In cases of anemia (inadequate number of red blood cells), transfusion of human blood may be indicated. The anemia may be due to a loss of blood by sudden hemorrhage, a continual slow hemorrhage, dietary lack of nutrients necessary for the body to manufacture red blood cells, or diseases which destroy the blood cells. In certain cases the physical condition may be depressed, so that the normal process of manufacturing blood cells in the body is impaired. In other diseases there may be a tendency to bleed caused by deficiencies of elements in the blood which normally stop bleeding by producing clot formation; transfusion of blood from a healthy individual may obviate the bleeding tendency by supplying the deficient elements.
Human beings have different factors in their blood which designate a specific blood type for each individual. A person’s blood type never changes. The blood for one individual cannot be given to another unless it is the correct type. The blood type is determined by two natural factors which are found in the human blood. These factors are designated as A and B. An individual’s blood may have neither of these, both of them, or either one of them. This is the basis for blood types, and several different systems of nomenclature have been devised. The most universally used system classifies these blood groups into:
- Type AB
- Type A
- Type B
- Type O
Type A has only the A factor; type B has only the B factor; type AB has both, and type O has neither. By another system of naming these are called types I, II, III, IV, corresponding to the lettered types as follows:
- Type AB is Type I
- Type A is Type II
- Type B is Type III
- Type O is Type IV
A laboratory technician can readily tell, by testing a drop of blood, what type it is. The A and B factors in the blood cause a coagulation of the cells of blood which does not have the same factor. If the wrong type of blood were given an individual, this coagulation of cells would take place in the blood stream, and the cells would be clumped together and finally disintegrate. Since type O has no type factor, it can be given safely to any other type, so it is called the universal donor. Type AB already has both type factors, so it can receive either factor and is the universal recipient.
Another factor which may be present in the blood is the Rh factor. This is designated as positive if present or negative if absent. This is the second step in typing an individual’s blood. It makes little difference if Rh negative blood is given to an Rh positive person, but if the Rh positive is given to an Rh negative individual the same type of reaction takes place in the recipient’s blood stream as with incorrect major types. Type O, Rh negative is the only real universal donor, therefore.
These types are the only differences ever found in human blood. There is absolutely no difference by race, color, or other traits.
Before blood can be administered to a patient, the donor’s blood is tested for the major type and the Rh factor, and it must correspond to the recipient’s blood. A further check is made by the crossmatch, which is done by mixing a drop of the donor’s blood with a drop of the recipient’s blood and observing it under a microscope to make certain that there is no clumping of cells. If donor and recipient have blood which matches properly, the transfusion may be given. If there is any doubt about the match, a new donor is located.
Formerly all transfusions were given directly from the donor to the patient through a pumping device connected to the veins of each. This is called the direct method. Today the indirect method is used, except in the infrequent situation where the direct method is indicated by a specific advantage. With the indirect method the donor’s blood is collected into a sterile container which contains a substance to prevent it from clotting. The blood is later administered to the patient from the same container, just as any intravenous infusion.
The indirect method of blood transfusion has the advantage of being able to store the blood until ready for use. Blood banks, which are an essential part of hospitals today, keep some blood of each type on hand at all times. The definite advantage of this in an emergency can easily be realized, and blood banks have saved many lives in recent years. Blood is stored in the banks under refrigeration, and the turnover keeps it fresh, but if a unit of blood is not used after its specified period of time, it is discarded.
There are, of course, different frequencies with which each type of blood is found in the general population; some types are rarer than others, but this all averages out because the need for the rarer types is less frequent too. Each blood bank has its own system for securing donors, and the family of any patient who receives a blood transfusion always has an obligation to replenish the blood so that the supply will be sufficient for the next patient who needs a transfusion. You must co-operate with the blood bank’s system for replacement. Your friends will be only too glad to help with your treatment by donating a pint of their blood. Even if their blood is not the same type as yours, it will replace the unit you have had, because in the long run the percentages of types donated and types administered average out.
Before a donor’s blood is accepted, a brief history is taken by the technician to see whether the donor has had any illnesses which may be harmful for him to give a unit of blood, or harmful to the recipient who receives it. The blood pressure is also taken. It is best that the donor has not eaten for 3 to 4 hours before donation. No more than one pint is taken from a donor at one time, although more could be safely taken, and at least 6 weeks must have elapsed since his last donation. After these precautions are checked, the withdrawal of blood may begin. The donor lies down on his back with one arm comfortably extended on an arm- board. A tourniquet is placed about the upper arm and the site prepared with antiseptics. A drop of local anesthetic may be injected into the area over the selected vein. The needle is inserted into the vein just as in any vein puncture. The needle is connected to a tube which is attached to the collecting container. The inside of all the equipment is absolutely sterile. The flow of blood begins immediately since there is a vacuum in the collecting bottle, which contains a small amount of a fluid which prevents clotting. This is rotated throughout the procedure so that the blood mixes with the anticlot fluid to prevent coagulation. In a short time the pint is collected; the tourniquet is released and the needle withdrawn. Pressure is applied to the puncture site for a few moments; then a small dressing is applied. The blood in the tube is used for the typing, crossmatch, and a test for syphilis which is routinely performed on all blood transfusions. The donor is asked to remain lying still for a few moments and is urged to drink a glass or two of water or other fluid. The blood is placed under refrigeration until needed.
If the syphilis test is negative, and the typing and the crossmatch found perfectly compatible, the transfusion may be given. The blood administration is exactly the same as any intravenous infusion. A clear solution may be started into the vein first, and when everything is functioning properly, the tube leading from the solution to the vein is switched to the bottle of blood. There is a filter in the course of the tubing which will trap any clots present. The flow is measured by the number of drops per minute and regulated by the clamp on the tubing and the height of the bottle. The pain from the needle insertion is the same quick sting as from any injection, and once the needle is in place there is no more discomfort. The arm must be held still, of course, and can be bound down if the patient desires.
Even though complications from blood transfusions are rare and every precaution is taken to prevent them, it is wise for the patient to notify the nurse of any new symptoms while receiving a transfusion. Inform your nurse if you have chills, fever, itching, chest pain, pain at the needle site, or any other symptoms you develop during or after a transfusion, but these are transient and easily corrected. Minor reactions may be due to foods eaten by the donor to which the recipient is allergic or sensitive.
Donors and recipients alike often ask the curious question of how much blood is in the human body. This may be quite accurately estimated in normal health. The blood makes up approximately Vfa of the body weight. Thus, a man of average weight has from 5 to 6 quarts, or 10 to 12 pints. Of this volume, about 55 per cent is fluid and 45 per cent is composed of the blood’s cells. After bleeding or blood donation the volume returns to normal within a few hours, but this is primarily by replacement with more fluid portions. The production of cells to the normal level takes appreciably longer.