12. An undue proportion of serum to crassamentum in the blood. This predominance of water in the blood has often checked sufficient blood-letting. But it should be constantly disregarded while it is attended with those states of pulse (to be mentioned hereafter) which require bleeding.
14. The presence of petechiæ on the skin. These, I have elsewhere said, are the effects of the gangrenous state of fever. Dr. Sydenham and Dr. de Haen have taught the safety and advantage of bleeding, when these spots are accompanied by an active pulse. A boy of Mr. John Carrol owes his recovery from the small-pox to the loss of fifty ounces of blood, by five bleedings, at a time when nearly every pock on his arms and legs had a purple appearance. Louis XIV was bled five times in the small-pox, when he was but thirteen years of age, and thereby probably saved from the grave, to the great honour and emolument of the single physician who urged it against the advice of all the other physicians of the court. Dr. Cleghorn mentions a single case of the success of bleeding in the petechial small-pox. His want of equal success afterwards, in similar cases, was probably occasioned by his bleeding too sparingly, that is, but three or four times.
Abscesses and sore breasts, which accompany or succeed fever, are no objections to blood-letting, provided the pulse indicate the continuance of inflammatory diathesis. They depend frequently upon the same state of the system as livid effusions on the skin.
14. The long duration of fever. Inflammatory diathesis is often protracted for many weeks, in the chronic state of fever. It, moreover, frequently revives after having disappeared, from an accidental irritant affecting some part of the body, particularly the lungs and brain. I bled a young man of James Cameron, in the autumn of 1794, four times between the 20th and 30th days of a chronic fever, in consequence of a pain in the side, accompanied by a tense pulse, which suddenly came on after the 20th day of his disease. His blood was sizy. His pain and tense pulse were subdued by the bleeding, and he recovered. I bled the late Dr. Prowl twelve times, in a fever which continued thirty days, in the autumn of the year 1800. I wish these cases to be attended to by young practitioners. The pulmonary consumption is often the effect of a chronic fever, terminating with fresh inflammatory symptoms, by effusions in the lungs. It may easily be prevented by forgetting the number of the days of our patient's fever, and treating the pulmonary affection as if it were a recent complaint.
15. Tremors and slight convulsions in the limbs. Bark, wine, laudanum, and musk are generally prescribed to remove these symptoms; but, to be effectual, they should, in most cases, be preceded by the loss of a few ounces of blood.
16. Bleeding is forbidden after the fifth or seventh day in a pleurisy. This prohibition was introduced into medicine at a time when a fear was entertained of arresting the progress of nature in preparing and expelling morbific matter from the system. From repeated experience I can assert, that bleeding is safe in every stage of pleurisy in which there is pain, and a tense and oppressed pulse; and that it has, when used for the first time after the fifth and seventh days, saved many lives. Bleeding has likewise been limited to a certain number of ounces in several states of fever. Were the force of the remote cause of a fever, its degrees of violence, and the habits of the subject of it, always the same, this rule would be a proper one; but, this not being the case, we must be governed wholly by the condition of the system, manifested chiefly by the state of the pulse. To admit of copious bleeding in one state of fever, and not in another, under equal circumstances of morbid excitement, is to prescribe for its name, and to forget the changes which climate, season, and previous habits create in all its different states.
17. The loss of a sufficient quantity of blood is often prevented by patients being apparently worse, after the first or second bleeding. This change for the worse, shows itself in some one or more of the following symptoms, viz. increase of heat, chills, delirium, hæmorrhages, convulsions, nausea, vomiting, faintness, coma, great weakness, pain, a tense, after a soft pulse, and a reduction of it in force and frequency. They are all occasioned by the system rising suddenly from a state of extreme depression, in consequence of the abstraction of the pressure of the blood to a state of vigour and activity, so great, in some instances, as to reproduce a depression below what existed in the system before a vein was opened; or it is occasioned by a translation of morbid action from one part of the body to another.
The chills which follow bleeding are the effects of a change in the fever, from an uncommon to a common state of malignity. They occur chiefly in those violent cases of fever which come on without a chilly fit.
The hæmorrhages produced by bleeding are chiefly from the nose, hæmorrhoidal vessels, or uterus, and of course are, for the most part, safe.
Uncommon weakness, succeeding blood-letting, is the effect of sudden depression induced upon the whole system, by the cause before-mentioned, or of a sudden translation of the excitement of the muscles into the blood-vessels, or some other part of the body. These symptoms, together with all the others which have been mentioned, are so far from forbidding, that they all most forcibly indicate a repetition of blood-letting.