Acute bronchiolitis in children

Bronchiolitis is an acute infectious disease of viral etiology with damage to the lower respiratory tract, occurring in children under 18 months and characterized by respiratory failure, wheezing and wheezing of various sizes. The diagnosis is suspected by the anamnesis, including an epidemic history; the etiologic agent, respiratory syncytial virus, can be identified using a rapid test. Treatment of bronchiolitis in children is supportive - oxygen and hydration.

Bronchiolitis occurs frequently in epidemics, predominantly in children under 18 months of age, with a peak incidence in infants under 6 months of age. The annual incidence in infants is approximately 11 cases/100 children. Most cases occur from November to April, with a peak incidence during January and February.

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What causes acute bronchiolitis in children?

Most cases are caused by respiratory syncytial virus and parainfluenza virus type 3; less common causes include influenza A and B viruses, parainfluenza types 1 and 2, metapneumovirus, and adenoviruses. Rare causes include rhinoviruses, enteroviruses, measles virus, and Mycoplasma pneumoniae.

The virus spreads from the upper respiratory tract to the medium and small bronchi and bronchioles, causing epithelial necrosis. The resulting edema and exudation lead to partial obstruction, which is most pronounced during exhalation and leads to the formation of an air trap. Complete obstruction and air absorption from the alveoli lead to the formation of multiple areas of atelectasis.

Symptoms of acute bronchiolitis

The child typically presents with symptoms of an acute upper respiratory tract infection with progressive respiratory failure characterized by tachypnea, chest wall retractions, and cough. Young children may present with recurrent apneic episodes, with more typical symptoms of bronchiolitis appearing 24 to 48 hours later. Signs of respiratory distress may include perioral cyanosis, increasing chest wall retractions, and wheezing. Fever is usually, but not always, present. The child is initially well with no signs of respiratory distress other than tachypnea and chest wall retractions, but may rapidly deteriorate as the infection progresses, leading to lethargy. Dehydration may develop due to vomiting and decreased fluid intake. As weakness progresses, breathing may become more shallow and ineffective, leading to respiratory acidosis. Auscultation reveals wheezing, prolonged expiration, and often fine, moist rales. Many children develop acute otitis media at the same time.

Diagnosis of acute bronchiolitis

The diagnosis is suspected based on the history, examination, manifestations of the disease, and its development into an epidemic. Symptoms similar to bronchiolitis may occur in asthma, which is more common in children over 18 months of age, especially in the presence of a history of wheezing and a family history of asthma. Gastroesophageal reflux with aspiration of gastric contents may also cause a clinical picture of bronchiolitis; multiple episodes in an infant may be a clue to this diagnosis. Foreign body aspiration rarely presents with wheezing and should be considered if there is a sudden onset not associated with manifestations of acute upper respiratory tract infection.

Patients suspected of having bronchiolitis should have pulse oximetry to assess oxygenation. No further testing is needed in mild cases with normal oxygenation, but in cases of hypoxemia, a chest radiograph should be obtained to confirm the diagnosis. The radiograph usually shows a flattened diaphragm, increased lung field transparency, and a marked hilar reaction. Infiltrative shadows due to atelectasis or RSV pneumonia, which are relatively common in children with RSV bronchiolitis, may be present. A rapid test for RSV antigen, done on a nasal swab or wash, is diagnostic but not always necessary; it can be reserved for patients severe enough to require hospitalization. Other laboratory tests are nonspecific; about two-thirds of children have a leukocytosis of 10,000-15,000/μL. Most people have 50-70% lymphocytes in their white blood cell count.

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Treatment of acute bronchiolitis

Treatment of acute bronchiolitis is supportive; most children can be treated at home with comfort and adequate hydration. Indications for hospitalization include increasing respiratory distress, severity of illness (cyanosis, weakness, lethargy), history of apnea, and presence of atelectasis on chest radiograph. Children with underlying conditions such as cardiac disease, immunodeficiency, or bronchopulmonary dysplasia that increase the severity of illness and the risk of complications should also be considered for hospitalization. In hospitalized children, 30-40% O is given by tent or mask. This is usually sufficient to maintain oxygen saturation greater than 90%. Tracheal intubation is indicated for severe recurrent apneas, hypoxemia unresponsive to oxygen, or CO2 retention, or if the child is unable to clear secretions from the bronchi.

Hydration should be maintained by frequent small fluids. Infusion therapy is indicated for children in more severe condition, the level of hydration should be assessed by monitoring urine output and specific gravity, as well as blood electrolytes.

There is evidence that systemic administration of glucocorticoids may be effective when administered early or in patients with diseases sensitive to glucocorticoid therapy (bronchopulmonary dysplasia, bronchial asthma), but for most hospitalized children the effect has not been proven.

Antibiotics should be avoided unless secondary bacterial infection (a rare complication) occurs. Bronchodilators are not always equally effective, but a significant proportion of children experience short-term improvement. This is especially true for children with a history of wheezing. Hospital stays are unlikely to be shortened.

Ribavirin, an antiviral drug with in vitro activity against RSV, influenza, and measles viruses, is not effective in the clinic and is no longer recommended for use; it is also potentially toxic to hospital staff. Anti-RSV immunoglobulin has been tried, but is not reliably effective.

How to prevent acute bronchiolitis in children?

Prevention of respiratory syncytial infection is carried out by passive immunoprophylaxis with monoclonal antibodies to RSV (palivizumab). This reduces the frequency of hospitalizations, but this is an expensive method and is indicated for children from the high-risk group.

What is the prognosis for acute bronchiolitis in children?

Acute bronchiolitis in children has a favorable prognosis; most children recover within 3-5 days without sequelae, the mortality rate is less than 1% with adequate medical care. Children who have had bronchiolitis in early childhood are expected to develop bronchial asthma, but this relationship is controversial.