Why Do Infants Wheeze?

Question 1

At how many weeks does surfactant start being produced?

Answer 1

About 24-25

Question 2

When is alveolar development completed?

Answer 2

36 weeks

Question 3

With bronchiectasis, what sign is seen on CT scan?

Answer 3

Signet ring sign (small circle of soft-tissue attenuation that abuts a ring of soft-tissue attenuation surrounding a larger low-attenuating circle of air).

Question 4

Define a wheeze.

Answer 4

Musical lung sound
From oscillations in narrowed airways
Frequency depends on degree of narrowing, elasticity of airway wall and local airflow
Inspiratory or expiratory
High or low pitched

Question 5

What causes wheeze?

Answer 5

Airway wall swelling

Question 6

Are wheezes inspiratory or expiratory? Why?

Answer 6

Normally expiratory
This is because on expiration the intrathoracic airways are narrowed due to the pressure, but they are widened on inspiration due to the negative pressure.

Question 7

What happens when there is a slight narrowing of the intrathoracic airways?

Answer 7

Velocity increases

Pressure decreases

Question 8

What happens when there is a greater narrowing?

Answer 8

Velocity decreases

Pressure increases

Question 9

Pre-school wheeze - how many % will wheeze at least once before 3 years old? What are attacks triggered by?

Answer 9

35%

Colds

Question 10

Which group has the highest admission rate for wheeze?
12-24 months
2-5 years
6-12 years
>12 years

Answer 10

2-5 years

Question 11

Are pre-school wheeze attacks long or short?

Answer 11

Short

Question 12

What are risk factors for pre-school wheeze?

Answer 12

Smoking in pregnancy (alters the airway structure)

Air pollution

Question 13

What is the prognosis for pre-school wheeze?

Answer 13

Most cases resolve

Question 14

What categories can pre-school wheeze be split into?

Answer 14

Transient early wheezers
Non-atopic wheezers
IgE-associated wheeze/asthma

Question 15

Which category has the best chance of resolving?

Answer 15

Transient early wheezers

Question 16

What commonly causes bronchiolitis? Which category does this fall into?

Answer 16

RSV

Non-atopic wheezers

Question 17

Define transient early wheezers.

Answer 17

Wheeze only during the first three years of life (normal lung functin by age 11)
Born with low lung function and a tendency to develop hyper-reactive airways with colds

Question 18

What is the difference with non-atopic wheezers compared to transient early wheezers?

Answer 18

They continue to wheeze beyond their third year (40% wheezing at age 6)

Question 19

How many % of wheezing infants will develop atopic asthma?

Answer 19

Less than 33%

Question 20

Describe atopic asthma.

Answer 20

Persistent inflammation throughout airways
Wheeze between colds
Wheeze attacks triggered by colds

Question 21

Describe the histology of an asthmatic.

Answer 21

Goblet cell hyperplasia
Thick sub basement membrane
Cellular infiltrate (lymphocytes and eosinophils)
Ragged

Question 22

What is step 1 treatment for asthma?

Answer 22

Inhaled short acting beta 2 agonist e.g. salbutamol

Question 23

What is added for step 2?

Answer 23

Inhaled steroid 200-400 mcg/day

Question 24

What is added for step 3?

Answer 24

Leukotriene receptor antagonist

Question 25

Why are spacer devices used for asthmatic children?

Answer 25

Because they can’t coordinate breathing in with the device

Question 26

What are bronchogenic cysts?

Answer 26

Thin walled cysts with ciliated columnar lining. They may contain cartilage, smooth muscle and some have gastro-oesophageal mucosa. They can be air or fluid filled.

Question 27

What are the differential diagnoses for pre-school wheeze?

Answer 27

Bronchogenic cysts

Congenital lobar emphysema

Question 28

How does congenital lobar emphysema present?

Answer 28

Over distension of lobe
Partial bronchial obstruction
Ball valve effect