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Vocal resonance

 

This is the auscultatory equivalent of vocal fiemitus. Place the stethoscope on the chest and ask the patient to say 'ninetynine". Normally the sound produced is 'fuzzy' and seems to come from the chest piece of the stethoscope. The changes

in disease should by now be predictable. The sound is increased in consolidation (better transmission through solid lung)and decreased if there is air, fluid or pleural thickening between the lung and the chest wall. The changes of vocal fremitus are the same. Both tests are of little value in themselves, yet a refinement of vocal resonance can be very uscful. Sometimes the increased transmission of sound is so

marked that even when the patient whispers, the sound is still heard clearly over the affected lung (whispering pectoriloquy). When this is well developed there is a striking difference between the normal side, where the sound appears to come from the end of the stethoscope and the abnormal side where the syllables are much clearer and seem as if they are being whispered into your ear.Bronchial breathing and whispering pectoriloquy often occur together. Consequently, if you are in doubt about the presence of bronchial breathing then whispering pectoriloquy may confirm it. Like bronchia] breathing, whispering pectoriloquy is characteristic of consolidation but can also occur with lung abscess and above an effusion.

 

 

Added sounds

 

There are three types of added sounds: wheezes, crackles and pleural rubs. Much confusion has been generated in the past by other terms such as rbonchi which are equivalent to wheezes and crepitations and rales which are equivalent to crackles. Further subdivision is often attempted but is of very limited value.

 

Wheezes

 

These are prolonged musical sounds largely occurring on expiration, sometimes on inspiration, and are due to localised narrowing within the bronchial tree. They are caused by the vibration of the walls of a bronchus near to its point of closure.

Most patients with wheeze have many, each coming from a single, narrowed area. As the lung gets smaller on expiration so the airways get smaller too, each narrowed airway reaches a critical phase when it produces a wheeze then ceases to do so. Thus, during expiration, numerous nanowings produce numerous wheezes in sequence and together. A single wheeze can occur and may then suggest a single narrowing often caused by a carcinoma or foreign body (fixed wheeze).

 

Wheezes are typical of airway narrowing from any cause. Asthma and chronic bronchitis are the most common and the narrowing is caused by a combination of smooth muscle contraction, inflammatory changes in the walls and increased bronchial secretions. Sometimes patients with these conditions have few or no wheezes. If so, ask the patient to take a deep breath and then to blow out hard. This may produce a marked wheeze. Occasionally, wheezing is heard in pulmonary edema, presumably because of bronchial wall edema. The term bronchospasm suggests narrowing caused only by smooth muscle contraction and should be avoided as the bronchial narrowing is usually multifactorial. Wheeze-like breath sounds can disappear in severe asthma and emphysema because of low rates of airflow. The amount of wheeze is not a good indicator to the degree of airways obstruction. Peak expiratory flow measurement is



much better.

Stridor

 

Stridor may be heard better without a stethoscope by putting your ear close to the patient's mouth and asking the patient to breathe in and out. As indicated earlier, it is a sign atlarge airway narrowing either in the larynx, trachea or main bronchi.

 


Date: 2015-02-03; view: 234


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