Complete Airway Closure

2021 ◽  
Vol 3 (1) ◽  
pp. 16
Author(s):  
Jianxin Zhou ◽  
Xiumei Sun ◽  
Lu Chen
Keyword(s):  
Airway Closure

scholarly journals Impact of artificial airway resistances on regional ventilation distribution during airway closure

2020 ◽  
Vol 6 (3) ◽  
pp. 32-35
Author(s):  
Melanie März ◽  
Sarah Howe ◽  
Bernhard Laufer ◽  
Knut Moeller ◽  
Sabine Krueger-Ziolek
Keyword(s):  
Pulmonary Function ◽  
Airway Resistance ◽  
Airway Closure ◽  
Ventilation Distribution ◽  
Regional Ventilation ◽  
Impedance Tomography ◽  
Artificial Airway ◽  
Normal Breathing ◽  
Airway Obstructions ◽  
Forced Breathing

AbstractElectrical impedance tomography (EIT), a noninvasive and radiation-free imaging technique can be used in pulmonary function monitoring for determining regional ventilation distribution within the lung. Gold standard in pulmonary function monitoring is spirometry/body plethysmography, a method using forced breathing maneuvers to obtain global lung function parameters. However, this method is heavily dependent on the cooperation of the patients. Within this observational study, a method under normal breathing was tested with 5 healthy volunteers, which provides regional information about ventilation distribution. The occlusion method Rocc, a method for determining airway resistance, was used to create a short-term airway closure. Regional ventilation during the airway closure was examined with EIT. Simultaneously four different artificial airway resistances were used to simulate airway obstructions. Results show that EIT in combination with the ROcc method is suitable for the detection of regional differences in ventilation during airway closure for all four artificial airway resistances. Although the sum of relative impedances at the end of the shutter maneuver are smaller (nearly -0.100 AU) for the airway resistances Ø 12.5 mm, Ø 10.5 mm and Ø 9.5 mm than for the smallest one with Ø 30.0 mm (~ -0.070 AU), the changes in impedance from the start to the end of the shutter maneuver differs only slightly between the four artificial airway resistances. All impedance changes are in the range of 0.100 to 0.130 AU. The combination of EIT and the ROcc method provides not only global parameters such as airway resistance under normal breathing conditions, but also results of regional ventilation, which could enable the identification of areas affected by airway obstructions. However, the obtained results indicate that EIT might be a useful tool in the diagnosis and follow-up of obstructive lung diseases.

scholarly journals The effect of viscoelasticity in an airway closure model

2021 ◽  
Vol 913 ◽  
Author(s):  
F. Romanò ◽  
M. Muradoglu ◽  
H. Fujioka ◽  
J.B. Grotberg
Keyword(s):  
Airway Closure ◽  
Closure Model

Abstract

scholarly journals Positive end-expiratory pressure in COVID-19-related ARDS: Do not forget the airway closure

2021 ◽  
Author(s):  
Clément Brault ◽  
Yoann Zerbib ◽  
Loay Kontar ◽  
Mathieu Carpentier ◽  
Julien Maizel ◽  
...  
Keyword(s):  
Airway Closure ◽  
Positive End Expiratory Pressure

AIRWAY CLOSURE, PEEP, AND AaDO2DURING ANESTHESIA

1980 ◽  
Vol 53 (3 Suppl) ◽  
pp. S413-S413
Author(s):  
Y. K. Tien ◽  
N. A. Bergman
Keyword(s):  
Airway Closure

Airway closure and reopening assessed by the alveolar capsule oscillation technique

1996 ◽  
Vol 80 (6) ◽  
pp. 2077-2084 ◽  
Author(s):  
D. R. Otis ◽  
F. Petak ◽  
Z. Hantos ◽  
J. J. Fredberg ◽  
R. D. Kamm
Keyword(s):  
Lung Volume ◽  
Input Impedance ◽  
Transpulmonary Pressure ◽  
Closing Volume ◽  
Airway Closure ◽  
Breathing Cycle ◽  
Abrupt Increase ◽  
Consistent Effect ◽  
Peripheral Airways

An alveolar capsule oscillation technique was used to determine 1) the lobe pressure and volume at which airways close and reopen, 2) the effect of expiration rate on closing volume and pressure, 3) the phase in the breathing cycle at which airway closure occurs, and 4) the site of airway closure. Experiments were conducted in excised dog lobes; closure was detected by an abrupt increase in the input impedance of surfacemounted alveolar capsules. Mean transpulmonary pressure (Ptp) at closure was slightly less than zero (Ptp = -2.3 cmH2O); the corresponding mean reopening pressure was Ptp = 14 cmH2O. The expiration rate varied between 1 and 20% of total lobe capacity per second and had no consistent effect on the closing volume and pressure. When lung volume was cycled up to frequencies of 0.2 Hz, closure generally occurred on expiration rather than inspiration. These observations support the conclusion that mechanical collapse, rather than meniscus formation, is the most likely mechanism producing airway closure in normal excised dog lungs. Analysis of measured acoustic impedances and reopening pressures suggests that closure occurs in the most peripheral airways. Reopening during inspiration was often observed to consist of a series of stepwise decreases in capsule impedance, indicating a sequence of opening events.

Positive Expiratory Pressure: A Potential Therapy to Mitigate Acute Bronchoconstriction in the Asthma of Obesity

2021 ◽  
Author(s):  
Swati a. Bhatawadekar ◽  
Anne E. Dixon ◽  
Ubong Peters ◽  
Nirav Daphtary ◽  
Kevin Hodgdon ◽  
...  
Keyword(s):  
Airway Resistance ◽  
Late Onset ◽  
Rescue Therapy ◽  
Pharmacologic Therapy ◽  
Airway Closure ◽  
Airway Narrowing ◽  
Asthma Patients ◽  
Peripheral Airway ◽  
Central Airway ◽  
Positive Expiratory Pressure

Late-onset non-allergic (LONA) asthma in obesity is characterized by increased peripheral airway closure secondary to abnormally collapsible airways. We hypothesized that positive expiratory pressure (PEP) would mitigate the tendency to airway closure during bronchoconstriction, potentially serving as rescue therapy for LONA asthma of obesity. The PC20 dose of methacholine was determined in 18 obese participants with LONA asthma. At each of 4 subsequent visits, we used oscillometry to measure input respiratory impedance (Zrs) over 8 minutes; participants received their PC20 concentration of methacholine aerosol during the first 4.5 minutes. PEP combinations of either 0 or 10 cmH2O either during and/or after the methacholine delivery were applied, randomized between visits. Parameters characterizing respiratory system mechanics were extracted from the Zrs spectra. In 18 LONA asthma patients (14 females, BMI: 39.6±3.4 kg/m2), 10 cmH2O PEP during methacholine reduced elevations in the central airway resistance, peripheral airway resistance and elastance, and breathing frequency was also reduced. During the 3.5 min following methacholine delivery, PEP of 10 cmH2O reduced Ax and peripheral elastance compared to no PEP. PEP mitigates the onset of airway narrowing brought on by methacholine challenge, and airway closure once it is established. PEP thus might serve as a non-pharmacologic therapy to manage acute airway narrowing for obese LONA asthma.

End-expiratory and tidal volumes measured in conscious mice using single projection x-ray images

2008 ◽  
Vol 104 (2) ◽  
pp. 521-533 ◽  
Author(s):  
Stephen J. Lai-Fook ◽  
Pamela K. Houtz ◽  
Yih-Loong Lai
Keyword(s):  
Body Temperature ◽  
Lung Volume ◽  
Airway Resistance ◽  
X Rays ◽  
Airway Closure ◽  
Exposure Phase ◽  
X Ray ◽  
Total Lung Volume ◽  
Aerosol Exposure ◽  
Lung Area

The evaluation of airway resistance (Raw) in conscious mice requires both end-expiratory (Ve) and tidal volumes (Vt) (Lai-Fook SJ and Lai YL. J Appl Physiol 98: 2204–2218, 2005). In anesthetized BALB/c mice we measured lung area (AL) from ventral-to-dorsal x-ray images taken at FRC (Ve) and after air inflation with 0.25 and 0.50 ml (ΔVL). Total lung volume (VL) described by equation: VL = ΔVL + VFRC = KAL1.5 assumed uniform (isotropic) inflation. Total VFRC averaged 0.55 ml, consisting of 0.10 ml tissue, 0.21 ml blood and 0.24 ml air. K averaged 1.84. In conscious mice in a sealed box, we measured the peak-to-peak box pressure excursions (ΔPb) and x-rays during several cycles. K was used to convert measured AL1.5 to VL values. We calculated Ve and Vt from the plot of VL vs. cos(α − φ). Phase angle α was the minimum point of the Pb cycle to the x-ray exposure. Phase difference between the Pb and VL cycles (φ) was measured from ΔPb values using both room- and body-temperature humidified box air. A similar analysis was used after aerosol exposures to bronchoconstrictor methacholine (Mch), except that φ depended also on increased Raw. In conscious mice, Ve (0.24 ml) doubled after Mch (50–125 mg/ml) aerosol exposure with constant Vt, frequency (f), ΔPb, and Raw. In anesthetized mice, in addition to an increased Ve, repeated 100 mg/ml Mch exposures increased both ΔPb and Raw and decreased f to apnea in 10 min. Thus conscious mice adapted to Mch by limiting Raw, while anesthesia resulted in airway closure followed by diaphragm fatigue and failure.

Effect of transpulmonary pressure on airway closure in immature and mature rabbits

1995 ◽  
Vol 78 (2) ◽  
pp. 505-512 ◽  
Author(s):  
R. S. Tepper ◽  
S. J. Gunst ◽  
C. M. Doerschuk ◽  
X. Shen ◽  
W. Bray
Keyword(s):  
Smooth Muscle ◽  
Small Volume ◽  
Transpulmonary Pressure ◽  
Lung Parenchyma ◽  
Tracheal Smooth Muscle ◽  
Airway Closure ◽  
Maximal Stimulation ◽  
In Vitro Sensitivity ◽  
Airway Opening

The transpulmonary pressures (Ptp values) at which airway closure occurred during maximal stimulation with methacholine were compared in 10 mature and 9 immature rabbit lungs by using an alveolar capsule technique to assess airway closure. After maximal constriction, airway opening and alveolar capsule pressures were recorded during small volume oscillations as Ptp was lowered from 12 to 4 cmH2O. At each Ptp, the proportion of alveolar capsules indicating airway closure was greater for the immature than for the mature lungs (P < 0.025). At Ptp of 4 cmH2O, only 20% of alveolar capsules indicated airway closure in the mature lungs in contrast to 85% indicating closure in the immature lungs (P < 0.001). The in vitro sensitivity of tracheal smooth muscle to acetylcholine and histamine was greater in tissues from immature than from mature rabbits. We conclude that the more frequent airway closure observed in immature rabbits could reflect maturational differences in the structure of the bronchi or lung parenchyma or differences in the coupling between the parenchyma and the airways.

scholarly journals Methacholine responsiveness of proximal and distal airways of monkeys and rats using videomicrometry

2002 ◽  
Vol 92 (3) ◽  
pp. 989-996 ◽  
Author(s):  
Kayleen S. Kott ◽  
Kent E. Pinkerton ◽  
John M. Bric ◽  
Charles G. Plopper ◽  
Krishna P. Avadhanam ◽  
...  
Keyword(s):  
Airway Hyperresponsiveness ◽  
Airway Responsiveness ◽  
Wall Structure ◽  
Airway Closure ◽  
Airway Wall ◽  
Human Airway ◽  
Wall Structures ◽  
Distal Airway ◽  
Luminal Area ◽  
Young Rat

Rat and monkey are species that are used in models of human airway hyperresponsiveness. However, the wall structures of rat and monkey airways are different from each other, with that of the monkey more closely resembling that of humans. We hypothesized that differences in wall structure would explain differences in airway responsiveness. Using videomicrometry, we measured airway luminal area in lung slices to compare proximal and distal airway responsiveness to methacholine in the rat and monkey. The airway type was then histologically identified. Proximal airways of the young rat and monkey were equally responsive to methacholine. In contrast, respiratory bronchioles of monkeys were less responsive than were their proximal bronchi, whereas the distal bronchioles of rats were more responsive than their proximal bronchioles. Both proximal and distal airways of younger monkeys were more responsive than those of older monkeys. Airway heterogeneity in young monkeys was greatest with regard to degree of airway closure of respiratory bronchioles. We conclude that responsiveness to methacholine varies with airway wall structure and location.

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