XIII. In drawing blood, the quantity should be large or small at a time, according to the state of the system. In cases where the pulse acts with force and freedom, from 10 to 20 ounces of blood may be taken at once; but in cases where the pulse is much depressed, it will be better to take away but a few ounces at a time, and to repeat it three or four times a day. By this means the blood-vessels more gradually recover their vigour, and the apparent bad effects of bleeding are thereby prevented. Perhaps the same advantages might be derived, in many other cases, from the gradual abstraction of stimuli, that are derived from the gradual increase of their force and number, in their application to the body. For a number of facts in support of this practice, the reader is referred to the history of the yellow fever, in the year 1793. In an inflammatory fever, the character of which is not accurately known, it is safest to begin with moderate bleeding, and to increase it in quantity, according as the violence and duration of the disease shall make it necessary. In fevers, and other diseases, which run their courses in a few days or hours, and which threaten immediate dissolution, there can be no limits fixed to the quantity of blood which may be drawn at once, or in a short time. Botallus drew three, four, and five pints in a day, in such cases. Dr. Jackson drew fifty-six ounces of blood, at one time, from a Mr. Thompson, of the British hospitals, in a fever of great violence and danger. This patient was instantly relieved from what he styled “chains and horrors.” In three or four hours he was out of danger, and in four days, the doctor adds, returned to his duty[60]. Dr. Physick drew ninety ounces, by weight, from Dr. Dewees, in a sudden attack of the apoplectic state of fever, at one bleeding, and thereby restored him so speedily to health, that he was able to attend to his business in three days afterwards. In chronic states of fever, of an inflammatory type, small and frequent bleedings, are to be preferred to large ones. We use mercury, antimony, and diet drinks as alteratives in many diseases with advantage. We do not expect to remove debility by two or three immersions in a cold bath. We persist with patience in prescribing all the above remedies for months and years, before we expect to reap the full benefits of them. Why should not blood-letting be used in the same way, and have the same chance of doing good? I have long ago adopted this alterative mode of using it, and I can now look around me, and with pleasure behold a number of persons of both sexes who owe their lives to it. In many cases I have prescribed it once in two or three months, for several years, and in some I have advised it every two weeks, for several months.
There is a state of fever in which an excess in the action of the blood-vessels is barely perceptible, but which often threatens immediate danger to life, by a determination of blood to a vital part. In this case I have frequently seen the scale turn in favour of life, by the loss of but four or five ounces of blood. The pressure of this, and even of a much less quantity of blood in the close of a fever, I believe, as effectually destroys life as the excess of several pounds does in its beginning.
In cases where bleeding does not cure, it may be used with advantage as a palliative remedy. Many diseases induce death in a full and highly excited state of the system. Here opium does harm, while bleeding affords certain relief. It belongs to this remedy, in such cases, to ease pain, to prevent convulsions, to compose the mind, to protract the use of reason, to induce sleep, and thus to smooth the passage out of life.
XIV. Bleeding from an artery, commonly called arteriotomy, would probably have many advantages over venesection, could it be performed at all times with ease and safety. Blood discharged by hæmorrhages affords more relief, in fevers, than an equal quantity drawn from a vein, chiefly because it is poured forth, in the former case, from a ruptured artery. I mentioned formerly, that Dr. Mitchell had found blood drawn from an artery to be what is called dense, at a time when that which was drawn from a vein, in the same persons, was dissolved. This fact may possibly admit of some application. In the close of malignant fevers, where bleeding has been omitted in the beginning of the disease, blood drawn from a vein is generally so dissolved, as to be beyond the reach of repeated bleedings to restore it to its natural texture. In this case, arteriotomy might probably be performed with advantage. The arteries, which retain their capacity of life longer than the veins, by being relieved from the immediate pressure of blood upon them, might be enabled so to act upon the torpid veins, as to restore their natural action, and thereby to arrest departing life. Arteriotomy might further be used with advantage in children, in whom it is difficult, and sometimes impracticable to open a vein.
XV. Much has been said about the proper place from whence blood should be drawn. Bleeding in the foot was much used formerly, in order to excite a revulsion from the head and breast; but our present ideas of the circulation of the blood have taught us, that it may be drawn from the arm with equal advantage in nearly all cases. To bleeding in the foot there are the following objections: 1. The difficulty of placing a patient in a situation favourable to it. 2. The greater danger of wounding a tendon in the foot than in the arm, And, 3. The impossibility of examining the blood after it is drawn; for, in this mode of bleeding, the blood generally flows into a basin or pail of water.
Under this head I shall decide upon the method of drawing blood by means of cups and leeches, in the inflammatory state of fever. Where an inflammatory fever arises from local affection, or from contusion in the head or breast, or from a morbid excitement in those, above other parts of the arterial system, they may be useful; but where local affection is a symptom of general and equable fever only, it can seldom be necessary, except where bleeding from the arm has been omitted, or used too sparingly, in the beginning of a fever; by which means such fixed congestion often takes place, as will not yield to general bleeding.