Bronchiolitis

Bronchiolitis

1. epidemiology

   • commonest serious respiratory infection of infancy
   • 2-3% of all infants admitted to hospital/ yr during annual winter epidemics
   • 90% of cases are 1-9 mths old
   • rare after 1 year of age

2. pathogen

   • virus
     • RSV
       • causes 80% of cases
       • highly infectious
     • human metapneumovirus
     • parainfluenza virus
     • rhinovirus
     • adenovirus
     • influenza
   • bacteria
     • Mycoplasma pneumoniae

3. clinical features

   • coryzal sx
     • followed by
       • dry cough
       • increasing breathlessness
   • feeding difficulty
     • assoc w/ increasing dyspnoea
       • often reason for hosp admission
   • on examination
     • sharp dry cough
     • tachypnoea
     • hyperinflation of chest
       • prominent sternum
       • liver displaced downwards
     • fine end-inspiratory crackles
     • +/- high pitched wheezes- exp> insp
     • tachycardia
     • cyanosis or pallor
     • subcostal & intercostal recession

4. complications

   • serious
     • recurrent apnoea
       • esp in young infants
         • < 4 mths old

5. high risk groups for severe bronchiolitis

   • premature infants
     • who developed bronchopulmonary dysplasia
     • w/ underlying lung disease
       • Cystic fibrosis
     • w/ congenital heart disease

6. Ix

   • nasopharyngeal secretions (aspirate?)
     • PCR
       • ID resp viruses
   • CXR
     • unnecessary in straightforward cases
       • rarely helpful in bronchiolitis
     • signs
       • hyperinflation of lungs
         • due to small airways obstruction
       • flattening of diaphragm
       • air trapping
       • focal atelectasis
       • horizontal ribs
       • increased hilar bronchial markings
   • pulse oximetry
     • continuous monitoring of arterial O2 sats
   • blood gas analysis
     • from capillary sample
       • done only in severe disease
         • to ID hypercarbia when additional ventilatory support is needed

7. Mx

   • supportive
     • humidified O2
       • via nasal cannulae
       • conc needed determined by pulse oximetry
     • monitoring
       • for apnoea
     • fluids
       • NG
       • IV
     • ventilation
       • assisted
         • nasal CPAP
         • facemask CPAP
       • full
   • infection control

8. Prognosis

   • most recover from acute infection within 2 weeks
   • 1/2 will have recurrent episodes of cough and wheeze
   • rare
     • ff adenovirus infection
       • bronchiolitis obliterans
         • permanent damage to airways

9. prevention

   • palivizumab
     • monoclonal antibody to RSV
     • monthly i.m. injection
     • reduces risk of hosp admissions in high-risk preterm infants
     • costly
     • multiple i.m injections needed