The Necessity for Absolute Purity in Chloroform

Admini­stration of Chloroform

Considerable attention has been directed to different methods of administering chloroform, and various forms of apparatus have been devised which claim to reduce to a minimum the dangers of anæsthesia. Assuming a most skilled and competent administrator, an ideal method of administration, and a suitable patient, an unsatisfactory result can only be attributed to the chloroform employed. Purity an essentialPurity of chloroform is a most important factor in contributing to safe anæsthesia. The physician claims that absolute purity shall characterise all medicinal agents, and the justice of the claim is acknowledged by the trend of recent legislation.Danger of impurities Purity is a prime essential of any anæsthetic. The presence of impurities largely increases the risk inseparable from the use of chloroform. The train of symptoms observed during the normal process of anæsthesia may be masked and altered, and dangerous results may supervene under the most competent, careful and observant administrator.

An Operation in the Twentieth Century

Expert testimony

That some of the chloroform offered to the profession may reasonably be regarded with suspicion is evidenced by the words of a prominent obstetrician, based on the experience of 40 years in the use of chloroform; this authority expresses himself as follows: “I may say I fear the chloroform in common use is often far from being as pure as it should be, and is sometimes very defective in this respect.”

Effects of impurities

Impurities may result from the process of manufacture, or from decomposition. Conspicuous amongst these undesirable elements are chlorine, hydrochloric acid and carbonyl chloride (phosgene), which irritate the lining membrane of the respiratory tract and interfere with the normal process of respiration. Such irritation may result in arrest of cardiac action or may produce a severe form of bronchitis. It is obviously of great importance that chloroform should be free from irritating properties, that the respiratory passages should not be obstructed, and that during anæsthesia the breathing and the circulation should approximate the normal. Superadded to these results, produced by local irritation, is the effect of other impurities which exert their action after absorption. These latter markedly increase the cardiac depression which has been shown to follow the administration of pure chloroform. Such an action is difficult of detection, and is, probably, in large degree responsible for a considerable number of the accidents reported.

Contradictory results

Of recent years increased knowledge has elaborated exact tests, which ensure the absence of these impurities. Nevertheless, anæsthetists of wide experience have obtained results which could not be reconciled with the use of pure chloroform. It has been observed that different chloroforms, all of which answer the official tests for purity, give effects which are difficult to harmonise, and the interpretation of which only appears satisfactory on the assumption that the chloroforms differ in composition. Whilst one chloroform acts most satisfactorily, another produces, during the early stages of administration, a marked excitement and an irregularity of breathing, which prolongs the period of induction. Recent researchFurther investigation has therefore been deemed necessary, and a comprehensive and careful research has elucidated the cause of these hitherto unexplained phenomena (Wade and Finnemore, “Journal of the Chemical Society,” 1904, 85, 938). In the chloroforms which produced anæsthesia in a satisfactory manner, has been demonstrated the presence of ethyl chloride in minute and varying quantities. Ethyl chlorideWhen the undesirable effects were noted, no ethyl chloride was detected in the anæsthetic. A physiological test conclusively proved that ethyl chloride was the factor which determined these differences.

Value of the investigation

A chloroform which had previously given undesirable effects, and in which the presence of ethyl chloride could not be demonstrated, was modified so as to contain a small proportion of the latter. The chloroform then proved a most satisfactory anæsthetic, and there was entire absence of the excitement and respiratory irregularity previously observed. The results of this research are of the utmost value. In the initial stages of the induction of chloroform anæsthesia, the presence of a small quantity of ethyl chloride has a beneficial effect, leading to the absence of mental excitement, and steadies the breathing. The respiration is stimulated and becomes regular and deep. In these circumstances, satisfactory anæsthesia is induced with rapidity and ease.