Wheeze

Question 1

What is a wheeze? causes?

Answer 1

Muscial expiratory sound/biphasic sound due to partial obstruction of the intrathoracic airways.
This can be from mucosal inflammation and swelling in bronchiolitis or bronchoconstriction in asthma or mechanical obstruction e.g. with foreign body or mcuus.

Question 2

What is bronchiolitis? Age?

Cause?

Answer 2

Respiratory infection of infancy.
90% 1-9 months old
Respiratory Syncytial Virus is most common cause (parainfluenza, rhinovirus, adenovirus, influenza, human metapneumovirus)

Question 3

What are symptoms and signs in bronchiolitis?

Answer 3

Coryza symptoms precede a dry cough and increasing breathlessness
Feeding difficulty associated with increased dyspnoea is often the reason for admission.
Recurrent apnoea is a serious complication.

Dry wheezy cough
Tachypnoea and tachycardia
Subcostal and intercostal recession
Hyperinflation of chest - sternum prominent, liver displaced downwards
Fine end-inspiratory crackles
High pitched wheezes (Expiratory>inspiratory)
cyanosis/pallor

Question 4

Which children are most at risk from severe bronchiolitis?

Answer 4

Infants born prematurely who develop bronchopulmonary dysplasia or CF or congenital hear disease are most at risk

Question 5

What investigations in bronchiolitis? When is hospital admission indicated?

Answer 5

Pulse oximetry
CXR/blood gases only if respiratory failure is suspected

Admit if:
Apnoea (observed or reported)
Persistent oxygen SaO2 of <90% on air
Inadequate oral fluid intake (50-75% of usual)
Severe respiratory distress - grunting, marked chest recession or respiratory rate over 70 breaths/min

Question 6

Describe management of bronchiolitis?

Answer 6

Supportive
Humidified oxygen via nasal cannulae - concentration based on SaO2
Monitor for apnoea
Fluids via NG tube or IV
Assisted ventilation - non-invasive respiratory support with CPAP or mechanical ventilation in small %.
Infection control measures, good hand hygiene, cohort nursing, gowns and gloves to prevent cross-infection to other infants.

Most recover within 2 weeks.
Rarely following adenovirus infection, bronchiolitis obliterates - permanent damage to airways

Question 7

How long does recovery take in bronchiolitis?

Answer 7

2 weeks

Question 8

Describe prevention of bronchiolitis?

Answer 8

Monoclonal antibody to RSV (palivizumab) give monthly by IM injection reduces number of hospital admissions in high risk preterm infants
NNT - 17 to avoid one admission
Limited by cost and need for multiple injections.

Question 9

Respiratory rate upper limits?

Answer 9

Newborn 60
Infant 50
Child 40
Adolescent 30

Question 10

What are other causes of wheeze?

Answer 10

Asthma,
Atypical pneumonia - mycoplasma, chlamydia, adenovirus
Foreign body inhalation - abrupt onset of wheeze, CXR in expiation will show hyperinflation of lungs distal to obstruction.
Anaphylaxis

Question 11

Patterns of wheeze in childhood?

Answer 11

Viral episodic wheeze - results from small airways being more likely to narrow due to infection and immune response. Episodic in nature, triggered by viruses that cause common cold. Risk factors fro reduced small airway diameter from birth - maternal smoking during and after pregnancy and prematurity.

Multiple trigger wheeze
Frequent wheeze triggered by many stimuli not just viruses but also cold air, dust, dander, exercise.
In pre-school age group where asthma diagnosis may be unjustified, this distibtiuon is helpful as many benefit from asthma preventer therapy and many go on to develop asthma.
Recurrent wheeze associated with symptoms between viral infection and evidence of allergy to inhaled allergens such as house dust mite, pollen, pets - atopic asthma.

Atopic asthma is associated with other atopic diseases - eczema, rhino conjunctivitis, food allergy.