Introduction:

Common disease of the lower respiratory tract in infants resulting from inflammatory obstruction of small airways.

Definition:

Bronchiolitis is defined as the first episode of expiratory wheeze of acute onset usualy in a child less than 2 years of age who has features of viral respiratory illness like coryza,otitis media or fever,with or without indications of respiratory distress,pneumonia and atopy.

Incidence:

  • It constitutes 8.5% of the total respiratory disease in hospitalized children.
  • Age-2mnths to 2 years,peak-6months.
  • Season-October to march
  • Sex-severe bronchiolitis is more common in males.

Aetiology:

  • Viral infections account for majority of the cases .most common viruses implicated are adeno virus ,parainfluenza virus,most important being the rsv.
  • Rarely mycoplasma pneumoniae.

Pathology:

  • It is characterized mechanical rather than bronchospastic airway obstruction.lesions develop in small airwayswith 70-300mum diameter.
  • Necrosis of respiratory epithelium in the bronchioles and is associated with peribronchiolar lymphocytic infiltration.
  • Submucosal edema.
  • All these changes lead to trapping of air beyond the lesion. this leads to obstructive emphysema and patch atelectasis manifesting clinically as expiratory wheeze .

Clinical features:

Symptoms:

  • Cough,dyspnoea,fever
  • Gradual development of respiratory distress.
  • Rhinorrhoea
  • Paroxysms of wheezy cough.

Signs:

  • Tachpneic infant(rr-60-80/min)
  • Tachycardia
  • Respiratory distress
  • Chest retractiona,hyperresonant noteon percussion,wheezing and rales
  • Characteristically more tachypneic and distress with minimal auscultatory findings.
  • In severe cases breath sounds are barely audible.

Complications:

short term-

  • Respiratory distress.
  • Dehydration and electrolyte imbalance with respiratory acidosis.
  • Ccf
  • Secondary bacterial infections.

Long term:

  • Broncholitis obliterans.
  • Hyperlucent lung syndrome (swyer-james/mcleod’s syndrome).

Investigations:

  • Chest x ray.
  • Arterial blood gas
  • Serum electrolytes.

Differential diagnosis:

  • Acute exacerbation of bronchial asthma
  • Bacterial bronchopneumonia
  • Ccf
  • Foreign body in trachea
  • Pertusis

Treatment:

  • Patient to be nursed in humid atmosphere in sitting position at angle of 30-40 degrees with head and neck elevated.
  • Oxygen to be administered to all by face mask at the rate of 2litres/min
  • I.v. fluids,antibiotics and antivirals(ribavirin).
  • Ventilatory support in cases of respiratory failure .