Airway and tissue impedances of canine lungs after step volume changes

Bates, Jason H. T.; Donoso, F Alejandro; Peslin, R

doi:10.1152/jappl.1993.75.4.1460

Cited by 3 publications

(1 citation statement)

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“…The X directional scan of the piezoelectric transducer in 10 Hz was simultaneously performed with the upward scan of 50 Am/sec in the vertical (Z) direction. Since the phase shift occurred in the echo signal from the stage, the interference phenomenon was observed by addition of the echo signal from the stage to that from the surface of the lens.…”

Section: X-z Scanning For Measurement Of Sound Speedmentioning

confidence: 99%

Evaluation of Left Atrial Wall Elasticity Using Acoustic Microscopy

Masugata¹,

Mizushige²,

Senda³

et al. 1999

Angiology

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Left atrial wall elasticity is one of the important factors regulating left atrial stiffness and functions. The authors evaluated left atrial wall elasticity by measuring the sound speed through the left atrial wall, based on the hypothesis that high elasticity tissues will yield larger sound speed values through the tissue, and examined age-associated changes in left atrial wall elasticity. Left atrium specimens were obtained from 30 normal subjects (age, 15-95 years) at autopsy. An acoustic microscope, operating at 450 MHz, was used to measure the sound speed in the endocardium and the myocardium of the left atrium. The sound speeds in endocardium and myocardium demonstrated significant correlation with age (r = 0.74, p<0.0001 and r = 0.47, p<0.01, respectively). These findings indicate that left atrial wall elasticity increased with advancing age. These changes may lead to deterioration of left atrial compliance and eventual left atrial failure in older subjects.

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Section: X-z Scanning For Measurement Of Sound Speedmentioning

confidence: 99%

Evaluation of Left Atrial Wall Elasticity Using Acoustic Microscopy

Masugata¹,

Mizushige²,

Senda³

et al. 1999

Angiology

View full text Add to dashboard Cite

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Influence of flow pattern on the parameter estimates of a simple breathing mechanics model

Avanzolini

Barbini

Cappello

et al. 1995

IEEE Trans. Biomed. Eng.

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The first-order model of breathing mechanics is widely used in clinical practice to assess the viscoelastic properties of the respiratory system. Although simple, this model takes the predominant features of the pressure-flow relationship into account but gives highly systematic residuals between measured and model-predicted variables. To achieve a better fit of the entire data set, an approach hypothesizing deterministic time-variations of model parameters, summarized by information-weighted histograms was recently proposed by Bates and Lauzon. The present study uses flow and pressure data measured in intensive care patients to evaluate the real potential of this approach in clinical practice. Information-weighted histograms of the model parameters, estimated by an on-line identification algorithm, were first constructed by taking into account the parameter percentage standard deviations. Then, the influence of the respiratory flow pattern on the calculated histograms was evaluated by the Kolmogorov-Smirnov statistical test. The results show that the method gives good reproducibility under stable experimental conditions. In addition, for a given airflow waveform, an increase in respiratory frequency shifts the histograms representing time-varying viscous properties strongly versus lower values, whereas it shifts the histograms representing time-varying elastic properties slightly versus higher values. On the other hand, the same histograms were highly dependent on the airflow waveform, especially for the viscous properties. Even in a limited experimental work, in all the conditions considered, the method provides results which agree well with the physiological knowledge of nonlinear and multicompartment behavior of respiratory mechanics.

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Airway diameter at different transpulmonary pressures in ex vivo sheep lungs: implications for deep inspiration-induced bronchodilation and bronchoprotection

Dong

Wang

Chitano

et al. 2021

American Journal of Physiology-Lung Cellular and Molecular Phys

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Deep inspiration (DI)-induced bronchodilation is the first line of defense against bronchoconstriction in healthy subjects. A hallmark of asthma is the lack of this beneficial effect of DI. The mechanism underlying the bronchodilatory effect of DI is not clear. Understanding the mechanism will help us unravel the mystery of asthma pathophysiology. It has been postulated that straining airway smooth muscle (ASM) during a DI could lead to bronchodilation and bronchoprotection. The hypothesis is currently under debate, and a central question is whether ASM is sufficiently stretched during a DI for its contractility to be compromised. Besides bronchoconstriction, another contributor to lung resistance is airway heterogeneity. The present study examines changes in airway diameter and heterogeneity at different lung volumes. Freshly explanted sheep lungs were used in plethysmographic measurements of lung resistance and elastance at different lung volumes while the airway dimensions were measured by computed tomography (CT). The change in airway diameter informed by CT measurements was applied to isolated airway ring preparations to determine the strain-induced loss of ASM contractility. We found that changing the transpulmonary pressure from 5 to 30 cmH2O led to a 51%-increase in lung volume, accompanied by a 46%-increase in the airway diameter with no change in airway heterogeneity. When comparable airway strains measured in the whole lung were applied to isolated airway rings in either relaxed or contracted state, a significant loss of ASM contractility was observed, suggesting that DI-induced bronchodilation and bronchoprotection can result from strain-induced loss of ASM contractility.

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Airway and tissue impedances of canine lungs after step volume changes

Cited by 3 publications

References 0 publications

Evaluation of Left Atrial Wall Elasticity Using Acoustic Microscopy

Evaluation of Left Atrial Wall Elasticity Using Acoustic Microscopy

Influence of flow pattern on the parameter estimates of a simple breathing mechanics model

Airway diameter at different transpulmonary pressures in ex vivo sheep lungs: implications for deep inspiration-induced bronchodilation and bronchoprotection

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