Intratidal Overdistention and Derecruitment in the Injured Lung: A Simulation Study

Amini, Reza; Herrmann, Jacob; Kaczka, David W.

doi:10.1109/tbme.2016.2572678

Cited by 21 publications

(20 citation statements)

References 45 publications

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“…The relative amplitude distributions in the flow waveforms delivered by the ventilator were largely preserved throughout the lung, according to the registration-based metrics (r 2 = 0.78). However, harmonic distortion measurements during HFOV indicated nearly 20% of the spectral power in regional strain was concentrated in the higher-order harmonics of the 5 Hz waveform (i.e., 10, 15, 20 Hz), whereas the ventilator volume waveform exhibited only 5% harmonic distortion (Zhang et al, 1995;Amini et al, 2017).…”

Section: Resultsmentioning

confidence: 98%

Quantifying Regional Lung Deformation Using Four-Dimensional Computed Tomography: A Comparison of Conventional and Oscillatory Ventilation

et al. 2020

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Mechanical ventilation strategies that reduce the heterogeneity of regional lung stress and strain may reduce the risk of ventilator-induced lung injury (VILI). In this study, we used registration of four-dimensional computed tomographic (4DCT) images to assess regional lung aeration and deformation in 10 pigs under baseline conditions and following acute lung injury induced with oleic acid. CT images were obtained via dynamic axial imaging (Siemens SOMATOM Force) during conventional pressure-controlled mechanical ventilation (CMV), as well as high-frequency and multi-frequency oscillatory ventilation modalities (HFOV and MFOV, respectively). Our results demonstrate that oscillatory modalities reduce intratidal strain throughout the lung in comparison to conventional ventilation, as well as the spatial gradients of dynamic strain along the dorsal-ventral axis. Harmonic distortion of parenchymal deformation was observed during HFOV with a single discrete sinusoid delivered at the airway opening, suggesting inherent mechanical nonlinearity of the lung tissues. MFOV may therefore provide improved lung-protective ventilation by reducing strain magnitudes and spatial gradients of strain compared to either CMV or HFOV.

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Section: Resultsmentioning

confidence: 98%

Quantifying Regional Lung Deformation Using Four-Dimensional Computed Tomography: A Comparison of Conventional and Oscillatory Ventilation

et al. 2020

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“…To simplify computation of mechanical impedance and flow distribution in the frequency-domain we did not consider intratidal variations in model structure or mechanical properties (2). Additionally, CO2 transport throughout the airway network was solved as a steady-state problem, i.e., time-averaged throughout the oscillatory ventilation cycle and with CO2 elimination equal to CO2 production.…”

Section: Methodsmentioning

confidence: 99%

“…The model also does not account for derecruitment, perfusion shunting, or any changes in airway mechanics. Furthermore, the model ignores intratidal variations in mechanics, which are especially relevant to overdistension and cyclic derecruitment (2,5).…”

Section: Limitationsmentioning

confidence: 99%

Regional gas transport in the heterogeneous lung during oscillatory ventilation

Herrmann

Tawhai

Kaczka

2016

Journal of Applied Physiology

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Regional ventilation in the injured lung is heterogeneous and frequency dependent, making it difficult to predict how an oscillatory flow waveform at a specified frequency will be distributed throughout the periphery. To predict the impact of mechanical heterogeneity on regional ventilation distribution and gas transport, we developed a computational model of distributed gas flow and CO elimination during oscillatory ventilation from 0.1 to 30 Hz. The model consists of a three-dimensional airway network of a canine lung, with heterogeneous parenchymal tissues to mimic effects of gravity and injury. Model CO elimination during single frequency oscillation was validated against previously published experimental data (Venegas JG, Hales CA, Strieder DJ, J Appl Physiol 60: 1025-1030, 1986). Simulations of gas transport demonstrated a critical transition in flow distribution at the resonant frequency, where the reactive components of mechanical impedance due to airway inertia and parenchymal elastance were equal. For frequencies above resonance, the distribution of ventilation became spatially clustered and frequency dependent. These results highlight the importance of oscillatory frequency in managing the regional distribution of ventilation and gas exchange in the heterogeneous lung.

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“…The open lung approach makes sound physiologic sense as a method to minimize the mechanisms of VILI at the alveolar level. Indeed, a link has been shown between optimal compliance/elastance and alveolar overdistension and instability in an animal model (6) and the role of driving pressure, which is calculated using compliance, as an indicator of mortality in ARDS patients (5). However, using compliance/elastance does not take advantage of the viscoelastic component of alveolar inflation and deflation.…”

Section: Translating Dynamic Alveolar Physiology To the Bedsidementioning

confidence: 99%

Physiology in Medicine: Understanding dynamic alveolar physiology to minimize ventilator-induced lung injury

Nieman

Satalin

Kollisch-Singule

et al. 2017

Journal of Applied Physiology

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Acute respiratory distress syndrome (ARDS) remains a serious clinical problem with the main treatment being supportive in the form of mechanical ventilation. However, mechanical ventilation can be a double-edged sword: if set improperly, it can exacerbate the tissue damage caused by ARDS; this is known as ventilator-induced lung injury (VILI). To minimize VILI, we must understand the pathophysiologic mechanisms of tissue damage at the alveolar level. In this Physiology in Medicine paper, the dynamic physiology of alveolar inflation and deflation during mechanical ventilation will be reviewed. In addition, the pathophysiologic mechanisms of VILI will be reviewed, and this knowledge will be used to suggest an optimal mechanical breath profile (MB: all airway pressures, volumes, flows, rates, and the duration that they are applied at both inspiration and expiration) necessary to minimize VILI. Our review suggests that the current protective ventilation strategy, known as the "open lung strategy," would be the optimal lung-protective approach. However, the viscoelastic behavior of dynamic alveolar inflation and deflation has not yet been incorporated into protective mechanical ventilation strategies. Using our knowledge of dynamic alveolar mechanics (i.e., the dynamic change in alveolar and alveolar duct size and shape during tidal ventilation) to modify the MB so as to minimize VILI will reduce the morbidity and mortality associated with ARDS.

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Intratidal Overdistention and Derecruitment in the Injured Lung: A Simulation Study

Cited by 21 publications

References 45 publications

Quantifying Regional Lung Deformation Using Four-Dimensional Computed Tomography: A Comparison of Conventional and Oscillatory Ventilation

Quantifying Regional Lung Deformation Using Four-Dimensional Computed Tomography: A Comparison of Conventional and Oscillatory Ventilation

Regional gas transport in the heterogeneous lung during oscillatory ventilation

Physiology in Medicine: Understanding dynamic alveolar physiology to minimize ventilator-induced lung injury

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