusion and Apheresis Science, Volume 56, Issue 1, 2017, Pages 28-30, ISSN 1473-0502, https://doi.org/10.1016/j.transci.2016.12.013.

 

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