Does the vesicular lung sound come only from the lungs? (original) (raw)

Lung sounds: Relative sites of origin and comparative amplitudes in normal subjects

Lung, 1983

Little is known about the comparative amplitude of the vesicular lung sounds heard over the tung apices and bases. Neither is the site of origin of these sounds known. Recent studies suggest that differences in amplitude between the left and right sides of the chest may be considerable. In order to better assess these differences, and to determine the relative sites of origin of these sounds, a new computerized tung sound measurement technique was employed to study the lung sound amplitude and phase relationships over the left and right posterior lung bases and anterior apices in 9 healthy volunteers. Twenty-four inspiratory breath sounds were recorded simultaneously using 2 microphones at 8 different intermicrophone separations (1 to 8 cm) at those locations. The mean amplitude of the lung sounds so recorded at each location was determined by automated flow-gated measurement at an inspirato~ air flow rate of 1.3 l/s. Simultaneously, the degree of similarity of phase between the sounds from both microphones (Subtraction intensity index -SII) was determined. In addition, 3 inspirations were recorded simultaneously by 1 microphone on either side of the sternum in the second intercostal space in order to assess the phase similarity of the lung sounds at these positions. The results showed that the sound intensity at one base (left or right) was significantly greater than at the opposite base in 7 of the 9 subjects. The sound intensity at the left apex was always louder than or equal to that at the right. The subtraction patterns suggested that the sound sources at the apex were more central than at the bases but that additional phase shifting may have occurred during transmission to the chest wall. The sounds recorded from opposite sides of the sternum showed little or no similarity indicating that the sound at this location, though bronchial in character, was not transmitted from the trachea. It is concluded that significant inequality in lung sound amplitude between homologous areas on opposite sides of the chest is a corn-* Supported in part by NHLBI Grant HL 26334 mon finding and that the vesicular sounds over the lung apices are possibly produced more centrally than those at the bases but that the trachea is not the source of these sounds.

Effects of lung volume and airflow on the frequency spectrum of vesicular lung sounds

Respiration physiology, 1986

The purpose of this study was to determine whether the vesicular lung sound frequency spectrum is affected by changes in lung volume and airflow. Nine healthy young nonsmokers were studied. The dependent variables were the points that divide the power spectrum of the vesicular lung sound into quarters (1st, 2nd and 3rd quartiles (Q1, Q2 and Q3]. Recording sites were the right upper anterior (RUL) and lower posterior (RLL) chest wall. Lung sounds were high-pass filtered at 100 Hz. To evaluate the effect of volume, lung sounds were recorded during an inspiratory vital capacity (VC) maneuver at near constant airflow rates. The spectral parameters were determined at each sixth of the VC. To assess the effects of airflow, 5 of the subjects breathed from resting lung volume at peak inspiratory airflows of between 1 and 3.0 L/sec for a total of 16 breaths each and the frequency parameters of the lung sounds occurring during peak inspiratory airflows were determined. Volume effects: only at...

Comparison of Lung Sound and Transmitted Sound Amplitude in Normal Men 1, 2

American Review of Respiratory Disease, 1981

Within the last 5 yr, several studies have suggested that if the lung sound intensity at the chest wall is compared with the intensity of white noise transmitted from the mouth to the same site, the acoustic transmitting properties of the thorax can be assessed and separated from the properties of the lung sound generator. In this study, we used a computer-aided rapid amplitude measuring technique to study this question over a much greater area on the chest wall in 7 subjects. Study locations were at 2cm intervals, apex to base, over both hemithoraxes, anteriorly and posteriorly. Lung sound intensity (LS) was measured by an air-flow-corrected technique. Colored noise (50 to 500 Hz) introduced at the mouth (TRANS) was measured on the chest wall and adjusted for glottic aperture by comparison with the signal from a reference microphone at a fixed location on the chest. The LS amplitude patterns that we observed were similar to those previously determined in this laboratory and were bilaterally equal for the group. The TRANS sound patterns were always of greater intensity near the apex and, over the right hemithorax, were approximately twice the amplitude of those over the left. Similar LS and TRANS maps performed at locations completely encircling the upper thorax in one upright subject revealed wide intensity variations in each that appeared unrelated to each other or to the presumed distribution of ventilation. The transmission of sounds introduced at the mouth appears to be influenced by factors other than simple propagation down airways in certain lung regions. Therefore, the use of such transmitted sounds may not be an appropriate way to correct for transmission characteristics affecting normal lung sounds in these regions.

Does laryngeal noise contribute to the vesicular lung sound?

The American review of respiratory disease

The precise sound sources that contribute to the vesicular lung sound heard on the chest wall have never been accurately determined. Current thinking favors the mainstem, lobar, and segmental airways as the principal sources contributing to the sound. The larynx has occasionally been said to be responsible for some or all of the vesicular sound, but its actual contribution has never been determined in humans. This study was designed around the hypothesis that, were the laryngeal noise to form an audible part of the vesicular sound heard on the chest wall during quiet breathing, the vesicular sound should get louder during voluntarily produced noisy breathing provided that the sounds are compared at approximately equal flow rates and lung volumes. In this study, sounds from the larynx and 4 sites on the chest wall were simultaneously recorded and displayed along with flow volume loops during quiet breathing and voluntarily produced noisy breathing without actual phonation in 3 healthy subjects. Although increases in amplitude of the laryngeal noise of severalfold were observed in both inspiration and expiration, the amplitude of the simultaneously recorded vesicular sound correlated only with flow rates and were completely unaffected by changes in laryngeal sound amplitude. This demonstrates that during quiet breathing in healthy subjects no detectable component of the laryngeal noise reaches the periphery.

Respiratory sounds in healthy people: A systematic review

Respiratory Medicine, 2014

Background: There is a lack of systematised information on respiratory sounds of healthy people. This impairs health professionals from differentiating respiratory sounds of healthy people from people with respiratory diseases, which may affect patients' diagnosis and treatment. Therefore, this systematic review aimed to characterise respiratory sounds of healthy people. Methods: The Web of knowledge, MEDLINE, EMBASE and SCOPUS databases were searched and studies using computerised analyses to detect/characterise respiratory sounds in healthy people were included. Data were extracted using a structured table-format. Results: Sixteen cross-sectional studies assessing respiratory sounds in 964 subjects (aged 1day-70yrs) were included: 13 investigated normal respiratory sounds (frequency, intensity and amplitude) and 3 adventitious respiratory sounds (crackles and wheezes). The highest sound frequencies were observed at the trachea (inspiration: 447e1323 Hz; expiration: 206 e540 Hz). Women (444e999 Hz) and infants (250e400 Hz) presented the highest frequencies at maximum power. Inspiratory sounds were more intense at the left posterior lower lobe (5.7e76.6 dB) and expiratory sounds at the trachea (45.4e85.1 dB). Nevertheless, studies establishing direct comparisons between inspiratory and expiratory sounds showed that inspiratory sounds presented the highest intensities (p < 0.001). Amplitude was higher at the left upper anterior chest (1.7 AE 0.8 V) and lower at the right posterior lower lobe (1.2 AE 0.7 V). Crackles were the adventitious respiratory sound most frequently reported. Conclusions: Respiratory sounds show different acoustic properties depending on subjects' characteristics, subjects' position, respiratory flow and place of recording. Further research with robust study designs, different populations and following the guidelines for computerised respiratory sound analysis are urgently needed to build evidence-base. ยช

The effect of low density gas breathing on vesicular lung sounds

Respiration physiology, 1985

Turbulent airflow (largely gas density dependent) in larger airways is believed by many lung sound researchers to be the mechanism responsible for the generation of vesicular lung sounds. To test the validity of this concept, we measured the amplitude of lung and tracheal sounds of 6 subjects alternately breathing air and a low density gas mixture (80% helium, 20% oxygen: He-O2). Lung sounds were recorded from 3 chest wall sites: Anterior right upper lobe (RUL), posterior and posterolateral right lower lobe (RLL), and a site over the proximal trachea below the larynx. The subjects rebreathed into an electronic spirometer filled with the test gas, and achieved a peak inspiratory and expiratory airflow of 2-2.5 L/sec. Lung sound amplitude was determined by an automated, flow-corrected measurement procedure. The mean decrease in sound amplitude when breathing He-O2 compared to air was: trachea, inspiration 44%; trachea, expiration 45%; RUL, inspiration 13%; RUL, expiration 25%; RLL, in...

Impact of Airflow Rate on Amplitude and Regional Distribution of Normal Lung Sounds

2017

In computerized lung sound research, the usage of a pneumotachograph, defining the phase of respiration and airflow velocity, is essential. To obviate its need, the influence of airflow rate on the characteristics of lung sounds is of great interest. Therefore, we investigate its effect on amplitude and regional distribution of normal lung sounds. We record lung sounds on the posterior chest of four lung-healthy male subjects in supine position with a 16-channel lung sound recording device at different airflow rates. We use acoustic thoracic images to discuss the influence of airflow rate on the regional distribution. At each airflow rate, we observe louder lung sounds over the left hemithorax and a constant regional distribution above an airflow rate of 0.7 l/s. Furthermore, we observe a linear relationship between the airflow rate and the amplitude of lung sounds.

The relationship between airflow and lung sound amplitude in normal subjects

CHEST Journal, 1984

Few investigators have examined the relationship between airflow and lung sound amplitude; the available data are contradictory. I measured airflow at the mouth and compared the peak flow (Vmax) to mean and peak lung sound amplitude (mean AMP and peak AMP) at four sites on the chest wall (right and left anterior apices and posterior bases) in four healthy young adults. At each site, the sounds produced by 20 breaths at Vmax ranging between 1.5 and 4 L/s (Vvar) were measured by an automated technique. Ten breaths during nearly constant Vmax breathing (Vcon) also were measured at each site. The lung sound amplitudes at the four sites in each subject were grouped and compared to Vmax by linear regression analysis. The same sounds were also submitted to an automated V-correction procedure to evaluate its adequacy in automatically adjusting for the effect of variations in Vmax on lung sound amplitude. The data showed that lung sound amplitude (mean or peak) was linearly related to V in all subjects (r for mean AMP vs Vmax:0.77, 0.85, 0.69, 0.89; r for peak AMP vs Vmax:0.80, 0.83, 0.79, 0.88), p less than 1 X 10(-7) in all cases. The average mean AMP vs Vmax regression line slope was 0.42, and the average peak AMP vs Vmax regression line slope was 0.45. V-correction decreased the coefficient of variation of the Vvar sounds by 61 percent and flattened the average regression line slopes to 0.128. For the Vcon series, V-correction diminished the coefficient of variation from 12.2 to 10.0 percent. The relationship between lung sound amplitude and airflow appears to be substantially linear and this relationship can be used to adjust effectively for variations in airflow.

Determination of the site of production of respiratory sounds by subtraction phonopneumography

The American review of respiratory disease

The site of origin of the vesicular lung sound has long been in question. A technique (subtraction phonopneumography) is described here for determining the relative distance of a sound source from the chest wall. This technique involves the simultaneous recording of lung sounds from two different sites on the chest wall, phase inversion of one of the signals, and then mixing the signals in a summing amplifier. The degree of cancellation that results is inversely proportional to the number of sources and the degree to which each source is detected by both microphones simultaneously. A study of six normal subjects revealed little or no cancellation of inspiratory vesicular sounds with microphones separated by 10 cm. During expiration, cancellation did occur at distances well beyond 10 cm and was detectable over several homologous segments of opposite lungs. This finding is consistent with an intrapulmonic and probably intralobar source for the inspiratory component and an upper airway source for at least some of the expiratory component.