Imagens das páginas
PDF
ePub

but one kidney, the probabilities are, that once or twice in the first eighteen hours after the operation a small quantity of urine will be passed. On examination the fluid will be found albuminous, and perhaps containing blood or fibrine.

The symptoms thus detailed usually continue for twenty-four or thirty hours without any striking modification. At last the gap in the respirations becomes more distinct, an interval of even ten seconds intervening between two inspirations, followed by a series of rapid expirations. At this stage the pulse will cease to beat altogether during the intermission of the respiration; but as the hurried breathing is remanifested, the action of the heart will follow, and be so quick as scarcely to admit of being counted. The temperature of the body, previously raised, now begins to fall; convulsive actions give way to an entire passivity and prostration of muscle. The coma continues, and at last death takes place as from universal muscular paralysis. The heart seems to me to die first.

After death, post mortem rigidity is fully developed. The blood in both systems is usually dark, and is often either fluid or in a soft jelly-like condition; it coagulates slowly if found fluid, or may not coagulate at all. There is great vascular congestion of the lungs, the abdominal viscera, and the brain; and sometimes there are effusions of serum into the serous cavities, in which effusions urea may be found. The muscles are dark; and the endocardial surface may be stained deeply. The alimentary tract may also show signs of redness and congestion.

Thus between uræmia as it occurs from disease, and as it is induced by the synthetic process, there is identity both as regards symptoms and pathology. The proposition founded on this identity accepted, we have next to ask-What is there in normal urine, (for we may take the urine as normal) capable of producing the toxæmic symptoms of uræmia?

Setting aside hypotheses which have been invented merely as verbal trophies, there are certain speculations which demand our careful attention. Let us note them.

The earliest accepted view is that which attributes the symptoms of uræmia to retained urea, which in fact accepts urea, or, in more correct words, cyanate of ammonia, as a narcotic poison. This view has been by some eminent authorities set aside, to be recently revived and most ably advocated by a distinguished American physiologist, Dr. Hammond.

Another hypothesis is one put forward by the justly eminent Frerichs. He argues that the retained urea, undergoing decomposition in the body, is converted into carbonate of ammonia. The carbonate of ammonia thus produced is, according to Frerichs, the toxic agent.

There have been at various times certain other hypotheses put forward, which have more or less ignored urea as a producing cause, either in a direct or indirect sense, and in substitution for it have suggested as the poisonous agent other constituents of the urine; as the water in excess in the blood, or the constituents of the urine altogether. Into all these later

hypotheses a certain vagueness enters, which throws us back at once on the first and fundamental proposition, and leaves us with that alone in our possession as a fact.

Men who know nothing of the immense difficulties of conducting physiological researches may, I am aware, be ready with their criticisms; and may twit their more inquisitive and laborious compeers on their failures in satisfactorily settling a question on the surface of it so simple. But, in truth, in actual practice the question is one of immense difficulty, requiring for its solution not only actual experiment, but experiment so devised as to give, on the one hand, direct affirmative or negative replies, and on the other hand to be so far free of side influences, that the facts which are either affirmatively or negatively given shall not admit afterwards of interpretation by any new reading of their cause.

Let us, in considering this question, divest our minds for the moment of all thoughts respecting the immense interests which attach to its solution; let us throw aside every prejudice or weight of past learning that may so easily beset us; let us make no ambitious strain towards divining the riddle; let us use no oracular obscurities, chemical or physical; let us ask the aid of bare common sense, rest on it alone, and, at the risk of being considered puerile, question nature with the simplicity of a child.

We know now with tolerable accuracy the composition of the urine; and we can prove therefore that a certain fluid, the constituents of which we can

analytically read off, is capable of producing the specific symptoms of uræmia. We turn naturally from this knowledge to an examination of the constituent parts of the urine, and ask, respecting each of them, one after the other, can this be the poison? We discard several at once, from a comprehension of the fact that the symptoms they produce when present in excess in the body are not of a character analogous to the symptoms of uræmia: by this principle we exclude, with safety, uric, hippuric, and phosphoric acids; the chloride of sodium; the sulphates of potassa and soda; the lime and magnesian phosphates; and the iron. We have, again, the cells of epithelium and mucus derived from the bladder and mucous tract, which to a certain amount are present in every specimen of urine. We may exclude these organic products as the cause of uræmia; for, although it has been stated that urine containing them is poisonous on injection into the veins of healthy animals, while urine from which they have been freed by filtration is not poisonous on such injection, it has never been shown that the symptoms produced by the injection of unfiltered urine are those of uræmia. Further, it is obvious that in uræmia arising from obstruction in the renal vessels, or from any other cause by which the secretion of urine is prevented at the source of the secretion, the epithelial cells and mucus derived from the conveying mucous channels beneath the source, cannot for a moment be considered as the cause of the symptoms.

Thus by the exclusion process we are driven at last to these constituent parts of the urine, the water,

the urea, the creatine and the creatinine. Are they by retention the cause of uræmic coma?

There can be no doubt that water in excess in the blood produces symptoms similar to those presented in some forms of uræmia. Some years ago I demonstrated this fact by producing in animals artificial dropsy. The facts elicited by these inquiries will be found in my essay on the Coagulation of the Blood; but the summary of them may be briefly stated as strictly in place here.

When an amount of fluid, equal to a fifth part of the weight of an animal (dogs were used exclusively in my experiments) is injected into the peritoneal cavity, death is the result. Very shortly after such injection the animal becomes drowsy, and eventually quite comatose; the coma advancing in proportion as the fluid is absorbed into the blood. The animal may now and then, at long intervals, get up and attempt to walk with a drowsy tottering gait, but quickly reclines again and sleeps on. The ordinary period of death is from ten to twelve hours after the operation; the death is so quiet that it seems like a continuation of sleep.

If the amount of water injected be less in weight than a fifth of the body of the animal, the symptoms induced are identical in character with those already described, but the animal gradually recovers from his somnolency; he remains feeble for a few days, refuses food and drink, passes large quantities of urine, presents loud anæmic bruit in the neck, staggers in his walk, and is very cold over the whole of the sur

« AnteriorContinuar »