Acute bronchiolitis is a common lower respiratory tract viral infection in infants under 2 years old, often caused by respiratory syncytial virus. It involves inflammation of the bronchioles and leads to respiratory distress. Management focuses on supportive care through hydration, oxygen therapy, and monitoring for complications like pneumonia or respiratory failure. Prevention emphasizes hand hygiene and palivizumab prophylaxis for high-risk infants.

1. Acute Bronchiolitis
AIMIEN Efosa
(MBBS, Zaria)

2. Outline
• Introduction
• Epidemiology
• Etiology
• Pathophysiology
• Risk factors
• Clinical manifestations
• Management
• Complications
• Prognosis
• Prevention
• Conclusion

3. Introduction
• Acute bronchiolitis is a diagnostic term used to describe the clinical
picture produced by several different viral lower respiratory tract
infections in infants and very young children.
• It is as a result of an acute inflammatory injury to the bronchioles that
as caused by a viral infection.
• It is the commonest lower respiratory tract infection in children less
than 1 year of age.

4. Epidemiology
• According to the WHO bulletin, an estimated 150 million new cases
occur annually.
• Over 100,000 young children are hospitalized annually in the United
States with the diagnosis of bronchiolitis,
• About 75% of cases occur in children younger than 1 year, and 95% in
children younger than 2 years.
• Incidence peaks in those aged 2-8 months (3-6months crescendo).
• Male to female ratio – 1.25-2 : 1
• Death is 1.5 times more likely in males.

5. Etiology
• Respiratory syncytial virus: >50% cases
• Human metapneumovirus: 9 – 30%
• Rhinovirus: (16%)
• Parainfluenza
• Influenza (6%)
• Bocavirus
• Adenovirus

6. Pathophysiology
• Bronchiolar injury and the consequent interplay between inflammatory
and mesenchymal cells can lead to diverse pathologic and clinical features:
Day 0 – 2 (upper respiratory tract): Virus damages the upper respiratory
tract epithelial cells which are sloughed to the lower respiratory tract, thus
constituting cellular debris.
Day 3 – 10 (lower respiratory tract): Further epilethial cell invasion.
Increased mucus production. Mucosal edema. Ciliary function impairment.
Proliferation and infiltration of polymorphonuclear cells and lymphocytes.
Air trapping. Atelectasis and ventilation-perfusion mismatch.
The above lead to significant narrowing of the bronchioles.
Day 11 – 22 (upper and lower respiratory tracts): Epithelial regeneration.

7. Risk Factors
• Low birthweight
• Age less than 3 months.
• Low socioeconomic group
• Chronic lung diseases e.g BPD
• Congenital heart or neurological diseases
• Exposure to second-hand tobacco smoke.
• Those who have not been breastfed
• crowded living conditions, daycare centers.
• Risk is also higher for infants with mothers who smoked during pregnancy.
• Older family members, including older siblings with respiratory tract
infection.

8. Clinical Manifestations
• Day 0 – 2
 Rhinorrhea
Nasal congestion
Low grade fever
Mild cough

9. Clinical Manifestations
• Day 3 – 10
Wheezing
Subcostal and intercostal retractions
Cough
Impaired feeding
Cyanosis, apnea
Rhonchi, crackles

10. Management
• Management of a child presenting with features suggestive of acute
bronchiolitis entails detailed history, physical examination, diagnostic
evaluation, treatment and follow-up.

11. Management
• History
usually preceded by exposure to contacts with a minor respiratory
illness within the previous week
The infant first develops signs of upper respiratory tract infection
with sneezing and clear rhinorrhea. This may be accompanied by
diminished appetite and fever. Gradually, respiratory distress ensues,
with paroxysmal cough, dyspnea, and irritability. The infant is often
tachypneic, which can interfere with feeding. Apnea may precede
lower respiratory signs early in the disease, particularly with very
young infants.

12. Management
• History
Birth history includes weeks of gestation, neonatal complications
including history of intubation or oxygen requirement, maternal
complications, and prenatal smoke exposure.
Past medical history includes any comorbid conditions.
Family history of cystic fibrosis, immunodeficiencies, asthma in a first-
degree relative, or any other recurrent respiratory conditions in
children should be obtained.

13. Management
• History
Social history should include any second-hand tobacco or other
smoke exposure, daycare exposure, number of siblings, pets, and
concerns regarding home environment (e.g., dust mites, construction
dust, heating and cooling techniques, mold, cockroaches).
The patient's growth chart should be reviewed for signs of failure to
thrive

14. Management
• Physical examination
Respiratory rate and oxygen saturation is an important initial step.
Wheezing and crackles.
Expiratory time may be prolonged.
Work of breathing may be markedly increased, with nasal flaring and
retractions.
Complete obstruction to airflow can eliminate the turbulence that causes
wheezing; thus the lack of audible wheezing is not reassuring if the infant
shows other signs of respiratory distress.
Poorly audible breath sounds suggest severe disease with nearly complete
bronchiolar obstruction

15. Management
• Diagnostic evaluation
Acute bronchiolitis is a clinical diagnosis and thus investigations to confirm the
diagnosis are seldom needed.
CBC: white blood cell and differential counts are usually normal and are not
predictive of bacterial superinfection, However, may show lymphocytosis
ABG: hypoxia and hypercapnia
Chest X-ray: might show findings misconstrued for bronchopneumonia thus
encouraging the unnecessary use of antibiotics.
Rapid antigen detection for RSV, parainfluenza, influenza and adenovirus
(sensitivity 80=90%)
Immunofluorescence, viral culture and PCR

16. Management
• Differential diagnosis
Bronchopneumonia
Asthma
Foreign body aspiration
GERD

17. Management
• Admission Criteria
SPO2 below 92% in room air
Markedly elevated respiratory rate (>70cpm)
Respiratory distress
Chronic lung disease
Congenital heart disease
Prematurity
Age <3 months
Inability or difficulty with feeding
Parental anxiety

18. Management
• Treatment
Among the many medications and interventions used in the
management of bronchiolitis, only oxygen appreciably improves the
condition of the ailing child.
Healthy children with bronchiolitis usually have limited disease and
do well with supportive care only.
Therapy is directed towards symptomatic relief and maintenance of
hydration and oxygenation.

19. Management
• Treatment
Supportive care includes:
Supplemental humidified oxygen
Maintenance of hydration
Nasal and oral suctioning
Apnea and cardiorespiratory monitoring
Thermoregulation
Mechanical ventilation.

20. Management
• Guidelines for treatment
• In 2006, the American Association of Paediatricians in conjunction
with the America College of Chest Physicians, American Thoracic
Society and American Academy of Family Physicians published the
following recommendations as guideline for the treatment of acute
bronchiolitis.

21. Management
• Treatment guidelines
Diagnosis and severity should be based on history and physical
findings.
Bronchodilators should not be routinely used.
Corticosteroids should not be routinely used.
Ribavirin should not be routinely used.
Antibiotics should be used only upon proven bacterial co-infection,
Hydration and the ability to take oral fluids should be assessed.

22. Management
• Treatment guidelines
Supplemental oxygen should be supplied for saturations below 90% on
pulse oximetry.
Palivizumab prophylaxis should be administered to selected children.
Hand decontamination is indicated to prevent nosocomial spread.
Infants should not be exposed to secondary smoking, and breastfeeding is
recommended.
Clinicians should inquire about use of complementary and alternative
medicine therapies.

23. Complications
• Otitis media
• Pneumonia
• Pneumothorax
• Dehydration
• Respiratory acidosis
• Respiratory failure
• Heart failure
• Prolonged apneic spells leading to death

24. Prognosis
• Infants with acute bronchiolitis are at highest risk for further respiratory
compromise in the first 72 hours after onset of cough and dyspnea.
• The case fatality rate is <1% in developed countries, with death attributable
to respiratory arrest and/or failure or severe dehydration and electrolyte
disturbances.
• A majority of deaths due to bronchiolitis occur in children with complex
medical conditions or comorbidities such as bronchopulmonary dysplasia,
congenital heart disease, or immunodeficiency.
• The median duration of symptoms in ambulatory patients is approximately
14 days; 10% may be symptomatic for 3 weeks.

25. Prevention
• Meticulous hand hygiene is the best measure to prevent transmission
of the viruses responsible for bronchiolitis.
• For high-risk populations, palivizumab, an intramuscular monoclonal
antibody to the RSV F protein, may be given as a prophylactic agent.
• Palivizumab has been demonstrated to reduce risk of hospitalization
due to RSV bronchiolitis in certain populations.
• It has not been shown to decrease mortality and does not protect
against bronchiolitis caused by other viruses and is also quite costly.
As a result, there is some controversy surrounding which populations
should receive palivizumab.

26. Prevention
• U.S. guidelines suggest use for children born at <29 weeks completed
gestation,
• those with significant heart disease or chronic lung disease of
prematurity, through the 1st or 2nd (for those with persistent chronic
lung disease of prematurity) year of life.
• Prophylaxis may be considered in infants with neuromuscular disease
and immunocompromised states.

27. Conclusion
• Acute bronchiolitis is a viral lower respiratory tract infection
commonest in under-2s which frequently presents with cough,
wheezing, respiratory distress, fever and impaired feeding. It is
usually preceded by rhinorrhea.
• RSV is implicated in more than 50% of cases of acute bronchiolitis.
• Hydration, oxygen optimization and other supportive care targeted
towards symptomatic relief are the main stay of management.
• Meticulous hand hygiene remains the best measure to prevent
transmission of the viruses responsible for bronchiolitis.

28. References
• Kliegman, R. (2020). Nelson textbook of pediatrics (Edition 21.).
Philadelphia, PA: Elsevier.
• Kumar, V., Abbass, A. K., & Aster, J. C. (2015). Robbins and Cotran
pathologic basis of disease (9th Edition.). Philadelphia, PA:
Elsevier/Saunders.
• Medscape