Step 5. This being reached, the plug is pulled out, the nozzle inserted into the cannula, and the blood slowly injected by depressing the piston gently, but without quite emptying the syringe. A minute should be spent in injecting one ounce and a half, and a pause of five minutes ensue before a second supply is introduced. This interval may be employed in cleaning the syringe, &c., and procuring a fresh supply of blood; 3-4 ounces of blood are usually sufficient, but 10 ounces have been injected on some occasions. The perturbation of the supplier (generally a near friend of the recipient), renders it necessary he should drink freely of brandy and water, that the blood flow forcibly when required.
Step 6. When sufficient blood has been introduced, both patients’ wounds are dressed, as after venesection (see page [20]), the long incision of the recipient being closed by a point of suture under the pad.
Tourniquets.—Tourniquets are of several kinds.
The Ring Tourniquet (fig. 97) is used when pressure is desired on the main artery of such a limb as the arm. It is less easily displaced than the Signoroni, but, like that, soon becomes irksome by its continual pressure.
Fig. 97.—Ring tourniquet.
When hæmorrhage has to be temporarily arrested, that of Petit (fig. 98) is generally used. It consists of a strap of stout webbing and buckle, that can be rapidly tightened by a few turns of a screw. To use this tourniquet, lay a roller over the artery and carry the end once or twice round the limb to steady the roller, then pass the strap over the roller, keeping the buckle about two inches away from the screw and the screw on the anterior or outer aspect of the limb, not over the pad, lest that be displaced when the screw is tightened. The tourniquet should be screwed up as quickly as possible, that the limb be not charged with blood by obstructing the venous, before the arterial flow is checked.
Fig. 98.—Petit’s tourniquet applied to the popliteal artery.
