Bronchiolitis Abdullah M. Al-Olayan MBBS, SBP, ABP. Assistant Professor of Pediatrics. Pediatric Pulmonologist.

Objectives ① Discuss the epidemiology, etiology and clinical manifestations of acute bronchiolitis. ② Discuss the differential diagnosis. ③ Discuss the diagnostic evaluation for recurrent wheezing. ④ Discuss the treatment of acute bronchiolitis.

Etiology  Bronchiolitis is a disease of small bronchioles with increased mucus production and occasional bronchospasm, sometimes leading to airway obstruction.  Bronchiolitis is most commonly seen in infants and young children.  Respiratory syncytial virus (RSV) is a primary cause of bronchiolitis.

 Other causative organisms : ① Human metapneumovirus. ② Parainfluenza viruses. ③ Pnfluenza viruses. ④ Adenoviruses. ⑤ Rhinoviruses. ⑥ Coronaviruses. ⑦ Mycoplasma pneumoniae. Etiology

 Viral bronchiolitis is extremely contagious and is spread by contact with infected respiratory secretions.  Hand carriage of contaminated secretions is the most frequent mode of transmission. Etiology

Epidemiology  Bronchiolitis is a leading cause of hospitalization of infants.  Bronchiolitis occurs almost exclusively during the first 2 years of life.  Peak age at 2 to 6 months.  In the US, annual peaks are usually in the late winter months from December through March.

 Bronchiolitis caused by RSV has an incubation period of 4 to 6 days.  its early phase started by cough and rhinorrhea.  It progresses over 3 to 7 days to : ① Noisy, and rapid breathing. ② Audible wheezing. ③ Low-grade fever. ④ Irritability. ⑤ Decreased oral intake. Clinical Manifestations

 Young infants infected with RSV may have apnea as the first sign of infection.  Physical signs include : ① Wheezing and crackles with Prolongation of the expiratory phase ② Nasal flaring. ③ Suprasternal and Intercostal retractions. ④ Air trapping with hyperexpansion of the lungs. ⑤ With more severe disease, grunting and cyanosis may be present. Clinical Manifestations

Laboratory and Imaging  Routine laboratory tests are not required to confirm the diagnosis. ① Pulse oximetry is adequate for monitoring oxygen saturation. ② Frequent, regular assessments and cardiorespiratory monitoring of infants are necessary because respiratory failure may develop. ③ Antigen tests of nasopharyngeal secretions for RSV, parainfluenza viruses, influenza viruses, and adenoviruses are sensitive tests to confirm the infection.

 Chest radiographs frequently show signs of lung hyperinflation, including : ① Increased lung lucency. ② Flattened or depressed diaphragms.  Areas of increased density may represent either viral pneumonia or localized atelectasis. Laboratory and Imaging

Differential Diagnosis  Asthma : ① Age of presentation. ② Presence of fever. ③ Absence of personal or family history of asthma.

 Airway foreign body.  Congenital airway obstructive lesion.  Cystic fibrosis.  Exacerbation of chronic lung disease.  Viral or bacterial pneumonia.  Cardiogenic asthma.  GERD. Differential Diagnosis

Treatment  Supportive therapy : ① Oxygen administration, if needed. ② Respiratory monitoring. ③ Control of fever. ④ Hydration. ⑤ Upper airway suctioning. ⑥ Bronchodilators and corticosteroids are seldom effective and are not generally recommended.

 Indications for hospitalization : ① Moderate to marked respiratory distress. ② Hypoxemia. ③ Apnea. ④ Inability to tolerate oral feeding. ⑤ Lack of appropriate care available at home. ⑥ High-risk children. Treatment

Complications and Prognosis  Most hospitalized children show marked improvement in 2 to 5 days.  Tachypnea and hypoxia may progress to respiratory failure requiring assisted ventilation.  Most cases of bronchiolitis resolve completely.  Recurrence is common but tends to be mild and should be assessed and treated similarly to the first episode.

 The incidence of asthma seems to be higher for children hospitalized for bronchiolitis as infants.  There is a 1% to 2% mortality rate, highest among infants with preexisting cardiopulmonary or immunologic impairment. Complications and Prognosis

Prevention  Monthly injections of palivizumab, an RSV specific monoclonal antibody.  Initiated just before the onset of the RSV season.  Indications :  Infants under 2 years old with : ① chronic lung disease with prematurity. ② Very low birth weight. ③ Hemodynamically significant cyanotic and acyanotic congenital heart disease.

 Immunization with influenza vaccine is recommended for all children older than 6 months and may prevent influenza- associated disease. Prevention

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