Bronchiolitis

Question 1

List the indications for admission in infants with bronchiolitis

Answer 1

Any of the following:

Demographics: prematurity; <3 months old.
Recent history: apnoeas, feeding less than maintenance volumes.
PMHx: chronic lung disease; congenital heart disease.
Examination: hypoxemia; severe respiratory distress.

Question 2

Bronchiolitis?

Answer 2

Bronchiolitis is characterized by narrowing of the lower respiratory tract due to inflammation of the bronchioles and build-up of mucus. It is a common respiratory condition in infancy. Around a third of infants develop bronchiolitis before the age of 1, with a peak incidence around 3 to 6 months of age.1

The incidence of bronchiolitis is linked with the winter period. Typically, children present during this time with episodes of bronchiolitis lasting for 7-10 days.2,3

Question 3

Causes of Bronchiolitis?

Answer 3

Bronchiolitis is usually caused by a viral infection. About 80% of cases are caused by the respiratory syncytial virus (RSV). The other less common viral causes of bronchiolitis include:

1. Parainfluenza virus
2. Rhinovirus
3. Adenovirus
4. Influenza
5. Human metapneumovirus

Question 4

Risk factors for admission to hospital in Bronchiolitis

Answer 4

Risk factors for admission to hospital with a severe episode of bronchiolitis include:

1. Chronic lung disease
2. Congenital heart disease
3. Younger than 3 months old
4. Prematurity
5. Down’s syndrome
6. Cystic fibrosis
7. Neuromuscular disease

Question 5

Clinical features

Answer 5

Typical symptoms of bronchiolitis include:

1. Persistent cough
2. Wheeze
3. Shortness of breath
4. A prodrome of upper respiratory tract features – fever, runny nose, cold
5. Symptoms typically worsen during the 2nd or 3rd night of illness

Other symptoms can include:

1. Apnoea – in infants younger than 6 weeks of age, also typically seen with RSV
2. Poor feeding – young children are obligate nasal breathers, making it difficult to feed and breathe at the same time during bronchiolitis
3. Symptoms of dehydration in severe disease – reduced urine output or fewer wet nappies

Question 6

Other important areas to cover in history?

Answer 6

Other important areas to cover in the history include:

1. Past medical history including birth history – ask about known risk factors for severe bronchiolitis, as listed above
2. Medications/allergies – this information may be useful if there are other possible differentials
3. Family history – ask if anyone in the family has been unwell, this may point towards other differentials. It is also essential to ask about any family history of atopic conditions
4. Social history – ask about parental smoking, as this will exacerbate symptoms of bronchiolitis. Also ask about the child’s situation at home (e.g. where they live, who is at home with them, the involvement of social services), as difficult social circumstances will reduce the threshold for admission.

Question 7

Clinical examination?

Answer 7

Typical clinical findings in bronchiolitis include:

1. Coryzal symptoms. These are the typical symptoms of a viral upper respiratory tract infection: running or snotty nose, sneezing, mucus in the throat, and watery eyes.
2. Signs of respiratory distress
3. Dyspnoea (heavy laboured breathing)
4. Bilateral polyphonic expiratory wheeze
5. Tachypnoea (fast breathing)
6. Tachycardia
7. Low-grade fever (<39c)
8. Irritability
9. Poor feeding

Question 8

Other clinical examination findings?

Answer 8

Other clinical findings can include:

1. Prolonged capillary refill time (>2 seconds)
2. Cyanosis
3. Signs of dehydration – dry mucous membranes, sunken fontanelle in young babies
4. Reduced conscious level
5. Recessions (intercostal, subcostal or sternal) – this is a result of children having a compliant rib cage, which makes an increased work of breathing clearly visible externally.

Question 9

Differential diagnoses of bronchiolitis?

Answer 9

1. Pneumonia:
   a) Fever >39
   b) Focal crackles
2. Viral-induced wheeze:
   a) Persistent wheeze without crackles
   b) Recurrent wheeze associated with a viral illness
   c) Personal or family history of atopy
   d) >1-year-old
   e) Responsive to salbutamol treatment
3. Early-onset Asthma:
   a) Persistent wheeze without crackles
   b) Recurrent wheeze associated with a viral illness
   c) Personal or family history of atopy
   d) >1-year-old
   e) Responsive to salbutamol treatment
4. Bordetella pertussis or whooping cough:
   a) Coryza
   b) Characteristic hacking cough followed by an inspiratory ‘whoop’
   c) Unvaccinated
5. Foreign body aspiration:
   a) May have a history of choking
   b) Monophonic wheeze

Question 10

Investigations?

Answer 10

Children are diagnosed clinically with bronchiolitis if they present with coryzal symptoms lasting up to 3 days, followed by:

1. Persistent cough and
2. Tachypnoea or chest recession and
3. Wheeze or crackles on chest auscultation.
   Investigations do not influence the treatment of bronchiolitis.

• Bedside investigations
  1. Pulse oximetry: children should be admitted if oxygen saturation is <92%

*Laboratory investigations
1. Blood tests (including arterial blood gases): these are not routinely performed
FBC + Differential count, blood culture, CRP, Glucose and electrolytes

• Imaging
  1. Chest X-ray: not routinely performed, but if there is an area of the lung with reduced air entry or focal crackles, this can be used to rule out pneumonia or pneumothorax. (Consolidation)

Question 11

Admission criteria:

Answer 11

Bronchiolitis is typically self-limiting. Not all children with bronchiolitis will require admission to the hospital. If a child does not require admission, it is important to provide safety netting to the parents or guardians to return if symptoms get worse.

The criteria for admission to secondary care depends on several factors including:

1. Apnoea
2. Reduced oxygen saturation: <92%
3. Reduced oral intake: <50-75% of normal
4. Persistent respiratory distress: significant chest recessions, grunting
5. Presence of risk factors for severe disease, as mentioned earlier
6. Difficult social factors: living very far from the hospital, lack of parental confidence

Question 12

Supportive management for Bronchiolitis?

Answer 12

The management of bronchiolitis is supportive:

1. Oxygen supplementation, humidified, 1-2L/min via nasal prongs or nasal cannula if saturations are persistently <92%.
2. Positive pressure such as high flow oxygen or CPAP may be required for respiratory distress. If these fail to work, intubation and ventilation may be required.
3. Nutritional and fluid supplementation – oral, nasogastric (NG) tube or intravenous (IV). Depending on the severity of the bronchiolitis, a stepwise approach may be considered:
   a) Small and frequent oral feeds,
   b) NG tube placement with small and frequent NG
   bolus feeds,
   c) Continuous NG feeds,
   d) IV fluids
4. Support parents/guardians with smoking cessation

Important points to note:

1. Bronchodilators are not effective as respiratory tract narrowing is due to increased secretions, not bronchoconstriction.
2. Antibiotics are also not effective due to the viral aetiology of bronchiolitis.

Question 13

Complications?

Answer 13

If bronchiolitis is not diagnosed and treated, complications can include:

1. Clinical dehydration
2. Syndrome of inappropriate antidiuretic hormone (SIADH) and subsequent hyponatraemia. Because of the risk of SIADH, some guidelines will advocate for 2/3 maintenance NG/IV fluids, please refer to local guidelines.
3. Apnoea and respiratory failure requiring intubation and ventilation.

Question 14

Signs of Respiratory Distress?

Answer 14

1. Raised respiratory rate
2. Use of accessory muscles of breathing, such as the sternocleidomastoid, abdominal and intercostal muscles
3. Intercostal and subcostal recessions
4. Nasal flaring
5. Head bobbing
6. Tracheal tugging
7. Cyanosis (due to low oxygen saturation)
8. Abnormal airway noises