The following is an excerpt....
BASICS
Description
- Result of turbulent airflow:
- High-pitched sound with dominant frequency at 400 Hz:
- Gas flowing through constricted airways analogous to a vibrating reed
- Resonant vibration of the bronchial walls when airflow velocity reaches critical values
- Caused by airway narrowing between 2–5 mm:
- Wheezing is very low pitched with airway diameters of 5 mm.
- Airways of <2 mm are unable to transmit sound because the energy is lost as friction heat.
- Airway narrowing is caused by a combination of ≥1 of the following:
- Constriction (as with reactive airway disease)
- Peribronchial interstitial edema
- Inflammation
- Obstruction
Etiology
- Pulmonary (small airway):
- Asthma
- Acute respiratory distress syndrome
- Anaphylaxis
- Aspiration pneumonia:
- Wheezing occurs early in the disease due to intense bronchospasm following the event.
- Byssinosis:
- Occupational lung disease of textile workers exposed to cotton dust
- Drugs:
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