BLOOD TRANSFUSION, the term used in medical litera ture for the process of transferring the blood from the circulation of one living animal to that of another. The first authentic record of it was not made until the middle of the i7th century. A Floren tine physician, Francesco Folli, claimed to have transfused blood from one animal to another on Aug. 13, 1654. Subsequently many experiments bearing on the subject were made by Dr. (later Sir Christopher) Wren, Richard Lower, Edmund King, and Thomas Cox, their experiences being recorded in the Philosophical Trans actions published by the Royal Society about 1666. Some of these experiments were witnessed by Samuel Pepys, who referred to them in his Diary. In spite of this activity in England the credit for first performing a blood transfusion upon a human being must be given to Jean Denys of Montpellier. An account of his experi ment done upon a boy aged 15, was published in the Philosophical Transactions for July 22, 1667.
On this occasion, and indeed throughout the i7th century, the blood for transfusion was taken from a lamb or calf, and, al though good therapeutic results were claimed at first, the operation soon fell into disrepute and was almost entirely abandoned. Little or nothing was heard of it during the i8th century and it was not until 1818 that attention was again focused upon its possibilities. The coagulation of the blood outside the body was always the prime difficulty. One way of overcoming this was to remove the fibrin which forms the basis of the clot, and from 1835 onwards this defibrinated blood was used by various operators.
Transfusion did not, however, come into general use as a thera peutic measure during the igth century, and after the year 1875 was largely neglected. This was probably due to the increased number of disasters which had attended the operation as soon as it began to come into fashion. An improvement in technique was initiated in America through advances in the surgery of the blood vessels, and this culminated in the work of Crile, who about 19°7 described in detail an efficient method of performing direct trans fusion by means of an anastomosis between an artery of the donor and a vein of the recipient.
Meanwhile discoveries were being made which tended to elimi nate the chief factor responsible for the fatal results of some of the earlier transfusions. It had long been known that the bloods of different species of animals were incompatible, that is to say, the blood of a calf introduced into the circulation of a man was inevitably and rapidly destroyed, this process being attended by more or less serious symptoms, or even by death, according to the amount of blood introduced. In go7 it was shown by Jansky in Scandinavia that an analogous incompatibility exists in all races of man between the bloods of different individuals, so that a given recipient may safely receive the blood of certain selected donors only. Hitherto no such selection had been practised. Jansky's work was repeated by Moss in America in ig o, and human beings have since that time been classified into four definite groups, the blood of only one of these being suitable for more or less indis criminate injection into all recipients.
A further advance was made in 1914 when Agote of Buenos Aires first used sodium citrate as an anti-coagulant for the donor's blood. This substance, when mixed with the blood as it issues from the donor's vein, combines with, and renders inert, the calcium which is present in the blood in small quantity and is an essential factor in the coagulation reaction. The blood then remains fluid for an indefinite time, and the small amount of citrate which it contains is usually harmless to the recipient. Direct transfusion by Crile's method was technically difficult to perform, and it was soon abandoned in favour of citrated blood. This method was introduced opportunely for use in the treatment of the wounded during the World War, though it was largely employed only after the entry of the American surgeons into the hospitals in France. Some surgeons, however, then believed, and still believe, that citrate is responsible for the reactions, usually mild in degree, which follow a certain percentage of all transfusions, however carefully the bloods of donor and of recipient may have been tested. In spite of much controversy the supposed harmful effect of citrate has not yet been proved, and this method, which has many advantages, is more often used than any other. If whole, or untreated, blood be preferred, coagulation may be retarded by receiving the blood into a glass vessel coated on the inside with paraffin ; it must then be transferred to the recipient as rapidly as possible.
In 1923 a return was made by Storer to the older method of using defibrinated blood to which no foreign substance has been added, and it is possible that this may prove to be the method of choice in the future. Storer's ground for eliminating the anti coagulant was the belief that its presence impaired the anti-bac terial properties of the donor's leucocytes, but his contention still has to be substantiated in practice.
Blood transfusion has been found to have its greatest clinical value in the treatment of acute anaemia (see ANAEMIA) due to loss of blood after injury, or in cases such as bleeding from a gastric ulcer or postpartum haemorrhage. Transfusion is also of value in combating the shock following severe surgical operations or injury, which may or may not have been accompanied by much loss of blood, and in the treatment of several diseased conditions in which, for one reason or another, the patient's blood is deficient in its power of coagulation. Thus, in the hereditary disease known as haemophilia, the patient may be rendered temporarily normal by transfusion of blood, and persistent bleeding will cease. Trans fusion has been used in the treatment of a very large number of patients suffering from pernicious anaemia, some having received as many as thirty injections of blood over a period of several years; but, although a temporary remission of the disease may be obtained and the patient's life be prolonged, the disease cannot thereby be cured. The limitations of transfusion as a therapeutic measure, are, therefore, fairly well defined. It is still used more widely in America than in other countries, but it is coming to be employed more frequently everywhere.
Transfusion may also be considered from the point of view of the donor. Here the chief point of interest is the amount of blood which he can afford to lose without danger. It has been found that a healthy young man can part with any amount up to a litre of blood without experiencing anything more than a transient faintness. Usually he is not called upon to give more than Soo to 7 5o cu. cm. for one transfusion.