2. ETIOLOGY B ronchiolitis is a disease of small bronchioles with increase mucus production and sometimes leading to airway obstruction. Respiratory syncytial virus (RSV) is a primary cause of bronchiolitis, followed in frequency by human meta - pneumovirus, parainfluenzaviruses, adenoviruses, rhinoviruses, coronaviruses, and Mycoplasma pneumoniae. Viral bronchiolitis is extremely contagious and is spread by contact with infected respiratory secretions. 1

3. EPIDEMIOLOGY Bronchiolitis occurs almost exclusively during the first 2 years of life, with a peak age at 2 to 6 months. Premature infants and children with chronic lungs disease of prematurity, significant congenital heart disease, neuromuscular weakness,or immunodeficiency are at increased risk of severe, potentially fatal disease. Children acquire infection after exposure to infected family members who typically have symptoms of an upper respiratory tract infection, or from infected children in day care. Annual peak are usually in the late winter months from December through March. 2

4. CLINICAL MANIFESTATIONS Bronchiolitis caused by RSV has an incubation period of 4 to 6 days, Bronchiolitis classically presents as a progressive respiratory illness similar to common cold in its early phase with cough & rhinorrhea. It progress over 3 to 7 days to noisy, raspy breathing and audible wheezing. There is a low grade fever accompanied by irritability. Yong infants with RSV may not have a prodrome and may have apnea as the first sign of infection. 3

5. Physical signs of bronchiolar obstruction include prolongation of the expiratory phase of breathing,nasal flaring, inter costal retractions, suprasternal retractions,and air trapping with hyperexpansion of the lungs. During the wheezing phase, percussion of the chest usually reveals only hyperresonance, but auscultation usually reveals diffuse wheezes and crackles throughout the breathing cycle. With more severe disease, grunting and cyanosis may be present. 4

6. LABORATORY AND IMAGINGS STUDIES It is important to assess oxygenation in severe case of bronchiolitis. Pulse oximetry is adequate for monitoring oxygen saturation, monitoring of cardiorespiratory system is necessary because respiratory failure may develop precipitously in very tired infants even through blood gas values taken before rapid decompensation are reassuring. Antigen test (by immunoflurescence or enzyme linked immunosorbent assay ELISA) of nasopharyngeal secretion for RSV, parainfluenza viruses,influenza viruses,and adenoviruses are sensitive test to confirm the infection,but chest radiograph frequently show signs of lungs hyper inflation including increased lung lucency and flattened or depressed diaphragms. Areas of increased density may represent either viral pneumonia or localized atelectasis. 5

7. DIFFERENTIAL DIAGNOSIN The major difficulty in the diagnosis of bronchiolitis is to differentiate other disease associated with wheezing, like asthma, foreign body,cystic fibrosis,viral or bacterial pneumonia, cardiogenic asthma, is wheezing associated with pulmonary congestion secondary to left-sides heart failure. Wheezing associated with gastroesophageal reflux. 6

8. TREATMENT Bronchiolitis treatment consist of supportive therapy, including respiratory monitoring control of fever, hydration,upper airway suctioning, and if needed oxygen administration. Indications for hospitalization include moderate to marked respiratory distress, hypoxemia, apnea, inability to tolerate oral feeding, and lack of appropriate care at home. Hospitalization of high-risk children with bronchiolitis should be considered. Among hospitalized infants, oxygen by nasal cannula is often necessary, but intubation and ventilatory assistance for respiratory failure or apnea are required in less than 10% of these infants. 7

9. COMPLICATIONS AND PROGNOSIS Most hospitalized children show marked improvement in 2 to 5 days with supportive treatment alone. Tachypnea and hypoxia may progress to respiratory failure requiring assisted ventilation. Apnea is a major concern for very young infant with bronchiolitis. Most cases of bronchiolitis resolve completely although bronchial hyperreactivity may persist for several years. Recurrence is common but tends to be mild. The incidence of asthma seems to be higher for children hospitalized for bronchiolitis as infants mortality is a 1% to 2%, highest among infants with preexisting cardiopulmonary or immunologic impairment. 8

10. PREVENTION Monthly injection of palivizumab, it is RSV specific monoclonal antibody, initiated just before the onset of RSV season, used for children under 2 years old with chronic lung disease, very low birth weight and those with significant cyanotic and acyanotic congenital heart disease. Immunization with influenza vaccine for all children older than 6 months and many prevent influenza - associated disease. 9

11. A wheeze is a musical and continuous sound that originates from oscillations in narrowed airways. Wheezing is polyphonic (asthma) or monophonic as in tracheomalacia and bronchomalasia. Obstruction occurs in the extrathoracic airways during inspiration, the noise is stridor. 11

12. Human metapneumovirus and human bacovirus which may be a primary cause of viral respiratory infection or occur as a co-infection with RSV. Other risk factors, infants with young mother or mothers who smoked during pregnancy. Co-infection with > 1 virus can alter the clinical manifestations and / or severity of presentation. 12

13. Three patterns of infant wheezing are: 1- Transient early wheezer. 2- Persistent wheezer. 3- Late onset wheezer. 13

14. The Transient early wheezer constituted 19.9% of general population, and they had wheezing at least once with a lower respiratory infection before the age of 3 years but never wheezed again. The persistent wheezer constituted 13.7% of general population, had wheezing episode before age 3 years and were still wheezing at 6 years of age. 14

15. The late-onset wheezer constituted 15% of the general population, has no wheezing by 3 years but was wheezing by 6 years. The other ½ of children had never wheezed by 6 years, of all the infants who wheeze before 3 years old almost 60% stopped wheezing by 6 years. 15

16. Frequent suctioning of nasal and oral secretions often provides relief of distress or cyanosis. Suctioning of secretions is an essential part of the treatment of bronchiolitis. Prevention of bronchiolitis Reduction in the severity and incidence of acute bronchiolitis due to RSV is possible through the administration of pooled hyperimmune RSV iv immunoglobulin and 16

17. Palivizumb, an IM monoclonal antibody to RSV F protein before and during RSV season. Palivizumab considered for infants < 2 years of age with chronic lung disease, history of prematurity and congenital heart disease. 17

18. ETIOLOGY AND EPIDEMIOLOGY Croup or laryngotracheobronchitis, is the most common infection of the middle respiratory tract. The most common cause of croup are Parainfluenza viruses (type 1,2,3, and 4) and respiratory syncytial virus. Larygotracheal airway inflammation disproportionately affects children in diameter secondary to mucosal edema and inflammation exponentially increases airway resistance and the work of breathing. During inspiration, the wall of the subglottic space are drawn together, aggravating the 1

19. the obstruction and producing the stridor which is characteristic of croup. Croup is most common in children 6 months to 3 years of age, with a peak in fall and early winter. It typically follows a common cold. Symptomatic reinfection is common, yet reinfections are usually mild. In adolescents, it manifests as laryngitis. ETIOLOGY AND EPIDEMIOLOGY 2

20. CLINICAL MANIFESTATIONS The manifestations of croup are a harsh cough described as barking or brassy, hoarseness, inspiratory stridor, low-grade fever, and respiratory distress that may develop slowly or quickly. Stridor is a harsh, high –pitched respiratory sound produced by turbulent airflow. It is usually inspiratory,but it may be biphasic and is a sign of upper airway obstruction. Signs of upper airway obstruction,such as labored breathing and marked suprasternal, intercostal,and subcostal retractions, may be evident on examination wheezing may be present if there is associated lower airway involvement. 3

21. LABORATORY AND IMAGING STUDIES Anteroposterior radiographs of the neck often show the diagnostic subglottic narrowing of croup known as the steeple sign. Routine laboratory studies are not useful in establishing the diagnosis. Leukocytosis is uncommon and suggests epiglottitis or bacterial tracheitis. Many rapid test (using polymerase chain reaction or fluorescent antibodies) are available for parainfluenza viruses, respiratory syncytial virus, and other less common viral causes of croup, such as influenza and adenoviruses. 4

22. DIFFERNTIAL DIAGNOSIS The diagnosis of croup usually is established by clinical manifestation. The infectious differential diagnosis includes epiglottitis,bacterial tracheitis, and parapharyngeal abscess. Noninfectious cause of stridor include mechanical and anatomic causes (foreign body aspiration,laryngomalacia, subglottic stenosis hemangioma, vascular ring, vocal cord paralysis). Stridor in infants younger than 4 months of age or persistence of symptoms for longer than 1 week indicates an increased probability of another lesion and the need for imaging and direct laryngoscopy. 5

23. DIFFERNTIAL DIAGNOSIS Epiglottitis is a medical emergency because of the risk of sudden airway obstruction. This illness is now rare and usually caused by group A streptococcus or Staphylococcus aureus or Haemophilus influenza type b in unimmunized patients. Patients typically prefer sitting. Often with the head held for ward, the mouth open, and the jaw thrust forward (sniffing position). Lateral radiograph reveals thickened and bulging epiglottis (thumb sign) and swelling of the aryepiglottic folds. The diagnosis is confirmed direct observation of the inflamed and swollen 6

24. DIFFERNTIAL DIAGNOSIS cherry-red epiglottitis,which should be performed only in the operating room with an anesthesiologist and a competent surgeon prepared to place an endotracheal tube or perform a tracheostomy if needed. Epiglottitis requires antibiotic therapy and endotracheal intubation to maintain the airway. Clinical recovery is rapid and most children can be extubated safely within 48 to 72 hours. 7

25. DIFFERNTIAL DIAGNOSIS Bacterial tracheitis is a rare but serious superinfection of the trachea that may follow viral croup and is most commonly caused by S.aureus. Spasmodic croup describes sudden onset of croup symptoms, usually at night, but without a significant upper respiratory tract prodrome. These episodes may be recurrent and severe but usually are of short duration. Spasmodic croup has a milder course than viral croup and responds to relatively simple therapies, such as exposure to cool or humidified air. The etiology is not well understood, and may be allergic. 8

26. TREATMENT Oral or intramuscular dexamethasone for children with mild, moderate, or severe croup reduces symptoms, the need for hospitalization, and shortens hospital stays. Dexamethasone phosphate (0.6 to 1 mg/kg) once orally. Alternatively prednisolone (2 mg/kg per day) may be given orally in two to three divided doses. For significant airway compromise administration of aerosolized racemic (D – and L-) epinephrine reduces subglottic edema by adrenergic vasoconstriction, temporary producing marked clinical improvement. The peak effect is within 10 to 30 minutes and fades within 60 to 90 minutes. A rebound effect may occur, with worsening of symptoms as the effect of the drug dissipates. 9

27. TREATMENT Aerosol treatment may need to be repeated every 20 minutes (for no more than 1 to 2 hours) in severe cases. Children should be kept as clam possible to minimize forceful inspiration. One useful calming method is for a child with croup to sit on the parent’s lap. Sedatives should be used cautiously and in the intensive care unit only. Cool mist administrator by face mask may help prevent drying of the secretions around the larynx. 10

28. TREATMENT Hospitalization is often required for children with stridor at rest. Children receiving aerosol treatment should be hospitalized or observed for at least 2 to 3 hours because of the risk of rebound airway obstruction. Decreased symptoms may indicate improvement or fatigue and impending respiratory failure. 11

29. COMPLICATIONS AND PROGNOSIS The most common complication of croup is viral pneumonia, which occurs in 1% to 2% of children. Parainfluenza virus pneumonia and secondary bacterial pneumonia are more common in immunocompromised persons. Bacterial tracheitis may also be a complication of croup. The prognosis for croup is excellent. Illness usually lasts approximately 5 days. As children grow, they become less susceptible to the airway effects of viral infections of the middle respiratory tract. 12

30. PREVENTION There is no vaccine for Parainfluenza. 13