Why do infants wheeze?

Question 1

At what age does the surfactant system kick in?

Answer 1

26 weeks

Question 2

What is a wheeze?

Answer 2

• musical lung sound

- oscillations (back and forth movement in regular rhythm)

Question 3

What are the 2 types of wheezing?

Answer 3

• mild obstruction (during expiration - wheeze of intrathoracic airways)
• severe obstruction (during inspiration and expiration - wheeze of extrathoracic airways)

Question 4

What is the frequency of a wheeze due to?

Answer 4

• degree of narrowing
• elasticity of airway wall
• local airflow

Question 5

What are the features of a wheeze in the intrathoracic airways?

Answer 5

• related to obstruction of intrathoracic airways
• wheeze of expiration
• fluttering between slight and greater narrowing
• caused by airway swelling

Question 6

What is the difference between slight and greater narrowing in wheeze of intrathoracic airways?

Answer 6

• slight = as velocity increases pressure decreases

- greater = as velocity decreases pressure increases

Question 7

Why is intrathoracic wheezing not heard on inspiration?

Answer 7

• intrathoracic airways expand

- heard on extrathoracic wheezing as they narrow

Question 8

What are the features of extrathoracic wheezing?

Answer 8

• related to obstruction of airway
• wheeze of inspiration
• causes extrathoracic airways narrow
• related to croup

Question 9

How can the timing of the sound in wheeze be helpful in diagnosis?

Answer 9

• if wheeze during inspiration = extrathoracic wheeze = airways obstructed/related to croup
• if wheeze during expiration = intrathoracic wheeze = airways swelling

Question 10

What is a preschool wheeze?

Answer 10

• common in preschool children (10 months to 6 years)
• triggered by colds
• few or not symptoms between wheezing attacks

Question 11

What are the risk factors of wheezing?

Answer 11

• smoking in pregnancy
• younger mother
• pollution

Question 12

What are the main wheeze types/phenotypes?

Answer 12

• transient early wheezers
• non-atopic wheezers
• atopic asthma

Question 13

What are the characteristics of transient early wheezers?

Answer 13

• only during first 3 years of life
• born with low lung function
• tend to develop hyper-reactive airways with colds
• normal lung function by age 11

Question 14

What are the characteristics of non-atopic wheezers?

Answer 14

• starts with symptomatic LRT viral infection in early life
• continue to wheeze beyond 3rd year
• most outgrow condition but if not -> progressively lose lung function over time

Question 15

What is atopy?

Answer 15

• predisposition toward developing certain allergic hypersensitivity reactions

Question 16

What are the features of atopic asthma in older children?

Answer 16

• wheeze between colds
• triggered by colds
• persistent inflammation throughout central and peripheral airways
• infiltration of lymphocytes and eosinophils

Question 17

In atopic asthma what happens at the cellular level of the lungs?

Answer 17

• epithelial goblet cell hyperplasia
• thick sub-basement membrane
• cellular infiltrate

Question 18

How is preschool wheeze treated?

Answer 18

1) Short acting beta-2-agonist inhale (salbutamol)
2) Steroid or LTRA
3) Steroid and LTRA
4) refer to respiratory paediatrician

Question 19

What is the differential diagnosis of preschool wheeze?

Answer 19

• bronchogenic cysts
• hyperinflation of left upper lobe
• congenital lobar emphysema

Question 20

What are the features of a large bronchogenic cyst?

Answer 20

• thin walled with ciliated columnar lining
• cartilage and SM
• gastro-oesophageal mucosa
• air/fluid filled

Question 21

How does a bronchogenic cyst present?

Answer 21

• early with respiratory distress
• later with infection
• asymptomatic

Question 22

How is a bronchogenic cyst treated?

Answer 22

• surgical removal

Question 23

What are the features on an X-ray of upper left lobe hyperinflation?

Answer 23

• over distension of love
• partial bronchial obstruction
• ball valve effect