When the body's thermal balance is disturbed, either hyperthermic or hypothermic states develop. Hyperthermic states are characterized by an increase, and hypothermic states are characterized by a decrease in body temperature above and below normal, respectively.
HYPERTHERMAL STATES
Hyperthermic conditions include overheating of the body (or hyperthermia itself), heatstroke, sunstroke, fever, and various hyperthermic reactions.
Hyperthermia proper
Hyperthermia- a typical form of heat exchange disorder, resulting, as a rule, from the action of high ambient temperature and heat transfer disturbance.
ETIOLOGY Causes of hyperthermia
Allocate external and internal reasons.
High ambient temperatures can affect the body:
♦ in hot summer time;
♦ in production conditions (at metallurgical and foundries, in glass and steel making);
♦ when extinguishing fires;
♦ with a long stay in a hot bath.
A decrease in heat transfer is a consequence of:
♦ primary disorder of the thermoregulatory system (for example, if the corresponding structures of the hypothalamus are damaged);
♦ violation of heat transfer to the environment (for example, in obese people, with a decrease in moisture permeability of clothing, high air humidity).
Risk factors
♦ Actions that increase heat production (intense muscular work).
♦ Age (hyperthermia develops more easily in children and the elderly, in whom the efficiency of the thermoregulation system is reduced).
♦ Certain diseases (hypertension, heart failure, endocrinopathies, hyperthyroidism, obesity, vegetative-vascular dystonia).
♦ Uncoupling of oxidation and phosphorylation processes in cell mitochondria by means of exogenous (2,4-dinitrophenol, dicumarol, oligomycin, amytal) and endogenous agents (excess of thyroid hormones, catecholamines, progesterone, IVH and mitochondrial uncouplers - thermogenins).
PATHOGENESIS OF HYPERTHERMIA
Under the action of the hyperthermic factor, a triad of emergency adaptive mechanisms is activated in the body: 1) behavioral response ("escape" from the action of the heat factor); 2) intensification of heat transfer and reduction of heat production; 3) stress. Lack of protective mechanisms is accompanied by overstrain and disruption of the thermoregulation system with the formation of hyperthermia.
During the development of hyperthermia, two main stages are distinguished: compensation (adaptation) and decompensation (maladjustment) of the body's thermoregulation mechanisms. Some authors distinguish the final stage of hyperthermia - hyperthermic coma. Compensation stagecharacterized by the activation of emergency mechanisms of adaptation to overheating. These mechanisms are aimed at increasing heat transfer and reducing heat production. Due to this, the body temperature remains within the upper limit of the normal range. There is a feeling of heat, dizziness, tinnitus, flashing "flies" and darkening in the eyes. Can develop thermal neurasthenic syndrome,characterized by a drop in performance, lethargy, weakness and apathy, drowsiness, physical inactivity, sleep disturbances, irritability, headaches.
Decompensation stage
The stage of decompensation is characterized by a breakdown and inefficiency of both central and local mechanisms of thermoregulation, which leads to a violation of the body's temperature homeostasis. The temperature of the internal environment rises to 41-43 ° C, which is accompanied by changes in metabolism and functions of organs and their systems.
♦ Sweating decreasesoften only scanty sticky sweat is noted; the skin becomes dry and hot. Dry skin is considered an important sign of hyperthermia decompensation.
♦ Hypohydration increases.The body loses a large amount of fluid as a result of increased sweating and urination at the stage of compensation, which leads to hypohydration of the body. Loss of 9-10% of fluid is associated with significant disorders of life. This state is denoted as "Desert disease syndrome".
♦ Hyperthermic cardiovascular syndrome develops:tachycardia increases, cardiac output decreases, IOC is maintained due to an increased heart rate, systolic blood pressure may increase briefly, and diastolic blood pressure decreases; microcirculation disorders develop.
♦ Signs of exhaustion build upmechanisms stressand the underlying adrenal and thyroid insufficiency: hypodynamia, muscle weakness, a decrease in myocardial contractile function, the development of hypotension, up to collapse are observed.
♦ The rheological properties of blood change:its viscosity increases, signs of sludge syndrome, disseminated intravascular coagulation of blood proteins (DIC syndrome) and fibrinolysis appear.
♦ Metabolic and physicochemical disorders develop:cl -, K +, Ca 2 +, Na +, Mg 2 + and other ions are lost; water-soluble vitamins are removed from the body.
♦ Acidosis is registered.Due to the increase in acidosis, ventilation of the lungs and the release of carbon dioxide increase; oxygen consumption increases; the dissociation of HbO 2 decreases.
♦ Concentration increasesin the blood plasma of the so-called average weight molecules(from 500 to 5000 Da) - oligosaccharides, polyamines, peptides, nucleotides, glyco- and nucleoproteins. These compounds are highly cytotoxic.
♦ Heat shock proteins appear.
♦ Substantially modifiedphysico-chemical state of lipids.SPOL is activated, the fluidity of membrane lipids increases, which disrupts the functional properties of membranes.
♦ In the tissues of the brain, liver, lungs, muscles, significantly the content of lipid peroxidation products increases- diene conjugates and lipid hydroperoxides.
The state of health in this stage sharply worsens, there is growing weakness, palpitations, throbbing headache, a feeling of intense heat and a feeling of thirst, mental agitation and restlessness, nausea and vomiting.
Hyperthermia can be accompanied (especially in hyperthermic coma) by edema of the brain and its membranes, neuronal death, myocardial, liver, kidney dystrophy, venous hyperemia, and petechial hemorrhages in the brain, heart, kidneys and other organs. Some patients have significant neuropsychiatric disorders (delusions, hallucinations).
With hyperthermic comadeafness and loss of consciousness develops; clonic and tetanic convulsions, nystagmus, dilation of the pupils, followed by their constriction can be observed.
OUTCOMES
With an unfavorable course of hyperthermia and the absence of medical care, the victims die as a result of circulatory failure, cessation of cardiac activity (ventricular fibrillation and asystole) and respiration.
Heatstroke
Heatstroke- acute form hyperthermia with the achievement of life-threatening body temperature values \u200b\u200bof 42-43 ° C (rectal) within a short time.
Etiology
High intensity heat action.
Low efficiency of the mechanisms of adaptation of the body to the increased temperature of the external environment.
Pathogenesis
Heatstroke is hyperthermia with a short stage of compensation, which quickly turns into a stage of decompensation. Body temperature tends to approach the ambient temperature. Heat stroke lethality reaches 30%. The death of patients is the result of acute progressive intoxication, heart failure and respiratory arrest.
Intoxication of the bodymolecules of average weight is accompanied by hemolysis of erythrocytes, increased permeability of the walls of blood vessels, the development of DIC syndrome.
Acute heart failureis the result of acute dystrophic changes in the myocardium, violation of actomyosin interaction and energy supply of cardiomyocytes.
Stop breathingmay be a consequence of increasing cerebral hypoxia, edema and cerebral hemorrhage.
Sunstroke
Sunstroke- a hyperthermic state due to the direct effect of solar radiation energy on the body.
Etiology.Sunstroke is caused by excessive sun exposure. The greatest pathogenic effect is exerted by the infrared part of solar radiation, i.e. radiation heat. The latter, in contrast to convection and conduction heat, simultaneously heats the surface and deep tissues of the body, including the brain tissue.
Pathogenesis.The leading link in pathogenesis is damage to the central nervous system.
Initially, arterial hyperemia of the brain develops. This leads to an increase in the formation of intercellular fluid and to compression of the substance of the brain. Compression of the venous vessels and sinuses located in the cranial cavity contributes to the development of venous hyperemia of the brain. In turn, venous hyperemia leads to hypoxia, edema, and small focal hemorrhages in the brain. As a result, focal symptoms appear in the form of disturbances in sensitivity, movement and autonomic functions.
The growing disorders of metabolism, energy supply and plastic processes in the neurons of the brain potentiate the decompensation of thermoregulatory mechanisms, disorders of the functions of the CVS, respiration, endocrine glands, blood, and other systems and organs.
Sunstroke is fraught with a high probability of death (due to dysfunction of the CVS and the respiratory system), as well as the development of paralysis, sensory disorders and nervous trophism.
Principles of therapy and prevention of hyperthermic conditions
Treatment of victims is organized taking into account the etiotropic, pathogenetic and symptomatic principles.
Etiotropic treatmentis aimed at stopping the action of the cause of hyperthermia and eliminating risk factors. For this purpose, methods are used aimed at normalizing heat transfer, stopping the action of high temperature and uncouplers of oxidative phosphorylation.
Pathogenetic therapyaims to block the key mechanisms of hyperthermia and stimulate adaptive processes (compensation, protection, recovery). These goals are achieved by:
Normalization of CVS functions, respiration, blood volume and viscosity, mechanisms of neurohumoral regulation of the function of sweat glands.
Elimination of shifts in the most important parameters of homeostasis (pH, osmotic and oncotic blood pressure, blood pressure).
Detoxification of the body (hemodilution and stimulation of the excretory function of the kidneys).
Symptomatic treatmentin case of hyperthermic conditions, it is aimed at eliminating unpleasant and painful sensations that aggravate the victim's condition ("unbearable" headache, increased sensitivity of the skin and mucous membranes to heat, a sense of fear of death and depression); treatment of complications and associated pathological processes.
Prevention of hyperthermic conditionsis aimed at preventing excessive exposure to the body of the heat factor.
HYPERTHERMAL REACTIONS
Hyperthermic reactionsare manifested by a temporary increase in body temperature due to the transient predominance of heat production over heat transfer while maintaining the mechanisms of thermoregulation.
According to the criterion of origin, hyperthermic reactions are distinguished: endogenous, exogenous and combined (malignant hyperthermia). Endogenous hyperthermic reactionssubdivided into psychogenic, neurogenic and endocrine.
Psychogenic hyperthermic reactions develop under severe stress and psychopathological conditions.
Neurogenic hyperthermic reactions are subdivided into centrogenic and reflex.
♦ Centrogenic hyperthermic reactions develop with direct stimulation of the neurons of the heat regulation center, which are responsible for heat production.
♦ Reflex hyperthermic reactions occur when various organs and tissues are severely irritated: the bile ducts of the liver and biliary tract; the pelvis of the kidneys and urinary tract when calculi pass through them.
Endocrine hyperthermic reactions develop as a result of overproduction of catecholamines (with pheochromocytoma) or thyroid hormones (with hyperthyroid conditions). The leading mechanism is the activation of exothermic metabolic processes, including the formation of oxidation and phosphorylation uncouplers.
Exogenous hyperthermic reactionssubdivided into medicinal and non-medicinal.
Medicinal (medication, pharmacological) hyperthermic reactions are caused by drugs that uncouple
effect: sympathomimetics (caffeine, ephedrine, dopamine), Ca 2 + - containing drugs.
Non-drug hyperthermic reactions are caused by substances with a thermogenic effect: 2,4-dinitrophenol, cyanides, amytal. These substances activate the sympathoadrenal and thyroid systems.
FEVER
Fever- a typical pathological process characterized by a temporary increase in body temperature due to the dynamic restructuring of the thermoregulation system under the influence of pyrogens.
ETIOLOGY
The cause of the fever is pyrogen. Primary and secondary pyrogens are isolated according to the source of occurrence and the mechanism of action.
Primary pyrogens
Primary pyrogens themselves do not affect the thermoregulatory center, but cause the expression of genes encoding the synthesis of cytokines (pyrogenic leukokines).
By origin, infectious and non-infectious primary pyrogens are distinguished.
Infectious pyrogens- the most common reason fever. Infectious pyrogens include lipopolysaccharides, lipoteichoic acid, and exotoxins acting as superantigens.
♦ Lipopolysaccharides(LPS, endotoxins) have the highest pyrogenicity. LPS is a part of the membranes of microorganisms, mainly gram-negative. The pyrogenic effect is characteristic of lipid A, which is part of the LPS.
♦ Lipoteichoic acid.Gram-positive microbes contain lipoteichoic acid and pyrogenic peptidoglycans.
By their structure, pyrogens of non-infectious origin are more often proteins, fats, less often nucleic acids or nucleoproteins. These substances can come from the outside (parenteral administration of blood components, vaccines, fat emulsions into the body) or be formed in the body itself (with non-infectious inflammation, myocardial infarction, tumor breakdown, erythrocyte hemolysis, allergic reactions).
Secondary pyrogens.Under the influence of primary pyrogens, cytokines (leukokines) are formed in leukocytes, which have pyrogenic activity in a negligible dose. Pyrogenic leukokines are called
are secondary, true, or leukocyte pyrogens. These substances directly affect the thermoregulatory center, changing its functional activity. Among the pyrogenic cytokines are IL1 (previously referred to as "endogenous pyrogen"), IL6, TNFα, γ-IFN.
PATHOGENESIS OF FEVER
Fever is a dynamic and staged process. According to the criterion of changes in body temperature, three stages of fever are distinguished: I- rise in temperature, II- standing temperature at an elevated level and III- lowering the temperature to the normal range.
Temperature rise stage
Stage of rise in body temperature (stage I, st. incrementi)characterized by the accumulation of additional heat in the body due to the predominance of heat production over heat transfer.
Pyrogenic leukokines from the blood penetrate the blood-brain barrier and in the preoptic zone of the anterior hypothalamus interact with the receptors of the nerve cells of the thermoregulation center. As a result, membrane-bound phospholipase A 2 is activated and arachidonic acid is released.
In the neurons of the thermoregulatory center, the activity of cyclooxygenase is significantly increased. The result of the metabolism of arachidonic acid by the cyclooxygenase pathway is an increase in the concentration of PgE 2.
Formation of PgE 2- one of the key links in the development of fever.
The argument for this is the fact that fever is prevented when cyclooxygenase activity is suppressed by non-steroidal anti-inflammatory drugs (NSAIDs, for example, acetylsalicylic acid or diclofenac).
PgE 2 activates adenylate cyclase, which catalyzes the formation of cyclic 3 ", 5" -adenosine monophosphate (cAMP) in neurons. This, in turn, increases the activity of cAMP-dependent protein kinases, which leads to a decrease in the excitability threshold of cold receptors (i.e., an increase in their sensitivity).
Due to this, the normal blood temperature is perceived as low: the impulse of cold-sensitive neurons to the effector neurons of the posterior hypothalamus increases significantly. In this regard, the so-called "Set point"center of heat regulation increases.
The changes described above are the central link in the development mechanism of stage I fever. They trigger peripheral thermoregulation mechanisms.
Heat transfer is reduced as a result of the activation of neurons in the nuclei of the sympathoadrenal system located in the posterior parts of the hypothalamus.
♦ An increase in sympathoadrenal effects leads to a generalized narrowing of the lumen of the arterioles of the skin and subcutaneous tissue, a decrease in their blood supply, which significantly reduces heat transfer.
♦ A decrease in skin temperature causes an increase in impulses from its cold receptors to the neurons of the thermoregulation center, as well as to the reticular formation.
Activation of heat production mechanisms (contractile and non-contractile thermogenesis).
♦ The activation of the structures of the reticular formation stimulates processes of contractile muscle thermogenesisin connection with the excitation of γ- and α-motor neurons of the spinal cord. A thermoregulatory myotonic state develops - tonic tension of skeletal muscles, which is accompanied by an increase in heat production in the muscles.
♦ The increasing efferent impulses of neurons in the posterior hypothalamus and the reticular formation of the brainstem causes synchronization of contractions of individual muscle bundles of skeletal muscles, which manifests itself as muscle tremors.
♦ Non-contractile (metabolic) thermogenesisis another important mechanism of heat production in fever. Its reasons: activation of sympathetic influences on metabolic processes and an increase in the level of thyroid hormones in the blood.
An increase in temperature is due to a simultaneous increase in heat production and a limitation of heat transfer, although the significance of each of these components may be different. At stage I of fever, an increase in basal metabolism increases body temperature by 10-20%, and the rest is the result of a decrease in heat transfer from the skin due to vasoconstriction.
The ambient temperature has a relatively small effect on the development of fever and the dynamics of body temperature. Consequently, with the development of fever, the thermoregulation system is not upset, but is dynamically rebuilt and works at a new functional level. This distinguishes fever from all other hyperthermic conditions.
The stage of standing body temperature at an elevated level
The stage of standing body temperature at an elevated level (stage II, st. fastigii)characterized by a relative balance of heat production and heat transfer at a level significantly exceeding the pre-febrile level.
Heat balanceestablished by the following mechanisms:
♦ increased activity of heat receptors in the preoptic zone of the anterior hypothalamus caused by elevated temperature blood;
♦ temperature activation of peripheral thermosensors of internal organs helps to establish a balance between adrenergic influences and increasing cholinergic influences;
♦ increased heat transfer is achieved due to the expansion of the arterioles of the skin and subcutaneous tissue and increased sweating;
♦ a decrease in heat production occurs due to a decrease in metabolic rate.
The combination of daily and stage dynamics in fever is denoted as temperature curve.There are several typical types of the temperature curve.
♦ Constant.With her, the daily range of fluctuations in body temperature does not exceed 1 ° C. This type of curve is often found in patients with lobar pneumonia or typhoid fever.
♦ Remitting.It is characterized by daily temperature fluctuations of more than 1 ° C, but without returning to the normal range (often observed when viral diseases).
♦ Laxativeor intermittent.Fluctuations in body temperature during the day reach 1-2 ° C, and it can return to normal for several hours, followed by an increase. This type of temperature curve is often recorded with abscesses of the lungs, liver, purulent infection, tuberculosis.
♦ Draining,or hectic.Characterized repeated promotions temperature during the day by more than 2-3 ° C with its rapid subsequent drops. This picture is often observed with sepsis.
Some other types of temperature curves are also distinguished. Considering that the temperature curve in infectious fever depends to a large extent on the characteristics of the microorganism, the determination of its type can be of diagnostic value.
With fever, several degrees of increase in body temperature:
♦ weak, or subfebrile (in the range of 37-38 ° C);
♦ moderate, or febrile (38-39 ° C);
♦ high, or pyretic (39-41 ° C);
♦ excessive, or hyperpyretic (above 41 ° C).
Stage of decrease in body temperature to normal
Stage of decrease in body temperature to values \u200b\u200bof the normal range (stage III fever, st. decrementi)characterized by a gradual decrease in the production of leukokines.
Cause:termination of the action of the primary pyrogen due to the destruction of microorganisms or non-infectious pyrogenic substances.
Effects:the content of leukokines and their effect on the thermoregulatory center are reduced, as a result of which the "set point" is reduced.
Varieties of temperature reductionin stage III fever:
♦ gradual decline, or lytic(more often);
♦ rapid decline, or critical(less often).
EXCHANGE OF SUBSTANCES IN FEVER
The development of fever is accompanied by a number of metabolic changes.
BXat stages I and II, fever increases due to the activation of the sympathoadrenal system, the release of iodine-containing thyroid hormones into the blood, and temperature stimulation of metabolism. This provides energy and metabolic substrates for increased functioning of several organs and contributes to an increase in body temperature. In stage III fever, the basal metabolism decreases.
Carbohydrate metabolismcharacterized by a significant activation of glycogenolysis and glycolysis, but (due to the action of uncouplers) is combined with its low energy efficiency. This greatly stimulates the breakdown of lipids.
Fat metabolismwith fever, it is characterized by the predominance of catabolic processes, especially with prolonged stage II. In fever, lipid oxidation is blocked at the stages of intermediates, mainly CT, which contributes to the development of acidosis. To prevent these disorders in long-term febrile conditions, patients must consume large amounts of carbohydrates.
Protein metabolismin acute moderate fever with a temperature rise of up to 39 ° C, it is not significantly upset. A prolonged course of fever, especially with a significant increase in body temperature, leads to disruption of plastic processes, the development of dystrophies in various organs and aggravation of disorders of the body as a whole.
Water-electrolyte exchangesubject to significant changes.
♦ At stage I, the body's loss of fluid increases due to an increase in the formation of sweat and urine, which is accompanied by the loss of Na +, Ca 2 +, Cl -.
♦ Stage II activates the release of corticosteroids from the adrenal glands (including aldosterone) and ADH in the pituitary gland. These hormones activate the reabsorption of water and salts in the kidney tubules.
♦ At stage III, the content of aldosterone and ADH decreases, and the water-electrolyte balance normalizes.
Signs of renal, hepatic or heart failure, various endocrinopathies, malabsorption syndromes appear with fever with significant damage to the corresponding organs.
FUNCTIONS OF ORGANS AND THEIR SYSTEMS IN FEVER
With fever, the functions of organs and physiological systems change. Causes:
♦ the impact on the body of the primary pyrogenic agent;
♦ fluctuations in body temperature;
♦ the influence of the body's regulatory systems;
♦ involvement of organs in the implementation of various thermoregulatory reactions.
Consequently, this or that deviation of the functions of organs with fever is their integrative response to the above factors.
Manifestations
Nervous system
♦ Nonspecific neuropsychiatric disorders: irritability, poor sleep, drowsiness, headache; confusion, lethargy, sometimes hallucinations.
♦ Hypersensitivity of the skin and mucous membranes.
♦ Violation of reflexes.
♦ Change in pain sensitivity, neuropathy.
Endocrine system
♦ Activation of the hypothalamic-pituitary complex leads to an increase in the synthesis of individual liberins, as well as ADH in the hypothalamus.
♦ Increased production of ACTH and TSH in the adenohypophysis.
♦ Increased blood levels of corticosteroids, catecholamines, T 3 and T 4, and insulin.
♦ Change in the content of tissue (local) BAS - Pg, leukotrienes, kinins and others.
The cardiovascular system
♦ Tachycardia. The rate of increase in heart rate is directly proportional to the increase in body temperature.
♦ Often - arrhythmias, hypertensive reactions, centralization of blood flow.
♦ Usually, with an increase in body temperature, an increase in the volume of ventilation of the lungs occurs. The main stimulants of respiration are an increase in pCO 2 and a decrease in blood pH.
♦ The frequency and depth of breathing change in different ways: unidirectional or multidirectional, i.e. an increase in the depth of breathing can be combined with a decrease in its frequency and vice versa.
Digestion
♦ Decreased appetite.
♦ Decrease in salivation, secretory and motor functions (the result of activation of the sympathoadrenal system, intoxication and increased body temperature).
♦ Suppression of the formation of digestive enzymes by the pancreas and bile by the liver.
Kidneys.Revealing changes reflect only the restructuring of various regulatory mechanisms and functions of other organs and systems in case of fever.
THE SIGNIFICANCE OF FEVER
Fever is an adaptive process, but under certain conditions it can be accompanied by pathogenic effects.
Fever adaptive effects
♦ Direct bacteriostatic and bactericidal effects: coagulation of foreign proteins and reduction of microbial activity.
♦ Indirect effects: potentiation of specific and nonspecific factors of the IBN system, initiation of stress.
Pathogenic Effects of Fever
♦ The direct damaging effect of high temperature is the coagulation of its own proteins, disruption of electrogenesis, and an increase in SPOL.
♦ Indirect damaging effect: functional overload of organs and their systems can lead to the development of pathological reactions.
DIFFERENCES OF FEVER FROM OTHER HYPERTHERMAL CONDITIONS
Hyperthermia is caused by high ambient temperature, impaired heat transfer and heat production, and the cause of fever is pyrogens.
When the body overheats, the mechanisms of thermoregulation are disturbed, with hyperthermic reactions, an inappropriate increase in heat production occurs, and with fever, the thermoregulation system is adaptively rebuilt.
When overheating, the body temperature rises passively, and with fever - actively, with the expenditure of a significant amount of energy.
PRINCIPLES AND METHODS OF TREATMENT OF FEVER
It must be remembered that a moderate increase in body temperature during fever has an adaptive value, which consists in activating a complex of protective, adaptive and compensatory reactions aimed at destroying or weakening pathogenic agents. Antipyretic therapy is advisable only when the damaging effect of hyperthermia on the vital activity of the body is observed or possible:
♦ with an excessive (more than 38.5 ° C) increase in body temperature;
♦ in patients with decompensated diabetes mellitus or circulatory failure;
♦ in newborns, infants and the elderly due to imperfection of the body's thermoregulation system.
Etiotropic treatmentaimed at stopping the action of the pyrogenic agent.
For infectious fever, antimicrobial therapy is performed.
In case of fever of non-infectious origin, measures are taken to stop the ingestion of pyrogenic substances (whole blood or plasma, vaccines, serums, protein-containing substances); removal from the body of a source of pyrogenic agents (for example, necrotic tissue, tumor, abscess contents).
Pathogenetic therapyaims to block the key links of pathogenesis and, as a result, to reduce excessively high body temperature. This is achieved:
Inhibition of production, prevention or reduction of the effects of substances formed in the neurons of the thermoregulatory center under the influence of leukokines: PgE, cAMP. For this, cyclooxygenase inhibitors are used - acetylsalicylic acid and others
Blockade of synthesis and effects of leukocyte pyrogens (IL1, IL6, TNF, γ-IFN).
Reduction of excess heat production by suppressing the intensity of oxidative reactions. The latter can be achieved, for example, through the use of quinine preparations.
Symptomatic treatmentsets the task of eliminating painful and unpleasant sensations and conditions that aggravate the patient's status. When
fever such symptoms include severe headache, nausea and vomiting, joint and muscle pain ("withdrawal"), arrhythmias of the heart.
Pyrotherapy
Artificial hyperthermia (pyrotherapy) has been used in medicine for a long time. Currently, curative pyrotherapy is used in combination with other medicinal and non-medicinal effects. Distinguish between general and local pyrotherapy. General pyrotherapy.General pyrotherapy is carried out by reproducing fever using purified pyrogens (for example, pyrogenal or substances that stimulate the synthesis of endogenous pyrogens). A moderate increase in body temperature stimulates the adaptive processes in the body:
♦ specific and non-specific mechanisms of the IBN system (for some infectious processes - syphilis, gonorrhea, post-infectious arthritis);
♦ plastic and reparative processes in bones, tissues and parenchymal organs (with their destruction, damage, dystrophies, after surgical interventions).
Local hyperthermia.Local hyperthermia per se,as well as in combination with other methods of treatment, reproduce to stimulate regional defense mechanisms (immune and non-immune), repair and blood circulation. Regional hyperthermia is induced in chronic inflammatory processes, erosions and ulcers of the skin, subcutaneous tissue, as well as in certain types of malignant neoplasms.
HYPOTHERMAL STATES
Hypothermic states are characterized by a decrease in body temperature below normal. Their development is based on a disorder of the thermoregulation mechanisms that ensure the optimal thermal regime of the body. Distinguish between cooling the body (actually hypothermia) and controlled (artificial) hypothermia, or medical hibernation.
Hypothermia
Hypothermia- a typical form of heat exchange disorder - occurs as a result of the effect on the body of a low temperature of the external environment and a significant decrease in heat production. Hypothermia is characterized by a violation (disruption) of the mechanisms of heat regulation and is manifested by a decrease in body temperature below normal.
ETIOLOGY
Development reasonscooling the body are manifold.
♦ Low ambient temperature is the most common cause of hypothermia. The development of hypothermia is possible not only at negative (below 0 ° C), but also at positive external temperatures. It has been shown that a decrease in body temperature (in the rectum) to 25 ° C is already life-threatening; up to 17-18 ° C - usually fatal.
♦ Extensive muscle paralysis or a decrease in their mass (for example, with their wasting or dystrophy).
♦ Metabolic disorders and decreased efficiency of exothermic metabolic processes. Such conditions can develop with adrenal insufficiency, leading to a deficiency in the body of catecholamines; with pronounced hypothyroid conditions; with injuries and dystrophic processes in the centers of the sympathetic nervous system.
♦ Extreme depletion of the body.
Risk factorscooling the body.
♦ High air humidity.
♦ High speed of air movement (strong wind).
♦ Excessive moisture in clothes or getting wet.
♦ Contact with cold water. Water is about 4 times more heat-retaining and 25 times more heat-conducting than air. In this regard, freezing in water can occur when relatively high temperature: at a water temperature of +15 ° C, a person remains viable for no more than 6 hours, at +1 ° C - about 0.5 hours.
♦ Prolonged starvation, physical overwork, alcohol intoxication, as well as various diseases, injuries and extreme conditions.
PATHOGENESIS OF HYPOTHERMIA
The development of hypothermia is a staged process. Its formation is based on more or less prolonged overstrain and, in the end, disruption of the body's thermoregulation mechanisms. In this regard, in hypothermia (as in hyperthermia), two stages of its development are distinguished: compensation (adaptation) and decompensation (maladjustment).
Compensation stage
The stage of compensation is characterized by the activation of emergency adaptive reactions aimed at reducing heat transfer and increasing heat production.
♦ Changing the behavior of the individual (directed withdrawal from the cold room, the use of warm clothing, heaters, etc.).
♦ Reduction of heat transfer (achieved by reducing and stopping sweating, narrowing of the arterial vessels of the skin and subcutaneous tissues).
♦ Activation of heat production (by increasing blood flow in internal organs and increasing muscle contractile thermogenesis).
♦ Activation of stress response (agitated state of the victim, increased electrical activity of thermoregulation centers, increased secretion of liberins in neurons of the hypothalamus, in pituitary adenocytes - ACTH and TSH, in the adrenal medulla - catecholamines, and in their cortex - corticosteroids, in the thyroid gland - ).
Thanks to the complex of these changes, the body temperature, although it decreases, still does not go beyond the lower limit of the norm. If the causative factor continues to act, then compensatory responses may become insufficient. At the same time, the temperature of not only the integumentary tissues, but also the internal organs, including the brain, decreases. The latter leads to disorders of the central mechanisms of thermoregulation, discoordination and inefficiency of heat production processes - their decompensation develops.
Decompensation stage
The stage of decompensation (maladjustment) is the result of disruption of the central mechanisms of thermoregulation. At the stage of decompensation, the body temperature drops below the normal level (in the rectum it drops to 35 ° C and below). Temperature homeostasis of the body is disturbed: the body becomes poikilothermic. Vicious circles are often formed that potentiate the development of hypothermia and disorders of the body's vital functions.
The metabolic vicious circle.A decrease in tissue temperature in combination with hypoxia inhibits metabolic reactions. The suppression of the metabolic rate is accompanied by a decrease in the release of free energy in the form of heat. As a result, the body temperature decreases even more, which further suppresses the metabolic rate, etc.
Vascular vicious circle.The increasing decrease in body temperature during cooling is accompanied by the expansion of arterial vessels (by the neuromyoparalytic mechanism) of the skin, mucous membranes, and subcutaneous tissue. The expansion of the vessels of the skin and the flow of warm blood to them from organs and tissues accelerates the process of loss of heat by the body. As a result, the body temperature decreases even more, the vessels dilate even more, etc.
The neuromuscular vicious circle.Progressive hypothermia causes a decrease in the excitability of nerve centers, including those that control muscle tone and contraction. As a result, such a powerful mechanism of heat production as muscle contractile thermogenesis is turned off. As a result, the body temperature decreases rapidly, which further suppresses neuromuscular excitability, etc.
The deepening of hypothermia causes inhibition of the functions of the cortical, and subsequently the subcortical nerve centers. Physical inactivity, apathy and drowsiness develop, which can result in a coma. In this regard, the stage of hypothermic "sleep" or coma is often distinguished.
With an increase in the effect of the cooling factor, freezing and death of the organism occurs.
PRINCIPLES OF HYPOTHERMIA TREATMENT
Treatment for hypothermia depends on the degree of decrease in body temperature and the severity of disorders of the body's vital functions. Compensation stage.At the stage of compensation, the victims mainly need to stop external cooling and warm the body (in a warm bath, heating pads, dry warm clothes, warm drink).
Decompensation stage
At the stage of decompensation of hypothermia, it is necessary to carry out intensive comprehensive medical care. It is based on three principles: etiotropic, pathogenetic and symptomatic.
Etiotropic treatmentincludes the following activities.
♦ Measures to stop the effect of the cooling factor and rewarming the body. Active body warming is stopped at a temperature in the rectum of 33-34 ° C in order to avoid the development of a hyperthermic state. The latter is quite possible, since the victim has not yet restored the adequate function of the body's heat regulation system.
♦ Warming of internal organs and tissues (through the rectum, stomach, lungs) has a greater effect.
Pathogenetic treatment.
♦ Restoration of effective blood circulation and respiration. If breathing is impaired, release airways (from mucus, sunken tongue) and conduct mechanical ventilation with air or gas mixtures with an increased oxygen content. If the activity of the heart is disrupted, then it is performed indirect massage, and if necessary, defibrillation.
♦ Correction of acid balance, balance of ions and liquid. For this purpose, balanced salt and buffer solutions (for example, sodium bicarbonate), colloidal dextran solutions are used.
♦ Elimination of glucose deficiency in the body is achieved by introducing its solutions of various concentrations in combination with insulin and vitamins.
♦ In case of blood loss, blood, plasma and plasma substitutes are transfused. Symptomatic treatmentaims to address changes
in the body, aggravating the condition of the victim.
♦ Use drugs that prevent swelling of the brain, lungs and other organs.
♦ Eliminate arterial hypotension.
♦ Normalize urine output.
♦ Eliminate strong headache.
♦ In the presence of frostbites, complications and concomitant diseases, they are treated.
PRINCIPLES FOR PREVENTING HYPOTHERMIA
The prevention of body cooling includes a set of measures.
♦ Use of dry warm clothes and shoes.
♦ Correct organization of work and rest during the cold season.
♦ Organization of heating points, provision of hot meals.
♦ Medical supervision of participants in winter hostilities, exercises, sports competitions.
♦ Prohibition of alcohol intake before prolonged exposure to cold.
♦ Hardening of the body and human acclimatization to environmental conditions.
Medical hibernation
Guided hypothermia(medical hibernation) - a method of controlled decrease in the temperature of the body or part of it in order to reduce the metabolic rate and functional activity of tissues, organs and their systems, as well as to increase their resistance to hypoxia.
Controlled (artificial) hypothermia is used in medicine in two varieties: general and local.
GENERAL CONTROLLED HYPOTHERMIA
Application area.Performing surgery under conditions of significant decline or even temporary discontinuation
regional circulation. This is called operations on "dry" organs: heart, brain and some others. Benefits.A significant increase in the resistance and survival of cells and tissues under conditions of hypoxia at a reduced temperature. This makes it possible to disconnect the organ from the blood supply for a few minutes, followed by the restoration of its vital activity and adequate functioning.
Temperature range.Hypothermia with a decrease in rectal temperature up to 30-28 ° C. If necessary, long-term manipulations create deeper hypothermia using a heart-lung machine, muscle relaxants, metabolism inhibitors and other influences.
LOCAL CONTROLLED HYPOTHERMIA
Local controlled hypothermia of individual organs or tissues (brain, kidneys, stomach, liver, prostate, etc.) is used when it is necessary to perform surgical interventions or other therapeutic manipulations on them: correction of blood flow, plastic processes, metabolism, drug effectiveness.
Violations and their causes alphabetically:
violation of the body's thermoregulation -
Thermoregulation disorders are violations of the constancy of body temperature caused by dysfunction of the central nervous system. Thermal homeostasis is one of the main functions of the hypothalamus, which contains specialized thermosensitive neurons.
The vegetative pathways begin from the hypothalamus, which, if necessary, can provide an increase in heat production, causing muscle tremors or dissipation of excess heat.
Which diseases there is a violation of the body's thermoregulation:
With the defeat of the hypothalamus, as well as the pathways following from it to the brain stem or spinal cord, thermoregulation disorders occur in the form of hyperthermia or hypothermia.
Heat transfer by the body to the external environment depends on the ambient temperature, on the amount of moisture (sweat) emitted by the body due to heat consumption for evaporation, on the severity of the work performed and the physical condition of a person.
At high air temperatures and irradiation, the blood vessels of the body surface expand, and blood, the main heat accumulator in the body, moves to the periphery (body surface).
As a result of this redistribution of blood, heat transfer from the body surface increases significantly.
Violations of the body's thermoregulation can occur when the central or peripheral link of the thermoregulation system is damaged - hemorrhages or tumors in the hypothalamus, with injuries accompanied by damage to the corresponding pathways, etc.
Thermoregulatory disorders are associated with many systemic diseases, usually manifested by fever or fever.
An increase in body temperature is such a reliable indicator of illness that thermometry has become the most commonly used procedure in the clinic.
Temperature changes can be detected even in the absence of an obvious febrile condition. They manifest as redness, blanching, sweating, trembling, abnormal sensations of warmth or cold, and may also consist of unstable fluctuations in body temperature within normal limits in patients with bed rest.
During physical work, the balance between heat production and heat transfer is temporarily disturbed, followed by a rapid restoration of normal temperature at rest due to long-term activation of heat transfer mechanisms.
In fact, with prolonged physical exertion, the vasodilation of the skin in response to an increase in the temperature of the core of the body stops in order to maintain this temperature.
With fever, the adaptive capacity decreases, since upon reaching a stable body temperature, heat production becomes equal to heat transfer, however, both are at a level higher than the initial one. Blood flow in the peripheral vessels of the skin plays a more important role in the regulation of heat production and heat transfer than sweating.
In fever, the body temperature, determined by thermoreceptors, is low, so the body reacts to it as if it were cooling.
Trembling leads to an increase in heat production, and narrowing of the skin vessels - to a decrease in heat transfer. These processes explain the sensations of coldness or chills that occur at the onset of the fever. Conversely, when the cause of the fever is removed, the temperature drops to normal, and the patient feels fever. Compensatory reactions in this case are vasodilation of the skin, sweating and suppression of tremors.
At high ambient temperatures, four clinical syndromes develop: heat cramps, heat exhaustion, heat stress injury, and heat stroke. Each of these states can be differentiated based on different clinical manifestations, however, they have much in common and these conditions can be considered as varieties of syndromes of the same origin.
The symptom complex of thermal injury develops at high temperatures (over 32 ° C) and at high relative humidity (over 60%). The most vulnerable are the elderly, people suffering from mental illness, alcoholism, taking antipsychotic, diuretic, anticholinergic drugs, as well as people in rooms with poor ventilation. Especially many heat syndromes develop in the first days of the heat, before acclimatization begins.
Which doctor should I contact if there is a violation of the body's thermoregulation:
Have you noticed a violation of the body's thermoregulation? Do you want to know more detailed information or do you need an inspection? You can make an appointment with the doctor - clinic Eurolab always at your service! The best doctors will examine you, study the external signs and help identify the disease by symptoms, advise you and provide the necessary assistance. you also can call a doctor at home... Clinic Eurolab open for you around the clock.
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Fever is a protective and adaptive reaction developed in the process of evolution, which develops as a result of exposure to the body of pyrogenic agents and consists in establishing its heat balance at a new, higher level.
The term febris (fever, fever) has been known in medicine since ancient times. Since the overwhelming majority of infectious diseases (in the ancient period and in the Middle Ages it was the leading pathology of mankind) was accompanied by a vivid picture of a feverish state (chills, fever, confusion of consciousness), fever has long been considered as a kind of typical reaction, but for a long time it was rather a nosological concept. , that is, it had the "status" of an independent disease ("febrile illness", "swamp fever", "forest fever", etc.). Traditionally, this trend has continued to this day: as independent nosological forms, they have been identified, for example. "Yellow fever", "Q fever", "rocky mountain fever", etc.
However, gradually in the medical world, the concept of fever as a symptom complex typical for many diseases of various etiologies (both infectious and non-infectious) began to be established. In this case, the main, leading symptom of fever was and remains overheating of the patient's body, the accumulation of heat in it. With the development of ideas about the physiological mechanisms of thermoregulation in homeothermic organisms, the first theories of the pathogenesis of febrile states appeared. So, back in the sixties of the XIX century, the idea arose that fever is the result of a significant increase in heat production in the human body in the absence of a level of heat transfer balanced with this process. At the same time, it was revealed that an increase in the body temperature of a febrile patient does not have a significant dependence on the ambient temperature. So it was established a radical difference between fever and hyperthermia. At the same time, it was suggested that "fever" (pyrogenic) substances cause fever due to their effect on the thermoregulatory centers located in the brain. Numerous studies of this common and characteristic symptom for a wide variety of diseases have made it possible at the present time to create a fairly clear theory of the onset and development of fever.
An increase in body temperature and the transition of the thermoregulation system to a new, higher level of functioning occurs as a result of exposure to the body of biologically active substances - pyrogens.
Pyrogens are classified into exo- and endogenous.
Exogenous pyrogens enter the body from the outside, while endogenous ones are formed in the body itself either during the decay of dying tissues, or are the result of the interaction of exogenous factors with certain cells of the body.
Microbiological and biochemical studies have made it possible to identify a number of both exo- and endogenous pyrogens. Thus, pyrogens were isolated from the cell membranes of some microbes by high purification, which in their own way chemical composition turned out to be polysaccharides or lipopolysaccharides (pyrogenal, pyromene, pyrexal, etc.). It was also found that some protein substances in the microbial cell also have a pyrogenic effect. Purified exogenous (microbial) pyrogens (poly- and lipopolysaccharides) are thermostable, non-toxic, have no antigenic properties.
Endogenous pyrogens are formed in the body in the process of phagocytosis of microbial cells, as well as tissues damaged by neutrophilic leukocytes and other phagocytic cells. Endogenous pyrogens, of which the best known is leukocyte pyrogen, are thermolabile.
The general scheme of the effect of pyrogenic substances on the body is as follows. When exogenous pyrogens enter the internal environment of the body, as a result of their phagocytosis, endogenous pyrogens are formed, most of which are of a protein nature. Endogenous pyrogens can persist for a long time in the internal environment of the body. It is their effect on the centers of thermoregulation that ensures the development of febrile conditions. In aseptic inflammation, fever is the product of exposure to the body only of endogenous pyrogens.
However, it should be borne in mind that fever can be caused by the introduction of simpler organic and inorganic compounds into the body. For example, β-tetrahydronaphthylamine, lysergic acid diethylamide (LSD-25), 2,4-α-dinitrophenol, as well as neurotropic drugs such as phenamine, caffeine, cocaine, etc., have these properties. Finally, fever can also be caused by large the amount of NaCl ("salt fever"). Of course, the mechanism of action of these substances on the body is different: this is a direct effect on the centers of thermoregulation, and the effect on metabolic processes. So, for example, 2,4-α-dinitrophenol not only sharply increases oxidative processes, but also contributes to the separation of respiration and phosphorylation processes.
According to modern concepts, the mechanism of action of pyrogenic substances includes humoral and reflex Components.
Humoral the component lies in the fact that pyrogenic substances, reaching the preoptic region of the anterior hypothalamus with the blood, significantly increase the excitability of cold heat-sensitive neurons and reduce the excitability of thermal ones, as a result of which heat production increases and heat transfer decreases. The body is accumulating heat, which is facilitated by a kind of "misinformation" of the thermoregulation system. The increased sensitivity of cold thermoneurons causes the body to perceive normal ambient temperature as an effect of cooling. As a result, the skin blood vessels spasm, sweating stops, an arbitrary contraction of individual groups of skeletal muscle fibers and skin muscle fibers going to the hair follicles begins, that is, muscle tremors develop - the most effective way of urgent heat production. The patient, even in a warm room, freezes, he has chills. This is how the first stage of a febrile reaction develops - stage of rise in body temperature (stadium incrementi). Subsequently, against the background of an increase in temperature, the heat transfer mechanisms begin to intensify. After a while, the levels of heat production and heat transfer are compared, their balance is established at a new, higher level. This is how it develops second stage of fever - stage of plateau (stadium fastigii). The chill stops, the opened cutaneous blood vessels cause the development of arterial hyperemia, and due to the increased flow of warm blood from the deep regions of the body, heat is "dumped" into the external environment.
The duration of the second stage of fever depends on the nature of the pathological process. After a certain period of time, it ends and changes the third stage - the stage of temperature decrease (stadium decrementi), during which the temperature drops to its initial value (or even to lower values \u200b\u200bdue to a certain inertness of thermoregulatory systems). The drop in temperature basically contains a significant predominance of heat transfer processes over heat production processes. The main mechanisms that ensure a drop in body temperature are the expansion of skin vessels and profuse sweating. By the end of this stage, heat production also begins to decrease, since dying microorganisms (in the case of the most common infectious fever) cannot supply new doses of exogenous pyrogens, and endogenous pyrogens are destroyed by actively acting enzyme systems. The drop in temperature can be gradual (lysis) and fast (a crisis). A critical drop in temperature, associated primarily with a sharp expansion of skin vessels, is often accompanied by collapse, that is, a state of vascular insufficiency with a rapid and significant drop in blood pressure, which can even lead to death.
In the development of a febrile reaction, a certain role is played by reflex component. In an experiment on animals, it was possible to induce the development of fever in response to presentation of a conditioned stimulus, if it was repeatedly combined with the introduction of a dose of pyrogen. A sharp slowdown in the febrile reaction was observed in the case when the pyrogen was injected subcutaneously into the previously novocainized area. These facts indicate that the role of the central nervous system and, in particular, the cerebral cortex in the development of a febrile reaction is quite large. Experiments with the introduction of neurotropic agents to experimental animals serve as additional confirmation of this. So, psychostimulants (caffeine, phenamine) intensify the febrile reaction, and deep anesthesia inhibits its development.
The vast experience accumulated by many generations of doctors who have observed and studied febrile states has made it possible to distinguish several types of temperature curves that characterize the development of fever.
First of all, the classification of febrile conditions is carried out according to the magnitude of the rise in temperature. From this point of view, the following types of fevers are distinguished:
1. Subfebrile fever at which the temperature ranges from 37.1 to 38.0 ° С.
2. Febrile fever with a rise in temperature from 38.1 to 39.5 ° С.
3. Pyretic fever characterized by temperature fluctuations in the range of 39.6 - 41.0 ° С.
4. Hyperpyretic fever - over 41.0 ° С.
Secondly, the classification of the types of temperature curves is carried out depending on their dynamics. ***** 29
1. Febris continua (permanent) - the temperature remains at the same level for a long time, and the difference between morning and evening temperatures does not exceed 1 ° С. This type of febrile curve is observed with croupous pneumonia, influenza.
2. Febris remittens (laxative) - fluctuations between morning and evening temperatures reach 1 - 3 ° C. This type of curve can be, for example, with severe angina.
3. Febris hectica (hectic, depleting) - fluctuations in the levels of morning and evening temperatures reach 3 - 5 ° C. Such a fever is observed, for example, with sepsis.
4. Febris intermittens (intermittent) - periodic, relatively short-term, but very high temperature rises are observed, which alternate with longer periods of their normalization, as, for example, in malaria.
5. Febris undulans (undulating) - characterized by a wave-like dynamics of the temperature curve over several days (as a rule, of a continuous type). This kind of curve is observed, for example, with relapsing fever.
With fever, significant violation of the functions of the body and the activity of its organs and systems.
The cardiovascular system. Tachycardia is observed: an increase in heart rate by about 10 beats per minute with an increase in temperature by 1 ° C. This phenomenon is due to the fact that pyrogens irritate the sinoauricular node. Tachycardia and the increase in cardiac output caused by it contributes to the intensification of the heat transfer process.
Respiratory system. In the second and third stages of the febrile process, deep and frequent breathing occurs, which enhances heat transfer.
Excretory system. At the very beginning of the first stage of fever, due to general vascular spasm, a weakening of urine formation occurs, followed by an increase in urine output due to the onset of vasodilation and increased renal blood flow. In the second stage of the febrile reaction, despite the expansion of the peripheral vessels, due to the increased secretion of aldosterone by the adrenal glands, sodium is retained, and therefore water in the tissues. Urine flow is reduced. In the third stage of fever, due to a sharp expansion of peripheral vessels and normalization of aldosterone production, urine output increases sharply.
Endocrine system. The activity of the endocrine glands changes with fever to varying degrees, without playing a leading role in its development. The state of the endocrine system largely determines the overall resistance of the body before the onset of the pathological process, thereby indirectly influencing the severity of the febrile reaction. The pathology of individual endocrine glands can increase or inhibit fever. So, for example, in patients with thyrotoxicosis, fever develops more acutely and in a shorter time than in people who do not suffer from this pathology. With hypothyroidism (myxedema), the intensity of fever, on the contrary, is significantly reduced.
For digestive system characterized by a pronounced suppression of the activity of the digestive glands, which leads to a decrease in appetite.
Intensification of metabolic processes in the liver increases with the development of fever and decreases by the end of the third stage.
Functional state nervous system differs at the beginning of a febrile reaction in excitement, which, with a significant increase in temperature, is replaced by inhibition and oppression.
From the side metabolism in general, the predominance of catabolic processes over anabolic processes is noted. This is especially true of protein metabolism, and that is why most feverish conditions are accompanied by a negative nitrogen balance.
As is clear from the definition given at the beginning of this section, fever is a protective-adaptive reaction of the organism, developed in the process of evolution. An increase in body temperature with fever has a beneficial effect on the synthesis of antibodies, phagocytosis, and can also lead to the death of the infection, since microorganisms can develop normally only in rather rigid temperature limits. It is on this feature of fever that pyrotherapy method some infectious diseases, in particular, the last stages of syphilis (progressive paralysis, tabes dorsalis). This method was first successfully applied by the Austrian psychiatrist Julius Wagner-Jaureg, who in 1916 cured patients from progressive paralysis by inoculating them with malaria and causing them a strong febrile reaction.
At present, progressive paralysis of malaria, of course, is not treated using pyrogenic substances for this purpose.
At the same time, fever can also have a negative meaning for the body due to metabolic disorders it causes, primarily as a result of increased protein breakdown. At hyperpyretic temperatures, immunity is suppressed, there is a deep inhibition of the activity of the central nervous system. Ultra-high fever can lead to the death of the body.
Each of us knows about the existence of such a thing as body temperature. In a healthy adult, its values \u200b\u200bshould be in the range of 36-37 ° C. Deviations in one direction or another indicate the occurrence of a disease of any etiology or a violation of the body's thermoregulation. This condition is not a disease as such, however, it can cause destabilization of the work of organs and systems, even lead to death. All warm-blooded mammals, including humans, have the ability to thermoregulate. This function was developed and consolidated in the course of evolution. It coordinates metabolic processes, makes it possible to adapt to the conditions of the external world, thereby helping living organisms fight for their existence. Each individual, regardless of type, status or age, is exposed to the environment every second, and dozens of different reactions continuously occur in his body. All these processes provoke fluctuations in body temperature, which, if it were not for thermoregulation, controlling them, would lead to the destruction of individual organs and the whole organism as a whole. In principle, this is what happens when there is a violation of thermoregulation. The causes of this pathology can be quite varied, from trivial hypothermia to serious diseases of the central nervous system, thyroid or hypothalamus. If the thermoregulation system of a person suffering from such ailments does not cope well with its functions, in order to correct the situation, the underlying disease must be treated. If thermoregulation is impaired in a healthy person, and the reason for this was external conditions, for example the weather, you need to be able to provide first aid to such a victim. Often his further health and life depend on this. This article offers information on how body temperature is regulated, what symptoms indicate malfunctioning thermoregulation, and what actions should be taken in this case.
Features of body temperature
Violation of thermoregulation is inextricably linked with body temperature. Most often it is measured in armpit, where it is normally assumed to be 36.6 ° C. This value is an indicator of heat exchange in the body and should be a biological constant. However, body temperature in small ranges can change, for example, depending on the time of day, which is also the norm. Its lowest values \u200b\u200bwere recorded between 2 and 4 am, and the highest between 4 and 7 pm. Temperature readings also change in different parts of the body, and this does not depend on the time of day. So, in the rectum, values \u200b\u200bfrom 37.2 ° C to 37.5 ° C are considered normal, and in the mouth from 36.5 ° C to 37.5 ° C. In addition, each organ has its own temperature norm. It is highest in the liver, where it reaches 38 ° C to 40 ° C. But the body temperature of warm-blooded animals should not change from climatic conditions. The role of thermoregulation is precisely to maintain it constant under any environmental conditions. In medicine, this phenomenon is called homeothermy, and constant temperature is called isothermy.
Impaired thermoregulation of the body is characterized by an increase or decrease in body temperature values. There is a clear range of its upper and lower values, beyond which it is impossible to go beyond, because this is fatal. With certain resuscitation measures, a person can survive if his body temperature drops to 25 ° C or rises to 42 ° C, although there are cases of survival at more extreme values.
Thermoregulation concept
Conventionally, the human body can be represented as a certain core with a constant temperature, and a shell where it changes. In the core, processes take place, as a result of which heat is released. Heat exchange occurs through the shell between the external environment and the core. The source of heat is the food we consume daily. When food is processed, fats, proteins, carbons are oxidized, that is, metabolic reactions. During their course, heat production is formed. The essence of thermoregulation is to maintain a balance between heat exchange and the formation of heat products. In other words, in order for the body temperature to stay within the normal range, the shell must give off heat to the environment as much as it is formed in the core. Violation of thermoregulation of the body is observed when there is an overexpenditure of heat production, or, conversely, it is formed much more than the shell is able to remove into the environment.
This can happen due to:
Environmental conditions (too hot or too cold);
Increased physical activity;
Clothing not suitable for the weather;
Taking certain medications;
Drinking alcohol;
The presence of diseases (vegetative-vascular dystonia, brain tumor, diabetes insipidus, various syndromes of hypothalamic malfunction, thyrotoxic crisis and others).
Thermoregulation is carried out in two ways:
1. Chemical.
2. Physical.
Let's consider them in more detail. 
Chemical method
It is based on the relationship between the amount of heat generated in the body and the rate of exothermic reactions. The chemical type includes two ways to maintain the desired temperature - contractile and non-contractile thermogenesis.
The contractile begins to act when you need to increase the body temperature, for example, when staying in the cold. We notice this by raising hairs on the body or by running "creeps", which are microvibrations. They allow increasing heat production by up to 40%. With more severe freezing, we begin to tremble. It is also nothing more than a thermoregulation method, in which the production of heat production increases by about 2.5 times. In addition to involuntary reflex reactions to cold, a person, while moving, can raise the temperature in his body himself. A violation of thermoregulation in this case occurs when the exposure to cold is too long, or the temperature of the environment is too low, as a result of which the activation of metabolic reactions does not help to generate the required amount of heat. In medicine, this condition is called hypothermia.
Thermogenesis can be non-contractile, that is, it can take place without the participation of muscles. Metabolism slows down or accelerates under the influence of certain medications, with increased production of hormones in the thyroid gland and in the adrenal medulla, with more active activity of the sympathetic nervous system. The reasons for the violation of human thermoregulation in this case lie in the diseases of the above organs of the thyroid gland, central nervous system, dysfunction of the adrenal glands. Information about temperature changes always comes to the central nervous system. The heat center is located in a tiny section of the diencephalon, the hypothalamus. In it, a front region is distinguished, which is responsible for heat transfer, and a back region, which is responsible for the production of heat products. Pathologies of the central nervous system or dysfunction of the hypothalamus disrupt the coordinated work of these parts, which negatively affects thermoregulation.
Thyroid hormones T3 and T4 also affect the intensity of heat exchange, and in addition, some functions of the vessels. In a normal state, in order to preserve heat, blood vessels constrict, and to reduce it, they expand. Californian scientists have proved that hormones can "interfere" with blood vessels, as a result of which they stop responding to the amount of heat generated and the body's need for it. In medical practice, there is often a violation of thermoregulation in patients with a diagnosis of a brain tumor or
Physical way
It does the job of releasing heat into the environment, which is done in several ways:
1. Radiation. It is characteristic of all bodies and objects, the temperature of which is greater than zero. Radiation occurs by electromagnetic waves in the infrared range. At an ambient temperature of 20 ° C and a humidity of about 60%, an adult loses up to 50% of his heat.
2. Conduction, which means heat loss when touching colder objects. It depends on the area of \u200b\u200bthe contacting surfaces and the duration of the contact.
3. Convection, which means cooling of the body by particles of the medium (air, water). Such particles touch the body, take heat, heat up and rise up, giving way to new colder particles. 
4. Evaporation. This is the familiar sweating, as well as evaporation of moisture from the mucous membranes during breathing.
In conditions of impossibility to use these methods, a violation of the body's thermoregulation is observed. There may be various reasons for this. So, convection and conduction are hampered or reduced to zero if a person is wrapped in clothing that excludes contact with air or any objects, and evaporation is impossible at 100% humidity. On the other hand, a significant activation of heat transfer also leads to a violation of thermoregulation. For example, convection intensifies in the wind and increases many times in cold water... This is one of the reasons why people, even those who know how to swim well, die in shipwrecks.
Thermoregulation in the elderly
Above, we examined what the thermoregulation of the human body is and the reasons for its violation, but without taking into account age characteristics. However, in humans, the ability to control body temperature changes throughout life.
In old people, the mechanisms of the hypothalamus are disrupted, which assess the temperature of the external environment. They do not immediately feel the cold, standing on the icy floor, and they also do not immediately react to hot water, for example, in the shower. Therefore, they can easily harm themselves (overcooled, burn themselves). It has been noticed that older people, who do not even complain about the cold, spoil their mood, appear unreasonable discontent, and when creating a comfortable climate for them, all these harmful "symptoms" of a senile nature diminish or disappear.
At the same time, many old people are freezing even at fairly comfortable temperatures. They can often be seen dressed like winter on a warm summer day. Such changes in thermoregulation occur due to circulatory disorders and a decrease in hemoglobin levels.
Old people not only react to cold, but also to heat in a slightly different way. At high ambient temperatures, they begin to sweat later, and the restoration of normal body temperature indicators is slower. In other words, symptoms of hypothermia or overheating begin to appear later in them than in young people, and the body's recovery is more difficult. 
Violation of thermoregulation in a child
The child's body is characterized by other features of the thermoregulation system. In newborns, it is very imperfect. Babies are born with a body temperature between 37.7 ° C and 38.2 ° C. After a few hours, it drops by about 2 ° C, and then again reaches 37 ° C, which should not be a cause for concern. Higher rates can be a signal of the onset of a disease. The imperfection of the thermoregulation system in infants must be compensated for by the creation of appropriate climatic conditions. So, up to 1 month in a nursery, the air temperature should be maintained at 32 ° C - 35 ° C if the baby is undressed, and 23 ° C - 26 ° C if he is swaddled. To stimulate thermoregulation, you need to start with the simplest thing - do not put a cap on the head. For babies older than 1 month, these temperature norms decrease by about 2 ° C.
Children born prematurely have more serious problems with thermoregulation, therefore, in the first days, and sometimes weeks, they are kept in special cuvettes. All manipulations with them, including processing the umbilical cord, washing and feeding, are also carried out in cuvettes.
The body's control over temperature is stabilized only by the age of 8.
Violation of thermoregulation in an infant can occur for the following reasons:
Oppressive effects on the hypothalamus (fetal hypoxia, birth hypoxia, intracranial trauma during obstetrics);
Congenital pathologies of the central nervous system;
Hypothermia;
Overheating (excessive wrapping);
Medicines (beta blockers)
Change in climatic conditions (happens when parents travel together with babies).
In infants, the temperature measured in the armpit is considered normal in the range of 36.4 ° C to 37.5 ° C. Lower values \u200b\u200bmay indicate dystrophy, vascular insufficiency. Higher values \u200b\u200bindicate inflammatory processes in the body. 
Symptoms of impaired thermoregulation in hypothermia
Depending on the cause of the failure in the control of body temperature, there are different signs indicating a violation of the body's thermoregulation. Symptoms of hypothermia or hypothermia begin to appear when the body temperature drops below 35 ° C. This condition can occur with prolonged exposure to frost or in water. For the average person, a water temperature in the range of 26-28 ° C is considered acceptable, that is, you can stay in it for a long time. With a decrease in these indicators, the time that can be in the aquatic environment without harming health sharply decreases. For example, at t \u003d 18 ° C, it does not exceed 30 minutes.
Hypothermia, depending on the complexity of the course, includes three stages:
Light (body temperature 35 ° C to 34 ° C);
Medium (t \u003d 34 ° C to 30 ° C);
Heavy (t \u003d 30 ° C to 25 ° C).
Symptoms for mild:
Goose pimples;
Body trembling;
Rapid breathing;
An increase in blood pressure values \u200b\u200bis sometimes observed.
In the future, the violation of thermoregulation processes progresses.
The victim develops the following symptoms:
Low blood pressure;
Bradycardia;
Rapid breathing;
Constriction of the pupils;
Stop trembling in the body;
Disappearance of pain sensitivity;
Suppression of reflexes;
Loss of consciousness;
Coma. 
Treatment for hypothermia
If, due to hypothermia, a violation of the body's thermoregulation has occurred, treatment should be aimed at increasing body temperature. In a mild form of hypothermia, it is enough to perform the following actions:
Enter a warm room;
Drink hot tea;
Rub your feet and put on warm socks;
Take a hot bath.
If there is no way to quickly get into the heat, you need to start active movements - jumping, rubbing your hands (not with snow), claps, any physical exercises.
First aid in case of violation of thermoregulation of the second, and especially the third degree should be provided by the nearest people, since the victim himself can no longer take care of himself. Algorithm of actions:
Transfer a person to warmth;
Quickly take off his clothes;
Rub the body with light movements;
Wrap up in a blanket, or better in a fabric that does not allow air to pass through;
If the swallowing reflex is not disturbed, give it a warm liquid (tea, broth, water, but not alcohol!).
If possible, you need to call an ambulance and take the patient to the hospital, where treatment will be carried out using antispasmodics, analgesics, antihistamines and anti-inflammatory drugs, vitamins. In some cases, it is sometimes necessary to amputate the frostbitten limbs.
In children, hypothermia is especially common. In case of hypothermia, they need to be warmed by wrapping, give breast or warm milk. An excellent means of stimulating thermoregulation is hardening, which parents should carry out to a baby from the first months of life. In the initial stages, it consists of air baths and walks in the fresh air. In the future, wiping the legs with a wet cloth, washing with cool water, bathing with a gradual decrease in water temperature, walking barefoot are added.
Hyperthermia
A rise in body temperature or hyperthermia almost always causes a violation of the body's thermoregulation. The reasons may be as follows:
Many diseases (trauma, infection, inflammation, vascular dystonia);
Prolonged exposure to the sun;
Antiperspirant clothing;
Increased physical activity;
Binge eating.
If the patient has signs of any disease (cough, gastrointestinal upset, complaints of pain in organs, and others), he should perform a series of diagnostic studies to identify the cause of the fever:
Blood test;
Analysis of urine;
X-ray;
Having made a diagnosis, they carry out therapy for the identified ailment, which in parallel restores the body temperature to normal values.
If, due to overheating, a violation of thermoregulation occurs, the treatment consists in creating conditions for the victim to restore the functioning of the body systems. With sunstroke, the following symptoms are observed:
General malaise;
Headache;
Nausea;
Temperature rise;
Increased sweating;
Sometimes there are seizures, loss of consciousness and nosebleeds.
The victim should be placed in a cool place (it is advisable to lay down and raise his legs) and:
If possible, undress;
Wipe the body with a damp cloth;
Put a cold compress on your forehead;
Drink with cool salted water.
Heatstroke comes in three types of intensity:
Light (body temperature is slightly increased);
Medium (t \u003d 39 ° C to 40 ° C);
Heavy (t \u003d 41 ° C to 42 ° C).
The mild form is manifested by headache, weakness, fatigue, rapid breathing, tachycardia. As a treatment, you can take a cool shower, drink mineral water. 
Violation of thermoregulation of the human body in an average form is manifested by the following symptoms:
Adinamia;
Nausea before vomiting;
Headache;
Tachycardia;
Sometimes loss of consciousness.
Severe symptoms:
Seizures;
The pulse is frequent, threadlike;
Respiration is frequent, shallow;
Deaf heart tone;
Hot and dry skin;
Delirium and hallucinations;
Change in blood composition (decrease in chlorides, increase in urea and residual nitrogen).
In moderate and severe forms, intensive therapy is carried out, including injections of "Diprazine" or "Diazepam", according to indications, the administration of analgesics, neuroleptics, cardiac glycosides. Before the arrival of an ambulance, the victim must be undressed, wiped off cold water, put ice in the groin, armpits, forehead and back of the head.
Thermoregulation disorder syndrome
This pathology is observed with dysfunction of the hypothalamus and can manifest itself as hypo- and hyperthermia.
Congenital pathologies;
Tumor;
Intracranial infection;
Exposure to radiation;
Bulimia;
Anorexia;
Malnutrition;
Excess iron.
Symptoms:
Patients are equally bad at withstanding cold and heat;
Constantly cold extremities;
During the day, the temperature remains unchanged;
Subfebrile temperatures do not respond to antibiotics, glucocorticoids;
Lowering the temperature to normal values \u200b\u200bafter sleep, after taking sedatives;
Connection of temperature fluctuations with psycho-emotional stress;
Other signs of hypothalamic dysfunction.
Treatment is carried out depending on the causes of problems with the hypothalamus. In some cases, it is enough to prescribe the correct diet to the patient, in others, hormone therapy is required, and in still others, surgery.
Chill syndrome also indicates a violation of thermoregulation. Those with this syndrome are constantly freezing, even in summer. At the same time, the temperature is often normal or slightly elevated, the subfebrile condition lasts a long time and monotonously. Such people may experience sudden surges in pressure, an increase in heart rate, breathing disorders and increased sweating, impaired drives and motivation. Research shows that chills are caused by disorders in the autonomic nervous system.
A person is a warm-blooded organism, which means that he can maintain a stable body temperature regardless of external factors. At the same time, each of us is faced with a situation when the temperature rises or, conversely, decreases. MedAboutMe will tell you what these changes can be a symptom of and when you should really see a doctor.
What is thermoregulation
For maintaining thermal homeostasis, constant temperature the human body is primarily responsible for the autonomic nervous system and the hypothalamus. Body temperature depends on the intensity of bioenergetic processes. Therefore, for example, in children, it may normally be higher than in old people, since metabolism slows down with age.
The thermoregulation process is provided in two phases:
- Chemical - due to various metabolic processes in the body, the temperature rises.
- Physical - due to the mechanisms of heat transfer, the temperature decreases. Heat dissipation is carried out with respiration, sweating (evaporation of water from the surface of the skin), etc. The skin plays a primary role here - it is the main heat-exchange organ.
For thermoregulation, hemodynamics is also important - the movement of blood through the vessels. So, for example, when there is a danger of freezing, the body distributes the volumes of circulating blood in such a way that most of it supplies the internal, vital organs. But from the limbs, on the contrary, it casts - this is associated with the danger of frostbite in these areas.
The hypothalamus, a small area in the diencephalon, is responsible for controlling the complex process of thermoregulation, namely, for determining when it is necessary to activate the mechanisms of cooling or warming. The neurons responsible for temperature regulation are located here. Previously, it was believed that the center of thermoregulation is located in the hypothalamus, but today it has been proven that the concept of a single center cannot fully explain all the mechanisms of body temperature stabilization. Heat-sensitive areas are found in the cerebral cortex, hippocampus, amygdala, and even the spinal cord.
External factors are the key cause of thermoregulation disorders in humans. Unlike other warm-blooded animals, in the course of evolution we have become less adapted to temperature changes. Therefore, in critical situations, thermal homeostasis cannot be fully maintained.
Long-term fluctuations of 1-2 degrees from the norm can lead to serious consequences. It should be said that the value of 36.6 ° C used in domestic medicine is not used by foreign doctors. Body temperature can have individual characteristics, and the range of 36.0-37.2 ° C is considered the norm.
- Autonomic dystonia syndrome. Today, VSD (vegetative vascular dystonia) is considered an outdated diagnosis, but some of its signs can be attributed to disorders of the autonomic nervous system.
- Vasomotor neurosis.
- Psychogenic fever.
- Neuroendocrine Disorders.
- Damage to the hypothalamus.
- Organic lesions of the central nervous system (CNS) - tumors, hemorrhages in the hypothalamus, traumatic brain injury.
- Intoxication.
In patients prone to similar manifestations of thermoregulation disorders, it is noted strong rise temperatures in infections and inflammatory processes, the inability to quickly eliminate fever with antipyretic drugs, prolonged fever with acute respiratory infections. It should be noted that in children, a high temperature may be a reaction to acclimatization. Moreover, the process of getting used to new conditions can be delayed for months. In addition, for infants, due to imperfect mechanisms of heat transfer, as well as with an increased metabolism, the temperature may rise to 38 ° C (rectal measurement).
Hypothermia is a condition in which the body temperature drops to 35 ° C and below. At the same time, a person develops lethargy, pulse and blood pressure may decrease, general weakness and "weakness" are observed.
A general decrease in body temperature is typical for older people - due to a slowdown in metabolism, it can fluctuate between 35.5-36.5 ° C. This is a physiological process and does not apply to thermoregulation disorders.
Also low temperature body (35.5 ° C) in the morning is the norm for young children.
In the event of a drop in temperature in people up to 60-70 years old, one can suspect such diseases or conditions:
- Defeat of the hypothalamus.
- Disruption of the central nervous system, in particular, the autonomic nervous system.
- Hypothyroidism (lack of thyroid hormones).
- Parkinson's disease.
- Exhaustion.
- Alcohol intoxication.
- Internal bleeding.
- Iron-deficiency anemia.
A low temperature for several weeks can be observed in people during the recovery period from illness. This is especially true for children and the elderly.
High fever is one of the main signs of infections inflammatory processes in the body. How to distinguish a symptom from systemic thermoregulation disorders?
- Other symptoms.
- Psycho-emotional state of a person.
- Reaction to non-steroidal anti-inflammatory drugs.
- General blood analysis.
- Virus antibody test or bacterial culture.