New York

by faithgibson on September 22, 2012

Transactions of the American Association of Obstetricians and Gynecologists VOL. XXX, 1917 pp. 289-293

Many drugs which are used with benefit in certain doses will produce toxic effects in larger doses.

We are all aware that strychnine in quantity many times greater than is needed for therapeutic effect will cause death. Witnessing the convulsions and tetany of a dog injected with a large dose of strychnine in a laboratory of pharmacology  we, as students, demonstrated the results of poisonous doses. Yet the memory of these symptoms of poisoning has not prevented us from using the drug in medicinal doses for the therapeutic effect. Clinical experience satisfies us with the safety of such administration, and we do not call up as relevant the memory of the symptoms in dogs subjected to overdosage.

A number of laboratory workers have made experiments on animals with chloroform inhalation. Pathological changes in the liver and other organs have been found at autopsy following this administration in excessive quantity, in dosage many times greater in proportion to body weight than is used in the practice of obstetrics. Yet in spite of the clinical experience, based on hundreds of thousands of cases, we find that obstetricians were overawed by the report of these experimental results of relatively overwhelming dosage on laboratory animals, and that many of them were ready to abandon the anesthetic on these laboratory findings alone.
 In June of last year I reported to the American Medical Association the results of my animal experimentation and clinical experience, as well as an exhaustive study of medical literature, and came to the conclusion that there was no analogy between such experimental work as has been done on animals and the careful administration of therapeutic doses of chloroform in labor.

I had been surprised at the tendency of obstetricians to discredit the use of the anesthetic that had been most useful in their practice, not on the evidence of what had occurred in obstetrics, but what had been found at times in deep surgical anesthesia and what was reported from animal experimentation. It would be reactionary and contrary to the purpose of scientific advancement to ignore the evidence of the laboratory. It seemed only practical, however, to study the reasons for the apparent discrepancy between obstetrical experience and laboratory findings and also between the use of this narcotic in labor and in general anesthesia.

About this same time Morley, of Detroit, had independently studied this question from the same viewpoint and had refused to be convinced that what he saw in obstetrics was wrong because of what he heard of animal experimentation. He analyzed the report of one of the experiments of Whipple and Sperry on chloroform poisoning, as follows: “A dog weighing 224 ounces was given 2.25 ounces of chloroform for four hours. The amount of chloroform was 1/100 of the body weight. In this same proportion, if an obstetrical patient weighing 150 pounds were given chloroform in the same proportion of her body weight, she would receive 1 1/2 pounds of chloroform in four hours or in the same period of time. She would no doubt have late chloroform poisoning if she could be made to live that long.”

There is nothing wrong with the animal experiments made by the pathologists. It definitely and conclusively shows central necrosis of the liver cells and changes in other organs as a result of chloroform. But it has no bearing on the chloroform analgesia in labor any more than has the poisoning of dogs with strychnine to the medical use of the drug. You cannot imitate the ideal chloroform analgesia of the woman in labor, in animal experiments. I endeavored to do this in a series of experiments on dogs and guinea-pigs.

Using quantities of chloroform that were absurdly overwhelming when compared to the quantity used to obtain a delightful analgesia in a woman in labor, there was no similar state in the animal. The chloroform analgesia of labor is largely a psychic condition. The woman experiences relief from an agonizing pain from a few drops of chloroform. After the first successful application during a pain, with each succeeding pain she has the physical effect of the chloroform plus the suggestion of relief derived from the first experience.

For this reason, I always give enough chloroform during the first few pains to actually dull the pain and subsequently use less, depending in part on the suggestive effect. In this way a condition of comfort and quietude is obtained on astonishingly small doses of chloroform.
 Take a guinea-pig, not strapped down, but resting comfortably and every few minutes for four hours let it smell J30 of a drop of chloroform; it will not have any analgesia, and its psychic state will probably be only one of mild wonder at your performance. But the amount of chloroform is comparable to that used for a woman in obstetrical analgesia and the guinea-pig’s liver would remain quite normal.

Our animal experimenters do not use such dosage in producing artificial liver necrosis. They say “just enough chloroform to produce narcosis.” In my own experiments the least quantity with which I could obtain any semblance of narcosis was 112 drops during four hours for a half-pound guineapig, the equivalent of 30,000 drops for an average-sized woman; that is 3% pints. It is sixty times as much as I have used to procure a perfect analgesia during the painful three and one-half hours of labor in a neurotic primipara, including a short period of complete anesthesia during the expulsion.

One of the exponents of another anesthesia in referring to my comments on the experiments on animals inferred that I claimed that the element of shock to these struggling and frightened animals played a part in the destructive changes. He argued that the same state of shock and fear existed in animals subjected to other anesthetics which did not show internal changes to the same extent.

I do not contend that shock is a potent factor. I described the struggling of the terrified animals to show how unlike the quieting effect of analgesic doses of chloroform to a parturient are the effects produced on animals to whom the narcosis is administered in experiments.
 You do not produce a benign happy semisomnolence in the laboratory animal. You irritate and excite it until you stupefy it with the narcosis, and, therefore, you never produce experimentally the conditions existing in the woman in labor. She is relieved from the anguish of labor pains and made quiet because the cause of her restlessness is removed. The animal is made restless and resistant and to narcotize it you must use quantities of the anesthetic so out of proportion to what is used in labor that there is no reason to consider the one as having any relation to the other.

Very evidently then, if we are to abandon chloroform in midwifery, it must not be on the evidence of its effect on animals given in a way that has no resemblance to its use in midwifery [i.e. maternity cases attended by MDs].
 But the objection to chloroform in obstetrics is based on other grounds also. There are also clinical reports of late poisoning from chloroform. Almost exclusively, however, these cases are taken from general surgery. For over fifty years this question of remote toxic effects has been before the profession, and in all that time hardly a case is reported in obstetrics in spite of the millions of times it has been used and the thousands of times it has been misused.

A few cases have been noted where there were complications in kidney or liver disease or preexisting sepsis.
 It must be kept in mind that in the course of an obstetrical case, complications may arise which demand a prolonged deep surgical anesthesia. The situation is then one of surgical anesthesia, and the choice of anesthetic must be made on the same principles that guide one in any surgical operation. For surgical narcosis, at least in America, we are agreed that chloroform is not the safest nor most desirable except in certain cases. For obstetrical surgery, just as for any other operative work, we would usually prefer ether. This has nothing to do with the obstetrical analgesia of which I am speaking and for which I consider chloroform most useful.

The idea which we are seeking is freedom from suffering without endangering the patient or interfering with the progress of labor. Armed with chloroform and with intelligence in its use, the accoucheur can reach this ideal. Its use is selective as to the time we begin in each case and to what extent we continue its administration.
 Twilight sleep was objectionable because once a patient was elected for it, she was put through it, though the same patient might otherwise have gone through a relatively pain-free labor in which little or no anesthetic would have been needed.
 The object of obstetrical analgesia is to make labor tolerable. But our object is not alone the desire to prevent suffering. Pain beyond the psychic endurance of the patient at any stage, inhibits labor. Analgesia which dulls the pain to a degree that can be endured by the patient prevents this inhibition and aids the progress of labor. So, according to the sensibility of the patient and her stability of psychic balance, chloroform is begun in the first stage, early in the second or just before or during expulsion.

At any of these periods either because of the patient’s hyperesthesia and instability of psychic equilibrium, or because of obstetrical conditions creating unusual suffering, the contractions are inhibited and labor progresses more readily as soon as the agony is dulled and the psychic balance restored.
 When a patient has been having a few drops with each pain the state of analgesia can be merged into anesthesia very readily with a small quantity of chloroform. This is a perfectly safe and wise procedure for managing the head on the perineum. It may also be employed for a few minutes where the forceps are used.

When, however, a condition exists requiring any obstetrical operation in which a state of complete anesthesia is needed for a considerable period of time, the question of chloroform or ether stands as the question stands in general surgery. Ether is chosen except where there are contraindications.

For the analgesia of labor chloroform correctly used is perfect in results and absolutely safe. Other men have found great satisfaction in the use of nitrous-oxide-oxygen, and it seems that as they become skilled in its use, they obtain a satisfactory analgesia just as we do with chloroform.
 It cannot be safer, however, and its exponents must not seek to establish it on the basis of experimental poisoning of animals with chloroform, nor on the use of chloroform in surgery for complete anesthesia, for neither has any bearing on the harmless chloroform analgesia of obstetrics.

Transactions of the American Association of Obstetricians and Gynecologists VOL. XXX, 1917 pp. 289-293