Computational Analyses of Airway Flow and Lung Tissue Dynamics

Kaczka, David W.; Colletti, Ashley A.; Tawhai, Merryn H.; Simon, Brett A.

doi:10.1007/978-1-4419-7350-4_10

Cited by 3 publications

(3 citation statements)

References 127 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the pipe-like airways, purely resistive elements were used. Womersley 's theory for pulsatile flow in tubes [32] was applied to account for inertial effects during normal breathing, which have a considerable effect on the flow resistance in bigger airways until the fifth generation [33] (see also S1 Appendix). In general, the pressure difference between two subsequent nodes with index i and j in the network of pipe-like airways reads p i − p j = R ij Q ij .…”

Section: Methodsmentioning

confidence: 99%

A multi-scale model of gas transport in the lung to study heterogeneous lung ventilation during the multiple-breath washout test

et al. 2019

View full text Add to dashboard Cite

The multiple-breath washout (MBW) is a lung function test that measures the degree of ventilation inhomogeneity (VI). The test is used to identify small airway impairment in patients with lung diseases like cystic fibrosis. However, the physical and physiological factors that influence the test outcomes and differentiate health from disease are not well understood. Computational models have been used to better understand the interaction between anatomical structure and physiological properties of the lung, but none of them has dealt in depth with the tracer gas washout test in a whole. Thus, our aim was to create a lung model that simulates the entire MBW and investigate the role of lung morphology and tissue mechanics on the tracer gas washout procedure. To this end, we developed a multi-scale lung model to simulate the inert gas transport in airways of all size. We then applied systematically different modifications to geometrical and mechanical properties of the lung model (compliance, residual airway volume and flow resistance) which have been associated with VI. The modifications were applied to distinct parts of the model, and their effects on the gas distribution within the lung and on the gas concentration profile were assessed. We found that variability in compliance and residual volume of the airways, as well as the spatial distribution of this variability in the lung had a direct influence on gas distribution among airways and on the MBW pattern (washout duration, characteristic concentration profile during each expiration), while the effects of variable flow resistance were negligible. Based on these findings, it is possible to classify different types of inhomogeneities in the lung and relate them to specific features of the MBW pattern, which builds the basis for a more detailed association of lung function and structure.

show abstract

Section: Methodsmentioning

confidence: 99%

A multi-scale model of gas transport in the lung to study heterogeneous lung ventilation during the multiple-breath washout test

et al. 2019

View full text Add to dashboard Cite

show abstract

“…This study had some limitations. First, the models did not take the peripheral airway into account, although the peripheral airway's contribution to total airway resistance has been reported as minimal [22]. Second, we simulated only steady flow under several boundary conditions.…”

Section: Limitationsmentioning

confidence: 99%

“…However, these tests cannot evaluate the gas flow in the airway tree. Regarding this aspect, a computer simulation study is useful because it can calculate and visualize the gas flow in the airway tree, dealing with morphological factors such as the branches' angles and changes in cross-sectional areas [21][22][23][24]. Recently, some computational gas flow analyses simulating the connection between a patient's airway and an ETT were performed.…”

Section: Introductionmentioning

confidence: 99%

Endotracheal tube, by the venturi effect, reduces the efficacy of increasing inlet pressure in improving pendelluft

Takahashi,

Toyama,

Ejima

et al. 2023

PLoS ONE

View full text Add to dashboard Cite

In mechanically ventilated severe acute respiratory distress syndrome patients, spontaneous inspiratory effort generates more negative pressure in the dorsal lung than in the ventral lung. The airflow caused by this pressure difference is called pendelluft, which is a possible mechanisms of patient self-inflicted lung injury. This study aimed to use computer simulation to understand how the endotracheal tube and insufficient ventilatory support contribute to pendelluft. We established two models. In the invasive model, an endotracheal tube was connected to the tracheobronchial tree with 34 outlets grouped into six locations: the right and left upper, lower, and middle lobes. In the non-invasive model, the upper airway, including the glottis, was connected to the tracheobronchial tree. To recreate the inspiratory effort of acute respiratory distress syndrome patients, the lower lobe pressure was set at -13 cmH2O, while the upper and middle lobe pressure was set at -6.4 cmH2O. The inlet pressure was set from 10 to 30 cmH2O to recreate ventilatory support. Using the finite volume method, the total flow rates through each model and toward each lobe were calculated. The invasive model had half the total flow rate of the non-invasive model (1.92 L/s versus 3.73 L/s under 10 cmH2O, respectively). More pendelluft (gas flow into the model from the outlets) was observed in the invasive model than in the non-invasive model. The inlet pressure increase from 10 to 30 cmH2O decreased pendelluft by 11% and 29% in the invasive and non-invasive models, respectively. In the invasive model, a faster jet flowed from the tip of the endotracheal tube toward the lower lobes, consequently entraining gas from the upper and middle lobes. Increasing ventilatory support intensifies the jet from the endotracheal tube, causing a venturi effect at the bifurcation in the tracheobronchial tree. Clinically acceptable ventilatory support cannot completely prevent pendelluft.

show abstract

Reverse Pneumatic Artificial Muscles for Application in Low-Cost Artificial Respirators

Mirvakili

Sim²,

Langer

2020

Preprint

View full text Add to dashboard Cite

One of the main challenges associated with mechanical ventilators is their limited availability in pandemics and other emergencies. Therefore, there is a great demand for mechanical ventilators to address this issue. In this work, we propose a low-cost, portable, yet high-performance design for a volume-controlled mechanical ventilator. We are employing pneumatic artificial muscles, such as air cylinders, in the reverse mode of operation to achieve mechanical ventilation. The current design of the device can operate in two modes: controlled mode and assisted mode. Unlike most ICU ventilators, our device does not need a high-pressure air pipeline to operate. With the current design, mechanical ventilation for respiration rate ranging from 10 b/min to 30 b/min with a tidal volume range of 150 mL to 1000 mL and I:E ratio of 1:1 to 1:5 can be performed. We achieved a total cost of less $400 USD to make one device. We estimate the device to cost less than $250 USD when produced in larger volumes.

show abstract

Computational Analyses of Airway Flow and Lung Tissue Dynamics

Cited by 3 publications

References 127 publications

A multi-scale model of gas transport in the lung to study heterogeneous lung ventilation during the multiple-breath washout test

A multi-scale model of gas transport in the lung to study heterogeneous lung ventilation during the multiple-breath washout test

Endotracheal tube, by the venturi effect, reduces the efficacy of increasing inlet pressure in improving pendelluft

Reverse Pneumatic Artificial Muscles for Application in Low-Cost Artificial Respirators

Contact Info

Product

Resources

About