This method was used as far back as 1848, by Arnott, but was soon improved upon by Richet and others who used ether or rhigolene sprayed on the part to be anesthetized. It was found that extremely low temperatures could be obtained in this way, especially if a current of air were blown across the field of operation to hasten evaporation, and that a good local insensibility could be brought about if the circulation of warm blood could be either stopped or retarded with an Esmarch bandage or tourniquet. The method of obtaining local anesthesia through the agency of cold was found to be best accomplished by ethyl chloride and this substance is used in preference to any of the others previously mentioned, at the present time. Some years ago Dr. Martin W. Ware of New York experimented with both ethyl chloride and ethyl bromide and he found that the former was more serviceable in producing local anesthesia.
The Sensibility of Various Tissues. Karl G. Lennander, of Upsala, Sweden, shortly before his death, completed a chapter on local anesthesia for Keen’s “Surgery” in which is set forth an elaborate account of the sensibility to heat, cold, pressure, and pain of the various nerve terminals throughout the body. In this great work he has given the world the results of many experiments on living tissues, experiments investigating the degree and kind of the tissues sensibilities; thus it is learned that “all internal organs receiving their nerve supply only from the sympathethic nerve and from the vagus, below the branching-off of the recurrent nerve, have no sensation, and that the abdominal and pelvic viscera are devoid of nerves to convey the sense of pain, heat, cold, or pressure.”
From the same authority we are taught that the parietal peritoneum is highly sensitive but that the visceral covering is devoid of all sensibility, enabling the operator much freedom of manipulation within the abdominal cavity.
In a work of this limited size the sensibility of the various tissues cannot be fully treated but it should be borne in mind that the integument and the subcutaneous tissue, fat and muscles as well as the tendons, their sheaths, the muscles and periosteum and perichondrium covering the bones and cartilages throughout the body, are all highly sensitive to pain. It is also equally true that the bone substance, the bone marrow, and the cartilages are devoid of any of the four modalities of sensation. Articular surfaces covered with cartilage have no sensation, neither have the fibrocartilages any sensation.
GENERAL CONSIDERATIONS
Effect of General Anesthesia. Local or regional anesthesia is obviously the method of choice in all cases in which it is applicable. Not only is it desirable in the minor surgical operations and the more important ones upon patients suffering with a cardiac or nephritic derangement, where a general anesthetic is positively contraindicated, but in every instance where it is at all possible, the dangers and annoyances of general anesthesia should be avoided, and the regional or local anesthesia should be employed.
Among the advantages, aside from the number of assistants required and the discomfort immediately following the administration of a general anesthesia, are the absence of remote ill effects of the invasion throughout the entire system of a noxious chemical substance and its direct deleterious effects on many large organs such as the lungs, heart, kidneys, and liver, and the assurance, when a proper drug, dosage, and technic are employed, that death cannot be ascribed to the anesthetic.
Of remote ills of general anesthesia no estimate can be made, but that they are legion and of great severity is established. Deaths from general anesthetics in persons apparently able to bear them well, are extremely numerous. It has been estimated that one in fifteen thousand succumbs from ether anesthesia and this number would probably swell greatly were it possible to obtain the exact figures. Even this minimum of danger does not exist in local anesthesia.
An accurate knowledge of the neural anatomy of a particular region enables the operator to anesthetize large areas and to operate with entire freedom from the necessity of observing the appearance and conduct of his patients, many of whom, notably the alcoholic ones, behave badly, become cyanotic and breathe intermittently when under the effects of inhalation anesthetics. The absorption into the body of the substances employed by inhalation may also exert a baneful influence by reducing the powers of resistance upon an economy already lowered by disease, and also by retarding convalescence.
Advantages of Local Anesthesia. In minor or trivial affairs the elimination of pain is not to be considered lightly, for every patient, even the strongest, will appreciate anything which will expedite a cure and at the same time will relieve him of suffering. Rather than lose time from their work or suffer the nausea and dangers of general anesthesia, these patients often bear for years conditions which could easily be cured by operations under local anesthesia. In this class one must first think of hemorrhoids; of cysts; of fatty tumors; of foreign bodies in the hands and feet; of verruca and of ingrown nails. These conditions would be promptly relieved were the element of pain in surgical interference not to enter as a factor.