Respiratory sounds

Respiratory sounds
Classification and external resources
Specialty
ICD-10	R06
ICD-9-CM	786.7
MedlinePlus	007535
Patient UK	Respiratory sounds
MeSH	D012135

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 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:

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.
Stridor	continuous	high	either, mostly inspiratory	whistling/sibilant, musical	epiglottitis, foreign body, laryngeal oedema, croup
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
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.

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.

External links

• Audio Breath Sounds - Multiple case studies with audio files of lung sounds.
• R.A.L.E. Repository - sound files of breath sounds
• MEDiscuss - Respiratory auscultation with audio examples
• Lehrer, Steven. Understanding Lung Sounds. Elsevier 2002.
• Lung Sounds - 20 recordings and waveforms