What is a fever? The stages of this condition, causes and symptoms will be discussed below. We will also tell you about how to treat the disease.
Definition of medical term
Non-specific pathological processes, characterized by a temporary increase in body temperature due to the dynamic restructuring of the thermoregulatory system under the influence of pyrogens (that is, elements that cause fever), are called fever. In medicine, it is believed that such a condition arose as a protective and adaptive reaction of a person or animal to an infection. It should also be noted that the fever, the stages of which will be listed below, is accompanied not only by an increase in body temperature, but also by other phenomena characteristic of an infectious disease.
The essence of the febrile syndrome
It's no secret that many infectious and viral diseases are accompanied by a rise in the patient's body temperature. Moreover, earlier all diseases that proceeded in this way were called fever. However, experts argue that in the modern scientific understanding, this condition is not a disease. But, despite this, in some nosological namesunits the term is still present (for example, Ebola hemorrhagic fever, pappatachi fever, Rocky Mountain spotted fever, etc.).
Why does the temperature rise with certain diseases? The essence of fever is that the thermoregulatory apparatus of humans and higher homoiothermic animals responds to specific substances called pyrogens. As a result of this, there is a temporary shift in the set point of homeostasis (temperature) to a higher level. At the same time, the mechanisms of thermoregulation are preserved. This is the fundamental difference between hyperthermia and fever.
Causes of fever
Why does the temperature rise in a person or animal? There are many reasons for the development of fever. However, the most common are:
- Microbes, infectious pathogenic viruses, parasites. Their waste products and constituents are pyrogen-chemical substances that act on the thermoregulatory center.
- Non-infectious causes. Among them, exogenous proteins are distinguished: vaccines, sera, snake venom, transfused blood, and so on. This also includes the own proteins of a living organism, which have changed their properties as a result of a burn, injury, tumor decay, hemorrhage in the tissue.
Other causes of febrile syndrome
Why does fever occur? A disease that provokes an increase in body temperature may be associated with a disorder of heat transfer in violation of the vegetativework in adolescents, children and young women (i.e. with thermoneurosis). Fever can also be caused by the following factors:
- Taking certain medications. Experts say that a number of medications can affect the thermoregulatory center, causing a slight rise in body temperature.
- Hereditary disorder in the process of thermoregulation. For example, some perfectly he althy children are already born with a temperature of 37.2-37.4 degrees. For them, this state is the norm.
- Subfebrile temperature often occurs due to overheating, regular physical activity, being in a stuffy room and extreme heat.
- Emotional overstrain and stressful situations are very often accompanied by an increase in heat production and activation of the hypothalamus, which contributes to the onset of fever.
- The increase in the hormone progesterone in pregnant women also causes a slight increase in temperature. At the same time, other signs of a viral or infectious disease are completely absent. This state can be maintained until the end of the first trimester. However, for some of the fairer sex, subfebrile temperature accompanies almost the entire pregnancy.
What are pyrogens?
As mentioned above, infectious and viral diseases very often contribute to an increase in body temperature. This happens under the influence of pyrogens. It is these substances that enter the body from the outside or are formed right inside that cause fever. Most often exogenouspyrogens are elements of infectious pathogens. The strongest of these are thermostable capsular lipopolysaccharides of bacteria (gram-negative). Such substances act indirectly. They contribute to the shift of the set point in the thermoregulatory center of the hypothalamus. Most of them are of leukocyte origin, which directly affects other important symptoms of the disease. The source of pyrogens are cells of the human immune system, as well as granulocytes.
Fever: Stages
During the development of a fever, there are three main stages. On the first - a person's temperature rises, on the second - it is held for some time, and on the third - it gradually decreases, reaching the initial one. About how such pathological processes occur, and what symptoms are inherent in them, we will describe further.
Rise in temperature
The first stage of fever is associated with the restructuring of thermoregulation, as a result of which heat production begins to significantly exceed heat transfer. The limitation of the latter occurs due to a decrease in the influx of warm blood into the tissues and narrowing of the vessels in the periphery. More important in this process is the spasm of the skin vessels, as well as the cessation of sweating under the influence of the sympathetic nervous system. The signs of fever in the first stage are as follows: blanching of the skin and a decrease in its temperature, as well as restriction of heat transfer due to radiation. Reduced sweat production prevents heat from escaping through evaporation.
The contraction of muscle tissue leads to the manifestation of the phenomenongoose bumps in humans and ruffled fur in animals. The subjective feeling of chills is associated with a decrease in skin temperature, as well as irritation of cold thermoreceptors located on the integument. From them, the signal enters the hypothalamus, which is an integrative center of thermoregulation. After that, he informs the cerebral cortex about the situation where human behavior is formed: he begins to wrap himself up, take appropriate poses, etc. A decrease in the temperature of the skin also explains the human muscle tremor. It is caused by the activation of the shiver center, which is located in the medulla oblongata and midbrain.
Temperature hold
The second stage of fever begins after reaching the set point. It can take several hours or days, and also be long. In this case, heat transfer and heat production balance each other. There is no further increase in body temperature.
Skin vessels dilate in the second stage. Their pallor also disappears. At the same time, the covers become hot to the touch, and chills and trembling disappear. A person at this stage experiences a fever. In this state, daily temperature fluctuations persist, but their amplitude is rather sharply higher than normal.
Depending on the degree of rise in body temperature, fever in the second stage is divided into types:
- subfebrile temperature - up to 38 degrees;
- low fever - up to 38.5;
- febrile or moderate - up to 39 degrees;
- pyretic orhigh temperature - up to 41;
- hyperpyretic or excessive - over 41 degrees.
It should be noted that hyperpyretic fever is extremely dangerous for human life, especially for young children.
Temperature drop
Decrease in body temperature can be abrupt or gradual. This stage of fever begins after the exhaustion of the supply of pyrogens or the cessation of their formation under the influence of natural or medicinal factors. When the temperature drops, the setpoint reaches the normal level. This leads to vasodilation in the skin. At the same time, excess heat begins to be gradually removed. A person has profuse sweating, increased perspiration and diuresis. The heat transfer at the third stage of fever sharply exceeds the heat production.
Types of fevers
Depending on changes in the daily temperature of the patient's body, fever is divided into several types:
- Constant is a long and steady increase in temperature, the daily fluctuations of which do not exceed 1 degree.
- Remitting - noticeable daily changes can be within 1.5-2 degrees. At the same time, the temperature does not reach normal numbers.
- Intermittent - this pathology is characterized by a rapid and significant rise in temperature. It lasts for several hours, after which it is replaced by a rather rapid drop to normal values.
- Exhausting or hectic - with this type, daily fluctuations can reach 3-5 degrees. At the same time, rises with a rapid decline are repeated several times throughout the day.
- Perverse - this fever is characterized by a change in the circadian rhythm with high rises in the morning.
- Wrong - characterized by fluctuations in body temperature throughout the day without a definite pattern.
- Return - with this type, periods of increased body temperature alternate with periods of normal values, which last for several days.
It should also be noted that the temperature - 35 degrees - does not contribute to the appearance of fever. To find out the reasons for this condition, you should consult a doctor.
Common fever symptoms
Low temperature (35 degrees) does not cause fever, as it is characterized by a rise of more than 37 degrees. Common signs of such a pathological condition are:
- feeling thirsty;
- facial redness;
- rapid breathing;
- bone ache, headache, unmotivated good mood;
- poor appetite;
- chills, shivering, profuse sweating;
- delirium and confusion, especially in older patients;
- irritability and crying in children.
It should also be noted that sometimes a rise in temperature can be accompanied by swelling and pain in the joints, a rash and the appearance of dark red blisters. In this case, you should immediately consult a doctor.
Treatment
How to get rid of such a state asfever, the stages of which were listed above? To begin with, the doctor must establish the cause of the rise in body temperature, and then prescribe the appropriate therapy. If required, the doctor can send the patient for additional examination. If a serious pathology is suspected, the specialist recommends hospitalization to the patient. Also, to eliminate fever, the patient is advised to observe bed rest. At the same time, it is forbidden to dress too warmly.
The patient needs to drink plenty of fluids. As for food, he is shown light and well digestible food. Body temperature should be measured every 4-6 hours. If necessary, you can take an antipyretic. But this is only if the patient has a severe headache, and a temperature of more than 38 degrees is also observed. To improve the patient's condition, it is recommended to use Paracetamol. Before taking this medicine, you must carefully study the instructions. If a child has a fever, then he is forbidden to give acetylsalicylic acid. This is due to the fact that such a drug can cause the development of Reye's syndrome. This is an extremely serious condition, leading to a coma or even death. Instead, paracetamol-based medicines are recommended for kids to relieve fever: Efferalgan, Panadol, Kalpol and Tylenol.
