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Journal of applied physiology: respiratory, environmental and exercise physiology1983; 54(1); 304-308; doi: 10.1152/jappl.1983.54.1.304

Sound speed in pulmonary parenchyma.

Abstract: The time it takes audible sound waves to travel across a lobe of excised horse lung was measured. Sound speed, which is the slope in the relationship between transit time and distance across the lobe, was estimated by linear regression analysis. Sound-speed estimates for air-filled lungs varied between 25 and 70 m/s, depending on lung volume. These speeds are less than 5% of sound speed in tissue and less than 20% of sound speed in air. Filling the lung with helium or sulfur hexafluoride, whose free-field sound speeds are 970 and 140 m/s, respectively, changed sound speed +/- 10% relative to air filling. Reducing the ambient pressure to 0.1 atm reduced sound speed to 30% of its 1-atm value. Increasing pressure to 7 atm increased sound speed by a factor of 2.6. These results suggest that 1) translobar sound travels through the bulk of the parenchyma and not along airways or blood vessels, and 2) the parenchyma acts as an elastic continuum to audible sound. The speed of sound is given by c = (B/rho)1/2, where B is composite volumetric stiffness of the medium and rho is average density. In the physiologic state B is affected by ambient pressure and percent gas phase. The average density includes both the tissue and gas phases of the parenchyma, so it is dependent on lung volume. These results may be helpful in the quantification of clinical observations of lung sounds.
Publication Date: 1983-01-01 PubMed ID: 6826415DOI: 10.1152/jappl.1983.54.1.304Google Scholar: Lookup
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  • Journal Article
  • Research Support
  • U.S. Gov't
  • P.H.S.

Summary

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This research study explores the speed of sound within the lung tissue—specifically, the pulmonary parenchyma—of horses. By altering variables such as medium gas and pressure, and examining their effect on sound speed, the study summarizes the impact of these changes and provides information that could be useful for the quantification of clinical observations of lung sounds.

Objective and Methodology

  • The researchers set out to measure the time taken for audible sound waves to travel across a lobe of excised horse lung and estimate the speed of that sound through the tissue.
  • This was achieved by applying linear regression analysis to measure the relationship between transit time and distance across the lobe.
  • The study performed tests under different conditions, altering factors such as ambient pressure, the filling gas (air, helium or sulfur hexafluoride), and lung volume.

Findings and Interpretation

  • The study discovered that the speed of sound through the lungs depends on lung volume, ranging between 25 and 70 meters per second in air-filled lungs.
  • Interesting to note, these values are less than 5% of the sound speed in tissue, and less than 20% of sound speed in air.
  • The investigation showed that when the lung was filled with helium or sulfur hexafluoride (gases with free-field sound speeds of 970 and 140 m/s respectively), the sound speed altered by +/- 10% compared to air filling.
  • By altering the ambient pressure, the study discovered that reducing it to 0.1 atm reduced the sound speed to 30% of its 1-atm value, while increasing it to 7 atm increased sound speed by a factor of 2.6.
  • These results led the researchers to conclude that the sound travels mainly through the bulk of the parenchyma, not along airways or blood vessels, and that the parenchyma behaves as an elastic continuum to sound.

Implications and Future Applications

  • The speed of sound within the pulmonary parenchyma is expressed through the formula c = (B/rho)1/2, where B represents the composite volumetric stiffness of the medium and rho stands for average density. The former is influenced by ambient pressure and percent gas phase while the latter reflects both the tissue and gas phases of the parenchyma, thus being dependent on lung volume.
  • The knowledge gained from this study can aid in the quantification of clinical observations of lung sounds, potentially opening new avenues for the diagnosis and investigation of lung-related ailments and conditions.

Cite This Article

APA
Rice DA. (1983). Sound speed in pulmonary parenchyma. J Appl Physiol Respir Environ Exerc Physiol, 54(1), 304-308. https://doi.org/10.1152/jappl.1983.54.1.304

Publication

ISSN: 0161-7567
NlmUniqueID: 7801242
Country: United States
Language: English
Volume: 54
Issue: 1
Pages: 304-308

Researcher Affiliations

Rice, D A

    MeSH Terms

    • Animals
    • Horses
    • Lung / anatomy & histology
    • Organ Size
    • Sound
    • Time Factors

    Grant Funding

    • 1-R-HL-21199 / NHLBI NIH HHS

    Citations

    This article has been cited 17 times.
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