The ventilation flow‐resistance and compliance of rat lungs

Mount, L. E.

doi:10.1113/jphysiol.1955.sp005246

Cited by 96 publications

(63 citation statements)

References 10 publications

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“…As in previous studies [1,4,5,10,14], standard mechanical variables were obtained after end-inspiratory occlusions performed at baseline ventilation in the present study. The values of Ers,st, Ers,dyn, Rrs,int, and DRrs obtained in normal subjects are within the range reported in the literature [1,4,5,10,14].…”

Section: Discussionmentioning

confidence: 98%

“…The mean SD intrasubject coefficients of variation of t2, R2, and E2 were 8 4%, 5 3%, and 7 2%, respectively, in normal subjects, and 11 5%, 6 3%, and 10 3% respectively, in ALI patients. Table 3 also depicts the mean SD of t2, R2, and E2 obtained with the MB test [1] in normal subjects and ALI patients. The mean SD differences between the results of the short-and-longbreath and MB methods in normal subjects were: t2, -0.17 0.26 s; R2, 0.43 0.77cmH 2 O .…”

Section: Discussionmentioning

confidence: 99%

“…A third useful variable, the viscoelastic time constant (t2), can also be obtained from R2/E2 [3]. Using the technique of rapid airway occlusion (RAO) during constant-flow (V') inflation, it has been possible to determine the values of these viscoelastic constants for the lung, chest wall and total respiratory system in normal mechanically ventilated humans [3±5] and experimental animals [1,6], based on either of the following functions:where Pvisc(t) is the viscoelastic pressure (Pvisc) dissipated within the lung, chest wall or both during constant-V' inflation started from the relaxed volume of the respiratory system, t is time during lung inflation and DRrs is viscoelastic resistance, obtained by dividing both sides of Equation 1 by V' [3]. This analysis, however, is timeconsuming and technically complex because it requires either a series of isovolumic inflations with different inspiratory V' , or multiple iso-V' inflations with different volumes [3,6].…”

mentioning

confidence: 99%

mentioning

confidence: 99%

“…Direct measurement of the viscoelastic inspiratory pressure can be performed by the technique of rapid end-inspiratory airway occlusion and the viscoelastic behaviour interpreted according to a Maxwell body. This linear viscoelastic model has been shown to provide an accurate description of the time-dependency of resistance and elastance of the respiratory system observed in normal animal [1] and human lungs [2] In this model, the viscoelastic properties which impact such time-dependency can be characterized by two parameters, the theoretical maximal viscoelastic resistance (R2) and elastance (E2). A third useful variable, the viscoelastic time constant (t2), can also be obtained from R2/E2 [3].…”

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confidence: 99%

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Bedside assessment of respiratory viscoelastic properties in ventilated patients

Antonaglia¹,

Peratoner²,

Simoni³

et al. 2000

Eur Respir J

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Viscoelasticity represents an important component of respiratory mechanics, being responsible, in some cases, for most of the pressure dissipated during breathing. Hitherto the methods available for determining the viscoelastic properties have been simplified, but are still time-demanding and depend on a great deal of calculation. In this study, a simple means of determining respiratory viscoelastic properties during mechanical ventilation was introduced.The viscoelastic constants of the respiratory system, modelled as a Maxwell body, were studied in 17 normal subjects and seven patients with acute lung injury (ALI) using two end-inspiratory occlusions; one with a short inspiratory time (tI) to determine the elastic component of viscoelasticity and the other with a long tI to assess the resistive component of viscoelasticity.The results were reproducible and similar to those provided by the previously described multiple-breath method (MB) Viscoelasticity represents an important component of respiratory mechanics, being responsible, in some cases, for most of the pressure dissipated during breathing. In order to study the viscoelastic behaviour of the respiratory system, it is necessary to assess the pressure developed by the viscoelastic components. Direct measurement of the viscoelastic inspiratory pressure can be performed by the technique of rapid end-inspiratory airway occlusion and the viscoelastic behaviour interpreted according to a Maxwell body. This linear viscoelastic model has been shown to provide an accurate description of the time-dependency of resistance and elastance of the respiratory system observed in normal animal [1] and human lungs [2] In this model, the viscoelastic properties which impact such time-dependency can be characterized by two parameters, the theoretical maximal viscoelastic resistance (R2) and elastance (E2). A third useful variable, the viscoelastic time constant (t2), can also be obtained from R2/E2 [3]. Using the technique of rapid airway occlusion (RAO) during constant-flow (V') inflation, it has been possible to determine the values of these viscoelastic constants for the lung, chest wall and total respiratory system in normal mechanically ventilated humans [3±5] and experimental animals [1,6], based on either of the following functions:where Pvisc(t) is the viscoelastic pressure (Pvisc) dissipated within the lung, chest wall or both during constant-V' inflation started from the relaxed volume of the respiratory system, t is time during lung inflation and DRrs is viscoelastic resistance, obtained by dividing both sides of Equation 1 by V' [3]. This analysis, however, is timeconsuming and technically complex because it requires either a series of isovolumic inflations with different inspiratory V' , or multiple iso-V' inflations with different volumes [3,6]. As a result, the above analysis has been used only in a limited number of studies on normal subjects [3±5] and patients [7±9]. Recently, a single-breath method was proposed for assessing the viscoelastic prope...

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Bedside assessment of respiratory viscoelastic properties in ventilated patients

Antonaglia¹,

Peratoner²,

Simoni³

et al. 2000

Eur Respir J

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Theory and Measurement of Respiratory Resistance

Bates¹

2020

Cotes’ Lung Function

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Lung Parenchymal Mechanics

Suki

Stamenović

Hubmayr

2011

Comprehensive Physiology

164

132

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The lung parenchyma comprises a large number of thin-walled alveoli, forming an enormous surface area, which serves to maintain proper gas exchange. The alveoli are held open by the transpulmonary pressure, or prestress, which is balanced by tissues forces and alveolar surface film forces. Gas exchange efficiency is thus inextricably linked to three fundamental features of the lung: parenchymal architecture, prestress, and the mechanical properties of the parenchyma. The prestress is a key determinant of lung deformability that influences many phenomena including local ventilation, regional blood flow, tissue stiffness, smooth muscle contractility, and alveolar stability. The main pathway for stress transmission is through the extracellular matrix. Thus, the mechanical properties of the matrix play a key role both in lung function and biology. These mechanical properties in turn are determined by the constituents of the tissue, including elastin, collagen, and proteoglycans. In addition, the macroscopic mechanical properties are also influenced by the surface tension and, to some extent, the contractile state of the adherent cells. This article focuses on the biomechanical properties of the main constituents of the parenchyma in the presence of prestress and how these properties define normal function or change in disease. An integrated view of lung mechanics is presented and the utility of parenchymal mechanics at the bedside as well as its possible future role in lung physiology and medicine are discussed.

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The ventilation flow‐resistance and compliance of rat lungs

Cited by 96 publications

References 10 publications

Bedside assessment of respiratory viscoelastic properties in ventilated patients

Bedside assessment of respiratory viscoelastic properties in ventilated patients

Theory and Measurement of Respiratory Resistance

Lung Parenchymal Mechanics

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