Wheezing

10.11.05

What is a wheeze? (Laennec, 1819)
Four groups of 'rales':
1. Moist.
2. Mucous.
3. Sonorous.
4. Sibilant.

Polyphonic wheezing = widespread narrowing with various pitches.
Monophonic wheeze = fixed obstruction in single airway.
Stridor = narrowing of extra thoracic airway (inspiration).

Types:
• Intermittent/episodic wheeze with wheeze-free intervals = reversible airflow obstruction.
• Constant wheeze with no wheeze-free period = fixed airflow obstruction.

P=ν (8lη/πr4)

Where P = pressure, ν = flow, η = viscosity, l = length, r = radius.

Lung function peaks between 10-20 years of age.

1:3 children attend GPs with a wheezing episode that are less than 3 years of age.

12-15% of children younger than 15 years of age have asthma; 25% wheeze.

13 million children have asthma.
50,000 childhood admissions per annum (5% total asthma admissions).
32 childhood deaths per annum (2% total asthma deaths).
£561 million spent by NHS on treating asthma.

Contributing factors to an episodic wheeze:
• Airway.
• Atopy.
• Viral infection.

Viral infection
• Viruses identified in more than 80% of wheezy episodes.
• RSV and rhinoviruses (para influenza).
• Often associated with reduced lung function beforehand.
• Wheezing with virus can occur without underlying asthma.

Why?
• Genetic small airways/genetic abnormal viral response.
• Premature birth, maternal smoking [between conception and birth].
• Environment, viral infection, maternal smoking [after birth].

Atopy - determines recurrent wheezing
• Family history of atopic illness (especially in mother).
• Other atopic diseases in infant.
• Multiple genes.
• Higher environmental house dust mite load.
• Birth between August and October.
• Maternal smoking during pregnancy.
• Normal lunch function at birth.
• Poverty.

Why is there more asthma?
• Parents
-Maternal smoking.
-Lack of breast-feeding.
-Poverty; ethnic minority.
-Broad spectrum antibiotics with change in maternal gut flora?
• Child
-Diet (vitamin E).
-Lack of exercise.
-Lack of infections.
-No worm infections?
• Home environment
-High house dust mite load.
-Indoor air quality.
-Gas stoves/NO2 level.
-Damp housing.
-Central heating.
-More pets?
• Outside environment
-Move from rural to city environment.
-Outdoor air pollution (So2 and ozone).
-High traffic.