31 October, 2011

Blood Transfusions

What is a transfusion?

Transfusion is a therapeutic procedure involving the intravenous injection to a person of a considerable amount of blood from a donor. For this to be made ​​with efficiency and safety is very important to note a number of clinical and laboratory procedures, from the time the blood is obtained from the donor to the recipient that is injected, to ensure maximum therapeutic benefit and minimum possible risk.

Stock and blood samples
The transfusion today is an extremely safe procedure

The donation

represents the solidarity gesture to donate a small part of our blood (which is no more than 10% of the total blood in our bodies) to benefit those in need is still necessary today while it is not possible to replace this precious tissue body.

When a person decides to donate their blood should be directed to a blood bank of a hospital or mobile unit donated scavenging on the streets. There shall be informed of the basic profile must have a suitable donor will be recognized medically and be asked about whether it meets basic conditions, or if instead it has some feature that makes it inadvisable donation. You will be asked to fill in this form where it reviews the conditions and requirements. This first phase is necessary to exclude persons who may reasonably doubt about their suitability as donors.

The donor's right conditions are regulated by law in all countries. In Spain you can summarize the basic criteria underlying the regulation according to the following sections:

  • Person aged 18 years and under 65, who came by choice and not have donated blood in the last 2 months.

  • In good general health and normal conditions (weight, blood pressure and heart rate normal, no fever, no complaints of unexplained causes, without having been recently operated without being subject to patents medication side effects, etc.)..

  • Free from any communicable disease or at risk of having acquired in the last year (living with infectious patients, having received transfusions in the last year, unsafe sex, because they come from areas or countries with endemic diseases or epidemics. ).

  • Also free of certain diseases (heart disease, hyperthyroidism , insulin-dependent diabetes , cancer, anemia , clotting diseases, epilepsy , peptic ulcer , asthma, severe allergies to medications , etc.)..

  • Free from the risk of being under the influence of toxic substances ( drug addicts , people taking certain drugs, etc.)..

Complying with the right conditions, the donation does not involve any particular risk to anyone. The donation process usually lasts no more than ten or fifteen minutes and the amount must be drawn that fills a bag of 450 cc. If you can get this number, the donation is usually discarded.

After obtaining the blood analysis is performed to check the same as the donor is healthy and free of communicable diseases. This is determined, usually by serological testing to detect the presence of antibodies to certain viruses, bacteria and parasites. These antibodies usually appear within days or weeks in people who contract an infection.

When concludes sure that donated blood is not receiving any possible risks, it is split in different components useful for transfusion: packed red blood cells (cells that carry oxygen), concentrated platelets (cells that repair damage to blood vessels) and plasma (blood fluid containing serum proteins remaining), mainly.

The blood fractionation because it makes possible the maximum use and more secure employment. The fractional blood is also used for clotting factor concentrates (proteins that are essential to stop bleeding) and other derivatives (albumin, immunoglobulins, white blood cells, etc.).

What types of transfusions exist?

transfusions may be of various types depending on the need to submit the recipient under the disease suffered. The donation is the most common of packed red blood cells (RBCs). Diseases that can make the necessary transfusion of packed red blood cells are numerous (severe bleeding, acute leukemia, anemia treatment after chemotherapy and radiation therapy for cancer, aplastic anemia, major surgery, myelodysplastic syndrome, hemolytic anemia, etc..), but all have as a common key that there is a severe anemia that can not be corrected by other means and seriously jeopardizing the cardiocirculatory function and blood oxygen in the body.

Anemia is a situation where there is a shortage of hemoglobin, which is the oxygen-carrying protein, present in red blood cells. If anemia occurs because it is always in the blood not enough hemoglobin, which generally corresponds to an excessively low number of red blood cells, but not always. Therefore, the key figure of the blood of a person who requires a transfusion is the level of hemoglobin, which indicates the capability of fully oxygenated blood. When this figure is less than 9 g / dL is usually necessary to transfuse packed red blood cells, but if the doctor is convinced that hemoglobin may be increased by the patient due to an expected good outcome of the disease or by other therapeutic means, you can decide not. The final key to the decision lies above all in the patient's general condition and the reversibility or otherwise of their anemia by other means.

The number of bags required packed red blood cells varies according to each case, but you must decide the total volume just to ensure the recovery of an adequate minimum hemoglobin level to overcome their bad situation, neither more nor less.

The transfusion of platelet transfusion is another necessary for certain patients. A platelet concentrate is obtained by adding the appropriate fractions from several donations of whole blood platelets are therefore derived from the blood more precious still.

The preparation of platelet concentrates not only done by the sum of the platelets of several withdrawals. It is also possible to concentrate platelets by apheresis procedures quote. This technique obtains a platelet concentrate from a single donor and is performed selectively extracting a small percentage of such cells in your blood. This is achieved by passing the blood of a donor's arms to a machine that is only removed in the same platelets. Then, the machine returns the remaining blood to the donor by injection into a vein in the opposite arm. The process usually lasts no more than 2 hours and carries no risks of note in the vast majority of donors.

The precise conditions that cause platelet donation are those that produce an acute shortage of these cells in the blood and an increased risk bleeding from this cause ( leukemia acute exacerbation of hemorrhagic syndrome, liver transplant surgery, aplastic anemia, myelodysplastic syndrome, politransfusión of red cells, etc..) Platelet transfusion is indicated generally in the blood when the figure drops to less platelets/mm3 of 50,000 in the risk of bleeding. When the level drops to less than 10,000 platelets/mm3 the risk of bleeding is so remarkable that transfusion is usually always indicated if there are no other therapeutic alternative elevate immediately get that figure.

Other possible transfusions are fresh frozen plasma or factor concentrates, which are often required in cases where there are partial or global deficits of certain blood proteins, especially coagulation factors. The transfusion of white blood cells is also possible for severely immunocompromised patients, but is rarely used today as usual.

Today it is very unusual to indicate transfusions of whole blood because it is rare that a patient requires more than a derivative transfusion and medically acceptable because it is the added risk and waste that can result from improper input from other blood components not needed.

What are the risks of transfusions?

transfusion today is an extremely safe procedure. This is because to comply with strict security measures to ensure a careful selection of suitable healthy donors, a careful fractionation, processing and preservation of blood products and transfusion bags assignment completely safe for the recipient in terms of compatibility. To carry out this last phase of the process is essential that concentrates transfused are the same blood group as the receiver. There are many known blood groups, but the most important of all the systems belonging to the ABO and Rh antigens, but there are other systems that must be taken into account in the allocation of blood transfusions.

For this reason, before transfusion is always done in the lab what are called cross-matching. These consist of a small sample meet the recipient's blood with different blood samples of concentrated pockets of the same ABO blood group and Rh thereof, and choose only those where there is not a rejection of the mix. Thus, only those products that are transfused do not react with the recipient's blood, thus ensuring a safe and appropriate transfusion therapy performance.

All these security measures get very low percentages reduce the possibility of adverse effects resulting from transfusion therapy. However, it may even eliminate these risks absolutely. Thus the general approach is to prescribe transfusion only when strictly necessary.

Some of the risks, often rare, are the transmission of infectious diseases, for various reasons, including: poor maintenance of products, transmission of a donor who is not clinically manifested infection (and not been detected prior to the study recently have contracted the disease) group incompatibility reactions, allergic reactions, fever posttransfusion (for the transmission of pyrogens, which are substances that promote onset of fever, or cells that produce these substances); complex immunological effects or effects of the politransfusión.

Why is still needed transfusion therapy?

For certain diseases exist today transfusion alternative treatments. In many patients, for a few years ago there was no other option, it is now possible treatment with erythropoietin, a hormone produced continuously by the kidney and whose main effect is to stimulate red blood cell production. In recent years it has managed to synthesize this material and now many patients with anemia benefit from the therapeutic use of this hormone. Unfortunately, there is still the possibility of use of a hormone similar drug on the production of platelets, called thrombopoietin, but hopefully this is a reality in the not too distant future.

The technology that permits the manufacture of synthetic preparations of blood or similar fluids ability to bind oxygen, and research is still expected to take several years to come.

Until then it remains imperative to maintain and stimulate solidarity which is the act of giving our blood, but on a regular basis, not to mention that throughout the year in our hospitals there is an ongoing need for blood products.

1 comment:

  1. I recently came across your blog and have been reading along. I thought I would leave my first comment. I don't know what to say except that I have enjoyed reading. Nice blog. I will keep visiting this blog very often.


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