Application by Injection. In order to bring the anesthetic in contact with the nerves, it is necessary, where a skin surface is to be incised, to inject the solution as already described. The technic, previously detailed, applies here, and any of the methods may be employed for the injection of solutions of cocaine, some preferring a single method to the exclusion of all others. The locality to be treated will also influence the operator as to method.
Endermically. The endermic method is the one most generally employed in securing cocaine local anesthesia by injection. The papillary layer of the skin is well infiltrated with a mild solution (one-eighth per cent. to one-half per cent.), frequently with adrenalin 1-1000, in the proportion of 15 to 20 drops to the ounce of the solution. The strongest of the formulas of Schleich may also be used for endermic infiltration.
The skin is injected to a fair degree of tension and a white ridge marks the line of injection which should be sufficiently extensive to permit the manipulation of the cut edges.
Edemitization. Schleich’s solutions are here of extreme value because large amounts of solution are necessary to produce the degree of distention required because of the minute quantity of cocaine present, though the added salt and morphine assist considerably.
Nerve Blocking and Perineural Blocking. Here a stronger solution must be employed; 1 per cent., or even stronger, is injected in small quantities, either into the substance of the nerve or under its sheath, as already described.
Strength of Solution. Schleich has worked out a method whereby very weak solutions of cocaine may be used advantageously. His plan is to enhance the action of the drug by the admixture of morphine in minute quantities and of sodium chloride in proper strength. These substances, in themselves, were found to possess anesthetic powers. Large quantities of Schleich’s solutions may be injected—even several ounces, without ill effects as they contain so little cocaine. The formulas used by him are:
| 1. | Cocaine hydrochlorate | 0. | 2 |
| Morphine hydrochlorate | 0. | 02 | |
| Sodium chloride | 0. | 2 | |
| Distilled water | 100. | ||
| 2. | Cocaine hydrochlorate | 0. | 1 |
| Morphine | 0. | 02 | |
| Sodium chloride | 0. | 2 | |
| Distilled water | 100. | ||
| 3. | Cocaine hydrochlorate | 0. | 01 |
| Morphine | 0. | 005 | |
| Sodium chloride | 0. | 02 | |
| Distilled water | 100. |
It will be seen that the strength of cocaine in the respective solutions is from one-fifth to one-hundredth of a gram.