There are two distinct diseases—or, more correctly, conditions—of the human body which are produced by exposure to heat, and which have a certain similarity in their symptoms, but are very different in their immediate pathology and require directly opposite methods of treatment. Although their individuality was pointed out as long ago as 1851 by the late D. F. Condie of this city,1 yet they have been frequently confounded by writers upon the subject, and the terms heat-exhaustion and sunstroke have not rarely been used as strictly synonymous. In the present article it is proposed to consider them as separate affections under the respective names of heat-exhaustion and thermic fever.
1 Amer. Journ. Med. Sci., Jan., 1852.
Heat-Exhaustion.
Any one who has been long exposed to a high temperature under circumstances requiring physical exertion must have noticed the feeling of general weakness and relaxation which results. Thus far reaches our every-day experience, but cases in which acute symptoms are severe enough to cause alarm occur, although somewhat infrequently. The attack may come on slowly, but may be as abrupt as that of true sunstroke, and the severest cases may happen in those who have been in robust health as well as in the weak and feeble. The mind is usually clear, the pulse rapid and feeble, the surface cool, the voice very weak, muscular strength greatly lessened, and the feeling of exhaustion extreme. If this condition be intensified, syncope may be developed with its usual symptoms. In all this there is nothing peculiar and little that is necessary to notice here; but there is a form of heat-exhaustion in which the heart does not seem to suffer principally, but in which there is collapse with palsy of the vaso-motor system, great fall of the bodily temperature, and marked general nervous symptoms. At the International Exhibition of 1876 a very powerful man, whilst working in an intensely hot, confined space, fell down without giving warning, and was brought into the hospital. He was in a state of restless, delirious unconsciousness, incessantly muttering to himself, and when shaken and shouted at responding only by a momentary grunt. The pulse was rapid, fluttering and feeble. The surface was covered with a very heavy sweat and exceedingly cold. The muscular relaxation was extreme. The facies was that of collapse, and the temperature, as taken in the mouth, 95.25° F.
The PATHOLOGY of heat-exhaustion is best discussed in conjunction with that of thermic fever, and will therefore be for the present postponed.
The TREATMENT of heat-exhaustion is a very obvious one. The indications are to stimulate the circulation and warm the body by external heat with an energy proportionate to the severity of the attack. In mild cases the exhibition of a whiskey punch or similar beverage may suffice, but in severer attacks alcohol acts too slowly and is not capable of filling all the indications. It may re-excite the flagging heart, but it is probably not a vaso-motor stimulant, and if given too freely may even increase the vaso-motor depression. Digitalis is an excellent stimulant of the heart, and probably also of the vessels. It acts, however, comparatively slowly even when hypodermically injected, but in severe cases it should always be employed. The tincture is the most eligible preparation, and when injected under the skin in doses of fifteen drops causes no local irritation. Ammonia would be a very valuable remedy did not its use offer so many difficulties of administration: injected into the cellular tissue, it causes great pain and usually sloughing, and its intravenous use is by no means always easy. As a vaso-motor stimulant atropia is an excellent remedy, and, as it has also a very powerful influence in arresting the secretion from the skin and in raising the animal temperature, it should produce very good results in the peculiar form of collapse under consideration.
When the bodily temperature is below normal the most important measure of treatment is the use of the hot bath: the water should be from 100° to 120° F.—i.e. as hot as can be borne—and the whole body should be immersed in it until the mouth temperature becomes normal.
Thermic Fever.
SYNONYMS.—Coup de soleil, Sunstroke, Heat apoplexy, Heat asphyxia, Heat fever, Sun fever, Thermohæmia, Erethismus tropicus, Insolation.
The immediate cause of thermic fever is always exposure to excessive heat in some form. As the body can cool itself much more readily in a dry than in a moist atmosphere, it is able to resist the influence of a dry, overheated air much better than when there is also moisture. It is for this reason that sunstroke is so much more infrequent upon the high table-lands of Abyssinia or in the dry belt of our Texan prairies than in the lowlands of India or upon our own seacoast. For the same reason it is especially prone to attack indoor workers in confined, moist factories, and especially in laundries and sugar-refineries. At one time it was thought that exposure to the direct rays of the sun was the chief cause of the disease, but there is now abundant clinical testimony to the fact that such exposure is in no sense necessary. Without occupying space in giving detailed references, it suffices, as an illustration of the fact that the most complete darkness is no protection, to allude to the epidemic upon the French man-of-war Duquesne, as recorded by M. Boudin, in which a hundred cases of sunstroke occurred in a short time, most of them at night when the men were lying in their bunks. Bonniman2 says: “By far the greater number of cases that yearly occur in India are of men who have not been exposed to the sun. It is not unusual for men to go to bed in apparent health, and to be seized during the night; and patients in hospitals who have been confined to bed for days previously are frequently the subjects of attack.”