Pediatric bronchiolitis

　　1. Etiology

　　Bronchiolitis can be caused by different viruses, respiratory syncytial virus (RSV) is the most common pathogen. In the cases observed in the Department of Pediatrics of the Academy of Medical Sciences of China, 58% were isolated with syncytial virus. In addition, parainfluenza virus (type 3 is more common), adenovirus, influenza virus, enterovirus, and rhinovirus can all cause bronchiolitis. A few are caused by human pneumonia mycoplasma. In the past, Haemophilus influenzae was occasionally isolated from children with this disease, which may be the pathogen in extremely rare cases, but it may also be a carrier or a mixed infection of bacteria and viruses.

　　2. Pathogenesis

　　The lesion mainly involves capillary bronchi with diameters of 75～300μm, with increased mucus secretion, cellular debris, fibrous obstruction, necrosis of epithelial cells, and infiltration of lymphocytes around the bronchi, inflammation can spread to alveoli, alveolar walls, and interstitial lung tissue, pulmonary atrophy and emphysema are more obvious.

　　Pediatric bronchiolitis is prone to respiratory failure, brain edema, heart failure, and other complications; dehydration and metabolic acidosis may occur. These have a serious impact on the health of patients, so it is necessary to treat the disease in a timely manner once the symptoms are found.

　　Persistent dry cough and episodic dyspnea may appear 2-3 days after an upper respiratory tract infection, with cough and dyspnea occurring simultaneously as a characteristic of the disease. The severity of symptoms varies, with severe cases developing dyspnea rapidly. The cough is slightly similar to whooping cough. Initially, respiratory symptoms are much more severe than toxic symptoms, with episodic dyspnea, varying body temperature, low fever (even without fever), moderate fever, and high fever accounting for about 1/3 each. There is no parallel relationship between body temperature and general condition. Generally, although there may be vomiting, it is not severe, and there is also no severe diarrhea. Due to emphysema and chest expansion compressing the abdomen, it is often easy to affect breastfeeding and eating. During the attack of dyspnea, breathing is fast and shallow, often accompanied by expiratory wheezing. The respiratory rate is about 60-80 times/min, even more than 100 times/min, the pulse is fast and thin, often reaching 160-200 times/min, with obvious nasal flaring and tracheal depression.

　　Rational feeding, good hygiene habits, avoiding contact with children with colds and other patients, not going to public places with poor air circulation, are the basic measures for preventing acute bronchiolitis. In winter, when the temperature fluctuates greatly, it is necessary to prevent respiratory diseases, first of all, to pay attention to keeping warm. At the same time, in autumn and winter, the air is very dry, and the dust content in the air is high. The nasal mucosa of the human body is easily damaged, so it is necessary to drink more water, maintain appropriate indoor humidity, and appropriately supplement vitamins, especially vitamin C, etc.

　　1. Blood count

　　The total white blood cell count and classification are mostly within the normal range, with neutrophils usually below 60%, and eosinophils are normal.

　　2. Blood gas analysis

　　In infants with severe illness, blood gas analysis may show metabolic acidosis, about 1/10 of the cases may have respiratory acidosis. Blood gas examination may show a decrease in blood pH, PaO2 and SaO2, and PaCO2 may decrease (hypercapnia) or increase (CO2 retention).

　　3. Pathogen examination

　　Rapid diagnosis of viruses can be made using immunofluorescence technology, enzyme-labeled antibody staining method, or ELISA, etc. Units with conditions can perform virus isolation and double-serum tests to determine various viral infections. Nasopharyngeal swab bacterial culture is not significantly different from healthy children (both may have bacterial carriage).

　　4. X-ray examination

　　It can be seen that the whole lung has varying degrees of obstructive emphysema, and the radiograph can show signs of bronchitis around the bronchi, or the lung vessels may be thickened. In many cases, the alveoli are also significantly affected, with small spots and patches of shadow, but without extensive consolidation, and it is different from adenovirus pneumonia.

　　5. Electrocardiogram

　　The heart rate may increase, and there may be signs of myocardial damage.

　　6. X-ray chest film examination

　　There are obvious signs of emphysema, and antibiotic treatment is ineffective, so it is easily distinguished from other acute pneumonia.

　　Children with capillary bronchitis should rest well, keep the bedroom air flowing, and maintain a suitable temperature and humidity. If there is a smoker in the family, it is best to quit smoking or smoke outside to prevent the adverse effects of smoke on the child. Give easily digestible food and drink plenty of water. Parents should adopt the method of small and frequent meals for children, and provide light, nutritionally rich, balanced, and easy-to-digest semi-liquid or liquid diet, such as congee, well-cooked noodles, egg custard, fresh vegetables, fruit juice, etc.

　　One. Treatment

　　1. Promoting Sputum Expectoration Increasing humidity in the air is extremely important, and generally an indoor humidifier can be used. Rational application of nebulization therapy for severe cases can be helpful for children, and nebulizers can be combined with oxygen for nebulization; ultrasonic nebulization is only used when there is a blockage in the respiratory tract, for 20 minutes each time, 3-4 times a day, and after nebulization, the back should be tapped to remove sputum. Application of heated humidification can sometimes make the child calm down. As for the method of directly rinsing the throat and pharynx and aspirating sputum from the larynx and bronchi, it can only be used for individual cases under the cooperation of otorhinolaryngology with the use of a laryngoscope.

　　2. Correcting Hypoxia For those with severe shortness of breath, the head and chest should be elevated to reduce respiratory distress; when obvious hypoxia occurs, it is best to use a nebulizer to provide oxygen, and the mask should be connected, or a hood can be used; for mild hypoxia cases, if conditions permit, cold air therapy can be tried, or oxygen can be administered through a nasopharyngeal tube, with the tip of the catheter placed in the anterior nares.

　　3. To relieve asthma during an attack, it is advisable to use promethazine to relieve bronchospasm, usually taken orally at a dose of about 1mg/(kg·time), three times a day, or bronchodilator inhalation can also be used. If restlessness is significant, it can be combined with an equal amount of chlorpromazine (dormition No. 2) for intramuscular injection, and chloral hydrate can be added to enhance the sedative effect. If the effect is still not obvious, hydrocortisone or dexamethasone can be administered intravenously, and infused within a few hours. If the shortness of breath is very severe and general methods are difficult to control, a trial can be made to slowly inject 3-5ml/kg of 5% sodium bicarbonate intravenously, which may produce significant effects. Phen妥拉明 and metaraminol (aramine) can also be tried for intravenous infusion or slow intravenous injection, or scopalamine can be administered intravenously. Recently, some people have reported using magnesium sulfate for intravenous infusion; vitamin K3 for nebulized inhalation; and small-dose isoproterenol for intravenous infusion to treat capillary bronchitis attacks. It can also be cautiously tried.

　　4. In order to maintain water and electrolyte balance, multiple oral rehydration solutions should be taken to supplement the water lost during rapid breathing. If insufficient, intravenous fluid administration can be used, usually with 10% glucose solution, with a small amount (about 1/5 of the volume) of normal saline added; in case of metabolic acidosis, 1/6g molecular concentration (1.4%) sodium bicarbonate can be administered intravenously. If blood gas measurement conditions are available, the formula can be used to calculate the amount of sodium bicarbonate to be administered: [0.3 × body weight (kg) × residual alkali (negative value) = molar equivalent number of sodium bicarbonate administered]. The first half of the total amount should be administered first, and the remaining half can be administered according to the situation.

　　5. Keeping the respiratory tract unobstructed. For respiratory acidosis, it is advisable to use atomization sputum aspiration to keep the respiratory tract unobstructed. For individual cases of extremely severe respiratory failure, tracheal intubation and assisted ventilation can be performed.

　　6. Correct heart failure. When concurrent heart failure occurs, it is necessary to use digitalis preparations in a timely manner. For suspected cases of heart failure, it can also be tried early.

　　7. For children suspected of having asthma, a small dose of adrenaline can be tried, and it will not be repeated if it is ineffective.

　　8. Recently, some people have tried interferon atomization therapy, which has a therapeutic effect on this disease and wheezing bronchitis. For children who can take herbal medicine, traditional Chinese medicine treatment is better. Generally, the herbal medicine can be modified with Herba Ephedrae, Radix Isatidis, and Radix Platycodon. For those with obvious heat signs such as yellow fur and red tongue, modified Mahuang Suanbing decoction can be used. Since this condition is caused by a virus, antibiotics are generally not needed. However, when the isolation conditions are poor, penicillin can be used to control secondary bacterial infections. If secondary infections such as Staphylococcus aureus or Haemophilus influenzae are found, active antibacterial treatment should be carried out. The atomization inhalation of ribavirin (triazine nucleoside) has a good therapeutic effect, as proven by Chinese research. The atomization inhalation of Shuanghuanglian also has a significant effect, and interferon α can be added. See also the antiviral treatment for RSV pneumonia.

　　Second, prognosis

　　The course of the disease is generally 5-15 days, with an average of 10 days. It can be shortened with appropriate treatment. Within 2-3 days after the onset of cough and asthma, the condition is often severe. After proper treatment, most patients recover rapidly and improve within a few days. The prognosis in recent years is generally good. The mortality rate is about 1% in hospitalized patients with bronchiolitis. The risk of death is high in infants with pre-existing heart, lung diseases, and other congenital malformations, as well as newborns and premature infants. Death is often due to prolonged shortness of breath, apnea, respiratory failure, non-compensatory respiratory acidosis, and severe dehydration acidosis. Children are prone to recurrent wheezing within a few years after the disease. Long-term follow-up observation shows that 22.1% to 53.2% of children have asthma.