Adventitious Lung Sounds Research Articles

A rhesus monkey model of respiratory syncytial virus infection.

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract disease in infants and young children worldwide. To date, there is no single animal model that adequately reproduces all human disease states. Here, we have developed a model of experimental infection with human RSV in infant Rhesus macaques. Infected animals demonstrated mild clinical disease including increased respiratory rates, fever and adventitious lung sounds. While more severe disease was not observed, preliminary virological and histopathological findings are promising. It is anticipated that with further optimization, this model will provide a useful system with which to study disease due to RSV infection and evaluate candidate vaccines.

A new medical education using a lung sound auscultation simulator called "Mr. Lung"

We developed a lung sound auscultation simulator "Mr. Lung" in 2001. To improve the auscultation skills of lung sounds, we utilized this new device in our educational training facility. From June 2001 to March 2002, we used "Mr. Lung" for our small group training in which one hundred of the fifth year medical students were divided into small groups from which one group was taught every other week. The class consisted of ninety-minute training periods for auscultation of lung sounds. At first, we explained the classification of lung sounds, and then auscultation tests were performed. Namely, students listened to three cases of abnormal or adventitious lung sounds on "Mr. Lung" through their stethoscopes. Next they answered questions corresponding to the portion and quality of the sounds. Then, we explained the correct answers and how to differentiate lung sounds on "Mr. Lung". Additionally, at the beginning and the end of the lecture, five degrees of self-assessment for the auscultation of the lung sounds were performed. The ratio of correct answers for lung sounds were 36.9% for differences between bilateral lung sounds, 52.5% for coarse crackles, 34.1% for fine crackles, 69.2% for wheezes, 62.1% for rhonchi and 22.2% for stridor. Self-assessment scores were significantly higher after the class than before. The ratio of correct lung sound answers was surprisingly low among medical students. We believe repetitive auscultation of the simulator to be extremely helpful for medical education.

A computer-based lung sound simulator

A novel lung sound simulator for teaching and research purposes is presented. While heart sound simulators have been used for many years in medical schools and schools of nursing, first algorithms for the simulation of lung sounds have become available only recently [M. Kompis and E. Russi, Med. Biol. Eng. Comput. 35, 231–238 (1997)], and no practically useful device has been presented up to now. The newly developed lung sound simulator requires no specialized hardware except for a personal computer, a standard sound card, and loudspeakers which are able to reproduce the predominately low-frequency sounds. Normal, bronchial, and tracheal respiratory sounds can be simulated, and continuous and discontinuous adventitious lung sounds, as well as heart sounds, can be added. The attributes of these sounds, such as, e.g., loudness, duration, and pitch, are controlled by the user. Changes in the simulation parameters can be made effective almost immediately. Simulated sounds can be saved for later use, and recordings of real lung sounds can be reproduced from within the lung sound simulator program, allowing direct comparison between real and simulated sounds. Simulation parameters can be stored and libraries of simulated lung sounds can be created.

Wheezes

Wheezes are continuous adventitious lung sounds. The American Thoracic Society Committee on pulmonary nomenclature define wheezes as high-pitched continuous sounds with a dominant frequency of 400 Hz or more. Rhonchi are characterized as low-pitched continuous sounds with a dominant frequency of about 200 Hz or less. The large variability in the predominant frequency of wheezes is one of the difficulties encountered with automated analysis and quantification of wheezes. The large variations observed in automated wheeze characterization emphasize the need for standardization of breath sound analysis. This standardization would help determine diagnostic criteria for wheeze identification. The mechanism of wheeze production was first compared to a toy trumpet whose sound is produced by a vibrating reed. The pitch of the wheeze is dependent on the mass and elasticity of the airway walls and on the flow velocity. More recently, a model of wheeze production based on the mathematical analysis of the stability of airflow through a collapsible tube has been proposed. According to this model, wheezes are produced by the fluttering of the airways walls and fluid together, induced by a critical airflow velocity. Many circumstances are suitable for the production of continuous adventitious lung sounds. Thus, wheezes can be heard in several diseases, not only asthma. Wheezes are usual clinical signs in patients with obstructive airway diseases and particularly during acute episodes of asthma. A relationship between the degree of bronchial obstruction and the presence and characteristics of wheezes has been demonstrated in several studies. The best result is observed when the degree of bronchial obstruction is compared to the proportion of the respiratory cycle occupied by wheeze (tw/ttot). However, the relationship is too scattered to predict forced expiratory volume in one second (FEV1) from wheeze duration. There is no relationship between the intensity or the pitch of wheezes and the pulmonary function. The presence or quantification of wheezes have also been evaluated for the assessment of bronchial hyperresponsiveness. Wheeze detection cannot fully replace spirometry during bronchial provocation testing but may add some interesting information. Continuous monitoring of wheezes might be a useful tool for evaluation of nocturnal asthma and its treatment.

Microbiologic changes during antimicrobial treatment and rate of relapse of distal respiratory tract infections in foals

Summary Despite the high incidence of distal respiratory tract infection of undetermined cause on farms, to our knowledge, the microbiologic effects of conventional antimicrobial treatment for this condition have not been studied. We evaluated the possible pathogenic role of bacterial isolates from the distal airways of foals with clinical respiratory tract disease, by correlating changes in their numbers (increase or decrease) with clinical, endoscopic, and pulmonary cytologic signs of disease resolution during treatment with antimicrobial drugs. We also determined qualitative changes in in vitro antimicrobial susceptibility of bacterial isolates after 7 days of treatment and relapse rate of foals. Significant (P < 0.05) decrease in the numbers of an isolate in the airways was considered strong evidence of a pathogenic role in this disease syndrome. Foals with endoscopically confirmed distal respiratory tract infection (drti; n = 65) were selected at random for treatment (n = 56) or nontreatment (n = 9), and bronchial lavage specimens were cultured and evaluated cytologically before and after 7 days of treatment with trimethoprim-sulfamethoxazole (tms) and a β-lactam drug (penicillin, ampicillin, or sulbactam-ampicillin), the standard treatment in all foals. The effect of treatment was to abruptly reduce the clinical (nasal discharge, cough, adventitious lung sounds) and cytologic signs of airway infection. Severity of disease in nontreated foals, however, did not change or did worsen over time. Reduction in the frequency and numbers of Streptococcus zooepidemicus isolated during treatment supported a causal role for this organism in the clinical syndrome observed. On the other hand, the frequency of non-Str zooepidemicus isolates (eg, Staphylococcus epidermidis, Streptomyces spp, α-hemolytic streptococci) actually increased during treatment, compatible with a commensal or competitive role for these organisms. Significantly (P < 0.001) more pretreatment isolates were susceptible in vitro to either tms or β-lactam drugs than to β-lactam drugs alone; more posttreatment isolates were susceptible to either tms or β-lactam than to either drug alone. These data indicate that there may be some benefit to combined use of tms plus β-lactam drugs in foals with drti. Mean ± sem relapse rate was 31 ± 6% (range 0 to 57%); risk factors (clinical signs of disease, laboratory variables) for relapse could not be identified. In conclusion, treatment resulted in significant (P < 0.001) reduction in airway inflammation in foals with clinical drti. The high reinfection rate indicates that a predisposing factor, possibly age-related immunodeficiency, may predispose foals to illness and persists after treatment.

Wave form of intrabronchial spark sound on the chest wall and sound transmission in the lung-thoracic system

A spark sound was generated in the canine bronchus and sound waves were observed on the surface (skin) and on each layer (pectoralis major muscle, intercostal muscle and parietal pleura) of the chest wall. The sound wave observed on the surface of the chest wall was 5-10 ms in duration, 400-500 Hz in dominant frequency and 0.6-1.2 ms in the duration of the initial deflection. Reverse dispersion of the waves, i.e., the later components of the wave having longer periods, was also recognized. These characteristics of the wave were similar to those of time-expanded wave-form of crackle, i.e., discontinuous adventitious lung sounds, in clinical cases. Both the spark sound and the sound wave observed on the visceral pleura were of short duration, being 0.7 ms and 1 ms, respectively. therefore, the main component of the sound wave observed on the chest surface was considered to reflect the physical properties of the chest wall itself. The analysis of place relationship within the chest wall suggested that transmission of the sound across the chest occurred not as a surface wave but as a longitudinal wave, therewith traversing the chest wall directly from the sound source. The arrival time of the sound was well correlated with the distance between the sound source and the positions of the pick-ups on the surface of the chest wall. Assuming that the medium between the source and the lung and in the chest wall were 71.5 and 29.6 m/sec, respectively. Further studies will be necessary to clarify the theory of the sound transmission through the living tissue as a viscoelastic body.

Lung Sound Nomenclature Survey

We report the terms used by 223 pulmonary physicians and 54 physicians in other specialties to describe eight recorded examples of lung sounds. The participants listened to the lung sounds at the 1988 American College of Chest Physicians annual convention and wrote "free form" answers. Pulmonary physicians used the terms "crackles" and "rales" with equal frequency to describe discontinuous adventitious lung sounds (ALS) and not at all to describe continuous ALS. Other physicians preferred the term "rales" in describing discontinuous ALS. The terms "wheeze" and "stridor" were used only in describing continuous ALS; however, the term "rhonchi" was frequently used to describe continuous and discontinuous ALS. The majority of participants recognized the normal breath sounds but not the pleural friction rub. Most did not use a qualifying adjective to describe ALS, and there was little agreement among those who did. The lung sound terminology used by physicians is not well standardized and the recommendations of the ATS/ACCP nomenclature subcommittee are not widely accepted.

Continuous Adventitious Lung Sounds

Recent research has increased the still limited understanding about the generation of continuous adventitious lung sounds. These sounds all have a definite pitch, such as in stridor and wheezing. With the use of waveform analysis, one can examine more closely the relationship between what is heard and the pathophysiology causing the sound. Clinical examples are given to show the utility and limitations of current lung sounds analysis techniques.

Digital Respirosonography: New Images of Lung Sounds

We used tape recordings from normal subjects and from patients with lung disease to generate spectrographic images of respiratory sounds on a personal computer. These digital respirosonograms presented timing and frequency content of lung sounds, with the sound intensities displayed on a color scale. Respiratory sounds during inspiration and expiration could be recognized by their association with concurrent respiration curves. Contributions of low-frequency cardiac sounds were visually identified by their relationship to simultaneously recorded ECGs. Typical characteristics of normal and adventitious lung sounds were documented and displayed both in the time and the frequency domain. Digital respirosonography provides an easy way to assess lung sound amplitudes, frequencies and timing over several breaths.

Surface distribution of crackling sounds.

It is widely known that the acoustical characteristics of adventitious lung sounds change considerably when the point of auscultation is changed. Some preliminary results of an experimental investigation of the surface distribution of crackles on the chest wall of patients are presented. Three microphones are used simultaneously, arranged in three different subsequent configurations. A method for describing the pattern of crackle distribution objectively is suggested. >

Nomenclature Used by Health Care Professionals to Describe Breath Sounds in Asthma

We studied the spontaneous, uninstructed description by 40 health care professionals of breath sounds in asthmatic patients, and their use of lung sound terminology following current recommendations. Tape play-back auscultation of recorded tracheal and lung sounds was performed by ten observers in each group of residents, nurses, staff physicians and physiotherapists. They repeated the test after two weeks to three months. Individual descriptions were compared to computer-aided characterization of the breath sound recordings. We found significant differences in the preferred terms for description of adventitious lung sounds between the groups of health care professionals. There was considerable intraobserver variability, with less agreement when suggestions for a more complex characterization were followed. Our observations indicate the importance of teaching a standardized nomenclature for lung sounds to health care professionals, using only terms which are clearly informative of pulmonary disease.

Wheezing and Stridor

Wheezes are defined as high-pitched, continuous, adventitious lung sounds. They are produced by oscillation of opposing airway walls whose lumen is narrowed. Although asthma is the most common cause of wheezing, a wide variety of disease processes may result in wheezing due to airway obstruction. This obstruction may be caused by airway edema, smooth muscle constriction, increased secretions, vascular congestion, mass lesions, scarring, or foreign bodies. Stridor is a special kind of wheeze described as a loud musical sound of constant pitch, which is heard in patients with tracheal or laryngeal obstruction. The full differential diagnosis of airway obstruction should be carefully considered in any patient with wheezing or stridor.

Phonopneumograph possible for real-time tracing

We constructed a new phonopneumograph that provides real-time tracing of lung sounds at a high speed without the steps of memory and playback by use of a thermal printer system. Accuracy of the recorded wave form was considered adequate even at the maximum speed of 750 mm/sec for detailed wave form analysis. The device is easily connected to a recording system for respiratory flow rate or volume. To test the clinical usefulness of this portable instrument, the difference in the interpretation of four types of basic adventitious lung sounds by different listeners was examined. The “trained” group who had experience in using this instrument interpreted adventitious lung sounds more accurately than did the “untrained” group. Even in the “trained” group, however, the accuracy of identifying certain sounds was sometimes low. These results suggest that this device is useful for bedside interpretation of adventitious lung sounds or for training of auscultation ability.

Discontinuous Adventitious Lung Sounds

Discontinuous Adventitious Lung Sounds

Continuous Adventitious Lung Sounds: Site and Method of Production and Significance

Continuous Adventitious Lung Sounds: Site and Method of Production and Significance

Survey of Adventitious Lung Sound Terminology in Case Reports

Descriptions of adventitious lung sounds in the case reports of eight authoritative medical journals from 1978 through 1982 were tabulated in an effort to identify recent changes in terminology. Adventitious lung sounds were described in 590 case reports. During the five years surveyed, there was a decrease in usage of the term, "rales," and an increase in usage of the terms, "crackles" and "wheezes." Usage of the terms, "rhonchi" and "crepitations," did not significantly change in frequency over the five years surveyed; however, when compared to a previous survey, usage of the term, "crepitations," has declined. British journals predominantly use the terms, "crackles" and "wheezes," to describe adventitious lung sounds. Although American journals most often use the terms, "rales," "wheezes," and "rhonchi," the term, "crackles," is increasing in usage.

A new method for classifying discontinuous adventitious lung sounds

A new method for classifying discontinuous adventitious lung sounds

Frequency analysis of adventitious lung sounds

Adventitious lung sounds from twenty patients with respiratory diseases have been recorded and analysed by analogue methods. The results obtained are compared with those from five normal subjects. The difference in the frequency components of lung sounds from patients with pulmonary obstruction in the airways and those from normal subjects are pointed out. This technique may well prove to be an objective method of diagnosis in pulmonary medicine.

Crackles and wheezes.

This is an essay on the genesis of adventitious lung sounds, based on clinical and experimental observations. Crackling is usually due to the explosive opening of airways in territories of the lung deflated to residual volume. Wheezing is generated by air passing at high velocity through an airway narrowed to the point of closure. The pitch of the wheeze is largely determined by the linear velocity of this jet of air and is independent of the calibre and length of the airway. The clinical interpretation of adventitious sounds is discussed in the light of these observations.