Bronchiolitis

Question 1

Definition bronchiolitis

Answer 1

An acute viral infection of the lower respiratory tract. The most common serious respiratory infection of infancy, resulting in admission to hospital in 2-3% of all infants during annual winter epidemics.

Question 2

Peak age of presentation

Answer 2

90% of children admitted are aged 1-9 months

Question 3

Causes of bronchiolitis

Answer 3

Respiratory Syncytial Virus (RSV) is the causative pathogen in 80% of cases. The remainder are accounted by:
* Parainfluenza virus, rhinovirus, adenovirus, influenza and human metapneumovirus.
* Evidence suggests that co-infection may lead to more severe illness (particularly RSV and human metapneumovirus)

Question 4

Pathophysiology and disease course of bronchiolitis

Answer 4

The virus infects the respiratory epithelial cells of the small airway and causes necrosis, inflammation, oedema and mucous secretion. These factors cause obstruction of the small airways.
Re-growth of epithelial cells does not occur until around 2 weeks after infection.
Therefore complete recovery requires 4-8 weeks

Question 5

Risk factors for developing bronchiolitis

Answer 5

Immunodeficiency, preterm, exposure to smoking, contact, non breast-fed

Question 6

Presentation of bronchiolitis

Answer 6

• Coryzal symptoms precede a cough and breathlessness
• Feeding difficulty associated with increasing dyspnoea
• Recurrent apnoea is a significant complication

Characteristic findings on examination include:
* Dry wheezy cough, cyanosis or pallor, tachypnoea and tachycardia, subcostal and intercostal recession, hyperinflation of the chest
* On auscultation: fine end-inspiratory crackles, high-pitched wheeze (more expiratory then inspiratory)

Question 7

Common causes of acute resiratory distress in children

Answer 7

Bronchiolitis, viral episodic wheeze, pneumonia, HF, foreign body, anaphylaxis, pneumothorax or PE, metabolic acidosis

Question 8

Investigations for bronchiolitis

Answer 8

• Pulse -oximatry- should be performed on all children with suspected bronchiolitis
• Nasopharyngeal aspirate will show the virus
• CXR and blood gases are only recommended if respiratory failure is suspected
• Should note the degree of agitation and consciousness, signs of exhaustion and cyanosis as well as accessory muscle use. Should assess hydration using cap refill time, skin turgor, mucous membranes

Question 9

When should infants be admitted

Answer 9

• Apnoea is observed or reported
• Child looks seriously unwell
• They are in severe respiratory distress: grunting, marked chest recession, respiratory rate > 70 breaths/minute
• Central cyanosis
• Failure to maintain adequate oxygen saturation despite oxygen supplementation
• Inadequate oral fluid intake (<70% of usual volume)
• Persistent oxygen saturation of less than 92% when breathing air.

Consider if:
* Respiratory rate > 60 breaths/minute
* Clinical dehydration

Question 10

What factors might lower the threshold for hospital admission

Answer 10

Factors such as immunodeficiency, chronic lung disease, haemodynamically significant congenital heart disease, age under three months and prematurity

Question 11

How can bronchiolitis be managed in seondary care

Answer 11

Management is supportive

• Give controlled supplementary (humidified) oxygen to all children whose oxygen saturation is persistently less than 92% in children under 6 weeks (90% for children aged 6 weeks and over)- nasal cannula or head box
• Consider continuous positive airway pressure (CPAP) in babies and children with bronchiolitis who have impending respiratory failure
• Give fluids by nasogastric or orogastric tube in babies and children with bronchiolitis if they cannot take enough fluid by mouth (IV if they cannot tolerate NG/OG, or have impending respiratory failure-> be careful since is associated with SIADH)
• Nebulised hypertonic (3%) saline can help reduce hospital stay in acute bronchiolitis
• Infection control measures are required in the ward the patient is placed as RSV is highly infectious
• Palivizumab (monoclonal antibody against RSV) reduces the number of hospital admissions in high-risk preterm infants
• Salbutamol does NOT work in those under 6 months as they do not have smooth muscle beta receptors (consider in 6m –1 year)

Question 12

How long doe it take mot infants to recover

Answer 12

2 weeks
Around 50% will have recurrent episodes of cough and wheeze-rarely may get bronchiolitis obliterans

Question 13

How can infants (not requiring hospital admission) be treated in primary care

Answer 13

• Advise the parents/carers that bronchiolitis is usually a self-limiting illness and that symptoms tend to peak between three and five days of onset
• Advise parents/ carers to check on the child regularly, including through the night, and to seek medical advice if they are unable to cope, or if the child deteriorates (particularly any change in behaviour, fluid intake, breathing rate increases, signs of apnoea etc.)
• Advise parents not to smoke at home
• Encourage fluid intake and paracetamol + ibuprofen