This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol1", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
In sudden prostration occurring in the advanced stages of low fevers, in prolonged asphyxia, in the collapse of cholera, haematemesis, and melaena, similar indications are afforded by the cold surface, the prostrated vital functions, and the interior congestion.
In the retrocession of cutaneous eruptions, the hot bath is often useful. In some instances, the apparent retrocession is nothing more than a sudden general prostration, in which the actions of the surface fail with those of the whole system, and which differs in nothing from the sinking spells of low fevers noticed in the last paragraph ; but, in most cases, it is owing to, or connected with the occurrence of severe internal irritation, which it is highly desirable to recall as quickly as possible to the surface. Not unfrequently, a similar condition existing previously to the eruption, retards its appearance, and sometimes it may even keep back the cutaneous affection altogether, to the great detriment of the patient. Under these circumstances, the hot bath proves serviceable by powerfully exciting the skin, and making this the seat of afflux for the irritative tendencies. The eruption again appears, or comes forth if not previously existing, and the symptoms of internal disorder cease almost instantaneously.
Painful internal spasms are generally more beneficially treated by the relaxing warm bath than by the stimulant hot bath; but sometimes they are so severe, and attended with so much general prostration, that the former remedy is quite inefficient, and it becomes desirable to have recourse to the greater energy of the latter. Violent attacks of nervous gout in the stomach and bowels, of colic, and of spasm of the diaphragm, are examples of this kind. The remedy acts by a revulsive impression on the general surface.
Internal inflammation is usually not a proper subject for the influence of the hot bath, which too much excites the circulation, and sends the blood too forcibly into the parts affected; but, in certain cases, the inflammation is so violent and extensive as to concentrate the blood and the nervous energy of the system in its own seat, with the effect of prostrating the general functions, and inducing great apparent debility, for which, indeed, the condition has sometimes been fatally mistaken. The cold and pale surface, and feeble pulse seem to call for active stimulation; while, in fact, prompt and free bleeding is indicated, and is sometimes the only remedy which will save the patient. Generally, under these circumstances, if a vein is opened, the blood will flow, slowly and scantily at first, but with a gradually increasing current; and, so far from still further failing, the pulse will rise, and become fuller and stronger, as the operation proceeds. This, however, is not always the case; and it is found impossible to continue the bleeding without endangering fatal prostration. In such a case, the hot bath is an admirable remedy. By its powerful revulsive action it calls the blood from the interior to the surface, stimulating the heart at the same time; and though of itself it would he altogether inadequate to the cure, and, if continued, might act injuriously upon the inflamed organ by sending the blood into it too vigorously, yet it prepares the system for the use of the lancet, and thus opens the way for a cure which might not otherwise be possible. It should of course be withdrawn the moment that it has answered its purpose. In cases of this kind, the warm bath, though useful in ordinary internal inflammations, would be quite inert; and might even be injurious by its sedative action on the surface and the heart. Extensive inflammation of the peritoneum, dysentery of extraordinary intensity, and violent pneumonia in the congestive stage, and occupying both lungs, sometimes present the condition referred to.
Obstinate chronic enteritis, with little or no excitement of the circulation, and an habitually dry, palish, and cool skin, may also be advantageously treated with the hot bath, repeated every day, especially if made somewhat more permanently irritant to the skin by the addition of common salt; and the same remark will apply to inflammation of other abdominal viscera, presenting the same conditions. In the first mentioned affection, I have found the hot salt-bath one of the most efficacious remedies.
It was stated above that the hot bath is indicated in some obstinate long-continued affections, in which it appears to act by breaking up morbid associations. Possibly it may operate by a penetrating stimulation of all the tissues, which are thus roused out of their habit of morbid, action into an over-excitement, from which they may afterwards subside into health. In some such method as this, it sometimes proves beneficial in cases of chronic rheumatism, and gout, occupying at the same time various parts of the system, distorting the joints, contracting the tendons, and not unfrequently, to a greater or less extent, paralyzing the muscles. It is not impossible, however, that the diaphoretic action of the bath may add to its efficiency. The bathing at hot springs has proved peculiarly useful in these diseases.
Perhaps in the same category may be placed certain chronic and indolent affections of the skin, in which the tissue requires to be roused alike out of its torpor, and out of its morbid habit of acting. Caution is necessary not to use the bath at too early a stage; and if, as often happens with stimulating applications made prematurely, it should be found to excite inflammation or high irritation, it should be immediately suspended. It should also be accompanied with alterative measures, to change the constitutional condition, while the attempt is made to relieve the local disease.
In paralytic cases of long standing, in which the original cause, if affecting the nervous centres, has quite ceased to operate, and the disease is sustained by a morbid indolence of the tissues concerned, whether nervous or muscular, some good may be hoped for from the hot bath, in connection with other measures.
The contraindications to the use of the hot bath are a plethoric state of system, determination of blood to the head, active hemorrhagic tendencies, general vascular irritation with active congestion, aneurisms and hypertrophy of the heart, acute inflammation with well-developed fever, the febrile state generally with a hot skin, and a peculiarly irritable state of the nervous system.