The central thermal apparatus which presides over heat-forma tion, heat-inhibition, and heat-elimination is necessarily in free com munication with the skin, for it is in the skin that sensations of heat and cold are felt, and it is through the skin that heat is eliminated. The superficial nerves which receive the impressions of heat and cold must be connected with the centres in which these sensations are registered, and such centres must be associated with the function of heat-inhibition. It is on the extremities of these nerves that the cold acts, and it is along these nerves that this peripheral excitation is transmitted to the inhibiting centres ; the action is essentially a stim ulant one ; but to stimulate inhibition is the physiological and scientific method of allaying undue functional activity. Just as heat (as in heat apoplexy) paralyzes inhibition and thus causes the tem perature rapidly to rise, so cold stimulates inhibition and thus causes this abnormal temperature to fall. Just as it is not the direct heating up of the body by the hot atmosphere that causes the very high tem perature of heat apoplexy, so it is not the direct cooling action of cold on the body that cures this condition. The heat acts by impairing, maybe even paralyzing, the function of inhibition; the cold acts by stimulating that function into renewed activity. Its action in this respect may be compared with, and illustrated by, the ictiou of digi talis in some forms of heart disease. When we find the heart acting in an unnecessarily disturbed and excited manner, as it frequently does in mitral disease, we do not combat this condition by efforts to soothe the excito-motor nerve of the heart; no, we rather gain our object indirectly by giving digitalis and stimulating to increased activity the counterbalancing force—the cardiac inhibitory nerve—the ragas. In doing so we adopt a line of treatment which is not only found in practice to be the most successful, but is also the most scientific, and that which is most in accord with the teachings of physiology and the operations of nature.
In treatment must be prompt and vigorous. In hibition, one of the most important functions of organic life—one which is absolutely essential to the continuance of life—is all but paralyzed. The remedy is the application in full dose of that which stimulates it into increased activity—the external applica tion of cold. Ice to the surface, pouring cold water over the body, wrapping it in a cold pack, putting it in a cold bath, are the active means by which inhibition is stimulated and the hyperpyretic condition subdued in urgent cases. In cases in which the danger is less urgent a tepid bath or tepid sponging may suffice ; but in all the principle is the same, the application to the surface of the body of water having a much lower temperature than the body. Where the temperature is very high and the danger very urgent, rubbing the body with ice or putting it in a cold bath till the tem perature falls to 100', is the most speedy means of attaining the desired end, care being taken not to cause too great depression. Where the danger is less urgent the desired end is sufficiently at tained by keeping ice applied to the head, and by, at the same time, frequently sponging the body with cold or tepid water. A simple
and efficacious plan is to keep flipping the surface of the body, now the chest and abdomen, now the back, and now the limbs, with a sponge slightly moistened with cold or tepid water; the sponge should be soft, of loose texture, not more than two inches thick, and four to six inches in diameter. A sponge of that sort is easily flopped lightly and rapidly up and down on the surface; the fanning action by which this is done aids the action of the cold water in pro ducing the stimulant action on the peripheral extremities of the nerves by which the desired impression is conveyed to the heat-inhibiting centre; it tends also to promote heat-elimination.
The practice of treating fever by cold baths is an old one, which had fallen into disuse. The good results got from this treatment in hyperpyrexia led to its revival. If the high fever which has to be dealt with in hyperpyrexia could be thus cured, might we not also by the same agency arrest the more moderate disturbance of an or dinary pyrexia? Such was the train of thought. Natural enough, but founded on a fallacy. It assumes that the two morbid conditions are similar in nature, and that hyperpyrexia is an exaggeration of pyrexia. But they are essentially different in their mode of produc tion: hyperpyrexia is of neurotic origin, dependent on impaired in hibition, while pyrexia (that of idiopathic fever at least, which is the form of fever chiefly dealt with) is of metabolic origin, dependent on increased production of heat. Its curing hyperpyrexia is no proof that cold can cure pyrexia. And experience shows that it does not; for though some German physicians tried to show that the course of typhoid fever may be arrested by the cold bath, their results have not been confirmed or accepted by subsequent observers.
Judiciously used, however, cold is a valuable agent in the treat ment of fever; for though it may not cure, it tends to alleviate some of the symptoms, especially those referable to the nervous system. Its mode of application—in other words, the dose administered— should vary in different cases.
In urgent cases of hyperpyrexia it should be given at once in full dose, that is, ice or ice-cold water should be applied to the whole sur face. In cases in which fever runs high, but in which the stage of pyrexia is not exceeded—that is to say, when the temperature ranges from 104° to 106°—cold sponging of the body with ice to the head will generally suffice. In cases in which it ranges from 102° to 104°, sponging with water from 80° to 90° F. is enough. In cases in which it does not exceed 102°, cold as an antipyretic is not called for, but tepid sponging is grateful to the patient, and it is not improbable that its regular use may, by gently stimulating inhibition, prevent that function from failing, and neurotic pyrexia from being developed. Cold is accumulative in its action, and should not be unduly pushed; its use should be omitted when the temperature falls below 101°—to be renewed if necessary. But it should be borne in mind that the temperature often continues to fall for some time after cold has ceased to be applied.