Beside the consequent circulatory changes in the skin or other organs (e.g., the muscles and the brain), hydriatic measures affect the nervous system directly, by the irritation of nerves arising in the skin, so that, whether in these or other ways, the psychical functions and the innervation of the different systems of organs may be strongly influenced.
It is necessary to dwell only briefly upon the subject of circum scribed cooling and heating of the skin. In using compresses. they must be changed so frequently (a detail which is often neglected) that instead of an alternation of heat and cold. the temperature will he constant. Prolonged cooling is made more effective when an ice bag of sufficiently large capacity and surface is placed upon the wet compress. Ifeat may be fairly constantly applied by means of cereal poultices (cataplasms) composed of oatmeal or flaxseed, which may be kept warm in a poultice warmer. Temperatures of any desired degree may be conveniently employed by means of coils made. of aluminum or metal tubing, coiled and sewed upon flannel and laid upon the part, water of the desired temperature being permitted to flow through the apparatus from a larger vessel situated above the level of the part, to a vessel placed upon the floor. Aside from surgical diseases. the prolonged action of cold may be employed in all acute inflammations; upon the head in inflamma tion of the brain or congestion from any cause, which produces headache: upon the chest in inflammation of the lungs, but especially in inflam mation of the pleura; over the heart in inflammation of that organ, or when, as in prolonged fevers, cardiac failure is threatened from being overtaxed: and, finally, upon the abdomen in circumscribed or general inflammation. If pressure cannot be tolerated, as in peritonitis, compresses are to be preferred, or the ice. bag is suspended in such a manner as to just touch the surface. If motion is to be avoided, and if pressure does not disturb the patient, the metal coils are perhaps prefer able. When wet compresses are used upon the rest of the body, they are to be covered with some impervious material, in order to prevent the unpleasant wetting which would otherwise occur.
The difference between cooling and hydropathic compresses is often misunderstood. In the one case. the compresses are so frequently changed that the skin remains constantly cool and antptuic; in the other, it is allowed to remain for a time upon the part, so that finally it acquires the temperature of the skin, which thus becomes congested; and not only does a subjective sense of pleasant warmth follow the fleet ing sensation of cold, but the moisture of the compress actually approx imates more and more the temperature of the blood. These hydropathic compresses, which attract the blood to the surface of the body, instead of driving it from the skin to the diseased organs. as the cold compresses probably do, are exceedingly efficient in diminishing pain at least, beside which they frequently improve the local disease.
Hydropathic compresses are applied, after first anointing the skin when it is sensitive, by taking a linen or raw-silk cloth, folding it into layers of sufficient thickness, immersing it in lukewarm water. wringing it out until it no longer drips, and covering it with a woollen cloth which overlaps it liberally, or with a woollen binder held in place by pins or a bandage the compress to be changed every two or three hours, or, under certain circumstances (c.v., at night), at longer intervals. ;Should it become necessary to apply such a compress to the chest of a small child, for instance, it is hest to place it all prepared upon the dressing table or bed, the woollen cloth underneath and the wet one upon that, and to lay the naked child upon it, so that the compress can be speedily wrapped about it. To change, a second compress is held in readiness. To avoid inflaming the tender skin of the child, new' cloths should be used daily Nvherever possible, those which have been used being washed before decomposition of the fabric, with its accompanying sweetish odor, has taken place, as this is capable of irritating the skin. For very young children, a chest compress may be prepared in the following manner: a wet. undershirt is put upon the child, over this a tricot shirt not too thin, and a binder is wound around all. If it is desired to cover the upper portion of the lungs with a compress, a cross bandage is necessary. This is applied by even turns of a hinder made of handkerchiefs or pieces of linen folded together, first one turn wet, then one turn dry. These are best covered with a woollen hinder or a woollen shirt. For example, one starts from the left side of the chest anteriorly, and below, over the right shoulder to the back, then to the left a xilla, passing forward under it and horizontally across the chest to the hack; from there over the left shoulder, across the chest anteriorly to the right axilla, and once more horizontally around the chest. The full pack is less frequently used than is the body compress, and differs from the latter in that it includes the extremities. In applying a full pack, the dry outer cloth should be somewhat larger than the wet one, and may he made of woollen blanket ing, or towelling; the inner wet compress may be of folded sheeting. These are spread out, the wet one uppermost, and arranged smoothly and evenly, ready for the child to be placed upon it in such a manner that the wet compress extends from the neck to beyond the heels. The child is then quickly enveloped in the compress, which is pushed down between the legs and thighs, and the arms and body, and is brought up over the feet; the dry blanket or towelling is wrapped around the body in the same way and is fastened by tucking it in at the neck and wrapping it around the feet. The bed cover is then placed over all.