Читать книгу Pharmacologia - John Ayrton Paris - Страница 74

Watery liquors, which increase the fluidity of the blood, and render several of the secreted and excreted fluids less viscid.

There are certainly few remedies whose operation is more simple, obvious, or important; and yet there are scarcely any whose value has been more mistaken, or whose application has been so frequently perverted through the suggestions of false theory; water is the universal beverage of animals, and the necessity of its supply is indicated by thirst, a sensation which in excess, is borne with less tranquillity even than that of hunger; in certain morbid states of the body its presence is to be regarded as indicating the necessity of copious potation; and yet how often has the prejudiced physician, under such circumstances, aggravated the pressure of disease, by adding the sufferings of Tantalus. In febrile affections, the irritation of thirst tends to keep up the disease, and hence diluents, besides the other beneficial effects which they may produce, must be regarded as important remedies. There are also diseases of the alimentary canal which may be removed by the same agents; when water is conveyed into the intestines it will have a tendency, by mixing with, and diluting the biliary secretion, to diminish its acrimony, and thus to obviate a source of morbid irritation; the dilution of the chyme and chyle may also have a salutary tendency, and favour the absorption of the finer and more nutritive parts of the lacteals; and by increasing the fluidity of the mass, expedite the numerous combinations which it is destined to undergo. The blood itself is also thus modified in its fluidity; although it has been very truly observed that in healthy bodies, or such as are without any obstruction of the excretions, an unusual distension of the vessels cannot be produced, or at least long subsist; for it is evident that such an increased quantity of water in the blood will immediately pass off by one or other of the excretions; this effect, however, in itself, renders the operation of diluents of signal service in the treatment of the disease; in consequence, for instance, of their disposition to pass off by urine, they furnish valuable resources in diseases of the urinary organs, allaying the pain of strangury, and the irritation from an inflamed bladder. From these observations, the practitioner will be led to appreciate the value of diluents; and many of the beneficial effects which are daily experienced from the copious potation of mineral waters, are, without doubt, to be wholly attributed to simple dilution. See Aqua.

It is here necessary to say a few words upon the misapplication of this order of remedies. Dr. Davy found by experiment that when an animal is bled to death, the last portions of blood that flow are of a much lower specific gravity than that which flows first, in consequence of the former containing more water, which it may be inferred was derived by the increased activity of the absorbents, exerted chiefly on mucous and serous membranes. Since then venesection promotes and accelerates absorption,^[236] it is clear that, in inflammatory diseases, where we have recourse to blood-letting, in order to diminish the volume of circulating fluids, we ought not to suffer the patient to indulge in an unrestrained use of liquids, which he eagerly demands to satisfy a thirst which, in all probability, is the natural consequence of increased absorption. In such cases, it is often better to take liquids in small divided doses, which will have the effect of moderating the thirst, without overloading the arterial system, and bringing on that tension and plenitude which are liable to be produced by swallowing too large a proportion of liquids.

In the use of water upon such occasions, it may moreover be observed, that its temperature ought to be attended to; as a general rule it may be laid down, that in the cold stage it should be hot, in the hot, cold, and in the sweating, tepid.

With regard to the value of diluents, as capable of promoting the operation of other remedies, many observations of great practical importance might be adduced; but this subject will be more properly elucidated when we come to consider the influence of solubility in modifying the activity of medicinal substances, and which constitutes a very curious and interesting object of chemico-medical enquiry.

While speaking of Diluents it may be cursorily noticed, that water appears, under certain circumstances of the body, to suffer decomposition, and to have its elements appropriated to new combinations. Count Rumford has endeavoured to prove, that the surprisingly small quantity of solid food which is sufficient for nourishment, when converted into rich and palatable soup, is owing to the culinary process having prepared the water for chemical decomposition,^[237] and that this is ultimately effected during the act of Digestion.^[238] It cannot be denied that the exorbitant potation of water has a tendency to produce fat, but this may depend upon the vascular distention which is thus occasioned. Gin drinkers, before they become materially injured by the habit, grow extremely corpulent, as may often be witnessed in unfortunate cyprians of the lower orders. Can the hydrogen of the spirit contribute to this effect?