These elements are being and will continue to be considered as preliminary to operative procedure and in consequence, general anesthesia will cease to be given in a routine way.
GENERAL PRINCIPLES AND ESSENTIALS
The first essential to the successful production of local anesthesia is a proper equipment and one that is in good working order. Not only is it necessary to employ the best drug to this end but also to use a syringe having perfect mechanical construction and one not injured by boiling; as also needles of the length, lumen and shape suitable for the surface to be injected.
The old leather pocket syringes, on account of their not bearing water at high temperature without deterioration, should not be employed; this applies also to that variety of glass barreled metal-mounted syringe in which the glass is screwed into the metal end pieces.
The best syringes are those made of all metal or of all glass, the latter being preferred because one may see the contents and express out the air before injecting. Syringes of this type, because of the accurate fitting piston, must be thoroughly dried out after use, as the piston may stick fast within the barrel. All-glass or all-metal syringes must be selected with care as they are often imperfect, the calibre of the barrel being unequal in different parts of its length causing the piston to fit tightly in some parts, and thus to work with difficulty; and in other parts fitting loosely, allowing the fluid to escape backwards.
Syringes are also made in various sizes and shapes to meet certain requirements. For the edematization of large areas of loose tissue, where a considerable amount of a weak solution is intended, the use of a large barreled syringe will be found to save time and the annoyance of refilling.
For such work a five or ten c.c. syringe would be the most useful. The ordinary hypodermic syringe is about of two c.c. capacity (thirty drops), and serves the purposes of every-day work. It does very well for the amount of an anesthetic solution employed in opening an abscess or in the removal of a small cyst or lipoma or papilloma.
A barrel, large in diameter, requires more pressure on the piston in its operation unless the needle employed is also correspondingly large. For this reason, if the tissue in which the solution is to be injected is not loose or cellular, it will be found better to use a syringe in which the barrel is long and narrow. Such is the shape of the syringe intended for the injection of the gums, the peridental membrane, and also for the periosteum, cartilage or bony cellular structure. A long instrument is also required for use in the large cavities of the body such as the mouth, the vagina, or the rectum. In these localities, an extension fitting is often required to lengthen the instrument sufficiently to reach the desired part. It is also possible to attain this end by using a long needle; this, however, sacrifices rigidity.
For accomplishing the best results, the needles must also be selected for the work at hand. For the initial puncture in sensitive or inflamed tissue, it is proper to use a needle of the finest lumen so as to cause the least possible amount of pain. The ordinary needle, which comes with the usual hypodermic outfit, is about the proper length for the ordinary work already mentioned, but could be improved upon for anesthesia by being made a little finer in calibre. This length (three-quarters of an inch) will be frequently found insufficient to reach the deeper tissues and in the removal of a more or less rounded growth, a longer needle must be selected at the start. Curved or angular ones are only needed in dentistry, where strength is also a consideration. Strength is afforded in those of short length by means of a reinforcement at the hub. Needles so augmented may also be of use in operations upon bone or dense structures in general; the curve, however, is not essential.
The surgeon should be fully conversant with the details of the operation which he is about to perform. His work should be definitely in his mind, for in operations under local anesthesia, there is no justification for a change of procedure after the beginning of the work. Account should be taken of the nature of the tissues to be anesthetized, for it is known that cicatricial tissues and inflammatory areas do not lend themselves to the action of these drugs. In a cicatrix, the diffusibility of the solution is impeded, and in an inflammatory or necrotic tissue, the changes in the quantity and quality of the fluids present, alter the action of the anesthetic.