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BY DR. H. B. FAVILL, OF MADISON.
Of all the modifications which the treatment of disease has undergone during the present century, probably none has been so important, so revolutionary and so universal as that arising out of enlarged knowledge and elaborated ideas of the nutritive life of the human individual, and the consequent attention to the specific demands of the diseased organism in the matter of food.
To discuss in general the period of our therapeutic development would lead me into a survey of the entire field of dietetics, one much 100 extensive to be traversed within the limits of my time and knowledge.
I shall therefore endeavor to confine my observations, first to the agents and methods used in the production of artificial digestion, and such questions of selection of foods as are inevitably involved therein, and second, artificial modes of ingestion and the correlative points here involved.
I have no hope of presenting anything hitherto unheard, nor even of very recent origin, but recognizing the tendency of us all to fail to avail ourselves of many new methods because of troublesome or illy understood detail,if I shall be able to present certain methods theoretically correct as at the same time eminently practical my object will have been fulfilled.
While the problems of providing appropriate food, and prescribing proper conditions for its use arise in every case of sickness, the cases in which artificial alimentation, as we are discussing it, is demanded, though very much fewer are daily becoming more frequent. The explanation of this fact I conceive to be twofold. ist. Our facilities for the pursuit of this line of practice are steadily being improved, and advantage of their existence is more easily taken, and 2nd, clearer recognition is given to the fact that the human organism is a self-reparative automaton, the integrity of whose parts, and the perfection of whose functions, depend upon the balance between vital performance and resistance, and in consequence the tendency of practice is, so to speak, to reduce the friction by removing so far as possible, the load, which load in many cases is the labor of digestion.
Hence we find that not only are daily more patients nourished by artificial means, but many more are being aided by plans which vary from this method chiefly in degree.
It would be a long and fruitless task to attempt to enumerate the diseases in which we may with advantage call to our aid the methods under consideration, but clearness demands that we note the general morbid conditions with which we endeavor thus to contend.
The steps from crude food to assimilated nourishment I conceive to be three, and the problems presented to us to derive their character from the essentially distinct, yet mutually dependent functions pertaining to each stage. We encounter first the functions covered by the term ingestion, including retention. Second, digestion including both chemical and mechanical elements. Third, absorption.
Each of these is subject to disturbance of remote and complex origins, but I can attempt no analysis of the remote causes of. perverted function. Resort should be had to artificial alimentation in most instances in accordance with one or all of three principles.
1. Either that nourishment so furnished will support life till morlid states shall disappear, or in hopeless disease will prolong life.
Or, that, by furnishing pabulum to depraved tissue, it may itself induce a return to normal. 3. Or, by relieving local conditions it may redound to the ultimate advantage of the part.
Difficulties of ingestion involve, ist, refusal to take food from any cause. 2nd, Mechanical obstruction to swallowing of food. 3. Inability to retain what is swallowed.
Difficulties of digestion involve, ist, Diminution of digestive fluids. 2d. Great impairment of quality of same. 3d. Mechanical interference, either from peristaltic insufficience, or from morbid secretions interfering with digestive processes.
With questions of absorption and failure thereof, though it is incumbent upon us to to recognize them, and give them due weight,
especially in our disappointments, we can deal very unsatisfactorily.
The nature of the process which embraces diffusion, absorption of emulsion, selection, or the part of different areas; and with all the uncertainties as to the exact stage of transformation of food to which each applies, lends an obscurity, which as yet can not be elucidated,
Fortunately the cases are rare in which absorption fails utterly. but in the presence of that condition, little lies within our power to accomplish, though our resources in all the other conditions are comparatively effective. Failure of absorption is the greatest stumbling block that a worker in this field will encounter, but the deficiency so far as we now know is best combatted by the excellence of our work in correcting the errors in this antecedent step of the nutritive sequence. While recognizing the fact that important lapses occur in our knowledge of human digestion it is still possible to assert with positiveness certain propositions.
That there are three principal digestive fluids, products of the salivary, gastric, and pancreatic glands.
That there are three principal classes of foods, proteid, starches and sugars and fats.
That the ultimate aim of all digestion is the conversion of some not absorbable food substance into one more absorbable, which with starches and proteids involves the production of solubility, with fats of emulsion.
That the digestive juices possess a selective power which renders each operative on special foods; the salivary upon starch, converting it into sugar; the gastric converting proteids into soluble peptones; the pancreatic converting starch into sugar, proteids into peptone, furnishing the special activity necessary to the curdling of milk (as does also the gastric juice), and rendering fat into an emulsion, the only form in which the absorbing mechanism can seize it.
Thus we discern that the most widely operative, and as has been demonstrated, the most powerful endowed fluid is the product of pancreatic secretion. Next in power and importance stands the gastric fluid, and least powerful in man the salivary fluid.
I cannot here discuss the steps whereby we have been finally led to the position we now occupy regarding the use and preparation of artificial digesting agents. In response to the demand put forth by the conditions of disease, chemists and clinicians have bent their energies, toward the preparation from the organs of lower animals, notably the pig, of agents which should produce artificially, results identical with the products of natural digestion.
Practical results have been obtained only with respect to the pancreatic and gastric or more properly the peptic secretions, but these are of the greatest value.
From the stomachs of certain of the lower animals especially the pig and calf, is separable a nitrogenous substance, pepsin, with characteristics which class it as a ferment. From the pancreas of the same is obtainable a substance called by many names, compound in its powers, hence regarded as complex in its nature, also a ferment.
What a ferment is, I will not presume to define; it does certain definite things; is capable of producing by its presence, without apparent loss of its own substance, chemical changes in bodies over which it has control. In the case of digestive ferments, insoluble food substances are rendered soluble.
The refinements of this process are still too occult to yield satisfaction in their discussion,
Our knowledge of the active agents is slight, and we probably err in regarding them as substances, but should rather regard them as powers liberated under certain conditions.
In the substances obtained from animals it has been possible to retain the powers which are designated as proteolytic, or proteid transforming, and amylolytic or starch transforming. By their effects only can they be distinguished and identified. Comparatively recently has been added to our accurate knowledge, valuable researches on the subject of the proteolytic ferment of vegetable origin papain, a derivative of the carica papaya, or papaw juice. Its character and properties will be discussed hereafter.
Pepsin in general may be said to be capable of transforming proteid or nitrogenous, matters into a soluble, diffusible form called peptone.
Wherein this change resides, we are unable to tell, but analogy would lead us to infer that some form of hydration, akin to that occurring in the change of starch into sugar is the essential process. Necessary to this process however, is the presence of acid, whose origin is doubtful, but whose presence is invariable.
These two factors being present together with proper temperature, proteids of which fibrin and egg albumen and casein of milk are types, will be changed into peptone. Herein we find a complete and satisfactory process, whose products are suitable for the maintenance of life. As a process for artificial preparation of food however it has grave objections, in cases where food is to be pre-digested It is incomplete having no activity toward starches and fats; thus rendering so to speak, mixed diet, impracticable. The acid, by rendering the preparation nauseous, is a source of annoyance. It is not possible to conduct the process in a manner, which shall produce a fluid, which will be tolerated by other portions of the alimentary canal than the stomach. Its utility therefore is limited to cases in which we wish to aid digestion in the stomach.
The pancreatic secretion, containing the amylolytic ferment, diastase, the proteolytic ferment, trypsin, the emulsifying ferment and the milk curdling ferment, is obviously a far reaching agent for producing artificially digested food.
Its activity, while most energetic in slightly alkaline media, is still sustained in neutral and slightly acid media, and by taking advantage of this fact, we may avoid several of the obstacles presented by peptic digestion, at the same time availing ourselves of the stomach as a receptacle, wherein the process may be perfected, when only partial predigestion is desired. Moreover it is operative upon all forms of food which the human animal demands.
Of papain in practical use only limited experience is at hand, but careful experiments yield the following results:
It contains ferments whose activities, as exerted upon milk, are very similar to those of pancreatic juice. The ferments are proteolytic and milk curdling. Emulsifying powers are said to be very slight. It is active in alkaline media, but is not free from the other objection to pepsin, in not being able to digest other foods than proteid. In these three substances we find the materials of known power and usefulness to which we may resort.
To discuss why and when the measures involved in artificial nourishing ought to be resorted to involves the difficulty of systematizing the indications for treatment in cases having great latitude; but in general we find ourselves driven to seek the aid of artificial feeding. ist, in systemic disease with simply participatory incompetency of the digestive apparatus. 2nd, in intrinsic disease of the gastro intestinal tract. In the first case we are seeking especially, better preparation of food for the use of the system. In the second we are