Influenza virus pneumonia in children

Introduction to pediatric influenza virus pneumonia The disease is a serious lung infection caused by influenza (hereinafter referred to as influenza) virus. Influenza virus pneumonia is a serious interstitial pneumonia, sometimes invading the central nervous system or the circulatory system. Infants and young children, concentrated in the age of 6 months to 2 years old, are more common in the cold season of winter and spring. Influenza B virus pneumonia is generally lighter than those caused by type A. basic knowledge Probability ratio: 0.4% of infants and young children Susceptible people: children Mode of infection: respiratory transmission Complications: pleural effusion, pulmonary edema, shock, myocarditis

Pediatric influenza virus pneumonia

Causes:

The influenza virus spreads through the droplets into the upper, lower respiratory tract or directly into the alveoli, and the influenza virus that stays in the mucous membrane of the epithelial cells of the respiratory tract can bind to specific receptors such as mucins of the host cells, and local mucus secretions. The antibody (mainly IgA) can be neutralized by the virus and neutralized. There is still glycoprotein in the mucus, which can bind to the virus and prevent the virus from attaching to the specific receptor of the host cell, so as to prevent infection, but These inhibitors are ultimately destroyed by the neuraminidase of the virus itself, which allows the virus to enter and reproduce in the airway epithelial cells, where newly synthesized viral particles can pass through the mucus of the respiratory tract and enter other cells or In the blood, causing progressive infection, resulting in a series of clinical symptoms, trachea, bronchi and bronchioles and alveolar duct epithelial cells, after the invasion of influenza virus, degeneration, necrosis and hemorrhage, lymphocytes, plasma cell infiltration As a result, the mucosa is swollen, the cells are detached and the lumen is narrowed, and the gas passes through the obstacle. The most obvious to exhale, causing emphysema, bronchioles gas is absorbed when the obstruction, may occur atelectasis.

Pathogenesis

The alveolar cavity is filled with inflammatory secretions containing neutrophils, monocytes and red blood cells, which seriously affects gas exchange, resulting in varying degrees of O2 deficiency. If progression continues, PO2 decreases, CO2 is retained, and influenza virus toxins are added. Factors such as action and metabolic abnormalities and acid-base balance disorders can cause symptoms such as hyperthermia, coma, convulsions and respiratory and circulatory failure. Fluorescent antibody staining proves that bronchi, bronchioles, alveolar epithelial cells and macrophages in alveoli exist. The virus infects the foci, but not in the vascular endothelial cells. The virus causes lesions in the epithelial cells of the respiratory tract, which reduces the resistance and creates conditions for secondary bacterial infections. The influenza virus infects the lungs, causing congestion, edema, and trachea. Bronchial and bronchiole mucosa congestion, bloody secretions can be seen in the tube, microscopic examination of cilia epithelial cells necrosis, some hyperplasia, submucosal focal hemorrhage and edema and cell infiltration, alveolar fibrin and exudate, mixed Granulocytes and monocytes, some visible transparent membrane, alveolar interstitial thickening.

Pediatric influenza virus pneumonia prevention

For the prevention of influenza virus pneumonia, the influenza should be prevented first, that is, the epidemic situation and virus mutation dynamics at home and abroad are often mastered, and the population immunity status is conducive to epidemic reconnaissance, so that preventive measures can be taken in time to strengthen publicity and education, and strive to achieve five early days. Early detection, early diagnosis, early reporting, early isolation, early treatment, while trying to reduce the chance of transmission, during the influenza epidemic, avoid entering crowded places, the patient's nasopharyngeal secretions and their pollutants should be disinfected at any time, there have been people The vaccine is used for vaccination. The vaccine is mainly type A, but the influenza virus is constantly mutated. The effect is to use attenuated strain to prepare the vaccine in time. The inoculation method of influenza inactivated vaccine is subcutaneous injection once, and replanted at intervals of 6-8 weeks. Once, it is usually carried out from September to October. After the autumn, it will be boosted once a year. The live attenuated vaccine has three kinds of monovalent A-type vaccines: chicken embryo urine live vaccine, whole embryo live vaccine and tissue culture culture live vaccine. The vaccine is inoculated by nasal spray.

Inoculation is better within 1 or 2 months before the epidemic. There are mild respiratory symptoms after vaccination, and some have fever. The effective protection time is 6 months to 1 year. Most observers have proved that the incidence rate can be reduced by 50% to 70%. Under normal circumstances, infants and the elderly are not suitable for vaccination. As for drug prevention methods, such as amantadine hydrochloride, because it can prevent the influenza virus from entering the human cells, it has a certain preventive effect. 100mg, 2 times / d, children reduce, even for 7 to 10 days, the toxicity is excitement, dizziness, ataxia, Ningbo and Hangzhou Health and Epidemic Prevention Station reported that morpholin (viral) is obvious to influenza A The effect of Chinese herbal medicine for preventing influenza can be tested in a variety of unilateral and compound Chinese herbal medicines. It has gained a lot of experience and deserves further study and observation.

Pediatric influenza virus pneumonia complications Complications pleural effusion pulmonary edema shock myocarditis

Can be complicated by pulmonary edema, pleural effusion; nervous system damage can occur toxic encephalopathy and cerebral edema; cardiovascular dysfunction, shock, easy to develop myocarditis, pericarditis; often with Reye syndrome; and can cause kidney disease, performance For hematuria, proteinuria; influenza pneumonia complicated by bacterial infections, common pathogens are Staphylococcus aureus, pneumococci, Haemophilus influenzae and hemolytic streptococcus, etc., the lesion can be bronchial pneumonia, large leaves Pneumonia or lung abscess, mostly manifested as simple influenza virus pneumonia, fever, fever and fever, systemic poisoning symptoms, elevated body temperature, increased cough, difficulty breathing, obvious cyanosis, chest auscultation has extensive wet voice, percussion Voiced, bloody white blood cells and neutrophils significantly increased, occasionally complicated by encephalitis, DIC and other diseases.

Pediatric influenza virus pneumonia symptoms common symptoms high fever wheezing vocal leukopenia diarrhea pronunciation coma convulsions intestinal bleeding

According to the cases seen in Tianjin in 1953, the influenza A virus (H1N1) was isolated. The clinical points are as follows:

1. Incidence: Most of the high fever persisted after 48 hours of onset, and a small number of patients gradually increased after 2 to 3 days of moderate fever.

2. Respiratory symptoms and signs: significant respiratory symptoms, severe wheezing, and sometimes asthma after fever, lung signs such as percussion dullness, changes in breath sounds and small wet voices or sputum pronunciation, gradually occur after onset, visible in the chest The effusion, mostly yellow mixed liquid, varies from tens to hundreds of milliliters. In a few cases, it has seen redness and swelling of the pharynx, a pseudomembrane, and easy peeling.

3. Digestive system: common vomiting, diarrhea, vomiting is sometimes very heavy, and even spit out coffee; diarrhea or pneumonia, or when the respiratory symptoms improve, and some severe cases with intestinal bleeding, the prognosis is poor.

4. Nervous system: Sometimes the symptoms of the nervous system are significant, even in the early stage, there is persistent coma, or convulsions occur. The cerebrospinal fluid examination is normal except for a slightly higher pressure.

5. Laboratory examination: Leukopenia, increased percentage of lymphocytes.

6. X-ray examination: In most cases, the lung fields on both sides of the hilum have irregular floccular or small spherical shadows, which are not extensive; in a few cases, large shadows can occur, in the short-term flu epidemic Many infants and young children have the same disease at the same time, continue to have high fever, and have symptoms and signs of pneumonia. When using antibiotics, the diagnosis of influenza pneumonia should be considered. The diagnosis requires virological examination for the separation and duplicate of nasopharyngeal secretion or throat swab virus. Serum erythrocyte agglutination inhibition test or complement fixation test, but it is still difficult to popularize in general hospitals. In recent years, monoclonal antibody indirect immunofluorescence method has been used for rapid virus diagnosis, and positive patients have diagnostic significance.

Pediatric influenza virus pneumonia check

1. Blood: Leukopenia can be as low as (1~2)×10 ⁹ /L, the percentage of lymphocytes is increased. Although there are no bacterial secondary infections in some influenza pneumonia, the total number of white blood cells and neutrophils can also increase. There is a nuclear left shift, and when the bacterial infection occurs, the blood leukocytes and neutrophils are significantly increased.

2. Cerebrospinal fluid examination: cerebrospinal fluid examination, except for increased pressure, other changes are not large, sometimes mild protein elevation.

3. Urine examination: kidney disease has hematuria, proteinuria.

4. Blood biochemistry: normal or rapid erythrocyte sedimentation rate, elevated blood ammonia, etc.

5. Virus isolation and serological examination: collection of pharyngeal secretions in children with acute phase, preferably collected within 3 days, the positive rate of separation gradually decreased after 3 days, foreign reports that nasopharyngeal lotion is higher than throat swab, the specimen should be Inoculated in the embryonic amniotic cavity of 10-12 days, or inoculated in primary human embryonic kidney or monkey kidney cells, but the sensitivity of the latter is not as good as the former, and the serum and antibody in the acute phase and recovery period should be taken for blood. Condensation inhibition test and complement fixation test, the serum antibody in the recovery period is greater than or equal to 4 times of the acute phase, which is positive, 16 hours earlier than the blood coagulation phenomenon, 48 hours earlier than the cytopathic effect. The difference between the immunoenzymatic staining method and the immunofluorescence method is different. The enzyme-labeled antibody was used for the detection, and as a result, the nucleus on the cell surface and/or the cytoplasm stained brown-yellow were positive cells.

6. X-ray examination: In most cases, the lung fields on both sides of the hilum have irregular floccular or small spherical shadows, which are not extensive; in a few cases, large shadows can occur.

7. Electrocardiogram: When the myocardial damage occurred, the electrocardiogram was abnormal.

8. B-ultrasound: There is a liver enlargement.

Diagnosis and identification of pediatric influenza virus pneumonia

diagnosis

Diagnosis is based on clinical manifestations.

Differential diagnosis

The disease should be differentiated from other viral pneumonia and tuberculosis.

1. Viral pneumonia is a bronchial pneumonia caused by a variety of viral infections, which occurs mostly in winter and spring. Clinical manifestations are generally mild. The main symptoms are dry cough, fever, difficulty breathing, purpura and loss of appetite, less signs of lungs, normal or slightly elevated white blood cell count. Chest X-ray examination has patchy inflammatory shadows, and the general course of disease is about 1-2 weeks.

2. Tuberculosis is a chronic infectious disease caused by Mycobacterium tuberculosis, which can invade many organs. Pulmonary tuberculosis is the most common form of pulmonary tuberculosis, and it is an important source of infection. Human infection with tuberculosis does not necessarily occur, and when the resistance is reduced or the cell-mediated allergic reaction is increased, it may cause clinical disease. The basic pathological features of the disease are exudation, caseous necrosis and other proliferative tissue reactions, which can form voids. In addition to a few onset of acute convulsions, clinically many chronic processes, manifested as low-heat, weight loss, fatigue and other systemic symptoms and cough, hemoptysis and other respiratory manifestations, if timely diagnosis, and reasonable treatment, most can be clinically cured.

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