The n e w e ng l a n d j o u r na l of m e dic i n ereview article Edward W. Campion, M.D., Editor Fundamentals of Lung Auscultation Abraham Bohadana, M.D., Gabriel Izbicki, M.D., and Steve S. Kraman, M.D. C From the Pulmonary Institute, Shaare Zedek hest auscultation has long been considered a useful part of Medical Center, and the Hebrew University the physical examination, going back to the time of Hippocrates. However, Hadassah Medical School, Jerusalem (A.B., G.I.); and the University of Kentucky School it did not become a widespread practice until the invention of the stetho- of Medicine, Lexington (S.S.K.). Address scope by René Laënnec in 1816, which made the practice convenient and hygienic.1 reprint requests to Dr. Bohadana at the Pul- During the second half of the 20th century, technological advances in ultrasonog- monary Institute, Shaare Zedek Medical Center, 12 Baiyt St., 91031 Jerusalem, Israel, raphy, radiographic computed tomography (CT), and magnetic resonance imaging or at
[email protected]. shifted interest from lung auscultation to imaging studies, which can detect lung N Engl J Med 2014;370:744-51. disease with an accuracy never previously imagined. However, modern computer- DOI: 10.1056/NEJMra1302901 assisted techniques have also allowed precise recording and analysis of lung sounds, Copyright © 2014 Massachusetts Medical Society. prompting the correlation of acoustic indexes with measures of lung mechanics. This innovative, though still little used, approach has improved our knowledge of acoustic mechanisms and increased the clinical usefulness of auscultation. In this review, we present an overview of lung auscultation in the light of modern concepts of lung acoustics. Nomencl at ur e The traditional nomenclature for lung sounds suffers from imprecision. Therefore, in this article, we have adopted the terminology proposed by the ad hoc committee of the International Lung Sounds Association.2 In this classification of lung sounds, the term “rale” is replaced by “crackle,” since the adjectives often used to qualify rales (e.g., “moist” or “dry”) can be misleading with regard to the means by which rales (or crackles) are produced. “Crackle” can be defined acoustically and does not suggest any means or site of generation. The clinical characteristics of normal and An interactive graphic is adventitious sounds are summarized in Table 1, and the lung sounds can be heard available at in an interactive graphic, available with the full text of this article at NEJM.org. NEJM.org Nor m a l R e spir at or y Sounds Tracheal Sounds Tracheal auscultation is not frequently performed, but in certain situations it can convey important clinical information. When heard at the suprasternal notch or the lateral neck, normal tracheal sounds characteristically contain a large amount of sound energy and are easily heard during the two phases of the respiratory cycle (Fig. 1A). The frequencies of these sounds range from 100 Hz to almost 5000 Hz, with a sharp drop in power at a frequency of approximately 800 Hz and little energy beyond 1500 Hz.4 They are produced by turbulent airflow in the pharynx, glottis, and subglottic region. Listening to tracheal sounds can be useful in a variety of circumstances. First, the trachea carries sound from within the lungs, allowing auscultation of other sounds without filtering from the chest cage. Second, the characteristics of tra- cheal sounds are similar in quality to the abnormal bronchial breathing heard 744 n engl j med 370;8 nejm.org february 20, 2014 The New England Journal of Medicine Downloaded from nejm.org on February 19, 2014. For personal use only. No other uses without permission. Copyright © 2014 Massachusetts Medical Society. All rights reserved. g. short. may be related inspiration and throughout expiration. bronchomalacia. may indicate pneumonia in patients who are acutely ill * Information is from Bohadana et al. used to monitor sleep apnea.. fundamentals of lung auscultation in patients with lung consolidation. in asthma. gravity-dependent. high-pitched. . explosive. expiration. explosive. lung destruction. laryngeal mass or web) when biphasic Wheeze Musical. associated with various diseases inspiration and occasionally on expiration. Copyright © 2014 Massachusetts Medical Society. is common with airway narrowing caused by mucosal thickening or edema or by bronchospasm (e.g.. asbestosis). 2014 745 The New England Journal of Medicine Downloaded from nejm. associated with intrathoracic lesions (e.g. Clinical Characteristics and Correlations of Respiratory Sounds. interstitial lung fibrosis. become more noisy or even musical) if upper-airway patency is altered. airway collapsibility.g. airway narrowing) or sound transmission (e. degree of airflow limitation proportional to number of airways generating wheezes.. 2014. transmitted to mouth idiopathic pulmonary fibrosis. indicating upper- of respiratory cycle airway patency. heard on both phases of respiratory Indicates patent airway surrounded by consolidated cycle (mimics tracheal sound) lung tissue (e. Recognizing this “tracheal wheeze” patients with upper-airway obstruction. or both (e. lower in Associated with rupture of fluid films and abnormal pitch than wheeze. can be earliest sign of disease (e.. similar to snoring. destructive emphysema) Rhonchus Musical.org on February 19. may be heard on inspiration..org february 20. in chronic bronchitis) cough. in tense wheeze. for the wheeze of asthma (as discussed in more Table 1. congestive heart failure. or both suggesting a role for secretions in larger airways. tated over the lung. bronchitis and chronic obstructive pulmonary disease) Fine crackle Nonmusical.. unaffected by cough. transmitted to mouth Pleural friction rub Nonmusical. may be absent if airflow is too low (e. associated with airways or at a distance without a stethoscope extrathoracic lesions (e. may be present before detection of changes on radiology Coarse crackle Nonmusical. can be disturbed (e. in. paralysis of both vocal cords. short.. extrinsic compression) when heard on expiration.g.g.. explosive sounds. tumor). heard on inspiration. nonmusical. Suggests airway narrowing or blockage when localized expiration. rules out clinically significant airway obstruction* Bronchial breathing Soft. lesion after extubation) when heard on inspiration. low-pitched.g. not pneumonia)..g. For personal use only... All rights reserved. is nonspecific. croup. in severe asthma. serves as a good model of bronchial breathing Normal lung sound Soft. assessed as an aggregate score with normal breath sound. laryngomalacia. Third. associated with generalized airway narrowing and airflow limitation when widespread (e.g.g.g. often clears with coughing.. Associated with pleural inflammation or pleural typically heard over basal regions tumors Squawk Mixed sound with short musical component (short Associated with conditions affecting distal airways. chronic obstructive lung disease). vocal- cord lesion. tracheomalacia. pneumothorax). No other uses without permission.g. foreign body. heard only on inspiration and on Is diminished by factors affecting sound generation early expiration (e. character.g. may be heard over the upper Indicates upper-airway obstruction. pneumonia) or fibrosis Stridor Musical. affected by to secretions (e.8 nejm. pleural effusion.. high-pitched. clearly heard in both phases Transports intrapulmonary sounds. Respiratory Sound Clinical Characteristics Clinical Correlation Normal tracheal sound Hollow and nonmusical. tracheal is clinically important because when auscul- sounds can become frankly musical. associated with fixed lesions (e. (e. heard on mid-to-late Unrelated to secretions.3 n engl j med 370. it is often mistakenly taken ized as either a typical stridor or a localized. nonmusical.. hypoventilation. usually biphasic sounds.g. heard on early Indicates intermittent airway opening. wheeze) accompanied or preceded by crackles may suggest hypersensitivity pneumonia or other types of interstitial lung disease in patients who are not acutely ill. Finally. with a tracheal stenosis or by a tumor in the central vertical line showing where the time-expanded sections airway. The unexpanded waveform of the tracheal sound when heard over the trachea or larynx. The n e w e ng l a n d j o u r na l of m e dic i n e detail below). sounds are evident only in the time-expanded tracing. including turbulent f low. normal lung sounds are heard clearly with random variation in amplitude. For personal use only. 1B). which appears as sinusoidal oscillations characteristic of studies support the idea of a double origin. fine crackles (Panel G) appear as Several mechanisms of vesicular sounds have spikes that correspond with the rapidly dampened wave been suggested. bulk flow.9 panded waveform.g. . All tracings begin with inspira- only the lungs are examined but is obvious tion. although for The left column shows typical values for the frequency practical reasons such monitoring cannot be (hertz) and duration (milliseconds) of the various performed by means of auscultation with a sounds.” Sounds neous mixture of sound waves extending over a wide The sound of normal breathing heard over the range of frequencies). monitoring tracheal sounds Figure 1 (facing page).) In bronchial breathing (Panel C).org february 20.8 nejm. regular spikes corre- surface of the chest is markedly influenced by the spond to heart sounds. this The pleural friction rub (Panel I) has an unexpanded loss of intensity can be due to a decrease in the waveform characterized by a series of vertical spikes in a amount of sound energy at the site of generation. when caused by bronchial or plots contain screenshots of the entire sound. panded waveform as a large vertical spike in the middle of eral conditions. The vertical. however. their Clinically. drug overdose)..org. pattern that is undistinguishable from that produced by impaired transmission. the fre. the narrower than that of tracheal sounds. The short musical component of the squawk (Panel J) is seen in the unex- inspiratory airflow.5 Whereas the stridorous breathing tude–time plots in unexpanded and time-expanded modes.g. teristically. Acoustics and Waveforms is a noninvasive means of monitoring patients of Lung Sounds. (A low-pass filter during inspiration but only in the early phase of allows easy passing of frequencies below a prescribed expiration (Fig. crackles. Airway conditions in. frequency limit. In the unex- component coming from more central sources. It may be missed when (200 msec) were obtained. Charac expanded waveform is similar to that of a tracheal sound. or both.8.) The unexpanded waveform of a diffusion from parts of the lung reached through wheeze (Panel E) has a strong expiratory component. stri- trary units.7 The idea that stridor (Panel D) has a strong inspiratory component that “vesicular” sound is produced by air entering the appears as sinusoidal oscillations in the time-expanded alveoli (“vesicles”) is incorrect. Most important. The fundamental frequency is the lowest fre- periphery gas molecules migrate by means of quency produced. with musical sounds in the time-expanded tracing. See the clude blockage (e. A rhonchus the inspiratory component generated within the (Panel F) can be distinguished from a wheeze by its lower frequency. 2014. The unexpanded waveform of at approximately 100 to 200 Hz. Numerous accompanying crackles can be seen as small vertical spikes on both inspiration and expiration.10-12 crackles (Panel H) cannot be distinguished from fine crackles in the unexpanded waveform. In sound analysis. tem (e. a silent process. by a foreign body or tumor) interactive graphic at NEJM.org on February 19. most common abnormality. the quency range of normal lung sounds appears to be unexpanded waveform is characterized by similar am- plitudes of the inspiratory and expiratory components. evident in the lower number of oscillations per lobar and segmental airways and the expiratory unit of time in the time-expanded waveform. The middle and right columns show ampli- stethoscope.. deflections seen in the time-expanded tracing. and the narrowing that occurs in obstructive 746 n engl j med 370.g. modern tracing. or “Vesicular. The unexpanded dor in adults. and time in seconds). respectively (amplitude is measured in arbi- of a child with croup is easily recognized. ranging from poor cooperation the inspiratory component of the normal breath sound. Mechanistically. Coarse and other. The unexpanded waveform of a anatomical structures between the site of sound normal (vesicular) breath (Panel B) has a strong inspira- tory component relative to the expiratory component. No other uses without permission. Copyright © 2014 Massachusetts Medical Society. All rights reserved. (The sinusoid is a waveform representing periodic concepts of physiology indicate that in the lung oscillations of constant amplitude. the sinusoidal oscillations typical of musical breath) to depression of the central nervous sys. as indicated by a sine function. 2014 The New England Journal of Medicine Downloaded from nejm. which can result from sev. for the sleep apnea syndrome.6 (Panel A) has strong inspiratory and expiratory compo- nents. the generation and the site of auscultation.. a decrease in sound intensity is the longer duration is apparent in the time-expanded tracing.3 Sound genera. vortexes. hitherto unknown mechanisms. The lower frequency of the pleural friction rub is tion can be decreased when there is a drop in apparent in the time-expanded tracing. Indeed. extending time-expanded waveform is like that seen with tracheal from below 100 Hz to 1000 Hz. is more subtle. with a sharp drop and normal breath sounds. the expanded waveform shows random fluctua- tions that are characteristic of white noise (a heteroge- Lung. (e. a patient’s unwillingness to take a deep However. 8 nejm.0 Rhythmic succession of short sounds 0.0 Typical frequency. >100–5000 Hz −0.0 0. fundamentals of lung auscultation Respiratory Sound Amplitude–Time Plot Acoustics Unexpanded time Expanded time A Tracheal Sound 1.5 and normal breathing −1.0 Sinusoid 0.0 6.0 5.0 5.0 8. 200–300 Hz −0.0 Typical frequency.0 5. >80 msec −1.0 C Bronchial Breathing 1.5 0.5 0. >500 Hz −0. about 350 Hz −0.0 2.0 White noise 0.0 2.0 Fundamental frequency.5 0.0 0.0 6.0 1.5 Drop of energy at 800 Hz −1.0 Typical frequency. about 150 Hz −0.0 J Squawk 1.0 8.0 4.5 Drop of energy at 200 Hz −1.0 D Stridor 1.0 Strong expiratory component 0.0 5.5 0.0 Sinusoid 0.5 Typical duration.0 4.0 0.0 1.0 1.0 3. about 5 msec −1.0 n engl j med 370.0 4.0 E Wheeze 1.0 F Rhonchus 1. >80 msec −1.0 4.0 3.5 −1.0 3.0 2. Copyright © 2014 Massachusetts Medical Society.5 Typical duration.0 4.0 4.0 0.5 Typical duration.0 B Normal (Vesicular) Lung Sound 1.0 0. All rights reserved.0 0 5 10 15 H Coarse Crackles 1.5 Typical duration.0 3.0 Typical frequency. >15 msec −1.0 Typical frequency.0 4.5 0. For personal use only.org on February 19. 2014.0 6.0 Typical frequency.0 2. 100–1000 Hz −0.0 0.0 Typical frequency. about 15 msec −1.0 1.0 2.0 Typical frequency.5 0.0 10. about 650 Hz −0.0 Sinusoid 0.5 Typical duration. No other uses without permission.0 Low-pass-filtered noise 0.0 0 5 10 15 20 G Fine Crackle 1.5 0.0 Rapidly dampened wave deflection 0. <350hz −0. 100–5000 Hz −0.org february 20. 2014 747 The New England Journal of Medicine Downloaded from nejm.0 An intermediate sound between tracheal −0.5 0.0 0.5 Typical duration. about 200 msec −1.0 2.5 0.0 2.0 I Pleural Friction Rub 1. .5 0.0 5.0 Followed or preceded by crackles 0.0 Sinusoid 0.0 Rapidly dampened wave deflection 0. In sound A bnor m a l R e spir at or y Sounds analysis the wheeze appears as sinusoidal oscil- lations with sound energy in the range of 100 to Musical Sounds 1000 Hz and with harmonics that exceed 1000 Hz Stridor on occasion (Fig.18 748 n engl j med 370. it can also be expiratory or biphasic.g. which The wheeze is probably the most easily recog- corresponds to the air bronchogram on chest nized adventitious sound. include dis. allows its musical qual- ity to be discerned by the human ear.18 In Evaluating stridor is especially useful in patients addition.g. peripheral airways and low-pitched wheezes to rowed segment of the upper respiratory tract. and second. Copyright © 2014 Massachusetts Medical Society.g.15 In addition. In cases of such obstruction. asthma (e. is a respiratory parenchyma (e. the model incorporates two principles: in the intensive care unit who have undergone first. The latter The stridorous sound of vocal-cord dysfunction include conditions such as obesity. or reversible. most had been treated with substantial doses of Incidentally. and 28% had creased breath sounds only if the embedded been intubated. fused with asthma and is responsible for numer- tention due to ascites. and tracheal carcinoma. stri. as in epiglottitis. If instead the airways are patent. than over the chest. pulmonary or extrapulmonary factors. vocal-cord dysfunction. chest defor.org on February 19. No other uses without permission.) In a review of 95 patients that has a different acoustic impedance from with vocal-cord dysfunction who were treated at that of the normal parenchyma (e. cord dysfunction to the medical care system. results in de. .. walls that have been narrowed to the point of often accompanied by several harmonics (Fig. which occurs in pneumonia. several reports have airways are blocked by inflammation or viscous documented the costs of misdiagnosed vocal- secretions. glucocorticoids. accompanied source of sound generation and the stethoscope by stridorous breathing. during a bronchial provocation test13 anaphylaxis. the development of lung consolida. musical sound pro. increas- ing the expiratory component.14 It the narrowing of central airways. The n e w e ng l a n d j o u r na l of m e dic i n e airway diseases (e. and abdominal dis. Purportedly. inhalation or an asthma attack).17 Its long duration. typi- radiographs.16 sound transmission is actually improved. In sound analysis it is char. collections the National Jewish Center.18 It is probably incorrect to Stridor is a high-pitched. airway edema after device removal. These patients also had an aver- tion. 1E). thickness of the airway wall. Wheeze acterized as “bronchial breathing” (Fig. piration and is more prominent over the neck and longitudinal tension. that although wheezes are always associat- extubation. being clearly heard without the wheezes are formed in the branches between the aid of a stethoscope. ous visits to the emergency department and hos- which can be harder to recognize. when its appearance can be a sign of ed with airflow limitation. airflow can be limit- extrathoracic airway obstruction requiring prompt ed in the absence of wheezes. deserves special mention because it is often con- mities (e. bending stiffness.14 Although stridor is usually tive pulmonary disease [COPD]). cally more than 100 msec. Sound transmission can be impaired by intra..8 nejm. For personal use only. second and seventh generations of the airway acterized by regular. is often intense. the intensity of breath sounds may be permanent.. 1D).org february 20. that intervention. kyphoscoliosis). 2014. condition characterized by the inappropriate ad- tion and parenchymal destruction in emphysema) duction of the vocal cord with resultant airflow or the interposition of a medium between the limitation at the level of the larynx. The decrease in inspiratory. of a foreign body. pitalizations.. credit high-pitched wheezes to the narrowing of duced as turbulent flow passes through a nar. All rights reserved. a combination of hyperdisten. asthma and chronic obstruc. laryngeal tumors. and intrapulmonary masses). 2014 The New England Journal of Medicine Downloaded from nejm. thyroiditis. 1C). (Vocal-cord dysfunction. apposition by a variety of mechanical forces. Other causes of stridor in adults include acute as in cases of pure emphysema. Intrapulmonary factors. also called ruption of the mechanical properties of the lung paradoxical vocal-cord motion. an incorrect diagnosis of asthma for years and thorax.g. hemothorax. the pitch of an individual wheeze is determined dor can be distinguished from wheeze because it not by the diameter of the airway but by the is more clearly heard on inspiration than on ex. age of six hospitalizations yearly. this effect is char. more than half carried of gas or liquid in the pleural space — pneumo.g. sinusoidal oscillations with tree by the coupled oscillation of gas and airway a fundamental frequency of approximately 500 Hz.. and are not influenced by changes in foreign body. quency (650 Hz vs. airway diseases. making their number difficult to heard over any lung region. 2014. fine crackles the wheeze.17 Two categories of crackles have been computerized acoustic analysis.org february 20. nonmusical sounds those who have many crackles are more likely to heard on inspiration and sometimes during expi. crackles appear recognize this type of wheeze can have serious as rapidly dampened wave deflections with a re- consequences for patients. For personal use only. This sound is considered to be a variant of been called Velcro rales. or tumor. 2014 749 The New England Journal of Medicine Downloaded from nejm. fine crackles are usually heard dur. Although typically present in obstructive pearing with changes in body position (e. They may be over the chest. Localized wheeze is often related to a ted to the mouth. fine crackles have a shorter are not referred to appropriate specialists for duration (5 msec vs. crackles are altered by gravity. ily affects the central lung zones not abutting the pleura. As compared misdiagnosis of “difficult-to-treat asthma”19 and with coarse crackles. the model cited the sudden inspiratory opening of small airways above predicts that the more severe the obstruc. held closed by surface forces during the previous tion. both the wheeze Because fine crackles have a distinctive sound and normal breath sounds reappear.21 Coarse crackles are probably pro- typical example is a severe asthma attack. they are also found in other interstitial dis- unlike the wheeze.17 The rhon. reduced or even absent. are usually transmit- estimate. are well perceived in pulmonary fibrosis and congestive heart failure. . Failure to body position. to the mouth. fine crackles are not chus and the wheeze probably share the same pathognomonic of idiopathic pulmonary fibro- mechanism of generation.g. and interstitial fibrosis associated Although many physicians still use the term with connective-tissue disorders. creating a clinical picture Evaluation for crackles is important because known as “silent lung. some prefer to refer to the character. duced by boluses of gas passing through airways as dition in which the low respiratory flows cannot they open and close intermittently. those with few crackles Crackles are more likely to have sarcoidosis. that is similar to the sound heard when joined Finally. which suggests that secretions play a role. Copyright © 2014 Massachusetts Medical Society. differing from the wheeze in its are prominent in idiopathic pulmonary fibrosis. especially asthma. but the rhonchus. crackles tend to be minimal or even absent in istic musical sounds simply as high-pitched or sarcoidosis. In sound analysis. the accom patients or in patients with abundant secretions. 1G and 1H). As a consequence. probably because sarcoidosis primar- low-pitched wheezes. which involves described: fine crackles and coarse crackles. Typically. such as asbestosis. No other uses without permission. sis. In fact. who often receive a petitive pattern (Fig. a word must be said about the rhon. and are not transmitted in addition to other cardiopulmonary disorders. can change or disappear with local phenomenon. may disappear after cough. have idiopathic pulmonary fibrosis. eases. All rights reserved. Notably. 15 msec) and higher fre- months or even years after the initial evaluation. or bi. they are not bending forward). pneumonitis. dependent lung regions. nonspecific interstitial ing. a con. the lower the likelihood of wheeze.. they have chus. lieved and airflow increases. Coarse crackles tend to appear pathognomonic of any particular disease. progression. panying normal breath sound is also severely crackles are probably not produced by secretions. Among patients with similar levels of Nonmusical Sounds scarring on chest films. vice. usually an obstruction by a coughing. whereas Crackles are short. expiratory. wheezes can be heard all tion and have a “popping” quality.20 The most likely Wheezes may be absent in patients with severe mechanism for the generation of fine crackles is airway obstruction.23 n engl j med 370. strips of Velcro are gently separated. In early during inspiration and throughout expira- asthma and COPD. has made it possible to diagnose idiopathic ing mid-to-late inspiration. The expiration.” As the obstruction is re. fine rhonchus.8 nejm. 1F). Advanced ration. lower pitch — typically near 150 Hz — which is appearing first in the basal areas of the lungs responsible for its resemblance to the sound of and progressing to the upper zones with disease snoring on auscultation (Fig. it can help with the differential diagnosis.17 With the ex- provide the energy necessary to generate wheezes ception of the crackling sounds heard in moribund (or any sounds). fundamentals of lung auscultation Wheezes can be inspiratory. Uninfluenced by cough.22 However. fine with good sensitivity and specificity. mucous plug. On the use of a multichannel sound-detection de- auscultation. explosive. 350 Hz).org on February 19. changing or disap- phasic. No other clinical pro- axillary regions than on auscultation of the up. with a fundamental congestive heart failure. the pleural friction abnormalities are detected and are thus consid. having also been documented in diseases such as bronchiectasis and pneumo- Pleural Friction Rub nia..patient. All rights reserved. 2014 The New England Journal of Medicine Downloaded from nejm. bronchiectasis. sounds mirroring the inspiratory sequence. diseases. but according to one theory.26 crackle detection by means flammatory diseases (e. crackles heard in the early phase give way to they are produced by the oscillation of peripheral shorter. The waveform is similar to that accepted as diagnostic of idiopathic pulmonary seen with crackles.25 Although the presence of Velcro rales Figure 1I shows individual components of a pleu- as heard on auscultation has not been formally ral friction rub.29 in healthy persons. for a given change in trans. except for its longer duration fibrosis. No other uses without permission. including analysis for a recorded squawk in a patient with COPD. with the expiratory sequence of ered to be an early sign of pulmonary impair. auscultation re- whereas the upper regions lie on the flat portion quires minimal cooperation on the part of the of the curve. pneumonia should be sus- slide over each other silently.org on February 19. frequency between 200 and 300 Hz.8 nejm. the char. gential energy from a lung surface that is tempo- ized detection of crackles has appeared to be as rarily prevented from sliding because of a fric- accurate as CT in locating disease that is not ra. tis. The n e w e ng l a n d j o u r na l of m e dic i n e In idiopathic pulmonary fibrosis and asbestosis. For personal use only.31 In a patient with squawk and no evidence In healthy persons. nant pleural diseases (e. they are not pathognomonic of tion for interstitial lung disease. One explanation for this difference relevant clinical information about the respira- is the fact that the basal regions lie on the steep tory system quickly. C onclusions rietal pleura produces crackling sounds heard as a friction rub. pleural friction rubs are heard in in- exposed to asbestos. containing musical and non- Coarse crackles are commonly heard in pa.29 diologically apparent. end-inspiratory crackles in the recovery airways (in deflated lung zones) whose walls re- phase.25 In a study of 386 workers Typically. and by nearly univer- portion of the static pressure–volume curve. auscultation is considered to be the only and lower frequency. this condition.30 However. usually in hypersensitivity pneumonitis. Figure 1J shows the sound tients with obstructive lung diseases. the basal regions undergo fine crackles can be discerned before radiologic greater expansion. and can be repeated as 750 n engl j med 370. the use of computer. the crackles tend to disap. rub is biphasic. Typically. The pleural friction rub is realistic means of detection early in the course of probably produced by the sudden release of tan- the disease. The short wheeze association with wheezes. Moreover. midinspiratory not entirely known. mesothelioma). The presence of the end of inspiration in patients with interstitial persistent crackles in both lungs in older per. . the parietal and visceral pleura of interstitial disease. cian correctly identified all the cases of asbesto- sis. They are also often appears as sinusoidal oscillations that are less heard in patients with pneumonia and those with than 200 msec in duration. pleuritis) or malig- of auscultation performed by a trained techni. musical components. The mecha- acteristics of the crackles may vary markedly nism underlying the production of squawks is during the disease: the coarse. especially hypersensitivity pneumoni- sons with dyspnea should prompt an investiga. In our experience. easily. Copyright © 2014 Massachusetts Medical Society. sally available means. the visceral pleura can be- come rough enough that its passage over the pa. is cost-effective. Thus.org february 20.22 In asbestosis. although crackles can be heard der the action of the inspiratory airflow. tional force between the two pleural layers.g. pulmonary pressure.g. In persons with pected.28 Finally.27 Fine and coarse crackles may also co main in apposition long enough to oscillate un- exist.29 ment..24.31 various lung diseases. In pneumonia. is a mixed sound. and asthma. 2014. suggesting that auscultation may have a role Mixed Sound — The Squawk to play as a noninvasive method of screening in Also called “short wheeze” or “squeak.cedure matches auscultation for the provision of per regions. Squawks are typically heard from the middle to pear after a few deep breaths.” the squawk these populations. this sound is Lung auscultation remains an essential part of more prominent on auscultation of the basal and the physical examination. because it is the next most likely cause. Christopher KL. toring during bronchial provocation test. Alhashem RM. Chest 1992. 3. Respir Dis 1984. et al. Changes in crackle charac- obstruction. 2014. Cottin V. and Dohme. Vyshedskiy A. Caramori G. Epler GR. Harper P. Holford 2010. Morris MJ.37: tribute to the vesicular lung sound? Am 651-7. The functional basis of pul. Mechanism of inspiratory and R. Ravenna F.33: 14. Chest 1987. Squawks in pneumonia. brosis. Peslin R.cal information. Chest 2009. An unusual case of congenital short 29. characteristics of normal breath sounds. Lock S. Carrington CB. Automated analysis of crackles synopsis of proceedings. Marsh K. al Jarad N. Butani L. Sanchez I. Shee TR. Rudd RM.8:341-9. fundamentals of lung auscultation often as necessary.org. Bana D. Kraman SS.79:91-9. 22.46: pulmonary fibroses. 11. 19. travel support from Novartis and GlaxoSmithKline.129:375-9. Copyright © 2014 Massachusetts Medical Society. Thorax 1982.50:1292-300. 12. Murphy R. Spectral way noise. Am Rev Respir Dis 1989. For personal use only.138: wave form analysis. Cordier J-F. Pearson MG. Bothamley G. fine and coarse crackles. The inspiratory “squawk” Rev Respir Dis 1980. London: 8. Murao M. Paris: Brosson generation? Clin Physiol 1988. Potential for lung sound moni.org february 20. et al. Ogilvie CM. Normal chest of airflow obstruction. O’Connell EJ. auscultation and high Sleep apnea monitoring and diagnosis 1213-23. No other uses without permission. . Murphy 10. Pasterkamp H. Strickland B. of vocal cord dysfunction. perhaps in the form AstraZeneca. Immunol 1997. International Symposium on Lung Sounds: Respir Crit Care Med 1996. sound signals. Functional re. Med Biol Eng Comput spiratory disorders. 64. Finally. Pauli G. Stridor: roentgenograms in chronic diffuse infil- 345-51. receive the journal’s table of contents each week by e-mail To receive the table of contents of the Journal by e-mail every Wednesday evening. N Engl J Med 2010.124:292-4. The effect of R.102:176-83. 25. Alroy G. Bohadana AB. J 1407-9. of production of respiratory sounds by bronchial asthma. Kraman analyze. 21. Pasterkamp H. lapsible tubes: a mechanism for genera. Thorax 1991. Vyshedskiy A. Epler G. n engl j med 370. The development of robust on its proper correlation with the available clini- acoustic devices for use at the bedside — as exem. Thorax 1978. Bohadana AB. Disclosure forms provided by the authors are available with further enhancing the usefulness of auscultation. 2014 751 The New England Journal of Medicine Downloaded from nejm.50:955-61. small convenient recorders. Gavriely N. 24. Uffholtz H. Velcro crackles: ate ou traité du diagnostic des maladies Does airway closure affect lung sound the key for early diagnosis of idiopathic des poumons et du coeur. sounds. Determination of the site trachea with very long bronchi mimicking Baillière Tindall. Lung sounds. and Dr. GlaxoSmithKline. Am 20.2011:590506. Rubin AHE.48:1087-97. Spectral and waveform characteristics of in extrinsic allergic alveolitis and other 9. Giannouli E. Laennec RTH. it must be kept in mind that auscultation We thank Dr. Vyshedskiy A. Appl Physiol Respir Environ Exerc Physiol 15. jects. early detection of asbestosis.org. Pulm Med 2011. Uffholtz H. Forgacs P. Peslin R. pneumonia. and store lung sounds just as any other reports providing expert testimony in workers’ compensation clinical information is measured and stored. Baughman RP. 27. McLoud TC. Am Rev Wodicka GR.8 nejm. Paciej 31. All rights reserved.153:1087-92. Hans Pasterkamp for providing the stridor sound file. Am J 23. 1819. Vyshedskiy A. 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