Why do Infants Wheeze Flashcards
What is the definition of a wheeze
- Musical lung sound caused by oscillations in narrowed airways
what does the frequency of a wheeze depend on
- degree of narrowing
- elasticity of airway wall
- local airflow
what generates the wheeze
- generated by the smaller airways oscillating
Is a wheeze usually expiratory or inspiratory
- Almost always expiratory clinically, might have an inspiratory component as well but it is very rare to get a pure inspiratory wheeze
What sounds can wheeze have
- Squeaky or whistling noises
- Wet rattly noises
- Both whistling and ratty noises
What type of airways generate wheeze
- smaller airways generate wheeze
What happens if there is a
- Slight narrowing
- greater narrowing
Slight narrowing
- velocity increases
- pressure decreases
greater narrowing
- velocity decreases
- pressure increases
What are two types of wheezes that you can have
- expiatory wheeze
- inspiratory wheeze
what causes an expiatory wheeze
Narrowing of the intrathoracic airways causes an expiratory wheeze
What causes an inspiratory wheeze
Narrowing of the extra thoracic airways causes an inspiratory wheeze
what would you hear in an inspiratory wheeze
- you wouldn’t hear anything in the chest that sounded like a wheeze vocally a wheeze in comparison in an expiratory wheeze can be hear in the chest as it is the intrathoracic airways that are narrowing
- intrathoracic airways expand so wheezing not usually heard (unless severe).
which age group is wheeze common in
episodes of wheeze are common in preschool children (10 mo to 6 yr)
how many people wheeze before 3 years
35% will wheeze at least once before 3 yr
what is wheezing usually triggered by in preschool children
attacks usually triggered by colds
few or no symptoms between attacks
What are the preschool wheeze risk factors
- smoking in pregnancy – risk factor as maternal smoking alters the airway structures
- air pollution – new onset preschool wheeze significantly associated with pollution at home-school address - more vulnerable to develop viral infections or it could affect the lung growth
- younger mother?
name the three types of preschool wheezers
- transient early wheezes
- non atopic wheezers
- IgE associated wheeze/asthma
Describe transient early wheezers
- wheeze between first and 3 years of age
- stop wheezing by 3 years
- due to being born with low lung function and the tendency to develop hyperactive airways with colds
- have normal lung function by the age of 11
describe non atopic wheezes
- between the ages of 3-6
- later onset but not all resolves
- starts with a symptomatic lower respiratory tract infection such as (RSV, bronchitis)
- continues to wheeze beyond their third year
- most outgrow condition but if not they will progressively lose lung function over time
less than 1/3 of wheezing infants…
• Less than 1/3 of wheezing infants will develop recurrent wheezing later in life (atopic asthma)
what does atopy mean
o Atopy = predisposition toward developing certain allergic hypersensitivity reactions
describe airway inflammation in preschool wheeze presentation
- No inflammation between attacks
* Pattern of inflammation between attacks unknown.
describe what atopic asthma in older children looks like
Wheeze between colds
Wheeze attacks triggered by colds
describe what the airways of children with atopic asthma look like
persistent inflammation throughout central and peripheral airways
denudation of airway epithelium
infiltration of lymphocytes and eosinophils
describe at a cellular level the differences between asthmatics lungs and non asthmatics lungs
Normal:
• Epithelium intact.
• No thickening of sub-basement membrane
• No cellular infiltrate.
Asthmatic:
• Goblet cell hyperplasia.
• Thick subbasement membrane.
• Cellular infiltrate.
