Blood Transfusion

by Geoffrey Keynes

When the blood is to be given, the delivery tube with the rubber bung is inserted in the flask, and the corpuscles which have gravitated to the bottom are distributed again through the fluid by gently shaking it. In administering the blood, it is very often advisable to inject it through a cannula which is tied into a vein. If the patient is a woman, it will usually be found that the veins are small and buried in fat. Also many transfusions will be given to combat the collapse due to shock and hæmorrhage, in which case the veins will be empty and the use of a cannula will be found essential. Sometimes, however, the patient will have large veins which can be readily distended; this may sometimes be encouraged by keeping the arm for half an hour beforehand in a bath of hot water. Under these circumstances the blood can be given through a needle introduced in exactly the same way as has already been described in the case of the donor. In the following account of the process it will be assumed that the use of a cannula is necessary.

When choosing a vein in the patient, the operator must be guided by circumstances. Usually the median basilic will be the most convenient, and if, in a collapsed patient, this is invisible, previous knowledge of the position of the vein must determine the site of the incision. If another operation is being done simultaneously upon the upper part of the patient’s body, it may be more convenient to use the internal saphenous vein in Scarpa’s triangle, or even one of the superficial veins about the ankle. In administering blood to an infant, several methods have been used. These are described separately at the end of the present chapter.

Fig. 11.—Transfusion Cannula
(Actual Size)

Whatever vein be chosen, the line of the incision is first infiltrated with a small quantity of a 2 per cent. solution of novocain. The vein is then dissected out, and is ligatured near the lower end of the incision. A ligature is also put loosely round the upper part. The operator now takes the barrel of the air-lock, which, together with the attached rubber tube and cannula, is filled with 0·9 per cent. saline solution, all air bubbles being carefully excluded. The tube is clipped near the cannula, so that the whole system, including the cannula, remains filled with the fluid. The form of the cannula used will depend upon the operator’s particular preference, but a type which I have found very convenient is shown in the accompanying figure. It is made of glass, and its extremity is ground down at an angle, which makes it very easy to introduce into the vein. The slight constriction near this end ensures that it can be securely tied into the vein and that no leakage round it shall occur. This is very necessary, because there is sometimes a considerable pressure to be overcome, due to venospasm in a collapsed patient, before the blood begins to flow.

An oblique cut is now made in the vein, as shown in the illustration, the cannula is introduced, and the upper ligature is tied.

Fig. 12.—Insertion of the Cannula in a Vein

The barrel of the air-lock, with its contained saline solution, is then fixed firmly on to the rubber bung, so that the nozzle of the delivery tube projects into the saline solution. Meanwhile, an assistant has fixed a rubber bellows on to the side tube of the flask; a short piece of glass tubing loosely packed with cotton-wool should be interposed between the bellows and the flask to prevent any particles of dust being blown over into the flask from the bellows, which is not sterilized. The clip near the cannula is released, and some positive pressure is produced inside the flask by means of the bellows. The citrated blood then rises in the delivery tube, and a corresponding quantity of saline solution is displaced from the air-lock into the patient’s circulation. The blood then flows from the nozzle of the delivery tube into the air-lock, and the remainder of the saline solution is driven on into the patient. Finally the blood flows steadily through the cannula, and the rate at which it is flowing can be observed in the air-lock.

The presence of this air-lock facilitates, as has been seen, the introduction of the cannula, into the vein, since there is no leakage of blood to obscure the operation. In addition, the operator can see at a glance whether the blood is flowing in properly, and can regulate the rate of flow to a nicety by varying the pressure in the flask by means of the bellows. If a very slow injection is required, the blood can even be made to run drop by drop. If the patient is suffering from acute anæmia, the blood can be pumped in rapidly, 750 cc. of blood being given in the course of twenty minutes. If, on the other hand, the patient has a plethora of fluids, such as is seen in some cases of secondary anæmia, the blood must be given very much more slowly than this, since it is dangerous rapidly to increase the blood volume. A half to three-quarters of an hour must be occupied in giving 500 cc., and even then the patient may complain of a sensation of tightness in the chest and of dyspnœa, due to embarrassment of the right heart during the transfusion. This complaint, however, is usually transient, and will disappear quickly if the injection be stopped for a few minutes.