This section is from the book "Dental Medicine. A Manual Of Dental Materia Medica And Therapeutics", by Ferdinand J. S. Gorgas. Also available from Amazon: Dental Medicine.
C2H5Br. Sp. gr. 1.420.
Bromide of Ethyl is obtained from bromide of potassium, sulphuric acid, alcohol and water, by distillation, and is re-distilled by chloride of calcium. It is a colorless and very volatile liquid, boiling at 400 C, heavier than water, and possesses an agreeable ethereal odor, and a pungent taste, strong and sweetish, with a somewhat burning after-taste. It is readily soluble in alcohol arid ether, and but sparingly soluble in water.
Bromide of ethyl, like all other agents of this class, must be administered with great care, and a pure article employed. There is no doubt but that it is pleas-anter to inhale than chloroform, exceedingly rapid in producing complete unconsciousness, and very evanescent in its action; but, from the fatalities attending its use, it is a dangerous agen. Like chloroform ethyl bromide destroys life by its effect upon the heart; on account of its being essentially poisonous owing to the large percentage of bromine which it contains; and its poisonous effect when not at once fatal is prolonged and dangerous to the heart, and other vital organs, especially the kidneys. Its poisonous effects are more pronounced when it is administered in an upright or even half reclining position as for dental operations.
Introduced into the stomach, bromide of ethyl does not produce anaesthesia, as when absorbed by the respiratory organs, and does not increase the pulse over its normal beat; and in the second stage, causes an intermission of the pulse every second beat.
Bromide of ethyl when employed as an anaesthetic is best administered in a folded starched napkin, so as to cover the face, and having inside of it a soft linen handkerchief. On the linen handkerchief one measured drachm of the agent should be poured, and the patient directed to take long, deep inspirations, or, what is better, to make prolonged and forced expirations. In two minutes from the time of administration of the first drachm, a second should be given, and this should be repeated at intervals of two minutes. Like all general anaesthetics, however, the quantity for inhalation differs according to the susceptibility of the patient. One drachm (or in some cases two drachms may be required, according to the susceptibility of the patient) of the bromide of ethyl will generally, in from one to three minutes, produce an anaesthesia as profound as that produced by an ounce of sulphuric ether. As it produces an anaesthetic effect on the muscles of the throat and upper parts of the pharynx, it is useful for operations on the mouth and throat.
The effect of an anaesthetic, however, is to be more regarded than the mere quantity of the agent poured upon a napkin or sponge, as the degree of anaesthesia should be governed, in most cases, by the nature of the operation to be performed under its influence.
The odor of bromide of ethyl is more rapidly removed, and is more agreeable than that of sulphuric ether, and its effects more rapid than even those of chloroform, as it is eliminated by respiration, and by the kidneys. Having no caustic action, it can be safely applied subcutaneously, and also to the external auditory meatus and to the mucous membrane. It evaporates upon the skin very rapidly, producing a very sensible feeling of cold. The general effects claimed for ethyl bromide are as follows: Moderate acceleration of the pulse and respiration; slight excitement or talking, and seldom any struggling; flushing of face; dilatation, sometimes preceded by contraction of pupil; diaphoresis, generally profuse; complete anaesthesia in two or three minutes; recovery of consciousness in from one to two minutes after the withdrawal of the anaesthetic agent; no after-vomiting.
Any specimen of bromide of ethyl which has a disagreeable odor, or which, on standing, becomes brown, or any that will explode and burn, is impure and should not be employed for inhalation. A common impurity is bromoform, produced by the action of bromine and caustic potassa on alcohol or wood spirit. Bromide of ethyl possesses properties intermediate between those of chloroform and ether. As a local anaesthetic it is highly spoken of, and, owing to its non-inflammability, is the only anaesthetic which can be used in connection with the actual cautery. Dr. Byrd strongly recommends an anaesthetic mixture of bromide of ethyl 1 part, chloroform 3 parts and alcohol 4 parts, a drachm of which is poured upon the sponge of the inhaler, which the patient is allowed to inhale with the stopper out, after which the stopper is replaced and the full strength of the mixture inhaled. Generally in five minutes the patient is fully anaesthetized, when the stopper may be taken out to permit a greater admixture of air, and replaced as the judgment of the operator may dictate. This mixture, it is claimed, is safer and less disagreeable in its effects than the bromide alone. For use as a local anaesthetic, the bromide of ethyl is atomized with the "spray apparatus," which should furnish enough of the liquid to moisten the skin. The extremity of the tube should be held some two or three inches from the surface on which the spray is to be thrown. Within two or three minutes after its first application, anaesthesia of the part occurs, which is shown by the appearance of a white spot. The formation of this spot may be hastened by superficially puncturing or scratching the skin. The sensation of cold thus produced is sometimes disagreeable, but is rarely painful.
Given internally it is also said to relieve gastric pain without affecting the appetite. Inhalations have been used to relieve convulsive cough; and, introduced on cotton wool into the external meatus, it is said to relieve the pain of otalgia, without causing any irritation.