Types of temperature curves

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					                            Types of temperature curves
A number of infectious processes have typical temperature curves characterizing the
manifestations of fever. The following forms of fever are distinguished, according to the
elevation of the temperature: a) subfebrile (not above 38 C, b) moderate (up to 39 C) , c) high
(39-41), and d) excessively high - hyperpyretic (41 C and higher). The body temperature very
rarely rises above 41 C.
The following main forms of fever are distinguished according to the character of the
temperature curves:
1 Continuous fever (febris continua) in which the elevated temperature for some time persists on
a high level, the difference between the morning and evening temperature not exceeding 1 C.
The fever may end abruptly (crisis) or gradually (lysis) . This form includes typhoid fever early
in the course of the disease, the fever in croupous pneumonia, typhus and certain other infectious
disease.
2. Remittent fever (febris remittens) in which the difference between the morning and evening
temperature exceeds 1 C. It includes the temperature curves observed during the late course to
typhoid fever, sepsis and catarrhal pneumonia.
3 Intermittent fever (febris intermittens) which is characterized by regular alternation of brief
attacks of fever (paroxysms) with feverless periods (apyrexia). High temperature persists for
several hours, drops to normal and then rises again. The length to the feverless periods may
vary. This form of temperature curve is characteristic of malaria. Attacks of fever may occur
every third day (febris quartana), every second day (febris tertina ) or every day (febris
quotidiana)
4 Recurrent fever (febris recurrents) which is characterized by longer periods of pyrexia than in
intermittent fever (5-8 days). The duration of these periods corresponds to that of the periods
corresponds to that of the periods of normal temperature. Such a curve is characteristic of
replasing fever.
There are fevers- which at first run the course of febris continua and then change to febris
remittens (for example, in typhoid fever). There are also fevers of short duration (ephemeral)
with an indefinite or irregular course (considerable diurnal variations in body temperature) and
fevers with a perverted course, for example, an elevation of temperature in the morning and a
drop in the evening (in some forms of sepsis and tuberculosis) . The aforementioned types of
temperature curves dc not exhaust their variety.
The type of temperature curve is determined not only by the character of the infection, but also
by the reactivity of the characterized by increased heat loss and its predominance over heat
production which may relatively even increase. Heat lass increases as a result of excessive
perspiration (sometimes very profuse) and considerable dilatation of the peripheral vessels. The
ratio of heat production to heat loss is the reverse of that observed during the first stage of fever.
Then heat production, heat loss and body temperature return to normal. At this stage the
temperature is often unstable.
The temperature drops either rapidly (crisis) or slowly, gradually (lysis). A critical drop in
temperature, especially in cases of cardiovascular insufficiency, in dangerous because it requires
a rapid adjustment of the organism to the new conditions of the internal environment. This may
result in a shock reaction (collapse).
In all the aforedescribed stages physical and chemical thermoregulation functions concertedly. In
man the disturbance in physical thermoregulation is of the utmost importance. The different
stages of the febrile reaction may be characterized by noticeable fluctuations in the heat balance
due to compensation for the disturbed functions, which is in its turn connected with the
physiologic defence role of the central nervous system.
Thus the course of the different stages of the febrile process is determined, not only by the
etioiogic factor, but also by the general state of the organism, its reactivity, metabolism and
intensity of the oxidative processes.
Metabolism in Fever
Metabolic disturbances in fever are caused by various factors. These factors are: I) etiological
peculiarities, most frequently of the infectious agent; 2) elevation of body temperature; 3)
starvation which in some measure accompanies fever since, owing to loss of appetite and
digestive disturbances, the organism consumes and assimilates less food than usual.
Metabolic disturbances vary with the various fevers, but are nevertheless subject to certain
regularities characteristic of most fevers. In most cases metabolism is increased, this increase
underlying the greater heat production. In moderately severe-fevers metabolism may increase
5—10 per cent and may even remain within normal limits (Du Bois). The oxidative processes
are somewhat intensified partly because of increased respiration and cardiac action. For example,
in the quinea pig a 1 rise in temperature is accompanied by a 3.3 per cent increase in oxygen
consumption. However, there may be a discrepancy between the amount of oxygen consumed by
the organism and heat production, with accumulation of underoxidised metabolites and, in
connection. with it, a decrease in the respiratory quotient.
In fever carbohydrate metabolism is increased; this can be seen from the decrease in glycogen in
the liver and the possible development of hyperglycemia.
The fat metabolism is appreciably increased mainly in lingering fevers of infectious origin. The
increased expenditure of fats is due not only to the fever, but also to the concurrent starvation
and, in a certain measure, perhaps to intoxication. Ketonemia and ketonuria are sometimes
observed as a result of carbohydrate deficiency and decreased oxidation of fats.
Protein metabolism may be disturbed. In fever involving a high temperature the expenditure of
protein is increased out of proportion to that of fats and carbohydrates; .elimination of nitrogen
in the urine is increased. In cases of moderate fever the share of protein in the total energy
balance is often normal (10-15 per cent), as is, for example, the case in influenza and certain
forms of tonsillitis. In fevers with a high temperature the share of protein may reach 30 per cent,
in which cases the amount of urea in the urine increases. Disintegration of protein is particularly
great in infectious fevers (toxogenic protein disintegration).
The loss of valuable proteins by the feverish organism may be in some measure compensated by
consumption of carbohydrates, fats and proteins.
The loss of valuable proteins by the feverish organism may be in some measure compensated by
consumption of carbohydrates, fats and proteins.
In severe fevers some investigators have observed an increased specific dynamic effect of
protein, which also explains the increased loss of nitrogen with the urine in high fever.
The problem of metabolism in fever is very important for the choice of diet for feverish patients.
It is difficult completely to eliminate the losses of tissue proteins in fever, especially infectious
fever involving high temperature. In severe infections it is necessary to strive for a possible
limitation of protein expenditure by a plentiful administration of carbohydrates. For this purpose
patients are intravenously administered glucose which is more easily oxidized and is in a certain
measure capable of making up for the caloric deficiency and the excessive expenditure of
protein, the latter imperilling the feverish organism which is fighting the active, in most cases
infectious, agent.
In fever the water and salt metabolism is more or less altered. As a result of increased
metabolism and accumulation of
underoxidized products the tissue retain water. The dysfunction of the renal filter due to
intoxication and the rise in organism, the extent of its sensation of foreign proteins, in
particular .
Stages of Fever
Three periods of stages may be distinguished in most fevers.
These are; 1) the stage of elevation of the body temperature (stadium incrementi) 2) the stage in
which the temperature is at its acme (stadium fastigii) and 3) the stage of decreasing
temperature (stadiuim decrementi). These three stages are characterized by a certain disturbance
in the interrelation between heat production and heat loss, and disorders of the different forms of
metabolism, excretion of urine, etc.
The first, usually short stage is characterized by a rapid or gradual elevation of body
temperature. The temperature rises because in the beginning of fever, as a result of spasm of the
vessels in the skin, less heat is lost, while heat production begins to increase. The ratio of heat
production to heat loss increases, the disparity between heat production and heat loss in cases of
rapidly rising temperature being accompanied by chills -a sensation of cold and shivering, pallor
of the skin and appearance of "goose flesh". At the same time the increase in muscle tone and.
the contraction of various groups of muscles lead to still greater heat production.
The chills are due to stimulation of the nerve endings in the skin as a result of the drop in its
temperature caused by spasm of the superficial vessels. The cooling of the superficial layer of
the skin reflexly causes shivering. Heat production increases also in the fever.
The faster fever develops, the greater the disparity between physical and chemical
thermoregulaton, and the more strongly pronounced the chills. In these cases heat production
always exceeds heat loss.
The second stage is characterized by establishment of the ratio of heat production to heat loss on
a definite level. The heat loss increases mainly by dilation of the vessels in the skin and
accelerated respiration. Compared with the first stage heat production may decrease, sometimes
even to normal, but the balance between heat production and heat loss is established on a higher
level than in healthy people.
The organism retains its ability to regulate the newly established temperature. Heat is lost
through the same channels as usual and only perspiration plays a less important role.
The therapeutic measures employed during this period (cupping, wrapping, rub-downs) are
aimed at facilitating physical
thermoregulation.
The third stage - the stage of falling temperature is temperature is also of same importance.
The second stage of fever is accompanied by decreased excretion of urine. The retention of.
water is noticeable excretion of water by the kidneys is observed in addition to the sharp increase
in heat loss and excessive perspiration.
It is not yet entirely clear precisely what tissues retain water in fever. As in inflammation, a very
important part is apparently played by connective tissue.
As for the salt metabolism, the disturbed water metabolism involves retention of chlorides;
during the third period, when the excretion of urine begins to increase, more chlorides are
eliminated. More phosphates and potassium salts are excreted as a result of tissue disintegration.
Changes in the Functions of the Internal Organs in Fever
Disturbances underlying the disorders of thermoregulation arise in the nervous system.
Moreover, phenomena due to changes in body temperature and intoxication are observed.
Hyperthermia may of itself (in so-called aseptic fevers) , depending on its intensity, stimulate
and subsequently inhibit the central nervous system. Infectious fever are not infrequently
accompanied by a sensation of heaviness in the head, general indisposition, clouded
consciousness, delirium, hallucinations, etc. Children react to pyrexia by greater excitement than
do adults. In emaciated patients fever is usually attended with phenomena of depression of the
nervous system.
As regards the vegetative nervous system, the functions of its sympathetic division predominate.
In fever the cardiac rhythm is accelerated as a result of excitation of the sympathetic nervous
system. The etiologic factors causing fever — mainly infectious agents and toxins, as well as
toxic metabolites - stimulate cardiac activity. Usually a 1 rise in temperature is accompanied by
an increase of 8-10 beats in the heart rate.
The extent of the functional changes in the heart muscle and
conduction system depends on the character of the infection and intoxication. Elevation of the
body temperature in fever is usually accompanied by an acceleration of the pulse, but there are
also reverse phenomena which are apparently connected with stimulation of the centre of the
vagus nerve in the medulla oblongata. For example, in inflammation of the meninges,
tuberculous meningitis in particular, the pulse rate clearly lags behind the rise in temperature.
The character of the pulse wave (hard, full, theady, dicrotic, etc.) is, in addition to the pulse rate,
also very important for evaluating the state of cardiovascular activity. The changes in the state of
the vessels are connected will disturbances in physical heat regulation; for example, chills are
accompanied by spasm of the peripheral vessels and a rush of blood to the internal organs;
during the second and, especially, the third stages of fever the vessels are dilated.
In the beginning of fever the blood pressure is somewhat elevated because of the increased
action of the heart and excitation of the vasomotor centers; during the last stage, however, the
blood pressure drops as a result of weakened heart action and dilatation of the vessels. The drop
in blood pressure may sometimes lead to shock or collapse.
In fever the respiration in accelerated simultaneously, with the quickening of the pulse and
elevation of the body temperature. Fever also involves a rise in the temperature of the blood and
acidosis developed as a result of accumulation of acid metabolites. Respiration participates in the
physical regulation of heat along with the vascular system and the sweat glands. A change in
respiration is thus one of the mechanisms of physical thermoregulation in fever.
The function of the digestive apparatus is altered: the secretion of digestive juices and bile is
decreased, the mucous membranes of the mouth and tongue are dry, and intestinal peristalsis is
Disturbed. Some cases are accompanied by constipation with increased putrefaction,
accumulation of gases and development of meteorism. Digestive insufficiency and diminished
absorption lead to a lack of appetite, decreased assimilation of nutritive substances and
phenomena of intoxication.
The function of the kidneys is also altered. Renal filtration is particularly affecfted by toxins in
infectious fevers (for example, scarlet fever, septic diseases). At the height of fever the amount
of urine perceptibly diminishes. The water is retained by the tissues. The content of nitrogenous
substances in the urine is increased. The amount of urine appreciably increase during the third
stage of fever when the body temperature begins to fall.
Protein, peptones and albumoses sometimes appear in the urine. The amount of excreted protein
in large measure depends on the character and severity of renal affection. Here an important part
is played not. so much by hyperthermia, as by the infection and intoxication which have initiated
the febrile process.
As for pathoanatomical changes, dystrophic phenomena are sometimes observed mainly in the
parenchymal organs in fevers with a high temperature. The changes are of the nature of a turbid
swelling, sometimes waxy degeneration, and adipose infiltration. Important in these cases is the
fever itself and, to an even greater extent, the infection and intoxication which have produced the
fever. Phenomena of dystrophy in the internal organs cause disturbances in their functions,
which in their turn affect the course of the febrile process.
Effects of Fever on the Course of Infectious Processes
The question of the effects of fever as a general reaction of the organism mainly to the action of
infectious agents is of fundamental importance. It is important to settle this question in order to
uncover the adaptive role of fever in the organisms fight against infection and for its therapy.
The investigators maintaining that fever harmfully affects the course of infection in the organism
point out the concurrent dysfunction of the cardiovascular system, deep metabolic disturbances
and dystrophic changes in the organs; however, some infectious diseases run a graver course in
the absence of fever or in cases a weak manifestations of fever (for example, croupous
pneumonia, influenza, typhus, etc.).
A more favourable course of phenomonia and chicken cholera is observed in hyperthermia
produced in animals by injury to the corpus striatum. Carefully conducted artificial overheating
favours the survival "or prolongs the life of animals infected with anthrax, the Streptococcus
pyogenes and the Staphylococcus.
There are also some indications that certain adaptive reactions become more intense at a high
temperature; these include phagocytosis and production of immune bodies, and such physiologic
functions as hematopoisesis, activity of the enzymes, and the barrier and antitoxic functions of
the liver.
To produce fever for therapeutic purposes, especially in certain chronic infections, pyrogenic
therapy is applied in the form of inoculation of malaria (in neurosyphilic) administration of
purified pyrogenic substances (pyrexial, pyrogenal, etc. or inductopyrexia, i.e., production of
fever by electromagnetic induction.
Body temperature is a valuable index of the state of the organism in its struggle against infection
since it reflects the reactive ability of the diseased organism. This does not mean that fever must
always be considered a positive phenomenon in the development of infectious process. Both an
excessive rise in temperature or its sudden drop may prove harmful to the organism. It follows
that the course of the fever and its significance to the organism must be given special
consideration to each concrete case. As one of the mechanisms formed in the process of
evolutionary development fever may, in cases of moderate elevation of body temperature, be
useful in the organisms 3 struggle against the infectious agent which has caused it.

				
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