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Page 9 of 14
Wheezes:
Wheezes are continuous, high pitched, musical sounds heard usually on expiration.
They are produced when air flows through airways narrowed by secretions, foreign bodies, or obstructive lesions. The proportion of the respiratory cycle occupied by the wheeze roughly corresponds to the degree of airway obstruction.
There are two types of wheezes:
- monophonic (suggesting obstruction of one airway) or
- polyphonic (suggesting generalized obstruction of airways).
- asthma
- chronic bronchitis
- acute bronchitis
- sometimes in pulmonary edema
The presence of expiratory wheezing signifies that the patient's peak
expiratory flow rate is less than 50% of normal, and due to a dynamic
bronchoconstriction as in bronchial asthma.
Wheezing heard during
inspiration most often signifies a more static bronchoconstriction
usually caused by tumors, foreign bodies or firosis. This is especially true if they are monophonic wheezes. These generally are sinister in their implication. They are usually seen when a single or a very limited number of bronchioles is/are compressed, commonly seen in bronchogenic carcinoma.
The location on the chest where the wheezes are heard also hints at the cause. If wheezes are heard in all areas, they are most likely due to generalized bronchoconstriction as in asthma, when it will also be polyphonic.
The term 'rhonchi' is also used sometimes as a synonym for wheezes. But they also have a different description as you can see in the next page.
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