Body Temperature

BODY TEMPERATURE of a human being is the result of the function of his heat-regulating apparatus and depends upon the balance between heat production and heat loss, maintained by the regulatory activity of the central nervous system (see Thermoregulation). In view of the fact that not all organs and tissues of the organism take an equal part in heat production and heat loss, the temperature of various parts of it is far from identical despite the significant equilibrating influence of the constantly circulating blood. Thus, the liver has the highest temperature, followed by the heart, kidneys, as well as muscles, especially after contraction; the skin has the lowest temperature, and on its various sections the temperature is also different (highest in the axillary hollow, lowest on the face). Usually, between the temperature of the integuments and the temperature of the internal organs, there is observed a sort of antagonism (Ostroumov, Heidenhain) consisting in the fact that with a rise in skin temperature, a certain drop in the temperature of the internal organs occurs and vice versa (the Dastre-Morat law). In the clinic, for judging body temperature, measurement in the armpit is most frequently used, less often in the rectum, and in some cases in the oral cavity (see below). The usual temperature of a healthy person, or as they say, the normal temperature, is not stable, but undergoes fairly regular fluctuations during the day, in most cases within the limits of one degree from 36.0 to 37.0° when measured in the armpit and from 36.5 to 37.5° with rectal measurement, and the amplitude of temperature fluctuations in different individuals is diverse. Usually, as a rule, during the day the temperature rises all the time, giving a maximum at 5–8 o'clock in the evening, and at night it drops, giving a minimum at 3–6 o'clock in the morning. The average daily temperature is 36.5–36.7° with axillary measurement and 36.9–37.2° with rectal measurement, and in childhood, especially in infants, it is somewhat higher, and in old age lower. Sex usually has little effect on the average body temperature; its influence is manifested only by a somewhat greater lability of it in women and a certain rise of it before the onset of menses. Food intake, especially that rich in proteins, somewhat increases the temperature due to the increased work of the digestive glands and the revitalization of the metabolic process. Movements and mainly muscular work particularly increase body temperature, since contracting muscles are the main heat generator. Changes in environmental temperature, even fairly large ones, with the correct function of the heat-regulating apparatus, usually do not affect the body temperature of a person; excessive changes in environmental temperature, especially with their prolonged action on the human organism, can hinder and even disrupt the correctness of thermoregulation and cause overheating or overcooling of the organism. Prolonged exposure of the organism to high temperature, especially combined with high humidity, sharply hinders heat loss by evaporation, and body temperature begins to gradually rise; hyperthermia sets in, accompanied by a whole series of painful phenomena, and a rise in body temperature above 4.0–6.0° against the normal temperature entails death (Bernard). Overheating of the organism sets in faster if, along with hindered heat loss, heat production is also enhanced, as happens during walking and muscular work (see Heat stroke). With prolonged exposure of the organism to low temperature, especially in combination with enhanced humidity, the compensation of heat losses by heat production is significantly hindered, and body temperature begins to gradually drop; hypothermia sets in, accompanied by a whole series of general phenomena, and a drop in body temperature to 20.0° leads to death (see Cooling). Overcooling sets in faster if, together with increased heat loss, heat production is weakened, as happens in starving people, those exhausted by diseases, and alcoholics. In pathological cases, the human body temperature can change significantly, and most often it changes in the direction of an increase, more rarely in the direction of a decrease. Elevated body temperature is the most striking, but not the only symptom of a febrile state (see Fever). According to the degree of temperature change, it is divided into the following types: 1) subfebrile—from 37.0° to 38.0°; 2) febrile—from 38.0° to 41.0°, which in turn is subdivided into moderate, from 38.0° to 39.0°, and high, from 39.0° to 41.0°; 3) hyperpyretic—above 41.0°; 4) subnormal—below 36.0°. The maximum figure of temperature rise noted in the literature is 44.6° (Wunderlich), the minimum (in rectum)—23.0° (Lemcke). Prolonged and especially sharp hyperpyretic temperatures cause degenerative changes in parenchymatous organs and lead to death. Depending on the causes causing them, temperature rises are divided into: 1) infectious-toxic, or septic, resulting from the action on the organism of microbial poisons (exo- and endotoxins) and poisonous products of pathological metabolism; this cause is the most frequent, causing the vast majority of body temperature rises; 2) resorption, or aseptic, appearing as a result of the absorption of pathological products of tissue breakdown (during the resorption of exudates, disintegrating erythrocytes in hemorrhages, in subcutaneous fractures, in tissue crushing, etc.); 3) due to increased muscular work (fièvre de surmenage) thanks to intensive heat production and intoxication with products of enhanced tissue breakdown (ketotoxins); 4) endocrine—in hyperfunction of the thyroid gland, as well as the adrenal glands and partly the anterior lobe of the pituitary gland (Weil); 5) neurogenic thermoregulation disorders of central (with cranial cavity tumors, spinal cord injuries, hysteria) or reflex (with visceral colics, e.g., hepatic, renal, with urethral catheterization, etc., if there is no infection influence) origin. The first two types of body temperature rise are accompanied by other elements of fever and therefore are called febrile rises, while the last type—nervous rises—can rather be attributed to simple hyperthermias; the middle two types of temperature rise occupy, as it were, an intermediate position between them. Rises in body temperature, especially of infectious-toxic origin, very often are distinguished by a fairly pronounced regularity and give very typical curves for a number of infectious diseases. According to the character of temperature rises, one distinguishes: 1) transient temperature (ephemera)—a short-term temperature rise lasting mostly several hours and not more than 1–2 days, far from always of clear etiology and in different cases of different origin (e.g., infectious-toxic in a single malaria attack, nervous in hysteria, etc.); 2) constant temperature (continua)—a more or less prolonged temperature with a rapid or gradual rise in the period of its increase (stadium incrementi), with small, not exceeding 1.0° daily fluctuations in the period of its development (stadium acme or fastigium) and with a rapid (see Crisis) or gradual drop (see Lysis) in the period of its decrease (stadium decrementi); the crisis is often preceded by a particularly sharp temperature rise—perturbatio critica (e.g., croupous pneumonia, typhus fever), before the onset of lysis sometimes the amplitude of daily temperature fluctuations becomes significantly greater—stadium amphibole (e.g., typhoid fever); 3) remittent temperature (remittens)—also a more or less prolonged temperature, like continua, but with an amplitude of daily fluctuations greater than 1.0° (e.g., bronchopneumonia, staphylo- and streptococcal infections); 4) intermittent temperature (intermittens)—with a more or less regular and sharp alternation of periods of high temperature with periods of apyrexia with normal and even subnormal temperature (malaria); 5) relapsing temperature (reccurrens)—also with a regular and striking alternation, but of significantly longer (by several days) periods of high temperature with periods of apyrexia (relapsing fever); 6) exhausting temperature (hectica)—prolonged temperature with large daily fluctuations, often reaching 4.0–5.0°, and the morning temperature sometimes drops to normal and even subnormal figures (e.g., in severe cases of pulmonary tuberculosis, in sepsis); 7) inverted temperature (inversa)—with an unusual type of daily fluctuations, namely, in it the morning figures are higher than the evening ones; very often this type of temperature is combined with hectic temperature (far-advanced pulmonary tuberculosis, septicopyemic processes); 8) undulating temperature (undulans)—with the alternation of periods of gradual temperature increase and its gradual decrease to subfebrile and even normal figures (e.g., lymphogranulomatosis); 9) monotermic temperature—with sluggish daily fluctuations, so that often the morning and evening figures are completely identical and its curves have the appearance of a straight line (in some cases of initial tuberculosis); 10) atypical temperature—temperature of various durations with completely irregular and disorderly daily fluctuations having no regularity (e.g., recurrent endocarditis, septic processes). Lately, protracted subfebrile temperatures, which sometimes last for months and even years, have been attracting special attention. In a large number of cases, they are caused by the presence in the organism of some infectious-toxic process, often proceeding very sluggishly and covertly.

Most frequently they are observed at the onset of a tuberculous process, especially pulmonary and glandular, in chronic tonsillitis, diseases of the accessory nasal sinuses, in dental granulomas, chronic cholecystitis, pyelitis, appendicitis, endocarditis lenta, chronic sepsis, and latent malaria. In some cases, the cause of prolonged subfebrile temperature is diseases of the endocrine glands, most frequently Basedow's disease. But quite often, cases of prolonged subfebrile temperature are observed that are not accompanied by any other more or less noticeable painful phenomena. Sometimes this subfebrile state persists after recovering from some acute infectious disease, but in many cases its appearance cannot be linked to anything. It occurs more frequently in women, especially at a young age, predominantly of an asthenic constitution and with a very labile nervous and cardiovascular system. Recently, some consider these types of protracted subfebrile states as a neurotic disorder of thermoregulation that shifts the level of average temperature to a somewhat higher step (thermoneurosis, according to B. A. Chernogubov). Even in the presence of latent and sluggish infectious foci in the body, in some cases this subfebrile state depends not so much on intoxication as on this neurotic shift in the thermoregulating apparatus. A distinctive feature of these neurotic subfebrile states is the comparatively low degree of temperature elevation (usually it does not exceed 37.5°) and the extreme monotony of its daily fluctuations with a small amplitude. Furthermore, for differentiating these neurotic subfebrile states from subfebrile states of infectious-toxic origin, it is recommended (B. A. Chernogubov, Weltmann) to use the pyramidon test, which consists of administering up to 1.5 g of pyramidon to the patient over one day. Temperature of infectious-toxic origin under the influence of this dose of pyramidon usually drops to normal figures, whereas neurotic temperature not only does not decrease from pyramidon, but does not even change its monotonous character. The elevation of human body temperature can also be induced artificially, by the parenteral administration (under the skin or into a vein) of certain substances, e.g., foreign protein (blood serum, milk), bile salts, various kinds of enzymes (fibrin ferment, pepsin, pancreatin, chymosin, diastase, invertin, etc.), glycerin, etc., and even distilled water, as well as by applying hot procedures (baths, Russian steam baths, and Roman-Irish baths). The lowering of human body temperature to subnormal figures (hypothermia) can be caused by: 1) intoxications of both exogenous origin, e.g., by many alkaloids (muscarine, nicotine, etc.), fatty series substances (alcohol, chloroform, ether, sleeping pills), antipyrine and its derivatives, aniline, etc. (see Poisoning), and especially of endogenous character (uremia, diabetic coma, cholemia, etc.); 2) the algogenic action of large quantities of microbial poisons and products of pathological metabolism in certain cases of acute infections (algid forms of cholera, dysentery, diphtheria, collapse, etc.), while small doses of them act pyrogenically; 3) exhaustion of the heat-regulating apparatus in chronic exhausting diseases and starvation; 4) nervous thermoregulation disorders of both central origin (in diseases of the nervous system, e.g., apoplexy, trauma) and reflex origin (upon sharp irritation of the sympathetic system, especially from the side of serous membranes). Very frequently, hypothermia is observed in certain complications of diseases, such as perforation of the stomach and intestines, internal hemorrhages, etc. Hypothermia occurs especially easily at the extremes of life (e.g., temperatureless pneumonias of the elderly and athreptic children) and in myocardial diseases. Prolonged hypothermia is an expression of the lowered reactive capacity of the organism and is an unfavorable prognostic sign (Peter). Artificial lowering of body temperature, especially elevated temperature, can be induced by applying cold hydrotherapeutic procedures (baths, showers, etc.), as well as antipyretic substances (see Antipyretica). Besides general elevation or lowering of body temperature, there are cases of local change in the temperature of its individual parts. Thus, a local temperature rise can be observed in the region of localized inflammatory processes, e.g., in lymphadenitis, arthritis, etc., as well as upon local application of heat (hot-water bottles, poultices, etc.). Local temperature lowering is encountered in circulation difficulties in one or another area of the body, and this most often occurs in its peripheral parts (extremities, etc.), e.g., in endarteritis obliterans, Raynaud's disease, etc., as well as upon local application of cold. Body thermometry is the measurement of body temperature. It is performed using thermometers—simple or, more frequently, maximum thermometers. Skin temperature is usually measured, with the thermometer inserted so that the mercury reservoir is in contact with the skin on all sides. Most often, temperature measurement in the armpit is used, with the thermometer reservoir inserted deep into its cavity and then the thermometer itself pressed by the arm against the chest wall. It is necessary to wipe the armpit dry beforehand, since measurement with moist skin will affect the accuracy of the thermometer readings. Sometimes, mainly in children, the temperature is measured in the inguinal fold, and after inserting the thermometer into it, the leg is bent somewhat at the hip joint so that the thermometer reservoir is hidden in the resulting skin fold. In some cases, the temperature of mucous membranes is measured—the oral cavity, vagina, and most often the rectum. When measuring temperature in the oral cavity, the thermometer reservoir is placed between the lower surface of the tongue and the floor of the mouth. When measuring in the rectum, the thermometer reservoir is introduced into the anus past the internal anal sphincter (for easier introduction, it is lubricated with vaseline), after which the buttocks are brought together, thereby fixing the position of the thermometer; rectal temperature measurement is very convenient in pediatric practice. Body temperature can be determined by measuring the temperature of voided urine, which for the most part is very close to the temperature of the skin in the armpit, exceeding it sometimes by only 0.1–0.2°. Also close to the axillary temperature is the temperature measured in the oral cavity, and in many cases it is even 0.1–0.2° lower than the axillary. The highest is the rectal temperature, which usually exceeds the temperature of the axillary region by 0.2–0.4°. The inserted thermometer must be kept in the armpit, inguinal fold, and oral cavity for at least 10 minutes, and in the rectum for at least 5 minutes, to give the mercury time to assume the temperature of the surrounding tissue and rise up the capillary to the maximum height. Even so-called minute thermometers designed for very rapid (within 1 minute) rise of mercury to the maximum are better kept for 2–3 minutes. If a simple thermometer is used to measure temperature, the reading of degrees is carried out without removing it from the place where it was placed, otherwise the level of the mercury column will rapidly drop down. When measuring temperature with a maximum thermometer, the latter can be freely removed for reading degrees; before placing the maximum thermometer, it is necessary to shake it several times and make sure that the mercury in it has dropped to the lowest figures of the scale. After use, the thermometer should always be wiped with some disinfecting solution. In patients, temperature is measured for the most part twice a day—usually in the morning on an empty stomach and in the evening before the last meal; measuring temperature shortly after a meal is not recommended, since higher figures are obtained, just as after exercise; temperature should be measured in a calm lying position. When it is necessary to capture short-term temperature changes or perform a more accurate analysis of its daily fluctuations, one has to measure temperature more frequently—3–4 times a day, sometimes every 2 hours and even hourly. The measured temperature is recommended to be immediately recorded in a temperature chart indicating the date and hours of temperature measurement or, even better, plotted graphically in the form of a temperature curve. Properly and systematically measured and accurately recorded temperature, especially if it is plotted as a curve, is of extremely great importance for the clinic, often serving as a decisive diagnostic symptom (in malaria, relapsing fever, pyemia, typhoid fever), and in addition providing the ability to monitor the course of the disease process (see Crisis, Lysis). At the present time, there is a method of electrothermography that allows obtaining a continuous curve of temperature fluctuations over one or another time interval. The apparatus used for this, the electrothermograph (manufactured by Siemens & Halske), is equipped with appropriate electrodes that are applied to the skin or introduced into cavities (e.g., the rectum). Recording is carried out on a kymograph. This method is very convenient for observing daily temperature fluctuation and the influence of various factors on them (e.g., food intake, physiotherapeutic procedures, etc.).

A. Molchanov