scholarly journals Hyperoxia-induced changes in mouse lung mechanics: forced oscillations vs. barometric plethysmography

2001 ◽  
Vol 90 (6) ◽  
pp. 2221-2230 ◽  
Author(s):  
Ferenc Peták ◽  
Walid Habre ◽  
Yves R. Donati ◽  
Zoltán Hantos ◽  
Constance Barazzone-Argiroffo
Keyword(s):  
Respiratory System ◽  
Airway Resistance ◽  
Tissue Mechanics ◽  
Lung Damage ◽  
Lung Mechanics ◽  
Forced Oscillations ◽  
Whole Body ◽  
Mouse Lung ◽  
Diffuse Lung Disease ◽  
Respiratory System Resistance

Hyperoxia-induced lung damage was investigated via airway and respiratory tissue mechanics measurements with low-frequency forced oscillations (LFOT) and analysis of spontaneous breathing indexes by barometric whole body plethysmography (WBP). WBP was performed in the unrestrained awake mice kept in room air ( n = 12) or in 100% oxygen for 24 ( n = 9), 48 ( n = 8), or 60 ( n = 9) h, and the indexes, including enhanced pause (Penh) and peak inspiratory and expiratory flows, were determined. The mice were then anesthetized, paralyzed, and mechanically ventilated. Airway resistance, respiratory system resistance at breathing frequency, and tissue damping and elastance were identified from the LFOT impedance data by model fitting. The monotonous decrease in airway resistance during hyperoxia correlated best with the increasing peak expiratory flow. Respiratory system resistance and tissue damping and elastance were unchanged up to 48 h of exposure but were markedly elevated at 60 h, with associated decreases in peak inspiratory flow. Penh was increased at 24 h and sharply elevated at 60 h. These results indicate no adverse effect of hyperoxia on the airway mechanics in mice, whereas marked parenchymal damage develops by 60 h. The inconsistent relationships between LFOT parameters and WBP indexes suggest that the changes in the latter reflect alterations in the breathing pattern rather than in the mechanical properties. It is concluded that, in the presence of diffuse lung disease, Penh is inadequate for characterization of the mechanical status of the respiratory system.

Quantification of nasal involvement in a guinea pig plethysmograph

1994 ◽  
Vol 76 (4) ◽  
pp. 1432-1438 ◽  
Author(s):  
M. J. Finney ◽  
K. I. Forsberg
Keyword(s):  
Lung Function ◽  
Guinea Pig ◽  
Respiratory System ◽  
Guinea Pigs ◽  
Repeated Measurement ◽  
Whole Body ◽  
Nasal Resistance ◽  
Rapid Technique ◽  
Respiratory System Resistance ◽  
Lower Airways

We have developed a technique for measuring lung function in conscious guinea pigs using a whole body plethysmograph. Because guinea pigs breathe through the nose, a technique was also developed to measure nasal and lower respiratory system conductance simultaneously in anesthetized animals. The upper and the lower airways could be challenged separately and studied in a manner similar to the conditions in the plethysmograph. Aerosols of histamine, carbachol, or ovalbumin delivered to the nose in sensitized animals had no effect on nasal conductance, even in doses 100 times higher than that required to reduce lower respiratory system conductance. However, intravenous histamine increased nasal conductance. Thus, although nasal resistance constitutes the majority of the total respiratory system resistance measured in the plethysmograph, nasal resistance is unaffected by the aerosol drugs studied. We therefore consider changes in resistance measured in the plethysmograph to originate at or below the larynx. The plethysmographic technique described here is a reliable, reproducible, and rapid technique that enables repeated measurement in animals and minimizes animal trauma.

Airway and tissue mechanics in a murine model of asthma: alveolar capsule vs. forced oscillations

2002 ◽  
Vol 93 (1) ◽  
pp. 263-270 ◽  
Author(s):  
Shinichiro Tomioka ◽  
Jason H. T. Bates ◽  
Charles G. Irvin
Keyword(s):  
Airway Resistance ◽  
Forced Oscillation ◽  
Tissue Mechanics ◽  
Forced Oscillations ◽  
Control Group ◽  
Bronchial Responsiveness ◽  
Lung Elastance ◽  
Functional Consequences ◽  
Lung Periphery ◽  
Tissue Elastance

To better address the functional consequences of inflammation on bronchial responsiveness, we studied two groups of BALB/c mice: a nonimmunized control group ( n = 8) and a group immunized and challenged with inhaled ovalbumin ( n = 8). An alveolar capsule (AC) measured airway resistance (RawAC) and lung elastance (El). A forced oscillation (FO) technique independently estimated airway resistance (RawFO) and a parameter H ti related to tissue elastance. Ovalbumin-immunized and -challenged mice had increased numbers of eosinophils in bronchoalveolar lavage and increased responsiveness to methacholine (MCh). Corresponding parameters from the AC and FO techniques were correlated: RawAC vs. RawFO( r = 0.76) and El vs. H ti ( r = 0.88, P< 0.0001 in all cases). AC and FO techniques showed significant increases in tissue elastance in response to MCh but no significant increases in airway resistance. These results demonstrated that the AC and FO techniques yield essentially equivalent results in mice, even when the lung is inhomogeneous, and that the bronchoconstrictive responses to MCh and inflammation in mice are predominantly located in the lung periphery.

scholarly journals Aging-related changes in respiratory system mechanics and morphometry in mice

2016 ◽  
Vol 311 (1) ◽  
pp. L167-L176 ◽  
Author(s):  
Jonathan E. Elliott ◽  
Carlos B. Mantilla ◽  
Christina M. Pabelick ◽  
Anja C. Roden ◽  
Gary C. Sieck
Keyword(s):  
Respiratory System ◽  
Dynamic Compliance ◽  
Lung Mechanics ◽  
Collagen Deposition ◽  
Impedance Spectra ◽  
Respiratory System Mechanics ◽  
Linear Evolution ◽  
Respiratory System Resistance ◽  
Old Mice ◽  
Related Increase

Previous work investigating respiratory system mechanics in mice has reported an aging-related increase in compliance and mean linear intercept ( Lm). However, these changes were assessed using only a young (2-mo-old) and old (20- and 26-mo-old) group yet were interpreted to reflect a linear evolution across the life span. Therefore, to investigate respiratory system mechanics and lung morphometry across a more complete spectrum of ages, we utilized 2 (100% survival, n = 6)-, 6 (100% survival, n = 12)-, 18 (90% survival, n = 12)-, 24 (75% survival, n = 12)-, and 30 (25% survival, n = 12)-mo-old C57BL/6 mice. We found a nonlinear aging-related decrease in respiratory system resistance and increase in dynamic compliance and hysteresis between 2- and 24-mo-old mice. However, in 30-mo-old mice, respiratory system resistance increased, and dynamic compliance and hysteresis decreased relative to 24-mo-old mice. Respiratory system impedance spectra were measured between 1–20.5 Hz at positive end-expiratory pressures (PEEP) of 1, 3, 5, and 7 cmH2O. Respiratory system resistance and reactance at each level of PEEP were increased and decreased, respectively, only in 2-mo-old animals. No differences in the respiratory system impedance spectra were observed in 6-, 18-, 24-, and 30-mo-old mice. Additionally, lungs were fixed following tracheal instillation of 4% paraformaldehyde at 25 cmH2O and processed for Lm and airway collagen deposition. There was an aging-related increase in Lm consistent with emphysematous-like changes and no evidence of increased airway collagen deposition. Accordingly, we demonstrate nonlinear aging-related changes in lung mechanics and morphometry in C57BL/6 mice.

Tracking of airway and tissue mechanics during TLC maneuvers in mice

2003 ◽  
Vol 95 (4) ◽  
pp. 1695-1705 ◽  
Author(s):  
Zoltán Hantos ◽  
Rachel A. Collins ◽  
Debra J. Turner ◽  
Tibor Z. Jánosi ◽  
Peter D. Sly
Keyword(s):  
Respiratory System ◽  
Functional Residual Capacity ◽  
Total Lung Capacity ◽  
Tissue Mechanics ◽  
Forced Oscillations ◽  
Single Frequency ◽  
Lower Airway ◽  
Tissue Impedance ◽  
Lung Capacity ◽  
Residual Capacity

A tracking impedance estimation technique was developed to follow the changes in total respiratory impedance (Zrs) during slow total lung capacity maneuvers in six anesthetized and mechanically ventilated BALB/c mice. Zrs was measured with the wave-tube technique and pseudorandom forced oscillations at nine frequencies between 4 and 38 Hz during inflation from a transrespiratory pressure of 0-20 cmH2O and subsequent deflation, each lasting for ∼20 s. Zrs was averaged for 0.125 s and fitted by a model featuring airway resistance (Raw) and inertance, and tissue damping and elastance ( H). Lower airway conductance (Glaw) was linearly related to volume above functional residual capacity (V) between 0 and 75-95% maximum V, with a mean slope of dGlaw/dV = 13.6 ± 4.6 cmH2O-1 · s-1. The interdependence of Raw and H was characterized by two distinct and closely linear relationships for the low- and high-volume regions, separated at ∼40% maximum V. Comparison of Raw with the highest-frequency resistance of the total respiratory system revealed a marked volume-dependent contribution of tissue resistance to total respiratory system resistance, resulting in the overestimation of Raw by 19 ± 8 and 163 ± 40% at functional residual capacity and total lung capacity, respectively, whereas the lowest frequency reactance was proportional to H; these findings indicate that single-frequency resistance values may become inappropriate as surrogates of Raw when tissue impedance is changing.

Low-frequency assessment of airway and tissue mechanics in ventilated COPD patients

2009 ◽  
Vol 107 (6) ◽  
pp. 1884-1892 ◽  
Author(s):  
András Lorx ◽  
Barna Szabó ◽  
Magdolna Hercsuth ◽  
István Pénzes ◽  
Zoltán Hantos
Keyword(s):  
Respiratory System ◽  
Model Fitting ◽  
Model Performance ◽  
Low Frequency ◽  
Tissue Mechanics ◽  
Forced Oscillations ◽  
Chronic Obstructive ◽  
Copd Patients ◽  
Airway Caliber ◽  
Few Data

Low-frequency forced oscillations have increasingly been employed to characterize airway and tissue mechanics separately in the normal respiratory system and animal models of lung disease; however, few data are available on the use of this method in chronic obstructive pulmonary disease (COPD). We studied 30 intubated and mechanically ventilated patients (COPD, n = 9; acute exacerbation of COPD, n = 21) during short apneic intervals at different levels of positive end-expiratory pressure (PEEP), with small-amplitude forced oscillations between 0.4 and 4.8 Hz. In 16 patients, measurements were made before and after inhalation of fenoterol hydrobromide plus ipratropium bromide (Berodual). Newtonian resistance and coefficients of tissue resistance (G) and elastance (H) were estimated from the respiratory system impedance (Zrs) data by model fitting. Apart from some extremely high Zrs data obtained primarily at relatively low PEEP levels, the model yielded a reasonable partitioning of the airway and tissue parameters, and the inclusion of further parameters did not improve the model performance. With increasing PEEP, Newtonian resistance and the ratio G/H decreased, reflecting the volume dependence of the airway caliber and the improved homogeneity of the lungs, respectively. Bronchodilation after the administration of Berodual was also associated with simultaneous decreases in G and H, indicating recruitment of lung units. In conclusion, the measurement of low-frequency Zrs can be accomplished in ventilated COPD patients during short apneic periods and offers valuable information on the mechanical status of the airways and tissues.

Comparison of Airway Resistance and Total Respiratory System Resistance in Infants

1993 ◽  
Vol 148 (4_pt_1) ◽  
pp. 1008-1012 ◽  
Author(s):  
Chaim Springer ◽  
Daphna Vilozni ◽  
Ephraim Bar-Yishay ◽  
Avraham Avital ◽  
Natan Noviski ◽  
...  
Keyword(s):  
Respiratory System ◽  
Airway Resistance ◽  
Respiratory System Resistance

Effects of lung volume on lung and chest wall mechanics in rats

1999 ◽  
Vol 86 (1) ◽  
pp. 16-21 ◽  
Author(s):  
T. Hirai ◽  
K. A. McKeown ◽  
R. F. M. Gomes ◽  
J. H. T. Bates
Keyword(s):  
Chest Wall ◽  
Respiratory System ◽  
Lung Volume ◽  
Small Animal ◽  
Tissue Mechanics ◽  
Lung Mechanics ◽  
Open Chest ◽  
Pressure Volume Relationship ◽  
Volume Resistance ◽  
Relationship Of

To investigate the effect of lung volume on chest wall and lung mechanics in the rats, we measured the impedance (Z) under closed- and open-chest conditions at various positive end-expiratory pressures (0–0.9 kPa) by using a computer-controlled small-animal ventilator (T. F. Schuessler and J. H. T. Bates. IEEE Trans. Biomed. Eng. 42: 860–866, 1995) that we have developed for determining accurately the respiratory Z in small animals. The Z of total respiratory system and lungs was measured with small-volume oscillations between 0.25 and 9.125 Hz. The measured Z was fitted to a model that featured a constant-phase tissue compartment (with dissipation and elastance characterized by constants G and H, respectively) and a constant airway resistance (Z. Hantos, B. Daroczy, B. Suki, S. Nagy, and J. J. Fredberg. J. Appl. Physiol. 72: 168–178, 1992). We matched the lung volume between the closed- and open-chest conditions by using the quasi-static pressure-volume relationship of the lungs to calculate Z as a function of lung volume. Resistance decreased with lung volume and was not significantly different between total respiratory system and lungs. However, G and H of the respiratory system were significantly higher than those of the lungs. We conclude that chest wall in rats has a significant influence on tissue mechanics of the total respiratory system.

scholarly journals Age-dependent changes of airway and lung parenchyma in C57BL/6J mice

2007 ◽  
Vol 102 (1) ◽  
pp. 200-206 ◽  
Author(s):  
Kewu Huang ◽  
Richard Rabold ◽  
Brian Schofield ◽  
Wayne Mitzner ◽  
Clarke G. Tankersley
Keyword(s):  
Respiratory System ◽  
Elastic Fiber ◽  
Lung Parenchyma ◽  
Tissue Mechanics ◽  
Fiber Content ◽  
Collagen Content ◽  
Lung Mechanics ◽  
Elastin Fiber ◽  
Age Dependent ◽  
Tissue Elastance

In the current study, we hypothesize that senescent-dependent changes between airway and lung parenchymal tissues of C57BL/6J (B6) mice are not synchronized with respect to altered lung mechanics. Furthermore, aging modifications in elastin fiber and collagen content of the airways and lung parenchyma are remodeling events that differ with time. To test these hypotheses, we performed quasi-static pressure-volume (PV) curves and impedance measurements of the respiratory system in 2-, 20-, and 26-mo-old B6 mice. From the PV curves, the lung volume at 30 cmH2O pressure (V30) and respiratory system compliance (Crs) were significantly ( P < 0.01) increased between 2 and 20 mo of age, representing about 80–84% of the total increase that occurred between 2 and 26 mo of age. Senescent-dependent changes in tissue damping and tissue elastance were analogous to changes in V30 and Crs; that is, a majority of the parenchymal alterations in the lung mechanics occurred between 2 and 20 mo of age. In contrast, significant decreases in airway resistance (R) occurred between 20 and 26 mo of age; that is, the decrease in R between 2 and 20 mo of age represented only 29% ( P > 0.05) of total decrease occurring through 26 mo. Morphometric analysis of the elastic fiber content in lung parenchyma was significantly ( P < 0.01) decreased between 2 and 20 mo of age. To the contrary, increased collagen content was significantly delayed until 26 mo of age ( P < 0.01, 2 vs. 26 mo). In conclusion, our data demonstrate that senescent-dependent changes in airway and lung tissue mechanics are not synchronized in B6 mice. Moreover, the reduction in elastic fiber content with age is an early lung remodeling event, and the increased collagen content in the lung parenchyma occurs later in senescence.

Desflurane but Not Sevoflurane Impairs Airway and Respiratory Tissue Mechanics in Children with Susceptible Airways

2008 ◽  
Vol 108 (2) ◽  
pp. 216-224 ◽  
Author(s):  
Britta S. von Ungern-Sternberg ◽  
Sonja Saudan ◽  
Ferenc Petak ◽  
Zoltan Hantos ◽  
Walid Habre
Keyword(s):  
Respiratory System ◽  
Airway Resistance ◽  
Model Fitting ◽  
Random Order ◽  
Tissue Mechanics ◽  
Airway Narrowing ◽  
Beneficial Effects ◽  
Healthy Control ◽  
Impedance Parameters ◽  
Respiratory Tissue

Background Although sevoflurane and desflurane exert bronchoactive effects, their impact on the airway and respiratory tissue mechanics have not been systematically compared in children, especially in those with airway susceptibility (AS). The aim of this study was to assess airway and respiratory tissue mechanics in children with and without AS during sevoflurane and desflurane anesthesia. Methods Respiratory system impedance was measured in healthy control children (group C, n = 20) and in those with AS (group AS, n = 20). Respiratory system impedance was determined during propofol anesthesia and during inhalation of sevoflurane and desflurane 1 minimum alveolar concentration in random order. Airway resistance, tissue damping, and elastance were determined from the respiratory system impedance spectra by model fitting. Results Children in group AS exhibited significantly higher respiratory impedance parameters compared with those in group C. Sevoflurane slightly decreased airway resistance (-7.0 +/- 1.5% vs. -4.8 +/- 2.4% in groups C and AS, respectively) in both groups. In contrast, desflurane caused elevations in airway resistance and tissue mechanical parameters, with markedly enhanced airway narrowing in children with AS (18.2 +/- 2.8% vs. 53.9 +/- 5%; P &lt; 0.001 for airway resistance in groups C and AS, respectively). Neither the order of drug administration nor the time after the establishment of their steady state concentrations affected these findings. Conclusions These results emphasized the deleterious effects of desflurane on the airways, particularly in children with susceptible airways in contrast with the consistent beneficial effects of sevoflurane, questioning the use of desflurane in children with AS.

scholarly journals A Microfluidic System to Measure Neonatal Lung Compliance Over Late Stage Development as a Functional Measure of Lung Tissue Mechanics

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Laurel E. Schappell ◽  
Daniel J. Minahan ◽  
Jason P. Gleghorn
Keyword(s):  
Lung Development ◽  
Morphological Changes ◽  
Microfluidic System ◽  
Lung Compliance ◽  
Tissue Mechanics ◽  
Neonatal Mouse ◽  
Lung Mechanics ◽  
Mouse Lung ◽  
Neonatal Lung ◽  
Functional Measure

Abstract Premature birth interrupts the development of the lung, resulting in functional deficiencies and the onset of complex pathologies, like bronchopulmonary dysplasia (BPD), that further decrease the functional capabilities of the immature lung. The dysregulation of molecular targets has been implicated in the presentation of BPD, but there is currently no method to correlate resultant morphological changes observed in tissue histology with these perturbations to differences in function throughout saccular and alveolar lung development. Lung compliance is an aggregate measure of the lung's mechanical properties that is highly sensitive to a number of molecular, cellular, and architectural characteristics, but little is known about compliance in the neonatal mouse lung due to measurement challenges. We have developed a novel method to quantify changes in lung volume and pressure to determine inspiratory and expiratory compliance throughout neonatal mouse lung development. The compliance measurements obtained were validated against compliance values from published studies using mature lungs following enzymatic degradation of the extracellular matrix (ECM). The system was then used to quantify changes in compliance that occurred over the entire span of neonatal mouse lung development. These methods fill a critically important gap connecting powerful mouse models of development and disease to measures of functional lung mechanics critical to respiration and enable insights into the genetic, molecular, and cellular underpinnings of BPD pathology to improve lung function in premature infants.

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