Adventitious sounds are abnormal pulmonary sounds that can be divided into:<\/p>\n
When describing adventitious sounds it is important to indicate in which section of the breathing cycle these noises are audible.<\/p>\n
Pleural adventitious sounds<\/strong> Bronchopulmonary adventitious sounds <\/strong> Wheezing and rhonchi<\/em> Crackles<\/em>
\nPleural adventitious sounds (pleural rubs) are usually easy to recognise as rubbing or crackling (\u2018footsteps in the snow\u2019). They occur during breathing as the result of the rubbing together of irritated or inflamed pleural membranes, separated by very little fluid (pleuritis sicca). A rubbing noise will not be audible if a substantial amount of fluid is present between the inflamed pleural membranes.
\nPleural rub is audible most clearly at the end of inspiration because movement of the visceral pleura is faster than the parietal pleura. However, in contrast to most other adventitious sounds, pleural rub is audible both during inspiration and expiration.<\/p>\n
\nBronchopulmonary adventitious sounds are abnormal sounds that can be divided on the basis of their duration:<\/p>\n\n
\nHigh-frequency wheezing and low-frequency rhonchi are continuous adventitious sounds lasting longer than 250 milli-seconds and caused by vibration of fairly large airways which are constricted. Such constriction can be the result of swelling and mucous membrane oedema, smooth muscle spasms or stasis of bronchial secretions. Depending on the degree of narrowing , these adventitious sounds can be audible either with breathing at rest or during deep breathing. Wheezing is identified particularly in constricted airways (as with asthma), whereas rhonchi are predominantly found in the presence of thick secretions (such as bronchitis).<\/p>\n
\nCrackles are discontinuous adventitious sounds that last for less than 20 milliseconds and have a much more explosive character than wheezing and rhonchi. One should describe where they are heard and whether they disappear upon coughing or deep sighing.
\nCrackles can be subdivided into fine (high-frequency) crackles or coarse (low-frequency) crackles. During inspiration, early inspiratory (often coarse) crackles are probably caused by the opening of larger airways (e.g. in COPD). Late inspiratory (often fine) crackles are probably caused by the opening of smaller airways (e.g. with pulmonary oedema). Furthermore, coarse and fine crackles can also occur during expiration. Expiratory coarse crackles usually occur as a result of bronchial secretion and often disappear with coughing. Expiratory fine crackles occur with respiratory tract weakness and deformation, such as emphysema and bronchiectasis, and often do not disappear upon coughing.<\/p>\nProcedure<\/h2>\n