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تقنيات المعمل - Lab's techniques الخطوات المعملية و التقنيات و الاجهزه

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قديم 11-25-2007, 12:16 AM   #1
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Rose Blood transfusion safety

[size=3][align=left] Blood transfusion safety




Millions of lives are saved each year through blood transfusions. In many countries, however, people still die due to an inadequate supply of blood and blood products

This has a particular impact on women (as a consequence of pregnancy-related complications), children (malnutrition, malaria and severe life-threatening anaemia), trauma victims and, especially, the poor and disadvantaged

The emergence of HIV in the 1980s highlighted the importance of ensuring the safety, as well as the adequacy, of national blood supplies. In many countries, even where blood is available, many recipients remain at risk of transfusion-transmissible infections (TTIs) as a result of poor blood donor recruitment and selection practices and the use of untested units of blood

Every country has a common need to ensure

Availability of adequate supplies of blood and blood products and their accessibility to all patients requiring transfusion
Safety of blood and blood products
Safe and appropriate clinical use of blood and blood products

The WHO Blood Transfusion Safety (BTS) team supports the establishment of sustainable of national blood programmes that can ensure the provision of safe, high quality blood and blood products that are accessible to all patients requiring transfusion and their safe and appropriate use

In support of this mission, the WHO BTS team recommends the following integrated strategy to national health authorities

Establishment of a well-organized, nationally coordinated blood transfusion service that can provide adequate and timely supplies of safe blood for all patients in need

Collection of blood only from voluntary unpaid blood donors at low risk of acquiring transfusion-transmissible infections, and stringent blood donor selection criteria

Testing of all donated blood for transfusion-transmissible infections, blood groups and compatibility

Production of blood components to maximize the use of donated blood and enable the provision of therapeutic support for patients with special transfusion requirements

Appropriate clinical use of blood and the use of alternatives, where possible, to minimize unnecessary transfusions
Safe transfusion practice at the bedside

Comprehensive quality system covering the entire transfusion process, from donor recruitment to the follow-up of recipients of transfusion



Testing of donated blood




The first step in reducing the risk of transmission of infectious diseases through blood is to select voluntary non-remunerated donors from low-risk populations who give blood on a regular basis as these individuals are at a lower risk of transmitting transfusion-transmissible infections than are family/replacement donors, or paid donors. However, even with the most careful selection, some donors may be seropositive for HIV or other infectious agents. Therefore, rigorous screening of all donated blood is required to ensure the safety of the blood supply

Unfortunately, not all donations in all countries are screened. GDBS data from 1998–1999 indicated that, globally, 13 million tests were not performed for HIV, hepatitis B (HBV), hepatitis C (HCV) and syphilis. Data for 2000–2001 indicate an improvement in the number of tests performed for these markers, largely because a number of countries had introduced testing for HCV since the previous collection of data. Nevertheless, more than 6 million tests were not performed on donated blood for either HIV, HBV, HCV and syphilis. The donated blood should also be tested for ABO and RhD to ensure the safety and compatibility of the transfusion for the patient

In order to ensure safety of the blood supply, several key activities must be implemented

the development and implementation of a national strategy for the screening of all donated blood for transfusion-transmissible infections, using the most appropriate and effective assays to test for HIV, hepatitis viruses, syphilis and other infectious agents, such as Chagas disease

the training of blood transfusion service laboratory technical staff in all aspects of blood screening and processing including blood grouping, compatibility testing, component preparation and storage and transportation of blood products

Maintenance of quality assurance systems and good laboratory practice, including the use of standard operating procedures, in all aspects of blood screening and processing

Compatibility testing of all whole blood and red cells with the patient to be transfused must always be performed even if, in life-threatening emergencies, this is done after the transfusion has been completed

The procurement, supply, central storage and distribution of reagents and materials to ensure continuity in testing at all sites

The maintenance of an effective blood cold chain for the storage and transportation of blood and blood products

Finnish Red Cross

WHO encourages and supports countries, through provision of advice and training, in the development and implementation of these activities in accordance with their needs. Guidelines, recommendations and reports on testing strategies and appropriate test kit selection have been developed, a bulk procurement scheme for HIV test kits has been established, and external quality assurance programmes are being carried out in several regions. The EHT Diagnostics laboratory section covers these and other aspects of blood screening in more detail[/align]
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من مواضيع فارس البادية في المنتدى


التعديل الأخير تم بواسطة فارس البادية ; 11-25-2007 الساعة 12:23 AM
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ياســــــــــــر أحـــمـــــد

   
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قديم 11-25-2007, 12:21 AM   #2
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Rose

[align=left]Processing of donated blood


Blood is a complex fluid consisting of different blood cells suspended in yellowish liquid called plasma. The blood cells comprise a mixture of red cells (erythrocytes), white cells (leukocytes) and platelets (thrombocytes). The plasma contains water, chemical substances (electrolytes), many different proteins such as clotting (coagulation) factors and immunoglobulins and numerous metabolic substances. Blood serves as a transport medium for carrying all its different components to and from the different organs of the body


Blood collected in an anticoagulant can be stored and transfused to a patient in an unmodified state. This is known as ‘whole blood’ transfusion. Blood may be used more effectively if component therapy is practised. One unit of donated blood may be divided into components, including red cells concentrates, fresh frozen plasma, cryoprecipitates and platelet concentrates, to meet the needs of more than one patient





Advantages of component therapy are

the recipient can be treated with only those blood components that are lacking, reducing the occurrence of adverse transfusion reactions
more than one patient can be treated with blood components derived from one donation
therapeutic support for patients with special transfusion requirements can be provided, for example, plasma that often is not directly needed for transfusion can be used manufacturing of Factor VIII concentrate for Haemophilia A patients
improved quality and functional capacity of each components when varied storage conditions and shelf lives were applied

For a safe and effective blood component processing, the following elements are required





Commitment and support by national health authorities for a sustainable, well-organised, nationally co-ordinated blood transfusion service, with adequate resources and quality system for all areas

Centralisation of blood processing and testing within major centres to permit economies of scale by maximising utilisation of personnel and equipment and uniform standards

Reliable supply of materials and consumables
Well-maintained equipment and spares available to keep down-time to a minimum

Effective and timely testing of all donated blood to ensure maximum safety and availability of blood components

A system for appropriate storage and transportation to ensure quality and efficacy of blood and blood components

Optimisation of the use of plasma for fractionation where facilities are available

Promotion of appropriate blood component therapy[/align]



[align=left]Safe and appropriate use




Blood transfusion is an essential part of modern health care. Used correctly, it can save life and improve health. However, as with any therapeutic intervention, it may result in acute or delayed complications and carries the risk of transmission of infectious agents, such as HIV, hepatitis viruses, syphilis and Chagas disease

The inappropriate use of blood and blood products, coupled with the transfusion of unscreened or improperly screened units, particularly in countries with poor blood programmes, increases the risk of TTIs to recipients. It also widen the gaps between supply and demands and contributes to shortages of blood and blood products for patient requiring transfusion. Thus, it is necessary to reduce the unnecessary transfusions. This can be achieved through the appropriate clinical use of blood, avoiding the needs for transfusion and use of alternatives to transfusion

The transfusion is deemed appropriate when it is used to treat condition leading to significant morbidity and mortality that cannot be prevented or managed effectively by other means. The commitment of the health authorities, health care providers and clinicians are important in prevention, early diagnosis and treatment of diseases/ conditions that could lead to the need for blood transfusion

Key elements of effective clinical use of blood

Consistently effective clinical transfusion practice cannot be achieved unless the following elements are in place


well organized blood programme, coordinated at national level to guarantee safe, adequate and timely supply
a national blood policy that addresses the clinical use of blood, with appropriate supportive legal frameworks
a national committee on the clinical use of blood and hospital transfusion committees at local level to implement, regularly review and update the national policy and guidelines
national guidelines on the clinical use of blood to aid prescribers of blood in their clinical decisions about transfusion, based on systematic reviews of evidence on clinical effectiveness. The development of these guidelines requires involvement of blood prescribers from different clinical disciplines working together with the blood transfusion services. These guidelines should suit local situation
the availability of simple alternatives for transfusion (crystalloids and colloids) for the correction of hypovolaemia, and pharmaceuticals and medical devices to reduce blood loss
the education and training of clinician, nurses and blood transfusion service staff involved in the transfusion process
monitoring and evaluation of the implementation of the national policy and guidelines and the use of monitoring data in quality improvement and education programme to assist clinicians to improve their practice
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من مواضيع فارس البادية في المنتدى

   
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قديم 11-25-2007, 12:42 AM   #3
فارس البادية
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Rose

[align=left]
TRANSFUSION TRANSMITTED DISEASES



There are many Blood borne, transfusion transmitted and related diseases. , many are openly and commonly written about in the press, and spoken of on the news..... some are not. Following here is a partial and growing list of the most commonly known Blood transfusion transmitted diseases, but for which no routine cost-effective laboratory testing is available

Clerical errors also contribute to transfusion transmission of harmful agents. These types of errors include, among others, the release of unsuitable units of Blood; accidental transfusion of autologous Blood to another recipient (autologous Blood may include infectious disease); and errors in testing


Hepatitis B

Hepatitis B virus (HBV) is transmitted through parenteral and sexual exposure. The mean incubation time is 90 days with a range of 30 to 180 days. Donor Blood is routinely tested for HBsAg and HBcAb. There is no routine testing for hepatitis A, because it is said to be rarely transmitted by Blood products . Recipients of Blood products can also be infected with hepatitis delta, which is a defective RNA virus that needs an HBV superinfection to replicate. Persons who have received a hepatitis B vaccination (recommended for all health care workers with patient contact) will have hepatitis B surface antibody present, but not HBsAg or HBcAb

Hepatitis C

The hepatitis C virus (HCV) currently affects over four million people . This disease has reached epidemic proportions. It is the primary reason for liver transplantation. hepatitis C virus (HCV) infection is still the most common transfusion transmitted infection. Persons at highest risk for the virus are those who received blood transfusions prior to 1991 or people with a history of IV drug abuse using shared needles. One attribute of this disease that contributes to the high rate of infection, is that the time from infection with the virus until manifestation of liver disease can be decades. The hepatitis C virus subtype varies worldwide. In Europe, types 1, 2 and 3 are the predominant genotypes with types 1a and 3a in the north-western countries and 1b in Hungary, Germany, Russia and Turkey. In North America, types 1a and 1b have been found. In Japan and Taiwan, types 1b, 2a and 2b predominate; type 6a in Hong Kong and Macau. Type 4 is found in Zaire, Central and North Africa; 5a in South Africa. The hepatitis C virus is taken into the body other than through the digestive tract. It must be inherited, transfused or injected in some manner. The sexual transmission rate is lower than once thought. At present, only testing for hepatitis C antibody is available. The antibody to the hepatitis C virus appears 54 to 192 days in a person's Blood after infection. If an infected person donates Blood prior to the appearance of this antibody the chance of that Blood being used in a transfusion is said to be one out of 103,000 donations, There are an estimated 15-million Blood transfusions each year

Human Immunodeficiency Virus -HIV

In 1982 the first cases of AIDS transmitted from Blood or Blood components were reported, but little of the infection was known at that time, and even less was talked about publicly. By 1983 radical changes began to occur in the donor criteria to exclude those at high risk for transmission of HIV. The testing of Blood products for HIV started in 1985. It was a test to detect the presence of the antibody directed against HIV, rather than a direct test for HIV. Testing for HIV p24 antigen was mandated in 1996

Human T-lymphocytotrophic Virus /HTLV-1

This is a retrovirus that is endemic in Japan and the Caribbean. It is implicated as causing adult T-cell leukemia/lymphoma and a neurological disorder similar to multiple sclerosis. Blood is routinely screened for antibodies to HTLV-1 utilizing this relatively inexpensive test

HGV

The Hepatitis G Virus is an RNA virus of the Flaviviridae family. HGV infection was originally associated with fulminant hepatitis, but recent studies have failed to prove a connection between HGV and clinical illness. It is primarily Blood borne and accounts for 0.3% of acute viral hepatitis estimated at 900 to 2000 infections per year in the United States In many countries, 1% to 2% of Blood donors test positive for HGV RNA & the prevalence of HGV infection is up to 10% to 15% in West African children. How this high prevalence is maintained is unknown, but this does suggest that sub-clinical infection is common. Therefore, HGV infection is probably much more frequent than studies of the prevalence of HGV RNA suggest
The virus is transmitted by the same routes as HCV and co-infection is common, however, this may represent a common source of infection rather than any clinical similarity between the two viruses. The clinical significance of HGV infection and HGV-HCV co-infection remains to be fully elucidated, but at present does not seem to be a major disease-causing factor. The majority of patients infected with HGV by Blood transfusion do not develop serious chronic hepatitis

Cryoglobulinemia

Cryoglobulinemia is a term given to a disorder of the Blood and refers to the presence of cryoglobulins in the blood. These are abnormal forms of protein molecules that precipitate (clump together) at cold temperatures and re-dissolve at normal body temperature. Therefore, when a person with cryoglobulinemia is exposed to cold, he or she may experience decreased circulation in the smaller blood vessels. This may lead to color changes in the skin, damage to the extremities, bleeding into the skin (purpura), hives and other problems. The underlying cause of this condition may include diseases of the immune system, such as Waldstrom's macroglobulinemia, or its malignant form, multiple myeloma, and some infectious diseases, such as the hepatitis C virus. There are treatments for Cryoglobulinemia, such as cryofiltration, which has proven extremely effective in easing complications of this disease such as organ damage and skin ulcers

TTV - Transfusion Transmitted Virus

TTV - Transfusion Transmitted Virus is a relatively new virus becoming widely known in 1997 in patients with fulminant hepatitis and chronic liver disease of unknown etiology. TTV is an unenveloped, single stranded DNA virus. Two genetic groups have been identified, differing by 30% in nucleotide sequences. TTV DNA was detected in 47% of patients with fulminant non-A-G hepatitis and 46% of patients with chronic liver diseases of unknown etiology. The result suggests that TTV may be the cause of some cryptogenic liver diseases. In testing, the presence of TTV, was found in approximately 10% of U. S. volunteer Blood donors, 13% of commercial Blood donors, and 17% of intravenous drug abusers. The rate of TTV infection among U. S. non-A, non-B, non-C, non-D, non-E hepatitis patients was only 2%

Cytomegalovirus - CMV

Cytomegalovirus/ CMV - The prevalence of the CMV antibody ranges from 50% to 80% of the population. Blood contaminated with CMV can cause problems in neonates or immunocompromised patients. Potential problems in selected patient populations can be prevented by transfusing CMV negative Blood or frozen, deglycerolized RBC's. Donor Blood is not routinely tested for CMV

Creutzfeldt-Jakob Disease - CJD

Creutzfeldt-Jakob Disease (CJD) - A degenerative and fatal nervous system disorder. Affected individuals can remain asymptomatic for decades after infection and then progress rapidly to dementia, severe loss of coordination and death. We are told by the Blood establishment that the risk of CJD being transmitted through Blood products is 'theoretical.' The infectious agent has (yes, has) been found in Blood products
Transmission of CJD has been proven from human to human by the transplantation of dura mater, the injection of pituitary-derived human growth hormone, and more rarely by the reuse of EEG electrodes and corneal transplantation. Currently, there is no test for the disease, however, all Blood banking organizations in Europe, and now in the United States, prohibit Blood donation by individuals who have symptoms or a family history of symptoms. Blood donors are carefully questioned about family history of CJD and surgeries that involved transplanted dura mater. If they answer affirmatively to any of these questions, they are permanently deferred as a donor. We see here again the potential danger in the 'honor system' of Blood donation in the United States. There is no possibility of contracting CJD by making a normal Blood donation

KS and HHV

KS and HHV-8 - While there appears to be association between Kaposi’s sarcoma (KS) and human herpes virus-8 (HHV-8) and), it is said to be unproven whether or not the virus is transfusion transmitted. Also, if it is transfusion transmitted, is it associated with development of KS. Again we see here at this time, in our opinion, another case of under-researching, under-investigating and extremely under-reporting

Leishmaniasis

Cases of transfusion-associated Leishmaniasis are growing each year world wide. This increase is increasingly associated with patients who are positive for HIV. Transfusion-associated Leishmaniasis requires that the parasites be present in the peripheral Blood of the donor, survive processing and storage in the Blood bank, and infect the recipient. In endemic areas where the population of potentially infected individuals may be much higher and the screening process for donors less rigorous, transfusion-associated Leishmaniasis is more common. Leishmaniasis is now found in over 90 countries. Again here we see the fact of world travel by a diverse population, and the 'honor system' Blood donor screening process, and too expensive testing, all contribute to the increase of transfusion transmitted Leishmaniasis

Lyme Disease

Lyme disease is associated with the bite of the eastern deer tick, and can cause an illness that affects many systems within the body. Donors with a history of Lyme disease can not donate Blood unless they no longer have symptoms whatever, have undergone a full course of antibiotic treatment, and are cleared by a physician. Public health and Blood agencies are closely monitoring this disease

Malaria

The popular statement, routinely given is that "malaria is rarely transmitted by Blood products." The number of transfusion associated cases of malaria, however, is at an all-time high. There are no practical laboratory tests available to test donor Blood, so donors travelling to high risk malaria areas are often deferred from donating Blood for six months. This policy, however, is not evenly applied in all areas and, believe it or not, depends on the honor system to work

Chagas Disease

Discovered a century ago by Brazilian doctor Carlos Chagas, this disease, properly named Chagas' Disease, is caused by a parasite that infects an estimated 18 million people worldwide, causing death from heart and digestive problems. Up to 20% of infected people never exhibit symptoms. Because of recent shifts in population, individuals from countries where this disease is common are migrating in large numbers to the United States and other countries

Babesiosis

An intraerythrocytic parasitic infection caused from the bite of the infected Ixodes tick. The disease closely resembles in some ways Lyme Disease, and in other ways, malaria. This significantly affects the hematological system, causing among other things, hemolytic anemia, thrombocytopenia, and atypical lymphocyte formation. The transmitted parasite only infects red Blood cells by altering the cell membranes that causes decreased conformability and increased red cell adherence, which, in turn, can lead to development of acute respiratory distress syndrome (ARDS) among those severely affected. Babesia parasites invade and survive within erythrocytes. These Blood-borne parasites remain viable under Blood bank conditions. In Europe, Babesiosis is a life-threatening disease and is a significant public health problem in regions of the northeastern United States. Of patients with Babesiosis, 84% are asplenic, and 53% become comatose and die. Those individuals with a history of the disease are to be permanently deferred from donating Blood, if they know and admit before Blood donation that they have carried the malady

Toxoplasmosis

A systemic protozoan infection that causes symptoms similar to infectious mononucleosis. In immunocompromised individuals this infection can have serious neurological symptoms and can cause fetal death in pregnant women. Toxoplasmosis is also transmitted by common house cats

Bacterial Contamination of Blood Products

This is another less often observed risk disorder directly associated with Blood transfusion. It is increasingly rare but a very serious complication of Blood transfusion. Most commonly associated with contamination during Blood collection or during handling of Blood products, such as preparation of platelet pools, and on occasion, associated with bacterial infection of the donor, it is sometimes recognizable by obvious changes in the appearance of the Blood product. Studies indicate that the rate of contamination of Blood products by bacterial pathogens may be significant. Since Blood recipient death continues to occur, in 1997, the CDC entered into an agreement with national Blood collection and distribution agencies to determine the frequency of transfusion reactions associated with bacterial contamination of Blood products. The new study will be a critical step in addressing this issue and will increase clinicians' awareness of bacterial contamination as a cause of transfusion reactions. Currently, the nation's Blood supply is not screened for bacterial contamination. Amazingly, when this contamination issue is raised, Blood donor deferral is merely recommended, and not mandatory [/align]



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قديم 12-03-2007, 04:57 PM   #5
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افتراضي رد: Blood transfusion safety

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قديم 12-11-2007, 12:42 AM   #6
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افتراضي رد: Blood transfusion safety

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