21. Why do Infants wheeze? Flashcards
Why is life of a preterm baby not viable if they are born prior to 24 weeks?
Do not have sufficient development of the lungs - lack of air/tissue interface
Lack of surfactant production
Why does the pulmonary artery have thin walls?
Carrying low pressure blood to the lungs
What is normal size relation of the broncus?
Normally roughly the same size as the pulmonary artery
Define ‘wheeze’
Breathe with a whistling or rattling sound in the chest, as a result of airway obstruction
Describe what is meant by a wheeze (lecture definition)
Musical lung sound
From oscillations in narrowed airways
Can be inspiratory or expiratory (virtually all wheezes will have some component of an expiratory wheeze - unusual to have just inspiratory wheeze)
High or low pitched
What does the frequency of a wheeze depend on?
Degree of narrowing
Elasticity of airway wall
Local airflow
Where does the sound appear to come from in wheezes?
The breathing sound comes from the ‘chest’ - not the throat
Wheezing comes from the intrathoracic airways?
What is the effect of expiration on the intrathoracic airways?
When expiring, this causes the intrathoracic airways to narrow
What is the relation of the intrathoracic airways to a wheeze?
If there is an over-narrowing of the intrathoracic airways on expiration, this will present as a wheeze
Does a narrowing of the extrathoracic airways result in a wheeze?
No - will hear a squeaking/barking noise depending on size of the individual
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How does a preschool wheeze present?
Attacks that are usually triggered by colds
There are few or no symptoms between the attacks
Most of these are triggered by viral colds with a cough and then resolves as the viral infection ends
The attacks are short (tend to trail off after about four days)
What age is the preschool range?
From 10 months up to 6 years of age
How common is a preschool wheeze?
This is very common - about a third of children will wheeze at least once before three years of age
What are the risk factors for a preschool wheeze?
Smoking during pregnancy
Air pollution
Why does smoking during pregnancy lead to wheezing in the infant/
Change to the structure of the membranous airway
The airways of the airways are not as rigid and have a lower threshold to narrow in response to e.g. the cold
What are the different types of wheeze causes during childhood?
Describe these
Transient early wheeze - during the first three years of life - born with low lung function and develop hyper-reactive airways with colds - have normal lung function by 11 years
Non-atopic wheezes - symptomatic lower respiratory tract viral infections e.g. bronchiolitis in early life - continue to wheeze beyond third year - tend to resolve but some (less than a third) will develop asthma later on
IgE associated wheeze i.e. asthma - persistent inflammation throughout central and peripheral airways - infiltration of lymphocytes and eosinophils
What is the difference to the histology of children with atopic asthma?
Goblet cell hyperplasia
Thick sub basement membrane
Cellular infiltration
What is the treatment for a preschool wheeze?
(Surprisingly very similar to treatment of atopic asthma)
Dependent on severity:
Inhaled short acting beta 2 agonist e.g. salbutamol
Add in inhaled steroids or leukotriene receptor antagonists
Refer to respiratory paediatrician
What are the differential diagnoses for a wheeze?
NB. These are incredibly world
Structural causes e.g. cystic abnormality
Bronchogenic cysts
Congenital lobar emphysema
