Respiratory sounds
Respiratory sounds, breath sounds, or lung sounds refer to the specific sounds generated by the movement of air through the respiratory system. These may be easily audible or identified through auscultation of the respiratory system through the lung fields[1] with a stethoscope. These include normal breath sounds and adventitious or "added" sounds such as rales, wheezes, pleural friction rubs, stertor and stridor.
Description and classification of the sounds usually involves auscultation of the inspiratory and expiratory phases of the breath cycle, noting both the pitch (typically described as low, medium or high) and intensity (soft, medium, loud or very loud) of the sounds heard.
Abnormal breath sounds
Common types of abnormal breath sounds include the following:[2]
| Name |
Continuous/discontinuous |
Frequency/Pitch |
Inspiratory/expiratory |
Quality |
Associated conditions |
Example |
| Wheeze or rhonchi |
continuous |
high (wheeze) or lower (rhonchi) |
expiratory or inspiratory |
whistling/sibilant, musical |
Caused by narrowing of airways, such as in asthma, chronic obstructive pulmonary disease, foreign body. |
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| Stridor |
continuous |
high |
either, mostly inspiratory |
whistling/sibilant, musical |
epiglottitis, foreign body, laryngeal oedema, croup |
|
Stridor
Inspiratory and expiratory stridor in a 13-month child with croup.
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| Inspiratory gasp |
continuous |
high |
inspiratory |
whoop |
pertussis (whooping cough) |
not available |
| Crackles (aka crepitations or rales) |
discontinuous |
high (fine) or low (coarse), nonmusical |
inspiratory |
cracking/clicking/rattling |
pneumonia, congestive heart failure |
|
Crackles
Crackles heard in the lungs of a person with pneumonia using a stethoscope.
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| Pleural friction rub |
continuous |
low |
inspiratory and expiratory |
nonmusical, many repeated rhythmic sounds |
inflammation of lung linings, lung tumors |
not available |
| Hamman's sign (or Mediastinal crunch) |
discontinuous |
|
neither (heartbeat) |
crunching, rasping |
pneumomediastinum, pneumopericardium |
not available |
Continued
- Rales: Small clicking, bubbling, or rattling sounds in the lungs. They are heard when a person breathes in (inhales). They are believed to occur when air opens closed air spaces. Rales can be further described as moist, dry, fine, and coarse.
- Rhonchi: Sounds that resemble snoring. They occur when air is blocked or air flow becomes rough through the large airways.
- Stridor: Wheeze-like sound heard when a person breathes. Usually it is due to a blockage of airflow in the windpipe (trachea) or in the back of the throat.
- Wheezing: High-pitched sounds produced by narrowed airways. They are most often heard when a person breathes out (exhales). Wheezing and other abnormal sounds can sometimes be heard without a stethoscope.[3]
Other tests of auscultation
Pectoriloquy, egophony and bronchophony are tests of auscultation. For example, in whispered pectoriloquy the person being examined whispers - typically a two syllable number as the clinician listens over the lung fields. The whisper is not normally heard over the lungs, but if heard may be indicative of pulmonary consolidation in that area. This is because sound travels differently through denser (fluid or solid) media than the air that should normally be predominant in lung tissue. In egophony, the person being examined continually speaks the English long-sound "E". The lungs are usually air filled, but if there is an abnormal solid component due to infection, fluid, or tumor, the higher frequencies of the "E" sound will be diminished. This changes the sound produced, from a long "E" sound to a long "A" sound.
References
External links
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| Medical examination and history taking | | | Auscultation | |
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