For the introduction of the solution the ordinary Pravaz syringe can be used, a modification of which being known as the “Simplex” ([Fig. 34]). It is a glass instrument, without screw threads within the needle base, and has a sterilizable fiber piston. The only disadvantage offered by this syringe is the lack of finger rests. The author has added a removable nickel-plated sleeve with finger rings to slip over the glass barrel, as shown in [Fig. 35]. The advantage of this modification will be appreciated when injections are made into dense or cicatricial tissue where considerable pressure is necessary for the introduction of the solution.
Another excellent syringe for the purpose is the metal-cased instrument known as the “Sub-Q” ([Fig. 36]); the barrel and piston in this are of glass, an asbestos packing being wound over the piston head.
Metal needles with large thread or smooth ends are employed. As the asbestos packing contracts in drying, the piston should be removed from the barrel and cleansed immediately after use, and not be introduced into the barrel until both the asbestos windings and the inside of the barrel have been moistened with warm sterile water. This precaution prevents the cracking of the instrument through undue pressure exerted on the end of the piston rod at the time of use.
To render the primary introduction of the needle painless the area might be sprayed for a moment with ethyl chlorid. After carefully preparing the site of operation, the subcutaneous injections are made in a somewhat oval or circular manner, the first infiltration of the cocain rendering the succeeding points analgesic.
It will be noted that the skin becomes whitened and is raised in little tumors, with the point of puncture as a center. The various punctures are so placed that the borders of these tumors meet, the entire site becoming edematous. If by constriction the part can be rendered ischemic, the analgesic effect is prolonged, reducing the systemic absorption to a minimum.
The subsequent nausea often following may be promptly overcome by the use of a mixture of creosote, four drops in limewater. For mucous surfaces the anesthetic may be applied with absorbent cotton and allowed to remain about five minutes. In deeper wounds than those involving skin, deeper injections must be made.
The effect of the anesthetic as above employed is practically immediate, and the operation can proceed at once. Its duration is from fifteen to twenty minutes for subcutaneous surgery, but where the deeper structures are involved subsequent injections must be made to control the pain.
Beta Eucain
(Benzoylvinyldiacetonalkamin)