Respiratory sounds

Respiratory sounds
Other namesBreath sounds, lung sounds
1) area for normal tracheal sound, 2) area for auscultation of upper lung fields, 3) area for normal bronchial sound. Blue marks auscultation area and red line marks heart.
SpecialtyRespirology

Respiratory sounds, also known as lung sounds or breath sounds, refer to the specific sounds generated by the movement of air through the respiratory system.[1] These may be easily audible or identified through auscultation of the respiratory system through the lung fields with a stethoscope as well as from the spectral characteristics of lung sounds.[2] These include normal breath sounds and adventitious or "added" sounds such as crackles, wheezes, pleural friction rubs, stertor, and stridor.

Description and classification of the sounds usually involve auscultation of the inspiratory and expiratory phases of the breath cycle, noting both the pitch (typically described as low (≤200hz), medium or high (≥400hz)) and intensity (soft, medium, loud or very loud) of the sounds heard.[3]


Normal breath sounds

According to the Bates' Guide to Physical Examination and History-Taking 11th ed., normal breath sounds are classified as vesicular, bronchovesicular, bronchial or tracheal based on the anatomical location of auscultation.[4][3] Normal breath sounds can also be identified by patterns of sound duration and the quality of the sound as described in the table below:[4]

Name Location where heard normally Quality of sound Sound duration Graphical representation Example
tracheal over the trachea very loud expiratory sound duration is equivalent to inspiratory sound not available
bronchial over the manubrium loud, high pitched expiratory sound duration is longer than inspiratory sound
bronchovesicular anteriorly between the 1st and 2nd intercostal space;

posteriorly in-between the scapulae

intermediate expiratory sound duration is about equivalent to inspiratory sound
vesicular over most of both lungs soft, low pitched expiratory sound duration is shorter than inspiratory sound


Abnormal breath sounds

Common types of abnormal breath sounds include the following:[5]

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) see New England Journal of Medicine, Classic Whooping Cough sound file, Supplement to the N Engl J Med 2004; 350:2023-2026
Crackles (aka crepitations or rales) discontinuous high (fine) or low (coarse), nonmusical inspiratory cracking/clicking/rattling pneumonia, pulmonary edema, tuberculosis, bronchitis, heart failure
Pleural friction rub discontinuous 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. This term is no longer much in use.
  • Rhonchi are coarse rattling respiratory sounds, usually caused by secretions in bronchial airways. The sounds resemble snoring. "Rhonchi" is the plural form of the singular word "rhonchus". Since the mid-1990s, it has no longer been considered appropriate terminology in auscultation of the thorax, as much confusion has been reported in the published literature which confuses this with crepitations and wheezes, so the exact nature of this term is unclear.[6]
  • 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.[7]

Other tests of auscultation

A clinician auscultating the posterior lung of a patient.

Pectoriloquy, egophony and bronchophony are tests of auscultation that utilize the phenomenon of vocal resonance.[8] Clinicians can utilize these tests during a physical exam to screen for pathological lung disease. 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" (/i/). 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 (/eɪ/).

History

In 1957, Robertson and Coope proposed the two main categories of adventitious (added) lung sounds. Those categories were "Continuous" and "Interrupted" (or non-continuous).[9] In 1976, the International Lung Sound Association simplified the sub-categories as follows:

Continuous
Wheezes (>400 Hz)
Rhonchi (<200 Hz)
Discontinuous
Fine crackles
Coarse crackles[10][11]

Several sources will also refer to "medium" crackles, as a crackling sound that seems to fall between the coarse and fine crackles. Crackles are defined as discrete sounds that last less than 250 ms, while the continuous sounds (rhonchi and wheezes) last approximately 250 ms. Rhonchi are usually caused by a stricture or blockage in the upper airway. These are different from stridor.

See also

References

  1. ↑ "Breath sounds: MedlinePlus Medical Encyclopedia". medlineplus.gov. Retrieved 2021-11-11.
  2. ↑ Sengupta, Nandini; Sahidullah, Md; Saha, Goutam (August 2016). "Lung sound classification using cepstral-based statistical features". Computers in Biology and Medicine. 75 (1): 118–129. doi:10.1016/j.compbiomed.2016.05.013. PMID 27286184.
  3. 1 2 Zimmerman, Barret; Williams, Donna (2021), "Lung Sounds", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 30725938, retrieved 2021-11-11
  4. 1 2 Bickley, Lynn S (2013). Bates' Guide to Physical Examination and History-Taking. Wolters Kluwer Health/Lippincott Williams & Wilkins. pp. 311–312. ISBN 978-1609137625.
  5. ↑ Bohadana, Abraham (February 20, 2014). "Fundamentals of Lung Auscultation". New England Journal of Medicine. 370 (8): 744–751. doi:10.1056/NEJMra1302901. PMID 24552321.
  6. ↑ Wilkins, Robert L.; Dexter, James R.; Murphy, Raymond L. H.; DelBono, Elizabeth A. (1990-10-01). "Lung Sound Nomenclature Survey". Chest. 98 (4): 886–889. doi:10.1378/chest.98.4.886. ISSN 0012-3692. PMID 2209143.
  7. ↑ "Breath sounds: Medline Plus". NIH. Retrieved 5 May 2015.
  8. ↑ Zimmerman, Barret; Williams, Donna (2021), "Lung Sounds", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 30725938, retrieved 2021-11-11
  9. ↑ Robertson, A (1957). "Rales, rhonchi, and Laennec". Lancet. 2 (6992): 417–23. doi:10.1016/S0140-6736(57)92359-0. PMID 13464086.
  10. ↑ American Thoracic Society Ad Hoc Committee on Pulmonary Nomenclature (1977). "Updated nomenclature for membership reaction". ATS News (3): 5–6.
  11. ↑ Loudon, R; Murphy, R (1984). "Lung Sounds". Am Rev Respir Dis. 130 (4): 663–73. doi:10.1164/arrd.1984.130.4.663 (inactive 31 October 2021). PMID 6385790.{{cite journal}}: CS1 maint: DOI inactive as of October 2021 (link)

Mansy, H. A.; Royston, T. J.; Balk, R. A.; Sandler, R. H. (2002). "Pneumothorax detection using computerised analysis of breath sounds". Medical & Biological Engineering & Computing. 40 (5): 526–532. doi:10.1007/BF02345450. PMID 12452412. S2CID 7413897.

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