Fever
Fever (also known as pyrexia) is one of the most common medical signs and is characterized by an increase in body temperature above the normal range of 36.5-37.5 °C (98-100 °F) due to an increase in the thermoregulatory set point. An increase in the thermoregulatory set point trigger point increases muscle tension and (shivering) chills.
The increase in temperature generally results in a chilling sensation, even though the body temperature is elevated. Once the new temperature is reached, there is a sensation of heat. From the beginning of a fever to a potentially dangerous fever, a fever can be caused by many different conditions. The question of whether fevers are useful is controversial, with arguments for and against. Except for very high temperatures, cooling therapy is often unnecessary. However, antipyretic drugs can be effective in lowering the temperature and may improve the comfort of the affected person.
Fever differs from uncontrolled high fever, which is due to excessive heat production and/or deficiencies in thermoregulation, where the body temperature rises above the body’s thermoregulatory set point.
Definition
A wide range of normal temperatures has been identified. Fever is often found to exist if the elevated body temperature is due to an elevated set point and? Anal temperature (rectal/rectal) is at or above 37.5 to 38.3°C (99.5 to 100.9°F)? Oral temperature (of the mouth) is at or above 37.7 °C (99.9 °F)? Underarm temperature (of the armpit) or in-ear (of the ear) temperature is at or above 37.2 °C (99.0 °F) In healthy adult men and women, normal, healthy oral temperature ranges from 33.2-38.2 °C (91.8-100.8 °F), rectal is 34.4-37.8 °C (93.9-100 °F), and tympanic (ear drum) is 35.4- 37.8°C (95.7-100°F), and axillary temperature (axillary) is 35.5-37.0°C (95.9-98.6°F). The Harrison textbook of internal medicine defines fever as a morning temperature > 37.2 °C (98.9 °F) or an evening temperature > 37.7 °C (99.9 °F), while the normal daily temperature variation is typically 0.5 °C (0.9 °F).
Normal body temperature variation depends on many factors including age, gender, time of day, ambient temperature, activity level, and more. An elevated body temperature is not always a fever. For example, a healthy person’s temperature rises when he or she exercises, but this is not considered a fever because the (body temperature) set point is normal. On the other hand, perhaps a “normal” temperature might be a fever – if a temperature is unusually high for a person. For example, older, frail people have a reduced ability to produce body heat, so a “normal” temperature of 37.3°C (99.1°F) may be a clinically significant fever for them.
The pattern of variation in type of temperature may suggest a diagnosis of.
1. Persistent fever: A temperature that is consistently higher than normal throughout the day, with fluctuations of no more than 1°C over 24 hours, for example: lobar pneumonia, typhoid fever, urinary tract infection, brucellosis, or typhus. Typhoid fever can exhibit a specific fever pattern (typhoid fever Wendlich curve), with a slow stepwise increase in temperature reaching a stable phase with a high temperature. (Except for cooling due to antipyretics).
2, intermittent fever: only for a certain period of time to show an increase in temperature, and then back to normal, such as malaria, black fever, sepsis, septicemia, etc.. The following are its types.
–daily fever, 24 hours periodic, typical of Plasmodium falciparum or Plasmodium norvegicum.
–Inter-day fever (48-hour cycle), typical of inter-day (unicellular animal) Plasmodium vivax and Plasmodium ovale malaria.
–Four-day fever (72-hour cycle), typical of three-day Plasmodium vivax malaria.
3. On and off fever (chilblains fever): temperature is higher than normal throughout the day and fluctuates by more than 1 °C in 24 hours, as in infective endocarditis.
4. Pey-E fever: a specific type of fever associated with Hodgkin’s lymphoma, manifesting as a fever one week and a drop in temperature the next, etc. However, there is controversy as to whether this pattern really exists.
Neutropenic fever, also known as febrile neutropenia, is a type of fever that lacks normal immune system function. Due to the lack of infection-fighting neutrophils, bacterial infections can spread rapidly, and this fever, is usually considered to require urgent medical attention. This fever is more common in people receiving immunosuppressive chemotherapy than in normal people.
Mild fever is an old term for a low fever, especially when the cause is unknown, no other symptoms are exhibited, and the patient recovers completely in less than a week.
Hyperthermia Hyperthermia is an extreme increase in body temperature greater than or equal to 41.5°C (106.7°F). A temperature this high is considered a medical emergency because it may indicate a serious, underlying condition, or a significant side effect. The most common cause is intracranial hemorrhage. Other possible causes include sepsis, Kawasaki syndrome, antipsychotic malignant syndrome, drug effects, pentraxin (serotonin) syndrome, and thyroid crisis. Infection is the most common cause of fever; however, as the temperature increases, other causes become more common. Infections are usually associated with high fever and include: erythema (roseola), measles, and enterovirus infections. Immediate and aggressive cooling to below 38.9 °C (102.0 °F) has been found to improve survival rates. Hyperthermia differs from overheating in that in hyperthermia the body’s thermoregulatory mechanisms set the body temperature higher than normal and then generate heat to reach that temperature, whereas in overheating the body temperature rises above the temperature set point due to exogenous factors. (e.g. heat stroke, etc.).
Hyperthermia Hyperthermia is an example of high temperature, which is not a fever. It has many causes, including heat stroke, antipsychotic malignant syndrome, malignant hyperthermia, stimulants such as amphetamines and cocaine, idiosyncratic drug reactions, and pentothal syndrome.
Signs of fever are usually accompanied by pathological behavior, including lethargy, depression, anorexia, lethargy, nociceptive sensitization, and inattention.
Differential diagnosis Fever is a common symptom of many physical illnesses:.
1. Infectious diseases such as influenza, HIV, malaria, infectious mononucleosis, or gastroenteritis? Various skin inflammations, such as boils, or abscesses? Immunological diseases, such as lupus erythematosus, tuberculosis, inflammatory bowel disease, Kawasaki disease? Tissue destruction, hemolysis, surgery, thrombosis, crush syndrome, rhabdomyolysis, cerebral hemorrhage, etc. can occur.
2. Incompatible reactions to blood products? Cancer, most commonly kidney cancer and leukemia and lymphoma? Metabolic diseases, such as gout or porphyria? Thromboembolic processes, for example, pulmonary embolism or deep vein thrombosis after repeated routine clinical inquiries unexplained persistent fever, known as unexplained fever pathophysiology body temperature ultimately regulated in the hypothalamus. The cause of the fever, the pyrogen, leads to the release of prostaglandin E2 (PGE2). PGE2 then acts back on the hypothalamus, which produces a systemic response back to the rest of the body, causing a thermogenic effect to match the new body temperature level.
In many ways, the hypothalamus acts as a thermostat. As the set point rises, the body increases its temperature by actively generating heat and retaining it. Vasoconstriction, which reduces heat loss through the skin, also causes a person to feel cold. If these measures are not enough to adapt the blood temperature in the brain to the new hypothalamic settings, chills begin to move the muscles to produce more heat. When the fever stops, the hypothalamus temperature set point is set lower, contrary to the fever process (vasodilation, the end of chilling and non-chilling heat production) and sweating, allowing the body temperature to cool to the new, lower temperature setting.
In contrast, with hyperthermia, there is no change in the normal body temperature setting and the body overheats due to excess heat or excessive heat production being tiresomely retained. Hyperthermia is usually the result of an extremely hot environment (heat stroke) or an adverse reaction to medication. It is possible to identify fever from hyperthermia by the surrounding situation and the response to antipyretic drugs.
Thermogenic substances Thermogenic substances are substances that cause fever and can be internal (endogenous, endogenous) or external (exogenous, exogenous) to the body. The bacterial substance lipopolysaccharide (LPS), found in the cell walls of some bacteria, is an example of an exogenous thermogen. Pyrogens are capable of change: in extreme examples, some bacterial pyrogens, called superantigens, can cause rapid and dangerous fevers. De-pyrogenation can be achieved by filtration, distillation, chromatography, passivation (deactivation) of these methods.
Endogenous in nature, all endogenous pyrogens are cytokines, molecularly part of the innate immune system, produced by phagocytes that cause an elevation of the thermoregulatory set point in the hypothalamus. The major endogenous pyrogens are interleukin 1 (α and β), interleukin 6 (IL-6), and tumor necrosis factor-α. Secondary endogenous pyrogens include interleukin 8 , tumor necrosis factor-α , tumor necrosis factor-β , macrophage inflammatory protein-α , macrophage inflammatory protein-β , and interferon-α , interferon-β , and gamma-interferon.
These cytokines are released into the systemic circulation and migrate to periventricular structures where they are more readily absorbed because the blood-brain barrier is there with reduced filtration. The cytokines then bind to receptors on endothelial cells in the vessel wall or interact with microglia there. When these cytokines bind, the arachidonic acid pathway is then activated.
One type of mechanism by which exogenous exogenous pyrogens cause fever includes lipopolysaccharide (LPS), a cell wall component of gram-negative bacteria. Immune protein binding to LPS is called lipopolysaccharide binding protein (LBP). Subsequently, the LBP-LPS complex binds the CD14 receptor of neighboring macrophages. This binding leads to the synthesis and release of various endogenous cytokines, such as interleukin 1 (IL-1), interleukin 6 (IL-6), and tumor necrosis factor-α. In other words, exogenous factors cause the release of endogenous factors, which, in turn, activate the arachidonic acid pathway.
Release of prostaglandin E2PGE2 release comes from the arachidonic acid pathway. This pathway (which is involved in fever), is mediated by phospholipase A2 (PLA2), cyclooxygenase-2 (COX-2) and prostaglandin E2 synthase. Ultimately these enzymes mediate the synthesis and release of prostaglandin E2 (PGE2).
PGE2 is the ultimate mediator of the febrile response. The body’s set point temperature will continue to rise until PGE2 is no longer present. PGE2 acts on neurons in the preoptic area (POA) via prostaglandin E receptor 3 (EP3). EP3-expressing POA neurons stimulate the dorsal medial hypothalamic nucleus (DMH), the median septal pallid nucleus of the medulla cephalad (rRPa), and the paraventricular nucleus of the hypothalamus (PVN). Fever signals sent to the DMH and rRPa stimulate the sympathetic output system, which evokes non-shivering thermogenesis to produce body heat, and cutaneous vasoconstriction to reduce heat loss from the body surface. It is hypothesized that the neural distribution from the POA to the PVN mediates the neuroendocrine effects of thermogenesis through the pituitary and various endocrine organ pathways.
The hypothalamus, through the autonomic (vegetative) nervous system, and the brain ultimately orchestrate the mechanisms of heat effects. These may be.
1. increase heat production by increased muscle tone, shivering (chills) and hormones such as adrenaline? Preventing heat loss, such as vasoconstriction in infants and children, the autonomic (vegetative) nervous system can also activate brown adipose tissue to produce heat (non-motor related thermogenesis, also known as non-shivering thermogenesis). Increased heart rate and vasoconstriction during fever lead to increased blood pressure.
The question of whether useful fever is useful is controversial, with arguments for and against it. Some proposals say that fever makes people recover faster from infections or critical illnesses, followed by in vivo studies using warm-blooded vertebrates and humans. A Finnish study showed that the presence of fever reduced mortality from bacterial infections.
Theoretically, fever could help the host’s defense. There must be some important immune response that is accelerated by fever, and there is a strict temperature preference for some pathogens to be disturbed.
Studies have shown that fever contributes to several important aspects of the healing process.
2. increased granulocyte mobility? Enhanced phagocytosis of granulocytes? Decrease in the effects of endotoxin? Increased proliferation of T cells Management of fever does not necessarily require treatment. Most people recover without specific medical treatment. Although it is not very comfortable, fever rarely rises to a dangerous level and is instantly untreated. Damage to the brain generally does not occur unless the temperature reaches 42°C (107.6°F), but untreated fevers above 41°C (105°F) are extremely rare. There is some limited evidence to support the use of warm water for body rubs or baths for children with fever. The use of fans or air conditioning may reduce the temperature and increase comfort. If the temperature reaches a very high fever, aggressive cooling is needed. In general, it is recommended that adequate hydration should be maintained. It is not known whether increasing fluid intake improves symptoms or shortens the course of a respiratory illness such as the common cold.
Medications to lower the temperature are known as antipyretics. The antipyretic drug ibuprofen is effective in children for cooling, and it is more effective than acetaminophen (paracetamol). Both ibuprofen and acetaminophen can be used safely in children with fever. Acetaminophen alone has been questioned for use in children with fever. For children with fever, ibuprofen is superior to aspirin. In addition, aspirin is not recommended for use in children and young adults (under 16 or 19 years of age, varies by country) because of the risk of Reye’s syndrome.
Epidemiology Approximately 5% of people who visit the emergency room have a fever.
History By the time of Hippocrates, several patterns of fever were recognized: including inter-day fever (every 48 hours) and four-day fever (every 72 hours) were fevers caused by malaria. In the following centuries a general consensus emerged on how fever develops, the difference between fever as a symptom and fever as a disease, an exhaustive classification scheme of the many types of fever, hypotheses about the causes of fever, and different methods of diagnosing and treating fever. In the 10th century, the Persian physician Akhawaynī created the concept of fever curve – the time corresponding to fever, as an aid to diagnosis.
Sociocultural fever phobia Fever phobia is the name given by medical experts to the misconceptions of parents of affected children about fever. Among other things, many parents mistakenly believe that fever is a disease without knowing that it is a medical sign, that a low fever is harmful, and that even a short period of time slightly above the “normal” number marked on a very simple thermometer is a clinically significant fever. They also feared harmless side effects such as sudden onset of fever and exaggeratedly overestimated the likelihood of long-term damage from a typical fever. The fundamental problem, notes pediatrics professor Barton D. Schmitt, is that “as parents, we tend to suspect that our children’s brains might melt. “As a result of these misconceptions, parents are eager to give their children fever-reducing medications, instantly when the temperature is technically normal or only mildly elevated, and to give their children more medications in order to keep them sleeping normally.
Etymology fever comes from the Greek PYR, which means fire. Fever etymologically comes from the Latin word febris, meaning fever, which in ancient times was known as malaria.
Fever in other animals fever is an important feature in the diagnosis of diseases in domesticated animals. The body temperature of animals, taken from the rectum, varies between species. For example, a fever in horses is said to be a body temperature over 101.0°F (38.3°C).
Species that allow the body to have a wide range of “normal” temperatures, such as camels, sometimes have difficulty determining the febrile stage.