Why do We get Fevers?

Fever refers to the fact that the body temperature exceeds the upper limit of the normal range and is a very common symptom in children. The temperature of normal children's axillary surface is 36 37 (the body temperature measured by the anal surface is about 0.3 higher than that of the oral surface, and the body temperature measured by the oral surface is about 0.4 higher than that of the axillary surface). heat. In most cases, fever is a protective response of the body against invading pathogens, and is a process in which the body is activating the immune system to fight infection. The abnormal increase in body temperature is not necessarily proportional to the severity of the disease, but excessive fever or long-term fever can affect the body's various regulatory functions and affect children's physical health. Therefore, children who have confirmed fever should actively identify the cause To treat the cause.

Basic Information

English name: fever
Visiting department: Pediatrics

Common causes: Short-term fever in children is mostly caused by infections such as viruses and bacteria
Common symptoms: Fever, fatigue, loss of appetite, rash, etc.

Causes of Pediatric Fever

1. Short-term fever (fever <2 weeks)

Short-term fever is mostly caused by infection in pediatrics, and generally has a good prognosis or a self-limiting disease, but fever may also be an early manifestation of critically ill children, especially those with severe symptoms such as depression, lethargy, and pale complexion. Pay attention to the patient's medical history, contact history of infectious diseases, and symptoms and signs of respiratory, digestive, urinary, and nervous systems, and whether there are rashes, bleeding points, jaundice, anemia, lymph nodes or hepatosplenomegaly and local infections Wait.

2. Long-term fever (fever 2 weeks)

(1) Infectious fever

1) Respiratory infections are the most common. Pathogens include viruses, mycoplasma, bacteria, and tuberculosis;

2) Other system infections Intestinal infections, urinary system infections, central nervous system infections (encephalitis, meningitis), cardiovascular system infections (such as infective endocarditis, pericarditis), and hepatobiliary system infections (such as hepatitis, bile ducts) Inflammation, liver abscess, etc.);

3) Systemic infections such as sepsis, tuberculosis, typhoid, paratyphoid, typhus, brucellosis, EB virus infection, cytomegalovirus infection, Lyme disease, leptospirosis, malaria, black fever, schistosomiasis and fungi Infection, etc.

4) Abscesses or local infections such as osteomyelitis, perirenal abscesses, subdiaphragmatic abscesses, appendix abscesses, and perianal abscesses.

(2) Non-infectious fever

1) Rheumatic diseases Juvenile rheumatoid arthritis is most common. With the timely control of streptococcal infections in recent years, rheumatic fever is now rare. Other rheumatic diseases that cause fever are systemic lupus erythematosus, nodular polyarteritis, Kawasaki disease, serum disease, dermatomyositis, nodular non-suppurative panniculitis, Wegg malignant granulomatosis, and angioimmune mother Cell lymphadenopathy and so on.

2) Malignant tumors with tissue destruction or necrosis . Leukemia is the most common. Other malignant lymphomas (including Hodgkin's and non-Hodgkin's lymphomas), neuroblastomas, malignant histiocytosis, Langerhans' histiocytosis And Ewing sarcoma, etc .; large area burns, major surgery, internal bleeding absorption process, vascular embolism, etc.

3) Excessive heat production or reduced heat production Excessive heat production is seen in hyperthyroidism, persistent epilepsy, and adrenal cortex hyperfunction; reduced heat dissipation is seen in generalized dermatitis, massive water loss, blood loss, heat stroke, congenital ectodermal dysplasia, and Newborns have too many packages and so on.

4) Central disorders such as hypothalamic body temperature regulation, such as skull injury, brain hypoplasia, intracranial tumors, subarachnoid hemorrhage, summer fever, toxic encephalopathy, sequelae of encephalitis, and inter-encephalopathy.

5) Autonomic dysfunction such as functional hypothermia and chronic nonspecific lymphocytosis.

6) Others Drug fever, drug poisoning (such as salicylic acid, atropine), blood transfusion or transfusion reaction, hypernatremia (pituitary or renal diabetes insipidus), inflammatory bowel disease, and immunodeficiency disease.

3. Chronic low fever (long-term low fever)

Refers to those whose onset is relatively slow, whose body temperature is between 37.5 and 38.0 ° C, and which lasts for more than 4 weeks. 40% had infectious fever, 57% had non-infectious fever, and 3% had unknown causes.

First, we need to exclude tuberculosis, including tuberculosis. Chronic hypothermia is often caused by infections, such as post-streptococcal syndrome and other post-infection fevers, and whether there are chronic lesions or small abscesses, such as chronic crypt tonsillitis and lymphadenitis. , Sinusitis, dental caries, gum abscess, perianal abscess, etc.

Non-infectious diseases of chronic hypothermia include hyperthyroidism, diabetes insipidus, rheumatic diseases, inflammatory bowel disease (clone disease and ulcerative colitis), blood diseases, low summer fever, high protein intake, and time spent testing body temperature Hold on.

Except for the above causes, if the cause of the low fever is still not found, but the child does not have any morbidity, only follow-up observation is required, and the low fever can return to normal after several weeks.

Clinical manifestations of pediatric fever

1. Classification of fever level (armpit table)

(1) Low heat 37.5 38.0 ;

(2) Medium heat: 38.1 39.0 ;

(3) High heat of 39.1 40.0 ;

(4) Super high temperature above 40 .

2. According to the length of fever, it can be divided into

(1) Short-term fever Fever <2 weeks, often accompanied by local symptoms and signs;

(2) Long-term fever Fever duration 2 weeks, some may have no obvious symptoms or signs;

(3) Unexplained fever (FUO) Fever persists or is intermittent for more than 3 weeks, and the diagnosis cannot be confirmed by physical examination and routine auxiliary examination;

(4) Chronic low fever and low fever persist for more than one month.

3. Common heat type of fever

The pediatric fever type is not as typical as adults. In recent years, due to the widespread use of antibiotics and the application of adrenal corticosteroids, the heat type has changed, and the significance of the heat type on the differential diagnosis of diseases has been affected.

(1) Remaining fever Persistent fever, body temperature fluctuation is small, generally does not exceed 0.6 ;

(2) Relaxation heat Fever body temperature fluctuates by 2 to 3 ° C, but it does not drop to normal;

(3) Intermittent fever Fever returns to normal for at least 24 hours and then fever;

(4) There are two peaks of fever within 24 hours;

(5) Recurrent or recurrent fever Fever onset, fever lasts for several days, and body temperature is normal during 1 to several days;

(6) Irregular heat The heat pattern has no regularity.

4. Staging of fever

In the process of heating, because the contradiction between heat generation and heat dissipation constantly changes, the heating can generally be divided into four stages:

(1) Prodromal stage Many fever diseases can be asymptomatic. The duration of the symptoms in this period varies according to the specific conditions of the fever disease. The main symptoms are general discomfort, fatigue, loss of appetite, emotional instability, and low fever. Some rashes may have pro-rash before the systemic rash appears. For example, during the prodromal stage of measles, Kirschner's plaques may appear on the oral mucosa.

(2) The period of rising body temperature is characterized by more heat production and less heat dissipation, so the heat production is dominant, so the body temperature rises. Appears as pale, dry, non-sweat, "goose bumps", the child feels cold when touching the skin; if chills occur, it indicates that high fever will occur. Young children may experience convulsions at this time. During the chills, most of the body temperature is above 38 ° C, and most of them reach the extreme fever stage within a few hours, such as malaria, lobar pneumonia, sepsis, drug-responsive fever, etc. The above are those who have a sudden rise in body temperature. The person whose temperature gradually rises refers to the person who has low fever at the initial stage of fever, and who gradually rises from low fever to high fever within a few days, which is called gradual fever. Ascending people often have prodromal symptoms, most of them have no chills, but sometimes they can feel cold, such as atypical typhoid. Some have a sudden fever, which may begin to be caused by low fever being ignored. In addition, the temperature of tuberculosis and other diseases is gradually increasing.

(3) The body temperature has reached its peak at this time during the duration of high temperature. This period is characterized by the heat dissipation process beginning to increase, but the heat production has not decreased. Therefore, the heat production and heat dissipation in this period re-establish a relative balance on a new basis to make body temperature Maintained to a certain high level. The clinical manifestations are flushing and burning of the skin, accelerated breathing, sweating, etc. This period of high fever can last for several hours (such as malaria) or days (such as pneumonia) or even more than a few weeks (such as typhoid fever).

(4) Decline period of body temperature This period is characterized by the predominant heat dissipation process and reduced heat production. At the same time, the heat dissipation is still at a high level through the adjustment of the body temperature adjustment center. Began to decline, and heat production and heat dissipation finally returned to a normal relative equilibrium. The way the body temperature drops is generally fading, that is, the body temperature gradually returns to normal within a few days (such as typhoid fever); there are also sudden declines, that is, the body temperature drops to normal within ten hours or less, or even lower than Normal (eg lobar pneumonia). When the body temperature drops, due to a large amount of sweating, a lot of body fluids are lost. Therefore, when using antipyretics in children with high fever, care must be taken to prevent collapse and other complications.

5. Fever accompanying signs

According to some accompanying signs can help find the cause of high fever in children:

(1) If congestion of the pharynx and swelling of the tonsils are found, it may be an upper respiratory infection or acute tonsillitis;

(2) If a rash appears on the skin, it may be a common eruptive infectious disease, such as infantile rash, measles, rubella, etc .;

(3) If herpes is found, it may be chicken pox, hand, foot and mouth disease;

(4) If it is found that the skin has ecchymosis, epidemic cerebrospinal meningitis and hematological diseases should be considered;

(5) If superficial lymph node enlargement is found, infectious mononucleosis and cutaneous mucosal lymph node syndrome should be considered. Leukemia and malignant lymphoma should also be paid attention to;

(6) If there are spots on the oral mucosa, it may be measles;

(7) If auscultation of the lungs and sputum or blistering sounds are signs of acute bronchitis or bronchial pneumonia, and wheezing in the auscultation of the lungs, wheezing bronchitis or bronchial asthma should be considered

(8) If there is obvious tenderness or other signs in the abdomen, attention should be paid to acute abdomen such as acute appendicitis and intestinal obstruction.

Pediatric fever check

Laboratory inspection

(1) Blood routine The white blood cell count in peripheral blood decreased, and most of them were viral infections. The percentage of white blood cells and neutrophils increased, mostly due to bacterial infections. Abnormal lymphocytes in peripheral blood suggest viral infection. Immature cells suggest leukemia.

(2) Blood culture of children with long-term fever , check C-reactive protein, procalcitonin, ESR, anti-streptolysin "O", liver and kidney function, fat response, Wai Fei reaction, heterophilic agglutination test Mycoplasma pneumoniae antibodies and rheumatoid factors should also be tested for tuberculin.

(3) Fecal routine and fecal culture Consider digestive infection.

(4) Urine routine examination when accompanied by urinary symptoms.

(5) Cerebrospinal fluid examination When children with high fever are accompanied by central nervous system symptoms such as headache, vomiting, convulsions, and disturbance of consciousness.

(6) Bone marrow aspiration When children with high fever are accompanied by symptoms such as anemia, liver and spleen, and lymphadenopathy.

2. Imaging, electrocardiogram and biopsy

According to the specific clinical situation, relevant auxiliary examinations, such as X-ray, CT, magnetic resonance, B-mode ultrasound, electrocardiogram and other biopsy examinations.

Pediatric fever diagnosis

For children with fever, especially those with long-term fever, we must understand the medical history in detail, pay attention to other symptoms accompanied by fever, and analyze based on the age, season of onset, and history of exposure to infectious diseases. Carry out a physical examination carefully. In addition to routine laboratory inspections, relevant auxiliary inspections should be targeted according to the specific clinical situation.

Febrile complications in children

1. Dehydration and disorders of acid-base balance

High fever is easy to cause dehydration, and it also loses water when sweating a lot with antipyretics. Dehydration not only makes fever difficult, but also affects metabolism and blood circulation, and causes acidosis. At the same time, the sodium concentration in the blood increases, and the blood is hypertonic. Children will have dry mouth, thirst, irritability and even nonsense or convulsions. The fever will not only go down, but will be higher, and hyponatremia may occur. Malnourished infants.

2. Fever convulsions

Some children may have convulsions when they have a fever. They usually occur when the fever is high. A fever usually occurs once, rarely more than two times. As long as the convulsions are not long, they are handled properly and have little effect on the child's health.

3. Brain Edema

When the body temperature exceeds 41 ° C, proteins in the body will decompose, which can cause cerebral edema and cause the death of the sick child or leave the sequelae of encephalopathy. Therefore, children must be treated urgently when they have a high temperature above 40 ° C.

Pediatric fever treatment

Treatment of primary disease

Fever is a manifestation of disease, not an independent disease. Therefore, fever in children should not simply focus on antipyretic fever, but should actively look for the cause of fever and treat the primary disease.

2. Antipyretic treatment

Children with persistent high fever need appropriate cooling measures to avoid brain cell damage and possible adverse effects due to excessive body temperature rise. Especially for children with a history of high fever and convulsions and children with high fever and extreme irritability, timely cooling measures are necessary. Febrile children need to be alert or urgently treated: the occurrence of febrile seizures; infants have fever within 3 months; fever persists for more than 5 days; fever> 40 ° C and cannot be effectively cooled within 2 hours by acetaminophen or ibuprofen ; Pediatric behavior changes significantly: such as not playing, no appetite, rarely talking, indifferent to surroundings or sudden emergence of special performances that have never before occurred; less urine, which indicates dehydration, such as infants diaper wet diapers <3, or Older children do not urinate for 8-12 hours.

3. Common cooling measures are

(1) Physical cooling. Wipe the bath with warm water, use ice-proof plastic bags to hold ice cubes, and wrap dry towels on the head and neck. You can also apply axillary and groin areas. Wiping baths with cold water or alcohol are not recommended.

(2) Acetaminophen (> 3 months pediatric) or ibuprofen (> 6 months pediatric) are usually administered orally or rectally to lower the temperature of the drug. The drug can be used every 4 to 6 hours. Children should be careful with aspirin (may be Leading to the Swiss syndrome), and generally do not advocate hormonal antipyretics.

It is not advisable to use drugs to reduce fever in newborns, because the thermoregulatory function of newborns is not well developed.

(3) Chinese medicine cooling Acupuncture, Chinese medicine oral, topical or enema, massage.

(4) Artificial hibernation therapy is a method of cooling by combining drugs (equivalent mixing of chlorpromazine and promethazine) and physical cooling. Artificial hibernation has a strong protective effect on the central nervous system, which can make the body fall asleep, cool down, reduce the metabolic rate, and reduce oxygen consumption. It is mainly applicable to those with persistent high fever or convulsions caused by severe infections, such as poisonous bacterial dysentery, viral encephalitis, and purulent meningitis.

4. Other symptomatic supportive treatments

(1) Provide a comfortable cooling environment. Place the child in a quiet, cool, and airy place. Wear clothing that is cool and breathable. Do not use a quilt to sweat.

(2) Replenish water and electrolytes in time to keep the bowel movements smooth.

(3) Give the child nutritionally rich, light, and easily digestible food.