REDUCTION OF VASCULAR TENSION.

333

GROUP H.

The intravascular pressure may be diminished by the dilatation of considerable number of vessels, as in the skin, by the action of heat, of an extensive mustard bath, of pilocarpine, and by the nitrites as described, or in the intestines by vigorous cathartics.

In the case of diaphoretics and cathartics, a certain amount of fluid is actually removed from the system, though probably much the greater part of the effect is produced by the altered distribution of the blood. Nitrite of amyl produces a sudden and great but temporary fall of tension, the other nitrites a longer continued one. Other drugs have a similar but less marked effect.

Counter-irritation is employed to reduce the amount of blood in the tissues of one part by withdrawing it to another part, although it is not probable that this is the whole, or perhaps even the most important effect of counter-irritation. (See Mustard, Cantharides, Hot Fomentations, etc.)

Dry cups withdraw a little blood from their immediate neighborhood and confine it, as it were, in the form of small localized congestions and extravasations.

They are small glass vessels, usually made for the purpose, although wide-mouthed phials, or small tumblers, can be used, from which the air is exhausted, either by a pump or by inflaming in them a few drops of alcohol, and applying them quickly to the skin before the air has had time to cool. Several may be applied at a time.

They are employed to relieve deep-seated chronic pains and often congestions of internal organs, as of the spinal cord and kidneys.

The correctness of the statement made in the section on Irritants, that the effect of local applications is not entirely due to the withdrawal of blood, or, at any rate, is not proportionate to the amount of blood withdrawn, may be shown by the fact that these dry cups, which remove no blood from the body, and cannot take any large amount of it away from deep-seated tissues, are often nearly or quite as effective as cut cups, where the skin is incised by a series of small knives mounted in a box and moved by a spring, before the application of the suction. The amount of the blood removed depends upon the size of the cups and the completeness of the vacuum. Properly applied, a cup may remove more than half its capacity, or even nearly the whole, of blood.

Various other contrivances, called artificial leeches, for doing the same thing on a smaller scale, are used.

Sanguisorba medicinalis, Sanguisorba officinalis, and Sanguisorba decora, are no longer officinal, and are much less used than formerly.

They adhere to the skin by suckers at each end, the anterior containing three jaws, which make a three-cornered cut, from which the blood is extracted by suction until the animal is filled.

The part to which they are to be applied must be clean, and the leeches applied usually in a tube. Moistening the skin, especially with a little blood, will sometimes induce them to take hold more readily. A single European leech will take from half an ounce to an ounce of blood. The native S. decora takes a smaller quantity. The bites not unfrequently bleed after the removal of the animal, and may require the use of pressure or a hemostatic to stop them.

Leeches are chiefly used to diminish the tension and pain accompanying acute inflammation, and are undoubtedly capable of giving great relief. The progress of the inflammation itself is not materially changed. If applied too frequently the amount of blood they take is not insignificant, and anæmia may be produced unawares.

The extreme repugnance inspired in some persons by the appearance of leeches, the difficulty of keeping them on hand in good health and ready for work, as well as a change in pathological views, have acted together to make their use rather exceptional at the present day.

GENERAL BLEEDING, VENESECTION, PHLEBOTOMY, or ARTERIOTOMY, is practised by an incision in a vessel of medium size, by far the most frequently a vein in the bend of the arm, the median cephalic, although many others have been used, and supposed to afford special advantages in special cases.

Arteries are seldom opened, but the temporal is occasionally incised, since from its position the bleeding can be easily checked by compression.

The extent of the bleeding may be regulated either by the exact quantity determined beforehand, or by the effect upon pulse, complexion, or pain, or may be carried to the point of fainting, the patient being bled in a sitting posture.

A small bleeding of eight or ten ounces is to most persons in health a trivial or imperceptible loss.

The tension of the vessels is restored almost immediately by their contraction, and the mass of the blood is soon brought back to the normal by the absorption of fluid. The red corpuscles remain deficient somewhat longer, and for some days may even decrease in relative proportion, owing to the increase of serum. The hematoblasts increase rapidly in number.

At the present day we rarely have the opportunity of seeing

the results of either a single excessive or frequently repeated venesections for therapeutic purposes.

It is stated that a single rapid loss of 2 to 2.5 kilos in a healthy man is always very serious, and frequently fatal. On the other hand, bleedings of 200 to 400 grammes (seven to fourteen ounces) may be renewed at quite short intervals without real danger. When a bleeding is sufficiently large to produce a decided effect the pulse becomes more rapid and the dicrotism more marked (loss of tension). With a large bleeding the pressure of the blood falls rapidly, but is also restored rapidly (if at all). The fall of pressure, together with the contraction of the bleeding vessels, is the cause of the spontaneous cessation of a hemorrhage.

The central temperature, either in healthy or febrile persons, is not greatly influenced. If it fall at all it is only slightly, and for a short time, the fall being followed by a slight rise. The peripheral temperature, however, is more depressed.

Bleeding was formerly practised in order to check inflammation. Careful study, however, both of the processes of inflammation and of clinical results, is decisive against any direct effect of this kind. The local congestion is a result of the call for blood on the part of inflamed tissues, and they will continue to attract more than their share, even when the total mass is diminished. Where a local diminution of the blood supply can be produced by cold, pressure, or counter-irritation, the intensity of the inflammatory process may be diminished. There is no reason to suppose that the duration of acute diseases was shortened by bleeding (except in the fatal cases), and there is little doubt that the mortality of pneumonia, which has for years been the battleground upon which all the contests of antiphlogistic, expectant, and supporting treatment have taken place, is greatly increased by the vigorous application of this procedure.

At the beginning, however, of some acute thoracic diseases, in previously healthy persons, a moderate bleeding may give relief to the pleuritic pain, and without seriously compromising the further progress of the case.

Even at a later period, if danger appears to arise from the inability of the heart to pump a large mass of blood, and signs of over-distention, together with great dyspnoea and cyanosis are present, a bleeding may give relief. In this case, however, it is done "not on account of the pneumonia, but in spite of the pneumonia."

It has even been proposed to tap the right auricle with a hollow needle under similar circumstances.

In cyanosis from failure of the heart in subacute parenchymatous nephritis, the temptation is strong to relieve it by the removal of blood, but the writer cannot felicitate himself upon having yielded to it on a few occasions.

Convulsions, and especially puerperal convulsions, are sometimes advantageously treated by bleeding. It is, of course, the plethoric who are most likely to be treated in this way, though cases which do not answer to this description have also yielded and recovered. It is probably by the relief of cerebral pressure and not by any removal of morbid material that relief is obtained.

SECTION XXIII.

GENERAL NERVOUS STIMULANTS AND

NARCOTICS.

Meconium, Succus Thebaicus.

OPIUM.

The concrete milky exudation, obtained in Asia Minor, by incising the unripe capsules of Papaver somniferum (Nat. Ord. Papaveracea). In its normal moist condition it should yield not less than 9 per cent. of morphine by the officinal process.

OPII PULVIS.-Powdered Opium.

Opium, dried at a temperature not exceeding 85° C., and reduced to a moderately fine powder. It should contain not less than 12, nor more than 16 per cent. of morphine, when assayed by the process given under Opium. Any powdered opium of a higher percentage may be brought within these limits by admixture with powdered opium of a lower percentage, in proper proportions.

OPIUM DENARCOTISATUM.-Denarcotized Opium.

Powdered Opium, containing fourteen (14) per cent. of morphine, macerated with ether, dried and brought up to its original weight with sugar of milk. A stronger opium may be used by making the necessary calculations.

Crude, sometimes improperly called "gum," opium, is seldom used in medicine, though occasionally convenient for pill-making on account of its extract-like consistency. The dose would be slightly larger than that of the same specimen in powder, although the limits of morphine contents allowed by the Pharmacopoeia in the Powdered Opium are sufficiently wide to make its dosage somewhat uncertain. The Denarcotized Opium represents a preparation of known morphine strength half-way between the extreme limits of the powdered opium. The minimum of morphine strength for dried opium, according to the edition of 1870, was ten per cent., no maximum being specified. In the present edition the minimum is stated as twelve per cent., and the maximum as sixteen, which percentages are slightly raised by a change in the method of assay, so as really to call for nearly thirteen to seventeen per cent. If a medium strength of fifteen per cent. be uniformly selected, as