# Tropical Diseases/Chapter 24

CHAPTER XXIV
HEAT-STROKE
THE term " heat-stroke " conveys the suggestion that heat is the leading etiological factor in the various morbid conditions which custom has grouped under this and similar names.
Until irrefutable evidence has clearly demonstrated the true cause of any given disease, it is a very grave error to base the name of such disease on some -crude hypothetical etiological conception. Such a nomenclature is sure to lead to confusion, to mistakes in practice, and to retard progress. There is no better illustration of the truth of this remark than that supplied by the group of diseases under consideration.
The expression "heat-stroke" covers several distinct, one might say of two of them almost opposite, clinical conditions. One of these is heat-exhaustion, virtually a syncope, which may occur anywhere and in any climate, high atmospheric temperature, whether natural or artificial, being its essential etiological factor. The other, of which hyperpyrexia is the most striking clinical feature, is a well-defined and possibly specific fever, having a peculiar endemicity and assuming at times in the endemic area almost epidemic characters. Like yellow fever, dengue, tropical elephantiasis, and other tropical diseases, this second form of heat-stroke occurs only in conditions of high atmospheric temperature; but, as with these diseases, it by no means follows that, though occurring in high temperature, it is caused by high temperature. To obviate confusion, and following the example of Sambon, I shall describe this disease under its ancient name siriasis.
Besides these two well-defined morbid states associated with high atmospheric temperatures there is another but ill-defined group of heat-stroke cases ​which, to all appearance, result exclusively from exposure to the direct rays of the sun. These cases might be classified under the term sun-traumatism.
Although not all of them are strictly classifiable as fevers, in deference to custom and for convenience I shall describe these three phases of so-called "heat-stroke " in this place and as a group.
HEAT-EXHAUSTION
Definition.— Sudden faintness, or fainting, brought about by exposure to high atmospheric temperature.
Etiology.— The healthy human body, when untrammelled by unsuitable clothing, when not exhausted by fatigue or excesses, when not clogged by surfeit of food, by alcoholic drinks or by drugs, can support with impunity very high atmospheric temperatures. In many parts of the world men live and work out of doors in temperatures of 100° or even of 120° F. Many industries are carried on at temperatures far above this ; glass-blowing, sugar-boiling, for example. The stokers of steamers, especially in the tropics, discharge for hours their arduous duties in a temperature often over 150° F.
When, however, the physiological activities have become impaired by disease, especially by heart disease, kidney, liver, or brain disease, by malaria, by alcoholic or other excesses, by fatigue, by living in overcrowded rooms ; or when the body is oppressed by unsuitable clothing; or in the presence of a combination of some of these, then high atmospheric temperatures are badly supported, the innervation of the heart may fail, and syncope may ensue. Chevers, than whom few have had better opportunities of forming a sound opinion, speaking of this subject, says: " Numerous as the constitutional causes of heat-strokes are, all Indian experience combines to show that drunkenness is the chief." The tropical practitioner will do well to bear this remark in mind; it applies not only to heat- exhaustion, but also to all forms of disease grouped under the term "heat-stroke." ​Heat-exhaustion, then, is one form of what, when the subject of it happens at the time to be exposed to the sun, is called "sun-stroke," or when the patient happens to be at the time under cover, is called " heat-stroke." In nine cases out of ten this sun-stroke, or heat-stroke, simply means syncope; syncope caused by solar or atmospheric heat, or a combination of these, acting on a body whose resistance has been impaired by disease, or by trying, unphysiological conditions. This form of heat-stroke, consequently, has no special geographical distribution and no special morbid anatomy or pathology. For obvious reasons it is most apt to occur in warm weather, and in tropical climates; and on this account its recognition, prevention, and treatment have special claims on the student of tropical medicine.
Symptoms.— When attacked with heat-exhaustion the patient feels giddy, and perhaps staggers and. falls. He is pale; his pulse is small, soft, and perhaps fluttering; his breathing is shallow, perhaps sighing, never stertorous; his pupils are dilated; his skin is cold; his temperature is subnormal; and he may be partially, more rarely wholly, unconscious. Usually after a short time he gradually recovers; very likely with a splitting headache and feelings of prostration. In a small proportion of cases the faint is not recovered from, and death ensues.
Treatment.— In syncopal heat-stroke the patient should be laid at once on his back in a cool, airy, and shaded place. His clothes should be loosened, a little water dashed on his face and chest, and ammonia held to his nostrils. If necessary, a stimulant may be given by the mouth, or injected into the rectum or hypodermically. It is a mistake to douche these cases too freely. The object is rather to stimulate than to depress.
SIRIASIS
Definition.— An acute disease developing in the presence of high atmospheric temperature, and characterized by sudden incidence of hyperpyrexia, coma, and extreme pulmonary congestion. ​ Nomenclature.—This is, perhaps, the most important of the several diseases covered by those loosely used terms—sun-stroke, heat-stroke, coup de soleil, insolation, heat-apoplexy, heat-asphyxia, thermic fever, and so forth. I adopt the name siriasis because, whilst distinctive, it embodies no etiological theory; it has the further merit of being the most ancient of the many names applied to the disease.
The geographical distribution of siriasis appears to be remarkably restricted. Although it is true that this type, or what passes for this type, of disease has been reported as occurring in many countries, on making careful examination it will be found that a large proportion of the reputed cases are really examples of other diseases, more especially of cerebro-spinal fever, apoplexy, tubercular meningitis, delirium tremens, pernicious malaria, or some other phase of acute disease, but not of true siriasis. According to Sambon, hyperpyrexial heat-stroke is rigidly confined to certain low-lying, sea-coast districts, and to the valleys of certain rivers. It is never found in high lands, nor above a relatively low altitude—600 feet.
It is unknown in Europe. The endemic areas are—in America, the east coast littoral of the United States, more especially in the great towns, the Mississippi valley, the coast of the Gulf of Mexico, the valleys of the Amazon and of the La Plata, and the South Atlantic coast; in Africa, the valley of the Nile, the coasts of the Red Sea, and a low-lying part of Algeria near Biskra; in Asia, Syria, the valleys of the Indus and Ganges, Lower Burma, Tonquin, and south-east China; in Australia, the Murray River district, the Queensland coast, and, possibly, the plains of Sydney. No doubt it occurs elsewhere in corresponding meteorological and telluric conditions; but many large areas in the tropical world, and especially so the interior of continents, are exempt from siriasis. It is not met with on the high seas, although it is well known on ships in the narrow, land-locked Red Sea and the Persian Gulf. ​ Etiology.—New-comers to the endemic areas and Europeans are more liable than natives or residents of long standing. Apparently, long residence confers a relative although not an absolute immunity.
All ages and both sexes are susceptible; but, in consequence of their habits and more frequent exposure to the predisposing and immediate causes, men are more subject to siriasis than are women.
Predisposing influences similar to those in heat-syncope and sun-traumatism powerfully influence the liability to siriasis. Amongst these are all physiological depressants; notably intemperance, fatigue, overcrowding, unsuitable clothing, malaria, acute disease, and, also, chronic organic diseases of the important viscera.
Siriasis has generally been attributed to a direct action of atmospheric or solar heat on the body. Many theories of the modus operandi of this assumed cause have been advanced. Among these may be mentioned superheating of the blood by the high temperature of the surrounding atmosphere; paralysis of the thermic centres causing (a) over-production of heat, or (b) retention of body-heat; pressure on the brain by expansion from heating of the cerebro-spinal fluid; vaso-motor paresis; paresis of the heart ganglia excess of carbonic acid in the blood; coagulation of myosin; suppression of sweat; deficient serosity of the blood from excessive sweating, and so forth.
It is well known that neither high atmospheric temperature per se, nor high bodily temperature, unless the latter be associated with some special toxins, gives rise to symptoms at all like those of siriasis. Considering these two facts, and at the same time the peculiar and capricious distribution of the disease, the circumstances that its prevalence curve does not always correspond with the atmospheric temperature curve; that the degree of prevalence varies in the endemic area from year to year that it is not most prevalent in the hottest years, seasons, or places; that it becomes epidemic at times; that it runs a definite course; that it may ​relapse; that in many instances it has definite premonitory symptoms; that it has peculiar lesions; and that it tends to terminate by crisis; in other words, that it behaves like pneumonia or any other specific fever—Sambon has boldly asserted that siriasis is a germ disease, like yellow fever or dengue, and, like these, is caused by some organism which demands for its development a high atmospheric temperature and certain, as yet unknown, local conditions. Time will show how far this hypothesis is correct. In my opinion it has more in its favour than any of the many theories that have been based on a purely thermic etiology.
Symptoms.—Though sometimes coming on suddenly during exposure to the sun, siriasis is very often preceded by a distinct prodromal stage. It is frequently developed independently of any direct exposure to the sun; not seldom the attack comes on during the night.
Among prodromata which may show themselves with greater or less distinctness for an hour or two or even for a day or two before the full development of the attack, may be mentioned great disinclination for exertion, pains in the limbs, drowsiness, vertigo, headache, mental confusion, sighing, anorexia, thirst, intolerance of light—sometimes accompanied by chromatic aberrations of vision, suffused eyes, nausea and perhaps vomiting, prsecordial anxiety, sometimes a sense of impending calamity, an hysterical tendency to weep, a very hot dry skin, and a quickened pulse. Longmore called attention to excessive irritability of the bladder as a common prodromal symptom. This is a valuable and easily recognized danger-signal when present, and one the significance of which has been confirmed and emphasized by subsequent writers; it is possible, however, that its frequency has been exaggerated.
Though generally present in greater or less degree, and for a longer or shorter time, in many instances these prodromal symptoms are not remarked, the first indication of anything wrong being perhaps a short stage of restlessness, or possibly of wild ​delirium. This brief preliminary stage rapidly culminates in coma, complete unconsciousness, and high fever, quickly passing into hyperpyrexia.
Wood thus describes the symptoms of the developed attack: "Total insensibility was always present, with, in rare instances, delirium of the talkative form, and still more rarely the capability of being roused by shaking or shouting. The breathing was always affected, sometimes rapid, sometimes deep and laboured, often stertorous, and not rarely accompanied by the rattle of mucus in the trachea. The face was often deeply suffused, sometimes with the whole face deeply cyanosed. The conjunctiva was often injected, the pupils various—sometimes dilated, sometimes nearly normal, sometimes contracted. The skin was always intensely hot, and generally, but not always, dry; when not dry it was bathed in a profuse perspiration. The intense burning heat of the skin, both as felt by the hand and measured by the thermometer, was one of the most marked features of the cases. The degree of heat reached during life was, in my cases, mostly 108°-109° F. The pulse was always exceedingly rapid, and early in the disease often wanting in force and volume; later it became irregular, intermittent, and thready. The motor nervous system was profoundly affected. Subsultus tendinum was a very common symptom; great restlessness was also very often present, and sometimes partial spasms or even violent general convulsions. The latter were at times epileptiform, occurring spontaneously; or they were tetanoid, and excited by the slightest irritation. Sometimes the spinal cord appeared to be paralysed, the patient absolutely not moving."
The pupils, unless immediately before death, when along with the other sphincters they relax, are contracted. The reflexes are partially or wholly in abeyance. There may also be, especially in the graver cases, free watery purging, the dejecta, as well as the skin of the patient, emitting a peculiar and distinctive mousy odour. The scanty urine may contain blood corpuscles, albumin, and casts. ​ Different writers mention a number of what may be described as minor symptoms. They vary in different cases, and are by no means always present or characteristic. Whether these minor symptoms are present or not, in siriasis the essential symptoms—high fever and profound nervous disturbance, generally associated with insensibility—are invariably in evidence.
Unless active measures to lower temperature are taken early in the progress of the case, and unless these measures are vigorously carried out, in the great majority of instances death will occur within a few hours, or even minutes, of the onset of insensibility. The immediate cause of death is generally the failure of respiration. Rarely do cases linger for a day or two. Partial recovery is sometimes followed by relapse. In favourable cases the disease usually terminates by crisis. Convalescence is rapid.
Mortality.—As might be supposed, some types of heat-stroke are much more dangerous than others; siriasis infinitely more so than ordinary heat-exhaustion. Treatment, if early instituted and judiciously carried out, has undoubtedly a powerful influence in reducing mortality. Taking one type of heat-stroke with another, the case mortality among English troops in India is about one in four; in the year 1892, of 223 European soldiers admitted to hospital for heat-stroke, 61 died.
Morbid anatomy.—A notable feature in fatal siriasis is the early appearance of rigor mortis. The blood is remarkably fluid, or but feebly clotted. The venous system is loaded, dark fluid blood pouring from the phenomenally engorged lungs and other viscera on section. Both blood and muscles are said to yield an acid reaction more or less pronounced. It has been stated that the red blood-corpuscles are crenated, and do not form rouleaux. If the post-mortem examination is made shortly after death and before decomposition changes have set in, the heart in early rigor mortis, particularly the left ventricle, will be found to be remarkably rigid; this rigidity is sometimes described as being of woodeny hardness. ​There may be some venous congestion of the meninges, but the brain itself shows no important vascular, or naked-eye, changes. The intestinal mucosa, as well as that of the stomach, is swollen and exhibits patches of congestion.
Pathology.—As may be gathered from the remarks on etiology, the pathology of siriasis, so far, is in a very unsettled state, and will continue to be so until the essential cause of the disease has been finally determined.
Diagnosis.—The presence of high fever is sufficient to differentiate siriasis from sudden insensibility caused by uraemia, by diabetic coma, by alcoholic and opium poisoning, and by all similar toxic conditions. Cerebral haemorrhage, particularly pontine, may, after some hours, be followed by high temperature; but here the febrile condition follows the insensibility, whereas in heat-stroke the febrile condition precedes insensibility. The diagnosis from a cerebral malarial attack may be very difficult; chief reliance has to be placed on the history—if obtainable, on the condition of the spleen, and, especially, on the result of microscopical examination of the blood. Malarial fevers, and the early stages of the eruptive fevers in children, are very apt to be regarded as heat-stroke, particularly if there has been recent exposure to a hot sun. Cerebro-spinal fever, so often mistaken for siriasis, may be recognized by the occipital retraction, the irregular pupils, the frequent occurrence of strabismus, the comparatively low and fluctuating temperature, the associated herpes, the initial rigor, and its long duration.
Treatment.—In all fulminating fevers, including siriasis, occurring in warm climates, if malaria be suspected, particularly if the parasite be discovered in the blood, quinine should be injected intravenously or intramuscularly at once (7 to 10 grains of the bihydrochloride), or given by enema as directed under Malaria (p. 125); this dose should bo repeated three or four times at intervals of four hours. In every case of siriasis, whether it has been deemed advisable to administer quinine or not, attention must at once be ​given to reduce temperature by such rapidly acting measures as the cold bath, or ice applied in various ways to the head and body. Antipyretic drugs are of very little service, even if, in consequence of their depressing action on the heart, they be not actually dangerous; in all serious cases of siriasis such drugs must be carefully avoided. Chandler, speaking from an experience of 197 cases in which the mortality amounted only to 12, gives some excellent rules for the management of hyperpyrexial cases. He directs that the patient be placed undressed on a stretcher, the head end of which is raised slightly so as to facilitate the escape of involuntary evacuations and to provide for drainage. A thermometer is kept in the rectum. The body is covered with a sheet upon which are laid numerous small pieces of ice, larger pieces being closely packed about the head. Iced water is then allowed to drip for thirty or forty minutes on the patient from drippers hung at an elevation of from five to ten feet. A fine stream of iced water poured on the forehead from an elevation will act as a stimulant and rouser; this is a very powerful measure, and must not be kept up for longer than one or two minutes. A hypodermic injection of 40 minims of tincture of digitalis is given as soon as possible, its administration being preceded, in the case of plethoric patients showing much arterial tension (but not otherwise), by a small bleeding. The application of cold should be at once discontinued so soon as the thermometer in the rectum has sunk to 104° F., or, in cases of simple thermic fever in which the temperature has not exceeded 106°, when it has fallen to 102°. If these powerful antipyretic measures are carried beyond this point the fall of temperature may continue below the normal, even to as low as 91°, and dangerous collapse ensue.
On discontinuance of the iced sheet the patient should be wrapped in a blanket, and hot bottles applied to limbs and trunk. Very likely perspiration, a very favourable sign, will then set in. Stimulants may now be necessary. Strychnine, owing to the marked tendency to convulsions that is ​present in heat-stroke, must on no account be used as a cardiac stimulant. Convulsions are best controlled by cautious chloroform inhalations. As death in heat-stroke generally results from failure of respiration, Chandler strongly recommends artificial respiration when the breathing threatens to become suspended; he claims to have obtained some marvellous results from this expedient. It should be kept up for half an hour or longer.
During convalescence great care must be exercised to shield the patient from all influences calculated to provoke relapse.
SUN-TRAUMATISM
There is a large, ill-defined, and difficult-to-define class of heat-stroke cases which belong neither to the category of heat-exhaustion nor to the very definite and possibly specific disease just described. The morbid phenomena in this class of sun-induced disease are attributable, apparently, to a peculiar physical action of the direct rays of the sun on the tissues. To this category belong, it seems to me, those sudden deaths occurring without warning during, and manifestly in consequence of, exposure to the sun. Such may have been the sudden deaths described by Parkes, Maclean, Fayrer and others, in which soldiers in the excitement and stress of battle, while oppressed with thick clothing and heavy accoutrements and exposed to a blazing sun, suddenly fell forward on their faces and, after a few convulsive gasps, died. In these instantaneously fatal cases the paralysis of the heart or respiration seems to be of the nature of shock, as from a blow or other sudden and violent impression on the encephalon.
Doubtless, indeed it is a well-known fact, the strain undergone in these and similar circumstances may, in some instances, causa an apoplexy or rupture of some description in tissues prepared for such a cataclysm by morbid degenerations of long standing.
Besides the foregoing there is another type of case in which, after prolonged exposure to the sun, a febrile condition is established. This is sometimes of great ​severity, being characterized by intense headache, a rapid full pulse, a pungent dry skin, intolerance of light, sound, and movement, and occasionally by vomiting or delirium. This condition suggests meningeal congestion, possibly inflammation. The acute phase may be quickly recovered from, or it may prove very persistent and last for days or weeks. It may leave no injurious effects; or it may be followed by a variety of transient or more permanent morbid nervous phenomena. Among the sequelæ authors have mentioned tremor, loss of memory, amaurosis, deafness, various paretic conditions, epilepsy, insanity, persistent headache, recurring headache, dyspeptic conditions. How far these sequelæ are entirely attributable to sun-exposure, or how far they depend on other diseases, as syphilis for example, the local cerebral manifestations of which may have been provoked, though not actually caused, by the suntraumatism, it is not always easy to say.
The morbid anatomy, as well as the clinical symptoms, indicates meningitis as a feature of these instances of reputed sun-traumatism. Authors refer to thickenings and opacities of the meninges, and even to thickening and roughening of the calvarium.
Many speculations have been advanced as to the pathogenesis. Manifestly it is not altogether, if at all, a question of caloric, for such effects do not result from exposure to the heat of a furnace, however intense. There appears to be some special element in the solar spectrum capable of injuriously affecting the tissues, particularly if they have not become gradually habituated to sun-exposure. That some such element does exist is proved by the phenomena of sun-erythema, of that form of skin pigmentation known as sun-burning, and, possibly, of leucodermia. The sensation of distress brought on by exposure to a hot sun, which is quite a different sensation from that produced by the heat of a fire, points in the same direction. In this connection we are forcibly reminded of the phenomena of the actinic rays of the solar spectrum, and of the remarkable tissue changes induced by the Kontgen rays. ​Treatment.— Patients suffering from sim-traumatism must be kept as quiet as possible in a cool, airy, and darkened room. For a time the head should be kept shaved, and cold applied to the scalp. The bowels must be free; food should be light and unstimulating, and alcohol in every form strictly forbidden. Restlessness and insomnia are best treated by the bromides. For a considerable time the patient will be conscious of loss of memory, and feebleness of intellectual power and of the faculty of concentration. He may be irritable, liable to headache, and extremely sensitive to heat more particularly the heat and glare of the sun. So soon as he is able to be moved he must be sent to a cold climate, and there remain until all trace of his illness has completely disappeared. Indeed, it is questionable if the subject of pronounced sun-trauma should ever again risk the dangers of a tropical climate; certain it is that he should not return to the tropics so long as the slightest evidence of cerebral trouble remains.
For persistent headache and other signs of chronic meningitis, courses of the iodides and bromides, repeated blistering of the neck and scalp, together with careful dieting and general hygiene, should be tried. In not a few instances, in spite of the most careful treatment, medicinal and climatic, serious permanent disease of the encephalon remains, giving rise to various and often incurable troubles, and, very commonly, to distressing intellectual enfeeblement.
PREVENTION OF HEAT-STROKE
In heat-stroke climates great attention should be paid to the general health; if this be not satisfactory, exposure to the sun and to high temperatures must, so far as possible, be avoided. Alcoholic drinks, gluttony, excess of animal food, too much tobacco -smoking— in fact, dissipation of all sorts— are especially to be deprecated. Individuals suffering from malarial or other fevers, or from chronic liver or kidney disease, run great risk if they are careless about exposing themsehestothesun. Violent ​exercise, excessive fatigue, want of sleep, constipation, are also to be avoided.
Clothing ought to be light and loose fitting, the under-garment being of thin woollen material. In going out in the sun the head must be protected by a wide -brimmed, well-ventilated pith hat shielding the temples and neck as well as the top of the head. An actinic theory of sun-traumatism, advocated many years ago by Maude and Duncan, and more recently by Sambon,* indicates the necessity for a radical change in the colour of the dress materials now in vogue among Europeans in the tropics. The natives of warm climates invariably have dark skins a natural provision of protection against the actinic rays of the solar spectrum. Exposure to the sun tans the European; a natural protective reaction. Therefore the European in the tropics, conformably to this hint from Nature, should invariably wear non-actinic colours a red or yellow shirt, or a fabric (solaro) into which these colours enter, and such as is now manufactured. The sun-hat should be similarly guarded. Experience has shown the comfort and value of such an arrangement. A pad of cotton sewn into the back of the coat in such a way as to protect the spine is a wise measure, and one adopted by experienced sportsmen in India. Puntone, who has shown by an ingenious experiment that the human cranium is diathermal to the yellow-red and ultra-violet rays but absorbs the red and green-blue rays, recommends green clothing covered with white material to protect important parts, more especially head, neck, and spine. The phenomena connected with the Rontgen rays suggest the possibility that there may be solar rays other than the ordinary heat and actinic rays which, although they may be able to pass through organic materials, can nevertheless be arrested by metals. If this be true for the sun as well as for the Rontgen rays, a useful addition to the sun-hat would be a thin plate of some light metal placed between the layers of pith constituting the basis of the ordinary solar topee. A sheet of tinfoil or other ​light metal would not perceptibly add to the weight of the head-gear. Such sun-hats are, I believe, now manufactured. A white umbrella, lined with green or orange, ought never to be despised. Tinted (smoke colour) goggles are probably a protection, as they certainly are a great comfort in mitigating solar glare.
Rooms should be kept dark during the day, and cooled by means of punkahs, thermantidotes, tatties, Venetians, and other contrivances. In barracks and ships there must be no overcrowding. In very hot weather European soldiers should, if possible, sleep under punkahs. Military drills should be reduced to a minimum, and take place in the cool of the morning only, and after the soldier has had a cup of tea or coffee and some light food. Marches should be short, interrupted by frequent halts, and be got through, if possible, in the early morning. While marching the men ought to be in open order, relieved of all unnecessary weights, belts and clothing, and well supplied with water. Camps should be pitched in cool and airy spots and on turf and under large spreading trees free from undergrowth. Double canvas, one layer of which should be nonactinic, and grass or boughs laid on the wall of the tent, will do much to mitigate the temperature within.