Questions about Blood Transfusion
What is the right interval between transfusions?
There are several possible "schemes" for transfusion. The scheme at your center depends on things like whether you come a long distance and stay overnight for your transfusions, or whether you live nearby and your center is able to provide "day transfusion". Some centers give small transfusion every 2 weeks (Cyprus), Other give bigger transfusions every 6 weeks (some centers in UK). Most give medium-sized transfusions every 3 or 4 weeks.
At What hemoglobin level should blood be given? (i.e. what is the best pre-transfusions Hb level?
There are some differences of opinion about this, and the answer also depends on the number of weeks between your transfusions. Everyone agrees that we should maintain a high hemoglobin level, that is to say, the Normal Hb level should be between 12 and 13 g/dl, but not everyone agrees on the exact best level, and to tell you the truth, it may not make a great deal of difference.
"This Table shows how the average Hb level may be the same, but Hb level before and after transfusion will be different, depending on the number of weeks between transfusions"
|Average Hb Level
You can see from the table, That different pre-transfusions hemoglobin levels are required, to keep the same mean hemoglobin level, depending on the number of weeks between transfusions. Whether you have you spleen in or out may also influence the ideal level, so you see it is best to discuss this question with your own doctor.
How many red cells should be given at each transfusions?
The commonest transfusion scheme in Italy allows for a transfusion of 10ml of "Packed" red cells for every kilogram of the thalassemic being transfused, and the interval between transfusions in about 21 days (3 weeks). Obviously if the interval is longer, as it usually is in England, more red cells need to be given each time. If the interval is shorter, as it usually is in Cyprus, less red cells are given. Rather less red cells should be transfused at any one time if there is any problem with the heart, or the hemoglobin is very low. This can be arranged by giving smaller transfusions every 2 weeks.
Is something wrong if the interval between transfusions gets shorter and shorter?
Sometimes the interval gets shorter because your doctor has decided to change your transfusions scheme, but then you would the reason.
If the interval between transfusions keeps getting shorter, without having been planned, something is not quite right.
The commonest reason is to do with the child's growth. As a child grows, more blood should be given each time. If the same amount of blood is always given at each transfusion, obviously with time it becomes necessary to give transfusions more often.
Another possibility is that the spleen is becoming over-active and destroying some of the transfused red cells.
It is not difficult for your doctor to find the cause.
Can you have Desferal with transfused blood?
Yes. This is done at many centers, because Desferal infused into a vein works even better than Desferal infused under the skin. Also, it is an opportunity to have Desferal without having to prick yourself. So many centers arrange to give 500mg, or 1 or 2 grams, depending on the size of the patient. Often it is given by the pump, with the needle stuck into the drip tubing instead of into the patient!
What complications can be caused by blood transfusion?
Very important problems can arise from mistakes in preparing the blood, or mistakes when blood bags are changed during a transfusion. But such mistakes are very rare, and in Europe they hardly happen at all
Rarely a thalassemic can develop "red cell antibodies." This means that they become sensitive to the red blood cells of many people. The result is, that they destroy red blood cells from such donors after they have been transfused, and their hemoglobin falls much faster than it should, after transfusions. This is an uncommon problem, but it can be very worrying when it happens. The solution is usually to find a "panel of compatible donors" - this means a set of donors whose red cells are not destroyed by the patients's antibodies.
The commonest problems arise from sensitization (allergy) to white blood cells or plasma from other people, and from infections. We will discuss the problems cause by iron in the transfused red cells on Chapter 5, when we talk about "Iron Chelation Therapy".
What are the signs of sensitization to white blood cells?
You can get a fever during the transfusion if you have become sensitive to white blood cells from other people. This means you have "antibodies" in your own blood, that react with white cells and platelets in the blood you receive. This sort of reaction, with a fever, is called a "febrile reaction".
What are the signs of sensitization to a component of the plasma?
The most usual sign is "urticaria" which means an itchi blotchy skin rash, that can come up either during or after the transfusion. A much rarer, but more serious problem is "anaphylactic shock" when the blood-pressure falls and some tissues may become puffy. If the tissues round the mouth and throat puff up, there could be some difficulty in breathing. On the rare occasions when this happens, it can be treated with cortisone and adrenaline.
How can you prevent transfusions reactions?
These reactions can be prevented in several ways. A rather old fashioned method is to "Wash" the white cells and plasma away from the red cells with salt solutions before the transfusion, so that only pure red cells are transfused. This may still be necessary for the few people who are allergic to a component of the plasma.
The modern method for preventing "Febrile reactions" to white blood is to "filter" the white cells out of the blood. These are several types of filters. Some are used to prepare the blood in the blood bank. Other can be attached to the tubing from the blood bottle, so that they remove white cells as the transfusion is going on. All seem to work well. However they are quite expensive, so now people are working to find the cheapest and most efficient way of using them.
In some places where thalassemia is common, filters are not available and there is no equipment for washing the blood. In these places the only way to prevent transfusion reaction for patients who suffer from them regularly, is to give a drug such as "cortisone" immediately before the transfusion.
What infections can be passed on in transfusions?
Some infectious organism can be transmitted through blood. For instance, malaria parasites, syphilis, and most recently the AIDS (Acquired Immune Deficiency Syndrome) virus have been shown to be transmitted by blood. However, transmission of these diseases is very rare indeed, because all blood donors are tested, and those who could pass on infections are identified and avoided. It is more difficulty to avoid a common virus called cytomegalovirus, but in people with normal immune defenses, it causes relatively little problem.
Hepatitis needs separate discussion. It means infection of the liver, and it can be caused by a number of different viruses that can be passed on in blood. Hepatitis is the commonest infection cause by the transfusion.
One of the viruses that causes hepatitis, hepatitis B virus, is known. It is possible to identify carriers of hepatitis B virus, and they are no longer accepted as blood donors, so hepatitis B infections are now very rarely caused by transfusion.
Also, it is possible to immunize people against hepatitis B with a course of hepatitis B vaccine. This involves three injections, two one month apart, and one six month later. All thalassemic patients should be immunized against hepatitis B.
However, there is another type of hepatitis, "hepatitis non-A non-B," caused by another type of virus (or even by a variety of viruses) that has not yet been identified. This virus is now the commonest cause of acute or chronic hepatitis caused by transfusion. Its frequency differs very much in different countries, and may differ from one region to another within the same country. This is because the proportion of healthy carriers of hepatitis non-A non-B differs in different parts of the world.
What are "neocytes"?
There has been quite a lot of talk about transfusing neocytes, so we had better explain what they are, and why people usually don't use them.
We already explained that red blood cells are made in the bone marrow, and that each one lives for about 120 days (4 months). therefore the red cells in blood are all different ages, ranging from 1 to 120 days old. When you receive a blood transfusion, the older cells start to be destroyed right away. That is why you hemoglobin starts to fall again immediately after a transfusion.
It is possible to partly separate younger red cells from older red cells, by special centrifuges or other methods. The younger red cells collected this way are sometimes called "neocytes". Because their average age is less than that of whole blood, they can last longer in the circulation. Some people have tried to use them instead of the usual kind of blood.
In fact, neocyte transfusions do last slightly better than usual transfusions. The interval between transfusions becomes a little longer, rather less blood has to be given every year, and the amount of iron laid down in the body is reduced. So the idea of using neocytes is reasonable. However, people don't use them as a rule, because they give only a very small advantage, and it is so expensive and complicated to prepare them.