BLOOD TRANSFUSION SAFETY
There are three pillars of transfusion safety:
- A donor selection – voluntary non-remunerated donors, screened by questionnaire and interview for behaviour and medical risk factors.
- Donation testing – serology and future nucleic acid testing for known transmissible diseases.
- Patient identification and monitoring – the greatest risk of severe morbidity or mortality is due to ABO incompatible blood due to incorrect patient or sample identification.
There are three pillars of transfusion safety:
- Optimise patient haemoglobin and red cell mass.
- Minimise blood loss and gain haemostasis.
- Optimise patient tolerance to anaemia.
1.1 PATIENT BLOOD MANAGEMENT
Patient blood management (PBM) is the timely application of evidence-based medical and surgical concepts designed to maintain haemoglobin concentration, optimise haemostasis and minimise blood loss in an effort to improve patient outcomes. A patient focus in all aspects of health care is important and is equally relevant to transfusion practice. Defining the patient needs helps define the safety, decision making and administration standards for the use of blood and blood products in Cambodia.
1.2 BLOOD TRANSFUSION SAFETY
Blood transfusion is an essential part of modern health care. Used correctly, it can save life and improve health. However blood is expensive, and as with any therapeutic intervention, may result in acute or delayed complications. Transfusion carries a risk of transmission of infectious agents, such as HIV, hepatitis viruses, syphilis and Chagas disease.
Donor selection is the first step in transfusion safety. WHO/BCT/BTS has developed guidelines and recommendations based on World Health Assembly Resolution 28.72 of 1975, which urges Member States to develop national blood transfusion services based on voluntary non-remunerated blood donation.
The risks associated with transfusion can only be avoided by close collaboration between the National Blood Transfusion Centre (NBTC) and clinicians in managing the components of the transfusion process for which they are each responsible:
- An adequate supply of safe blood and blood products.
- The effective clinical use of blood and blood products.
Safe and adequate supplies of blood are dependent on the implementation of an integrated strategy for blood safety:
- The establishment of well-organized, nationally-coordinated blood transfusion service, with quality systems in all areas.
- The collection of blood only from voluntary non-remunerated donors from low-risk populations.
- The screening of all donated blood and blood products for transfusion transmissible infections (TTIs), including the human immunodeficiency virus (HIV), hepatitis viruses, syphilis and other infectious agents, and good laboratory practice in all aspects of blood grouping, compatibility testing, component preparation and the storage and transportation of blood
- A reduction in unnecessary transfusions through the appropriate clinical use of blood and blood products, and the use of alternatives to transfusion, wherever
1.3 BLOOD AND BLOOD PRODUCT SAFETY
A prerequisite for the effective clinical use of blood is a well-organized blood transfusion service (BTS) that is able to provide blood and blood products that are safe, accessible at reasonable cost and adequate to meet national needs.
Only blood which has been obtained from appropriately selected low-risk voluntary non-remunerated donors and has been screened for transfusion-transmissible infectious agents, in accordance with national requirements, should be issued for transfusion.
Prior to each donation the potential donor is selected according to national / international suitability guidelines. This means that the potential donor completes a questionnaire that is focused on risk behaviour. Further the donor’s health is checked to minimize the risk for the donor as well as the recipients. Potential donors with increased risk of infectious diseases, like hepatitis or AIDS are requested not to donate blood anymore.
Each unit of donor blood (donation) needs to be tested for:
- hepatitis B surface antigen (HBsAg),
- antibodies against Treponema pallidum (TP),
- antibodies against hepatitis C virus (HCV), and
- antibodies against human immune deficiency virus type 1 and 2 (HIV-1/2).
The following tests should be performed where feasible:
- antibodies against human T-cell lymphotrophic virus type I and II (HTLV-I and II),
- other viral and parasite antibody testing where appropriate eg Malaria, Chagas disease, and
- bacterial testing of platelets.
Nucleic acid amplification tests (NAT) are designed to narrow the infection window phase however they are not currently available in Cambodia:
- HCV RNA (HCV NAT)
- HBV DNA (HBV NAT)
- HIV DNA (HIV NAT)
Only units that are negative to required tests are released for distribution. In rare cases of medical urgency it might be considered appropriate to release products based on the results of the previous (historic) tests. In these rare occasions a medical statement from the clinician, including patient consent when possible, is mandatory.
Currently not available in Cambodia are specific pathogen reduction technologies and timed quarantine methods. Further increase of the safety by application of specific virus inactivation methods is at the moment not yet possible for erythrocytes and platelets. The restricted expiry time makes the application of a quarantine method to increase the safety, impossible. The safety of plasma for transfusion purposes is increased by application of a quarantine policy or a virus inactivation method.
The pillars of safety to minimize pathogen transmission are:
- a reliable, stable voluntary non-remunerated and regular, donor system,
- appropriate suitability testing (donor selection),
- proper documentation, and
- standardized laboratory testing.
Together these minimize the risk of infection with blood transmissible infectious agents.
1.3.1 Whole blood donation
Male donors may give blood 4 times per year, female donors 3 times per year.
The standard in Cambodia is 350 mL blood, collected in 49 mL sodium citrate, phosphate-dextrose-adenine (CPDA-1) anticoagulant / preservation solution. Currently most blood is stored as whole blood in CPDA-1. Whole blood, stored at 20–24º C, can also be further processed within 24 hours into blood components. Blood components produced from whole blood are erythrocytes, platelets and plasma. The plasma is frozen and stored below –30ºC as Fresh Frozen Plasma. Pooled plasma can be manufactured into products such as albumin and immunoglobulins.
Platelets are usually isolated from platelet rich plasma after centrifugation of whole blood.
Blood donation by apheresis is not yet available in Cambodia. The apheresis process allows the collection of single components e.g. plasma or platelets, with the return of non-collected components to the donor. In this way a relatively large amount of one component can be harvested from one donor.
1.4 PRODUCT LABEL
Each blood product (in-process, intermediate and finished product) must be labelled with a product label containing at least the following information:
- unit identification number (donation number),
- product identification,
- producer identification (blood establishment),
- collection date,
- expiry date / time,
- ABO blood group and RhD type,
- test information (tested and found negative),
- possible other typing (eg c, E and K), and
- possible modifications (eg irradiation/leukocyte depletion/washing).
Units used for autologous or directed (specific for a special patient) transfusion are provided with a label on which this is specifically indicated.
1.5 PATIENT IDENTIFICATION
There must be a robust mechanism for positive patient identification (ID). This is very important for transfusion practice but is also important for pharmaceuticals, surgery and other aspects of health care.
All patients should be identified on admission and by their full name and at least 2 other identifiers. These could include:
- full name,
- age or date of birth,
- full address,
- hospital identification number, and
- government issued ID (preferably photo ID).
Prior to any medical intervention (e.g. sample collection, transfusion) the patient should be identified by their full name and at least one other identifier, usually age, date of birth or hospital identification number (if wristbands are used).
If a patient is unconscious or cannot provide verbal confirmation of identity, a family member may be used to confirm identification. If no family member is available, each hospital needs to have a policy and procedure in order to provide a temporary identification to a patient. This temporary identification must be used for all patient identification, sample collection and transfusion.
1.6 TRANSFUSION SAFETY
The recipient of a transfusion may experience adverse events unrelated to transmissible disease risk. All adverse events require specific clinical management.
Immune based transfusion adverse events may be immediate or delayed:
- Haemolytic transfusion reaction - most commonly due to ABO mismatch caused by patient identification or clerical mistakes. In many countries this is the most common fatal transfusion reaction.
- Allergy - mild urticaria is relatively common and life-threatening anaphylaxis is rare.
- Febrile non-haemolytic transfusion reactions are due to residual leucocytes and cytokines in the blood components.
- Transfusion related acute lung injury (TRALI) is the leading cause of transfusion mortality in some countries. It is characterized by acute respiratory failure and radiological changes within 6 hours of a transfusion.
- Haemolysis due to antibodies to transfused antigens.
- Post-transfusion purpura is characterized by thrombocytopenia within 2 weeks of a transfusion due to anti-platelet antibodies.
- Transfusion associated graft versus host disease is rare and due to engraftment of donor lymphocytes into a patient.
Non-immune adverse events include bacterial sepsis, circulatory overload and iron overload.