Cocaine. It is often desirable to secure a slight degree of local anæsthesia to facilitate complete exploration of the nose. Many operations can be carried out by rendering the nasal mucosa absolutely insensitive with cocaine.
Applied in the nose cocaine is (a) an anæsthetic, (b) a powerful vaso-constrictor, and, consequently, it (c) produces local anæmia. Hence cocaine is of great value in nasal surgery, not only because it renders the mucous membrane insensitive, but also because it retracts the tissues and reduces the hæmorrhage.
Methods of use. A small area can be anæsthetized by placing a few crystals of hydrochlorate of cocaine on the required spot, where the mucus will dissolve it in situ. A 2 to 5% solution may be sprayed into narrow nostrils, to facilitate examination. It is a better plan to moisten pledgets of cotton-wool or ribbon gauze with a 10% solution, and place them in direct contact with the part to be operated on. The addition of a little suprarenal extract will not only facilitate examination and treatment by its hæmostatic action, but, for the same reason, will tend to prevent the cocaine being absorbed and producing its toxic effects.
For the more complete anæsthesia required for operation the following plan is advised. Equal parts of a 20% solution of cocaine and the standard 1–1,000 extract of suprarenal gland are mixed together. Short strips of 1-inch wide ribbon gauze are moistened with this solution and laid flat in close contact with the nasal area to be operated on. They are left in place for at least half an hour, and even at the end of one hour local anæsthesia will only be more marked. While the final preparations are being made for operation a fresh layer of moistened gauze may be applied. Finally, if there should still remain the slightest degree of sensation over the spot to be treated, a few cocaine crystals will render it quite numb.
Submucous injection of cocaine. Great caution is necessary in making intracellular injection of cocaine, as the drug is intensely toxic in this form, and, fortunately, only a small dose is required. It is a good plan never to exceed 1 centigramme (1/6 grain) of the salt. As the hæmostatic effect of suprarenal gland extract is required at the same time, the two are combined; 1/6 grain of cocaine, 2 drops of adrenalin, 1/6 grain of sodium chloride, and 1/50 grain of morphia are dissolved in 60 minims or more of sterilized water, and slowly injected below the mucosa. At least 20 minutes must elapse to secure full effects.
Substitutes for cocaine. For submucous injection it is better to substitute eucaine or novocaine. Eucaine can be kept in a ready and portable form in small glass ampoules in the dose of 1/6 grain with 1/2000 grain of adrenalin, and tablets are sold containing 1 centigramme (1/6 grain) of either of these drugs in combination with adrenalin and chloride of sodium. One of these tablets is dissolved in 60 minims or more of water and boiled. It is reported that as much as 1 grain of novocaine may be injected at one sitting, but I prefer to keep to the limit of 1/6 grain, and have always been able to obtain complete local anæsthesia with it.
Eucaine is much less toxic than cocaine, and novocaine is said to be still safer. They act just as well for submucous injection, but, applied to the mucous surface, the anæsthesia is not so complete, and the vaso-constrictor effect is less. Still, for susceptible subjects, either is to be preferred to the more toxic cocaine.
LOCAL ISCHÆMIA
Adrenalin. The delicate manipulations of intranasal surgery have been greatly facilitated by the employment of the extract of the suprarenal gland under various names—adrenalin, adrenine, adrin, perinephrin, adnephrin, epinephrin, suprarenalin, suprarenin, epirenin, paranephrin, renaglandin, hemesine, hæmostasine, vasoconstrictine, renostypticin, &c. These liquids are generally of the strength of 1 in 1,000, and can be used undiluted on mucous surfaces. But they can be diluted with normal saline solution, solutions of cocaine, or other drugs. If kept in well-stoppered, tinted glass bottles the solution can be preserved for many weeks. The solid extract is useful for those who only employ it occasionally, and in this form it is conveniently made up with cocaine, eucaine, or novocaine, so that solutions of the desired strength are prepared as required.
Applied to a mucous surface adrenalin produces a local ischæmia by contracting the blood-vessels, so that the surface becomes pale and shrunken. At least 20 minutes are required to secure this effect and it is only more marked at the end of an hour. An extensive operation, such as submucous resection of the septum, can then be performed without the loss of more than a trifling amount of blood in most cases. The vaso-constrictor action is followed by a stage of dilatation, disposing to secondary hæmorrhage, which, according to some authorities, may be ‘violent and sometimes serious’.[47] I have been fortunate in not meeting with this occurrence. Its possibility can generally be guarded against, and need never prevent the employment of the drug when indicated.