Читать книгу Treatise on Poisons - Robert Sir Christison - Страница 45

The action of oxalic acid on the animal economy is very peculiar.

When injected in a state of concentration into the stomach of a dog or cat, it causes exquisite pain, expressed by cries and struggling. In a few minutes this is succeeded by violent efforts to vomit; then by sudden dulness, languor, and great debility; and death soon takes place without a struggle. The period which elapses before death varies from two to twenty minutes, when the dose is considerable,—half an ounce, for example. After death the stomach is found to contain black extravasated blood, exactly like blood acted on by oxalic acid out of the body; the inner coat of the stomach is of a cherry-red colour, with streaks of black granular warty extravasation; and in some places the surface of the coat is very brittle and the subjacent stratum gelatinized, evidently by the chemical action of the poison.^[400] If the stomach is examined immediately after death, little corrosion will be found, compared with what is seen if the inspection be delayed a day or two.^[401]

Such are the effects of the concentrated acid. When considerably diluted, the phenomena are totally different. When dissolved in twenty parts of water, oxalic acid, like the mineral acids in the same circumstances, cease to corrode; nay it hardly even irritates. But, unlike them, it continues a deadly poison; for it causes death by acting indirectly on the brain, spine, and heart. The symptoms then induced vary with the dose. When the quantity is large, the most prominent symptoms are those of palsy of the heart; and immediately after death that organ is found to have lost its contractility, and to contain arterial blood in its left cavities. When the dose is less the animal perishes after several fits of violent tetanus, which affects the respiratory muscles of the chest in particular, causing spasmodic fixing of the chest and consequent suffocation. When the dose is still less, the spasms are slight or altogether wanting, and death occurs under symptoms of pure narcotism like those caused by opium: the animal appears to sleep away.

This poison acts with violence, and produces nearly the same effects to whatever texture of the body it is applied. It causes death with great rapidity when injected into the sac of the peritonæum, or into that of the pleura; it acts with still greater quickness when injected into a vein; and it also acts when injected into the cellular tissue beneath the skin, but with much less celerity than through any other channel. Eight grains injected into the jugular vein of a dog occasioned almost immediate death: Thirty-three grains injected into the pleura killed another in twelve minutes. The same quantity did not prove fatal, though it caused violent effects, when retained in the stomach by a ligature on the gullet. One hundred and sixty grains injected under the skin of the thigh and belly did not prove fatal for about ten hours. The symptoms were nearly the same in every case.^[402]

It is probable from the facts now stated, that oxalic acid, when not sufficiently concentrated to occasion death by the local injury produced, acts on the nervous system through the medium of the blood. Nevertheless it is a remarkable circumstance that it cannot be detected in that fluid. Mention has already been made of an experiment performed by Dr. Coindet and myself (p. 22), where even after the injection of eight grains of oxalic acid into the femoral vein, and the consequent death of the animal in thirty seconds, none of the poison could be detected in the blood of the iliac vein or vena cava. Similar results have been more lately obtained by Dr. Pommer. In dogs killed by the gradual injection of from five to thirty grains into the femoral vein, he never could detect the poison in the blood of the right side of the heart or great veins, except in the instance of the largest doses, where a little could be detected near the opening in the vein. Dr. Pommer’s experiments likewise agree with those of Dr. Coindet and myself as to the absence of any change in the physical qualities of the blood.^[403] When to these circumstances it is added that very small quantities of oxalic acid may be detected in blood, into which it has been introduced immediately after removal from the body by venesection, it appears reasonable to conclude that the poison is quickly decomposed in the blood by vital operations.

According to Orfila, however, it may be detected in the urine, in which crystals of oxalate of lime form on cooling, and more may be obtained on the addition of hydrochlorate of lime. Yet he could not detect any oxalic acid in the liver or spleen.^[404]

In man the most prominent symptoms hitherto observed have been those of excessive irritation, because it has been almost always swallowed in a large dose and much concentrated.

It is the most rapid and unerring of all the common poisons. The London Courier contains an inquest on the body of a young man who appears to have survived hardly ten minutes;^[405] an equally rapid case of a young lady, who poisoned herself with an ounce, is mentioned in the St. James’s Chronicle;^[406] and few of those who have died survived above an hour. This rule, however, is by no means without exception. Mr. Hebb has described a case which did not prove fatal for thirteen hours;^[407] Dr. Arrowsmith of Coventry has favoured me with the particulars of a very interesting case which lasted for the same period: and Mr. Frazer has accurately described another, in which, after the patient seemed to be doing tolerably well, an exhausting fever, with dyspepsia and singultus, carried him off in twenty-three days.^[408]

Among the fatal cases the smallest dose has been half an ounce; but there can be little doubt that less would be sufficient to cause death. Dr. Babington of Coleraine has published a case where very severe effects were produced by only two scruples.^[409]

Very few persons have recovered where the quantity was considerable.

In every instance in which the dose was considerable, and the solution concentrated, the first symptoms have been immediate burning pain in the stomach, and generally also in the throat. But when the dose was small, more particularly if the solution was also rather diluted, the pain has sometimes been slight, or slow in commencing. Mr. Hebb’s patient, who took only half an ounce dissolved in ten parts of water, and diluted it immediately after with copious draughts of water, had not any pain in the belly for six hours.

In general, violent vomiting follows the accession of pain, either immediately, or in a few minutes; and it commonly continues till near death. Some, however, have not vomited at all, even when the acid was strong and in a large dose; and this is still more apt to happen when the poison has been taken much diluted. The man last mentioned did not vomit at all for seven hours, except when emetics were administered. The vomited matter, as in this man’s case, and in that of Mr. Frazer’s patient, is sometimes bloody. Instant discharge of the poison by vomiting does not always save the patient’s life: A woman who swallowed two ounces died in twenty minutes, although she vomited almost immediately after taking the poison.^[410]

The tongue and mouth occasionally become inflamed if the case lasts long enough. In an instance of recovery, which happened not long ago in St. Thomas’s Hospital, London, the tongue was red, swollen, tense and tender, the day after the acid was swallowed.^[411]

Death commonly takes place so soon, that the bowels are seldom much affected. But when life is prolonged a few hours, they are evidently much irritated. Dr. Arrowsmith’s patient, who lived thirteen hours, had severe pain in the bowels and frequent inclination to go to stool, and Mr. Hebb’s patient, who also lived thirteen hours, had a constant, involuntary discharge of fluid fæces, occasionally mixed with blood. Bloody diarrhœa is very common in dogs.

The signs of depressed circulation are always very striking. In general the pulse fails altogether, it is always very feeble, and the skin is cold and clammy. Contrary to the general fact, however, I once remarked in a dog the pulsation of the heart so strong as to be audible at a distance of several yards.

In some cases nervous symptoms have occurred, but in none so distinctly as in animals that have taken the diluted acid. It should be remarked, however, that few published cases contain good histories of the symptoms; since they commonly come to an end before being seen by the physician. Convulsions appear to have occurred in some instances either at the time of death or soon before it. In the slower cases various nervous affections have been observed. A girl, who swallowed by mistake about two drachms, and did not vomit till emetics were given, complained much at first of pain, but afterwards chiefly of great lassitude and weakness of the limbs, and next morning of numbness and weakness there as well as in the back. This affection was at first so severe that she could hardly walk up stairs; but in a few days she recovered entirely.^[412] Analogous effects took place in Mr. Hebb’s patient and in Dr. Arrowsmith’s case. The first thing the former complained of was acute pain in the back, gradually extending down the thighs, occasioning ere long great torture, and continuing almost till the moment of death. Dr. Arrowsmith’s patient had the same symptoms, complained more of the pain shooting down from the loins to the limbs than of the pain in the belly, and was constantly seeking relief in a fresh change of posture. Mr. Frazer’s patient had from an early period a peculiar general numbness, approaching to palsy. Dr. Babington’s patient, who took two scruples by mistake for tartaric acid in an effervescing draught, suffered, after the first twenty-four hours, chiefly from headache, extreme feebleness of the pulse, and a sense of numbness and tingling or pricking in the back and thighs. In a recent case described by Mr. Tapson, which occurred in London, and where it was supposed, but on insufficient grounds,^[413] that so much as two ounces had been taken, violent symptoms of irritation in the alimentary canal came on as usual, but soon afterwards a sense as if the hands were dead, loss of consciousness for eight hours, and then lividity, coldness, and almost complete loss of the power of motion in the legs; which symptoms were not entirely removed for fifteen days. In a case related by Mr. Alfred Taylor, where death was caused by seven drachms in fifteen or twenty minutes, there was first violent vomiting, then severe pain in the stomach, and finally clammy perspiration and convulsions, with two or three deep inspirations before death.^[414] The effects in this case came very near those generally observed in animals.

In Dr. Arrowsmith’s case two symptoms occurred, which I have not seen mentioned in any other. The first was an eruption or mottled appearance of the skin in circular patches, not unlike the roundish red marks on the arms of stout healthy children, but of a deeper tint. The second was the poisoning and death of leeches applied to the stomach. “They were healthy,” says Dr. Arrowsmith in the notes with which he obligingly furnished me, “small, and fastened immediately. On looking at them in a few minutes I remarked that they did not seem to fill, and on touching one it felt hard and immediately fell off, motionless and dead. The others were all in the same state. They had all bitten and the marks were conspicuous; but they had drawn scarcely any blood. They were applied about six hours after the acid was taken.” This curious fact illustrates the observations formerly quoted from Vernière’s experiments [p. 67]. It will be observed that the leeches were applied several hours after the poison was swallowed, and in a case in which the acid was largely diluted in the stomach;—so that it might have entered the blood and been diffused throughout the body before the observation was made.