Common cause of wheezing. Understand mechanism of wheezing.

1. • Definition
• Mechanism
• Causes
Izatty Lim
0308188
Batch 4

2. 
 Palpable and audible vibrations
 Musical in character
 Produced when airflow is restricted
DEFINITION
 The American Thoracic Society Committee
Wheeze: High pitched continuous sounds with a dominant
frequency of 400 Hz or more.

3. 
 MC: expiratory wheeze
 Typically reflect lower airway obstruction
 MC found with asthma & bronchiolitis
 Other causes: CHF & foreign body aspiration
 http://www.stethographics.com/main/physiology_ls_wheeze.html
 https://www.youtube.com/watch?v=BvnphT1QnNY
WHEEZE
Polyphonic Monophonic
Various pitch Single- pitch sound
Widespread narrowing of airways Narrowing of larger airways
Asthma Tracheomalacia, bronchomalacia

4.  Airway Narrowing
 Bronchoconstriction
 Mucosal edema
 External compression
 Partial obstruction by
 tumor
 foreign body
 tenacious secretion
MECHANISM
 Wheeze
 Generated by vibrations/oscillations of nearly closed airway walls
 Air passing through narrowed portion at high velocity
 ↓ gas pressure and flow
 Airway pressure slightly ↑ and barely reopens airway lumen
 Alternating between nearly closed and nearly open
 fluttering of the airway walls and a musical, ‘continuous’ sound.
 Wheeze
 Generated by vibrations/oscillations of nearly closed airway walls
 Air passing through narrowed portion at high velocity
 ↓ gas pressure and flow
 Airway pressure slightly ↑ and barely reopens airway lumen
 Alternating between nearly closed and nearly open
 fluttering of the airway walls and a musical, ‘continuous’ sound.
 Wheeze
 Generated by vibrations/oscillations of nearly closed airway walls
 Air passing through narrowed portion at high velocity
 ↓ gas pressure and flow
 Airway pressure slightly ↑ and barely reopens airway lumen
 Alternating between nearly closed and nearly open
 fluttering of the airway walls and a musical, ‘continuous’ sound.
 Wheeze
 Generated by vibrations/oscillations of nearly closed airway walls
 Air passing through narrowed portion at high velocity
 ↓ gas pressure and flow
 Airway pressure slightly ↑ and barely reopens airway lumen
 Alternating between nearly closed and nearly open
 fluttering of the airway walls and a musical, ‘continuous’ sound.

5. 

6.  Toy trumpet
 sound is produced by a vibrating reed.
 Pitch
• dependent on the mass and elasticity of the airway walls &
on the flow velocity.
 Wheeze production model  collapsible tube
• the fluttering of airways walls & fluid together, induced by a
critical airflow velocity.
 Many circumstances are suitable for the production of continuous adventitious
lung sounds. Thus, wheezes can be heard in several diseases, not only asthma.
MECHANISM

7. 
 Viral infection
 Asthma
 Foreign body aspiration
 Cystic fibrosis
 Anatomic abnormalities
 Tracheomalacia, bronchomalacia
 Mediastinal mass
 Congenital heart disease (R to L shunt)
 GERD
 Anaphylaxis
Causes of Wheeze

8. 
www.aafp.org/aafp

9. 
Done! Thank you.

10. 
 N M, al et. Wheezes. - PubMed [Internet]. 1995 [cited 2015 Jun 21].
Available from: http://www.ncbi.nlm.nih.gov/m/pubmed/8620967/
 O’Brien N, Gill D, Hickey D. Paediatric Clinical Examination Made Easy.
Edinburgh: Churchill Livingstone Elsevier; 2007.
 Zorc JJ, editor. Schwartz’s clinical handbook of pediatrics. Philadelphia:
Lippincott Williams and Wilkins; 2008.
 Lissauer, Tom, Graham Clayden, and Alan Craft. Illustrated Textbook Of
Paediatrics. Edinburgh: Mosby, 2012. Print.
 Weiss LN. The Diagnosis of Wheezing in Children - American Family
Physician [Internet]. [cited 2015 Jun 21]. Available from:
http://www.aafp.org/afp/2008/0415/p1109.html
References