Acute bronchiolitis in Pediatrics

Question 1

Acute bronchiolitis definition, pathogenesis, C/P AND risk factors.

Answer 1

Definition: viral lower respiratory tract infection induces acute inflammation, oedema, mucus production, and epithelial necrosis → bronchiolar obstruction.

Pathogenesis
- Acute inflammation → bronchiolar obstruction by oedema, mucus & cellular debris → respiratory distress
- Impaired pulmonary gas exchange may occur; early hypoxemia occurs with severe disease → hypercapnia develops.

Clinical picture :
- Symptoms:
o Begins with upper respiratory catarrh (rhinitis, cough & mild fever) for few days then progress to → dyspnoea, more cough, and wheezy chest
o Due to increased respiratory effort → poor oral intake and irritability.
- Signs:
o Respiratory distress (tachypnoea, retractions, grunting ± cyanosis)
o Young patients (<1 month or young preterm) are at risk of apnoea.
o Chest examination:
-Inspection: Hyperinflated chest.
-Palpation: May be palpable wheezes.
-Percussion: Bilateral hyper resonance.
-Auscultation: decreased air entry on both sides, harsh vesicular breath sounds with prolonged expiration, and bilateral expiratory rhonchi and fine crepitations.
-Liver & spleen may be palpable due to hyperinflated chest (normal liver span).

Risk factors indicating severe disease:
-Severe respiratory distress with hypoxaemia
-Signs of dehydration
-Recurrent apnoeas
-Change in mental status.
-Age < 12 weeks or history of prematurity
-Underlying cardiopulmonary disease
-Immunodeficiency.

Question 2

Acute bronchiolitis DD

Answer 2

From other causes of wheezy chest in infants
- Congestive heart failure by tachypnoea, tachycardia and enlarged tender liver
- Foreign body inhalation by history of choking, stridor, asymmetric breath sounds.
- Pulmonary T.B.
- Cystic fibrosis.

Bronchial asthma the difference in the following:
-Age: < 2 years VS At any age but usually > 2 years
-Recurrence: Not common VS Recurrent
-Effect of allergens or exercise: No effect VS Precipitate the attacks
-Effect of bronchodilators: Poor response VS Good response
-Family history of allergy: Negative Usually, VS positive

Question 3

Acute bronchiolitis Investigations, complications and management.

Answer 3

Investigations: the diagnosis is mainly clinical.
- Chest X-ray: hyperinflated lung (horizontal ribs+ flat diaphragm) with bilateral perihilar infiltrates and evidence of complications as collapse or pneumothorax.
- CBC and CRP are usually normal
- Detect RSV antigens in nasopharyngeal secretions by immunofluorescence.
- Arterial blood gases to assess severity of the disease.

Complications:
- Dehydration: due to tachypnoea & poor feeding.
- Lung collapse or pneumothorax → sudden deterioration.
- Low oxygen levels with cyanosis and respiratory failure.
- Secondary bacterial pneumonia
- Recurrence

Treatment:
- Supportive: maintain hydration via oral intake (in mild respiratory distress) or IV/ nasogastric administration (in significant severe cases)
- Hospitalization for severe cases with risk factors especially if < 6 months, severe hypoxemia, or hypercapnia or respiratory rate > 60/ minute
- Humidified oxygen inhalation.
- IV. Fluids to avoid the high risk of aspiration
- Humidified O2 inhalation with high flow nasal cannula.
- CPAP via nasal prongs or intubation and ventilation if deterioration with exhaustion or persistent apnoea.
- Medications:
o No role for bronchodilators or steroids → gives only effect if there is underlying asthma and in severe cases. But, adrenaline nebulizer (0.5 mg/kg of 1.1000) ² temporary relief of bronchiolar obstruction. (Nebulized hypertonic saline may be used)
o No role for antibiotic unless there is a strong suspicion of concurrent bacterial infection.
o Antiviral: Ribavirin aerosol for high risky infants.
- Treatment of complications.

Prevention:
- By RSV intravenous immunoglobulin
- Palivizumab which is monoclonal antibody to RSV given for high-risk cases.

Prognosis:
is good in most cases but, mortality rate 1% due to: apnoea, respiratory failure, dehydration