In the summer season the temperature rises to 32.3° C. (90° F.) and even much higher in certain localities. During the prevalence of such heat, the mortality among young children, the aged and enfeebled is very marked; these two periods of life being very susceptible to the depressing effects of heat. A high temperature is easily borne if the air be pure and the atmosphere be not saturated with moisture. Telluric electric conditions also have a modifying influence, undoubted though obscure.
In certain occupations an intensely heated atmosphere is endured with impunity for a considerable time, provided the air be maintained in a condition of purity and water be supplied to the person exposed. The stokers upon ocean steam-ships, where a forced draught is employed, are subjected to extreme heat, sometimes reaching 60° C. (140° F.). Resort to forced and continuous ventilation of the stoke-rooms, with short hours of duty, renders tolerance of the high temperatures possible.
SUNSTROKE.
The terms “sunstroke,” “insolation,” “coup de soleil,” are applied to conditions induced, not alone by exposure to the rays of the sun, but rather by a combination of great heat with other exciting causes. They are used to designate attacks occurring in very hot weather after exposure to solar or other sources of extreme heat. The striking and usual phenomena are exhaustion, unconsciousness, stertorous respiration, and death, occurring by syncope, within a few moments or hours. In a number of cases the symptoms of cerebral apoplexy with death by coma are present.
In others, the condition seems one of complete exhaustion. The majority of cases seem to be a combination of these several conditions, with death resulting from syncope.
The ordinary phenomena of the attack are pain in the head, hurried respiration sometimes stertorous, violent beating of the heart with failing of its power, oppression within the chest and, occasionally, nausea and vomiting. The pupils are sometimes dilated and sometimes contracted, but in all cases exhibit lessened sensitiveness to light. The suddenness of the attack modifies the symptoms developed.
Pathological Conditions.
These are exhaustion with syncopic tendency and a rapid rise in the temperature of the body to a point destructive to the activity of the nervous centres. This is accompanied by an abnormal condition of the blood, resulting from loss of its watery portions, with retention of effete products and impaired aeration. A tendency to general stasis, specially marked by congestions of the lungs and brain, is present. The change in the blood is a very important factor. In some cases, not fatal at the outset, this induces a septic condition.
The greatly elevated temperature of the body undoubtedly produces certain modifications which type it, in some respects, as a febrile disease; but this, with the septic tendency due to blood changes, is not sufficient to designate it as a purely “thermal fever,” as some have claimed. It is something more than this.
Sunstroke occurs more commonly in tropical than temperate climates;[694] and usually in the day-time, at the period of greatest solar activity, those attacked being engaged in labor involving considerable exertion. It occasionally, though rarely, occurs at night. The military service affords abundant opportunity for observation. Here the seizures are on the march, rarely in camp. Fatigue, prolonged and extreme exertion, ill-adjusted clothing and accoutrements, with the deprivation of cool water, are fully as active factors as the heat of the sun. The death-rate ranges between forty and fifty per cent, the mild cases being excluded. Death in some cases is marked by syncope, in others by apnœa, though the majority seem to die by a combination of both, as in most cases the pulmonary congestion is more or less pronounced. Undoubtedly the character of the symptoms and mode of death are influenced, in many cases, by individual tendencies leading to apoplectic conditions or to cardiac or other complications.