Bronchiolitis

=Bronchiolitis=

What it is
Viral bronchiolitis is the commonest lower respiratory tract infection in children less than 12 months of age and is the most frequent cause of hospitalisation in infants under 6 months of age. Although RSV generally causes only mild symptoms in an adult, it can cause a severe illness in an infant.

It is caused by viral infections of the lower respiratory tract, principally by respiratory syncytial virus (RSV) - 75%, which gives rise to widespread small-airway narrowing due to airway oedema, resulting in air trapping.
 * What causes it**

Other viruses that can cause bronchiolitis include: - Adenovirus - Influenza - Parainfluenza

- Being exposed to cigarette smoke - Being younger than 6 months old (usually affects children under the age of 2, with a peak age of 3 to 6 months) - Living in crowded conditions - Never being breastfed - Prematurity (born before 37 weeks gestation) - Appears more often in the fall and winter months
 * Risk Factors**

//Factors increasing the likelihood of hospital admission:// - History of significant apnoea before assessment - Known structural cardiac anomaly, especially large left-to-right shunt (eg, ventricular septal defect) - Known pre-existing lung disease (eg, cystic fibrosis) - Chronological age less than 6 weeks - Significant prematurity (< 32 weeks) and/or chronic neonatal lung disease - Severe degree of respiratory distress or apnoea - Significant dehydration - Hypoxaemia (Sp o 2 < 93%) - Re-presentation to the emergency department within 24 hour - Uncertain diagnosis.

Symptoms
//As the hallmark of bronchiolitis is crackles (crepitations) on chest auscultation, the recurrence of wheezing as the predominant feature, and factors such as the presence of eczema in an older infant and a history of atopy or asthma in one or both parents, suggest that the infant is less likely to have viral bronchiolitis.// - Nasal obstruction ± rhinorrhoea and an irritating cough are noticed first. - After 1–3 days there follows increasing tachypnoea and respiratory distress. The chest is often overexpanded. - Auscultatory signs are very variable: fine inspiratory crackles are often heard early, becoming coarser during recovery; expiratory wheeze is often present, initially high-pitched, with prolonged expiration. - Respiratory distress may be mild, moderate or severe. - Fever of 38.5 ° C or greater is seen in about 50% of infants with bronchiolitis. - Apnoea may be the presenting feature, especially in very young, premature or low-birthweight infants. It often disappears, to be replaced by severe respiratory distress.

- Developing features of severe respiratory distress - Frequent or prolonged apnoeic episodes with oxygen desaturation (O2 less than 90%) - Requiring greater than 50% oxygen to maintain oxygen saturations greater than 92% - Showing fatigue, poor respiratory effort, maximal accessory muscle use/exhaustion or altered conscious state. - Developing circulatory compromise
 * Children need to be reviewed by ICU if:**

How to Treat

 * Mild bronchiolitis** requires explanation and reassurance, but no specific pharmacological or other therapy. Bronchodilators and, to a lesser extent, systemic corticosteroids are frequently prescribed in general practice.

In the management of **moderate to severe viral bronchiolitis** in infants, “first principles” and common sense support the following recommendations. Supplemental oxygen is the single most useful therapy, usually delivered via nasal prongs — care with feeding and minimal interference is required, and intravenous fluids are likely to be needed. Careful observation is necessary with high-risk and more unwell infants to facilitate timely introduction of ventilatory support in the few infants who will need it. Increasingly, this involves using mask or nasopharyngeal continuous positive airway pressure ventilation, which often obviates the need for endotracheal ventilation.

The **only role for antibiotics** is in complicated bronchiolitis where a **secondary bacterial infection**, such as with streptococcus or staphylococcus, is suspected. This is rare, but not easily excluded in a sick infant with fever, toxicity and significant opacities on the chest radiograph. Unfortunately, antibiotics are most frequently prescribed in children with mild bronchiolitis with minimal chest radiographic changes, such as partial right upper lobe collapse, which are commonplace in uncomplicated RSV bronchiolitis.



Other advice
Most infants can be discharged in less than 3 days, depending on their ability to sustain adequate levels of hydration and oxygenation (Sp o 2 > 90%–92%) and the ability of the parents to attend to the needs of the recovering infant. All children admitted to hospital should be reviewed by their general practitioner within 7 days. If persisting cough, tachypnoea or wheeze develops, then review by a paediatrician or respiratory paediatrician is appropriate.

Consider a trial of a single dose of β2agonist bronchodilators in patients older than 9 months, particularly those with recurrent wheezing. An infant or child with bronchiolitis-like symptoms who responds to treatment with a bronchodilator, such as salbutamol, is likely to have asthma and should be treated according to asthma management guidelines.

Additional Resources
[|Medical Journal of Australia - Bronchiolitis: assessment and evidence-based management] [|MedlinePlus: Bronchiolitis] [|Princess Margaret Hospital - Bronchiolitis Clinical Practice Guidelines]