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.

Late response of the upper airway of the rat to inhaled antigen

1990 ◽  
Vol 69 (4) ◽  
pp. 1360-1365 ◽  
Author(s):  
L. J. Xu ◽  
D. H. Eidelman ◽  
J. H. Bates ◽  
J. G. Martin
Keyword(s):  
Time Course ◽  
Airway Resistance ◽  
Upper Airway ◽  
Brown Norway ◽  
Control Group ◽  
Late Response ◽  
Lung Elastance ◽  
Upper Airway Resistance ◽  
Airway Responses ◽  
Peak Value

We studied the magnitude and time course of changes in upper airway resistance (Ruaw) of actively sensitized Brown-Norway rats after aerosol challenge with ovalbumin (OA). Two weeks after sensitization, eight rats were challenged by inhalation of aerosolized OA through the nose. The airway responses of these rats 5-10 h after OA challenge were compared with those of seven animals challenged with saline. Seven of eight test rats had increased Ruaw, and six displayed discrete late responses (LR). Ruaw during expiration was highly alinear so analysis was confined to Ruaw during inspiration (Ruaw,I). The Ruaw,I averaged over 5 h was 1.262 +/- 0.09 (SE) cmH2O.ml-1.s, 2.6 times the value for saline-challenged animals (0.476 +/- 0.143 cmH2O.ml-1.s), and it reached a peak value of 3.454 +/- 0.45 cmH2O.ml-1.s. The time to the peak of the LR was 446 +/- 37.3 min. The duration of the LR in the upper airway was 146 +/- 34.9 min. At the time corresponding to the peak value of Ruaw,I, the lung elastance in the test rats was double the value preceding the peak. Lung elastance was unchanged in the control group. We conclude that inhalation of antigen through the upper airway of the sensitized rat results in a substantial increase in upper airway resistance and a distinct LR. The predominant site of the change in respiratory system resistance is in the upper airway.

Assessment of local lung impedance by the alveolar capsule oscillator in dogs: a model analysis

1996 ◽  
Vol 80 (4) ◽  
pp. 1165-1172 ◽  
Author(s):  
M. Mishima ◽  
Z. Balassy ◽  
J. H. Bates
Keyword(s):  
Computer Simulations ◽  
Acoustic Impedance ◽  
Airway Resistance ◽  
Lung Region ◽  
Bronchial Challenge ◽  
Airway Constriction ◽  
Branching Model ◽  
Peripheral Airway ◽  
Lung Periphery ◽  
Tissue Elastance

The alveolar capsule oscillator technique has shown that the response of the lung periphery to intravenous histamine injection in dogs is extremely inhomogeneous both in terms of local peripheral airway resistance (RA) and local peripheral elastance (EA) (M. Mishima, Z Balassy, and J. H. T. Bates. J. Appl. Physiol. 77: 2140-2148, 1994). To assess the physical extent of the local lung region identified by this technique, we performed computer simulations using an asymmetrical branching model of the canine lung proposed by K. Horsfield, W. Kemp, and S. Philips (J. Appl. Physiol. 52: 21-26, 1982). The acoustic impedance of the model from 26 to 200 Hz as seen from the alveolar capsule oscillator was calculated. RA and EA were estimated from the simulated acoustic impedance between 26 and 200 Hz and were found to be 492 hPa.s.l-1 and 156,300 hPa/l, respectively. These values are similar to those found experimentally in previous studies. By simulating data using the model in various stages of completeness, we determined that approximately 50% of RA is determined by the acinus to which the alveolar capsule is attached, whereas the remainder is determined by airways < or = 1 mm diameter that converge on this acinus. By contrast, EA was determined almost entirely (95%) by the acinus directly under the capsule. Inhomogeneous peripheral airway constriction altered RA severalfold but did not affect EA by >5%. This suggests that the previously observed changes induced in EA by bronchial challenge reflect real changes in intrinsic tissue elastance rather than merely regional mechanical inhomogeneities.

Differential responses of global airway, terminal airway, and tissue impedances to histamine

1995 ◽  
Vol 79 (5) ◽  
pp. 1440-1448 ◽  
Author(s):  
Z. Hantos ◽  
F. Petak ◽  
A. Adamicza ◽  
B. Daroczy ◽  
J. J. Fredberg
Keyword(s):  
Airway Resistance ◽  
Forced Oscillation ◽  
Transfer Resistance ◽  
The Real ◽  
Control Value ◽  
Impedance Data ◽  
Lung Periphery ◽  
Control State ◽  
Sensitive Method ◽  
Zero Frequency

The forced oscillation and alveolar capsule techniques were applied to determine the input impedance of the lungs and the airway transfer impedances between 0.2 and 20 Hz in six open-chest dogs in the control state, during intravenous infusion of histamine at seven rates between 0.25 and 16 micrograms.kg-1.min-1, and after the infusion. In each condition, the input impedances seen from the alveolar capsules, i.e., terminal airway impedance (Zaw,ter), were measured by imposing 2- to 200-Hz oscillations from the capsules (B. L. K. Davey and J. H. T. Bates. Respir. Physiol. 91:165–182, 1993). Airway resistance (Raw) and inertance and tissue damping and elastance were derived from the lung impedance data. For all dogs, histamine progressively increased Raw and the real part of airway transfer impedance (airway transfer resistance), reaching, at 16 micrograms.kg-1.min-1, 241 +/- 109 (SD) and 370 +/- 186%, respectively, of the control value but caused greater, although locally highly variable, increases (769 +/- 716% of the control value) in the real part of Zaw,ter extrapolated to zero frequency (R0). With increasing doses of histamine, the changes in R0 always preceded those in Raw and airway transfer resistance implying that bronchoconstriction developed first in the lung periphery. It is therefore concluded that the measurement of Zaw,ter offers a sensitive method for the detection of early nonuniform responses to bronchoconstrictor stimuli that are not yet reflected by the values of the overall Raw. In one-half of the cases, significant increases in tissue damping and elastance occurred before any change in R0; this suggests that the mechanisms of airway and parenchymal constrictions may be unrelated.

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.

Protective Effects of Volatile Agents against Methacholine-induced Bronchoconstriction in Rats

2001 ◽  
Vol 94 (2) ◽  
pp. 348-353 ◽  
Author(s):  
Walid Habre ◽  
Ferenc Peták ◽  
Peter D. Sly ◽  
Zoltán Hantos ◽  
Denis R. Morel
Keyword(s):  
Airway Resistance ◽  
Model Fitting ◽  
Low Frequency ◽  
Tissue Mechanics ◽  
Control Group ◽  
Protective Effects ◽  
Airway Constriction ◽  
Impedance Data ◽  
Significant Difference ◽  
Volatile Agents

Background The protective properties of common volatile agents against generalized lung constriction have previously been addressed only via estimations of parameters that combine airway and tissue mechanics. Their effectiveness in preventing airway constriction have not been compared systematically. Therefore, the authors investigated the abilities of halothane, isoflurane, sevoflurane, and desflurane to provide protection against airway constriction induced by methacholine. Methods Low-frequency pulmonary impedance data were collected in open-chest rats under baseline conditions and during three consecutive intravenous infusions of methacholine (32 microg x kg(-1) x min(-1)) while the animals were anesthetized with intravenous pentobarbital (control group). Methacholine challenges were performed in four other groups of rats, first during intravenous anesthesia and then repeated during the inhalation of halothane, isoflurane, sevoflurane, or desflurane at concentrations of 1 and 2 minimum alveolar concentration (MAC). Airway resistance and inertance, parenchymal damping, and elastance were estimated from the impedance data by model fitting. Results The methacholine-induced increases in airway resistance during intravenous pentobarbital anesthesia (204 +/- 53%) were markedly and significantly (P &lt; 0.005) reduced by 1-MAC doses of halothane (80 +/- 48%), isoflurane (112 +/- 59%), sevoflurane (68 +/- 34%), and desflurane (96 +/- 34%), with no significant difference between the gases applied. Increasing the concentration to 2 MAC did not lead to any significant further protection against the increase in airway resistance. Conclusions These data demonstrate that isoflurane, sevoflurane, and desflurane are as effective as the widely accepted halothane in protecting against methacholine-induced airway constriction.

scholarly journals Developmental changes in airway and tissue mechanics in mice

2005 ◽  
Vol 99 (1) ◽  
pp. 108-113 ◽  
Author(s):  
Elizabeth M. Bozanich ◽  
Rachel A. Collins ◽  
Cindy Thamrin ◽  
Zoltán Hantos ◽  
Peter D. Sly ◽  
...  
Keyword(s):  
Airway Resistance ◽  
Structural Changes ◽  
Low Frequency ◽  
Postnatal Period ◽  
Tissue Mechanics ◽  
Forced Oscillation Technique ◽  
Impedance Data ◽  
Age Related ◽  
System Pressure ◽  
Tissue Elastance

Most studies using mice to model human lung diseases are carried out in adults, although there is emerging interest in the effects of allergen, bacterial, and viral exposure early in life. This study aims to characterize lung function in BALB/c mice from infancy (2 wk) through to adulthood (8 wk). The low-frequency forced oscillation technique was used to obtain impedance data, partitioned into components representing airway resistance, tissue damping, tissue elastance, and hysteresivity (tissue damping/tissue elastance). Measurements were made at end-expiratory pause (transrespiratory system pressure = 2 cmH2O) and during relaxed slow expiration from 20 to 0 cmH2O. Airway resistance decreased with age from 0.63 cmH2O·ml−1·s at 2 wk to 0.24 cmH2O·ml−1·s at 8 wk ( P < 0.001). Both tissue damping and tissue elastance decreased with age ( P < 0.001) from 2 to 5 wk, then plateaued through to 8 wk ( P < 0.001). This pattern was seen both in measurements taken at end-expiratory pause and during expiration. There were no age-related changes seen in hysteresivity when measured at end-expiratory pause, but the pattern of volume dependence did differ with the age of the mice. These changes in respiratory mechanics parallel the reported structural changes of the murine lung from the postnatal period into adulthood.

scholarly journals Comparison of unrestrained plethysmography and forced oscillation for identifying genetic variability of airway responsiveness in inbred mice

2011 ◽  
Vol 43 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Annerose Berndt ◽  
Adriana S. Leme ◽  
Laura K. Williams ◽  
Randy Von Smith ◽  
Holly S. Savage ◽  
...  
Keyword(s):  
Lung Function ◽  
Airway Resistance ◽  
Forced Oscillation ◽  
Association Studies ◽  
Genome Wide Association ◽  
Mouse Strains ◽  
Forced Oscillation Technique ◽  
Genome Wide Association Studies ◽  
Lung Elastance ◽  
Genome Wide

Lung function detection in mice is currently most accurately measured by invasive techniques, which are costly, labor intensive, and terminal. This limits their use for large-scale or longitudinal studies. Noninvasive assays are often used instead, but their accuracy for measuring lung function parameters such as resistance and elastance has been questioned in studies involving small numbers of mouse strains. Here we compared parameters detected by two different methods using 29 inbred mouse strains: enhanced pause (Penh), detected by unrestrained plethysmography, and central airway resistance and lung elastance, detected by a forced oscillation technique. We further tested whether the phenotypic variations were determined by the same genomic location in genome-wide association studies using a linear mixed model algorithm. Penh, resistance, and elastance were measured in nonexposed mice or mice exposed to saline and increasing doses of aerosolized methacholine. Because Penh differed from airway resistance in several strains and because the peak genetic associations found for Penh, resistance, or elastance were located at different genomic regions, we conclude that using Penh as an indicator for lung function changes in high-throughput genetic studies (i.e., genome-wide association studies or quantitative trait locus studies) measures something fundamentally different than airway resistance and lung elastance.

Objective assessment of nasal resistance among electronic cigarette users

2021 ◽  
pp. 1-4
Author(s):  
S W Lim ◽  
AB Zulkiflee
Keyword(s):  
Tobacco Smoking ◽  
Repeated Measures ◽  
Airway Resistance ◽  
Electronic Cigarettes ◽  
Objective Assessment ◽  
Control Group ◽  
Nasal Airway ◽  
Nasal Resistance ◽  
Short Term ◽  
Nasal Airway Resistance

Abstract Background Electronic cigarettes have been a popular alternative to tobacco smoking. The effect of tobacco smoking on nasal airway resistance has been investigated before; however, the effect of the aerosol generated by electronic cigarettes is still unknown. This study aimed to evaluate the short-term effects of e-cigarettes on nasal airway resistance. Methods Sixty-one participants were recruited into a vapers group and a control group. The vapers group was instructed to smoke for 5 minutes, and their nasal resistance was measured pre-procedure and at 1 and 5 minutes post-procedure. The results were compared between both groups. Results Repeated measures analysis of variance demonstrated that vaping has no statistically significant effect on total nasal airway resistance. Conclusion Although the differences between both groups were not statistically significant overall, the vapers group showed a reduction in nasal airway resistance in the short term.

scholarly journals Damping forced oscillations in power system via interline power flow controller with additional repetitive control

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Shirui Feng ◽  
Xi Wu ◽  
Zhenquan Wang ◽  
Tao Niu ◽  
Qiong Chen
Keyword(s):  
Power Flow ◽  
Forced Oscillation ◽  
Control Method ◽  
Damping Ratio ◽  
Repetitive Control ◽  
Oscillation Amplitude ◽  
Reference Value ◽  
Forced Oscillations ◽  
Flow Controller ◽  
Power Flow Controller

AbstractWith the continuous expansion of power systems and the application of power electronic equipment, forced oscillation has become one of the key problems in terms of system safety and stability. In this paper, an interline power flow controller (IPFC) is used as a power suppression carrier and its mechanism is analyzed using the linearized state-space method to improve the system damping ratio. It is shown that although the IPFC can suppress forced oscillation with well-designed parameters, its capability of improving the system damping ratio is limited. Thus, combined with the repetitive control method, an additional repetitive controller (ARC) is proposed to further dampen the forced power oscillation. The ARC control scheme is characterized by outstanding tracking performance to a system steady reference value, and the main IPFC controller with the ARC can provide higher damping, and further reduce the amplitude of oscillations to zero compared with a supplementary damping controller (SDC). Simulation results show that the IPFC with an ARC can not only greatly reduce the oscillation amplitude, but also actively output the compensation power according to the reference value of the ARC tracking system.

391 Upper Airway Resistance Syndrome is associated with high Cyclic Alternating Pattern

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A155-A156
Author(s):  
Luciana Godoy ◽  
Letícia Soster ◽  
Clarissa Bueno ◽  
Sonia Togeiro ◽  
Dalva Poyares ◽  
...  
Keyword(s):  
Airway Resistance ◽  
Upper Airway ◽  
Sleep Fragmentation ◽  
Control Group ◽  
Flow Limitation ◽  
Upper Airway Resistance Syndrome ◽  
Arousal Index ◽  
Upper Airway Resistance ◽  
Cyclic Alternating Pattern ◽  
Cap Rate

Abstract Introduction Upper Airway Resistance Syndrome (UARS) is suspected in individuals with excessive daytime sleepiness, fatigue, and sleep fragmentation associated with increased respiratory effort. UARS can negatively impact daytime function. Conventional polysomnography parameters do not demonstrate significant abnormalities in UARS patients but increase in RERAs and arousal index. Cyclic alternating pattern (CAP) is a periodic electroencephalogram activity of non-REM sleep that expresses a condition of sleep instability. The objective of the study was to compare CAP components between UARS patients and health individuals. Methods Fifteen subjects with UARS and 15 age- and sex- matched controls had their sleep study blinded analyzed. UARS criteria were the presence of sleepiness (Epworth Sleepiness Scale – ESS - ≥ 10) and/or fatigue (Modified Fatigue Impact Scale ≥ 38) associated with an apnea/hypopnea index (AHI) ≤ 5 and a respiratory disturbance index (RDI) &gt; 5 events/hour of sleep, and/or flow limitation in more than 30% of total sleep time. Control group criteria were AHI &lt; 5 events/hour, RDI ≤ 5 events/hour and &lt; 30% of TST with flow limitation and ESS &lt; 10, without sleep, clinical, neurological, or psychiatric disorder. CAP electroencephalogram of both groups was analyzed. Results We found higher CAP rate (p = 0.05) and CAP index in N1 stage (p &lt; 0.001) and in N3 stage (p &lt; 0.001) in UARS patients compared to control group. Considering only CAP phase A1 analysis, UARS patients presented higher CAP rate (p = 0.05) and CAP index in N1 stage (p &lt; 0.001) as well as CAP index in N3 stage (p &lt; 0.001) compared to control group. Considering only CAP phase A2 analysis, UARS patients also presented higher number of CAP in N1 stage (p = 0.05). There was no significant difference for CAP phase A3 between groups. Conclusion Although UARS is associated with high arousal index, we found increase in CAP phase A1 and A2, which do not include necessarily AASM arousals, suggesting not only sleep fragmentation but also sleep instability. Support (if any) Associação Fundo de Incentivo à Pesquisa (AFIP) and Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP).

Sign in / Sign up

Export Citation Format

Share Document