Geometric features of pig airways using computed tomography

Azad, Khurshidul; Mansy, Hansen A.; Gamage, Peshala T.

doi:10.14814/phy2.12995

Cited by 14 publications

(16 citation statements)

References 36 publications

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“…This high inhomogeneity is mainly due to the asymmetric architecture of the rat airway tree, very different from that of the human. A cautionary note is that pig and sheep lungs also have monopodial architecture and have been used for SRT experimentation [65,66]. Thus, generalizing results of surfactant delivery between different species might be misleading, even for mammals of similar size or weight.…”

Section: Resultsmentioning

confidence: 99%

Surfactant delivery in rat lungs: Comparing 3D geometrical simulation model with experimental instillation

Kazemi¹,

Louis²,

Isabey³

et al. 2019

PLoS Comput Biol

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Surfactant Replacement Therapy (SRT), which involves instillation of a liquid-surfactant mixture directly into the lung airway tree, is a major therapeutic treatment in neonatal patients with respiratory distress syndrome (RDS). This procedure has proved to be remarkably effective in premature newborns, inducing a five-fold decrease of mortality in the past 35 years. Disappointingly, its use in adults for treating acute respiratory distress syndrome (ARDS) experienced initial success followed by failures. Our recently developed numerical model has demonstrated that transition from success to failure of SRT in adults could, in fact, have a fluid mechanical origin that is potentially reversible. Here, we present the first numerical simulations of surfactant delivery into a realistic asymmetric conducting airway tree of the rat lung and compare them with experimental results. The roles of dose volume (VD), flow rate, and multiple aliquot delivery are investigated. We find that our simulations of surfactant delivery in rat lungs are in good agreement with our experimental data. In particular, we show that the monopodial architecture of the rat airway tree plays a major role in surfactant delivery, contributing to the poor homogeneity of the end distribution of surfactant. In addition, we observe that increasing VD increases the amount of surfactant delivered to the acini after losing a portion to coating the involved airways, the coating cost volume, VCC. Finally, we quantitatively assess the improvement resulting from a multiple aliquot delivery, a method sometimes employed clinically, and find that a much larger fraction of surfactant reaches the alveolar regions in this case. This is the first direct qualitative and quantitative comparison of our numerical model with experimental studies, which enhances our previous predictions in adults and neonates while providing a tool for predicting, engineering, and optimizing patient-specific surfactant delivery in complex situations.

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Section: Resultsmentioning

confidence: 99%

Surfactant delivery in rat lungs: Comparing 3D geometrical simulation model with experimental instillation

Kazemi¹,

Louis²,

Isabey³

et al. 2019

PLoS Comput Biol

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“… 41 The same observation has been noted in porcine models. 42 Using the decay assumption, we modeled the relationship between the arc length and the cross-sectional area as

where

is the arc length of the spline,

is the proposed tapering measurement,

is the cross-sectional area, and

is an arbitrary constant.…”

Section: Methodsmentioning

confidence: 99%

Reproducibility of an airway tapering measurement in computed tomography with application to bronchiectasis

et al. 2019

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Purpose: This paper proposes a pipeline to acquire a scalar tapering measurement from the carina to the most distal point of an individual airway visible on CT. We show the applicability of using tapering measurements on clinically acquired data by quantifying the reproducibility of the tapering measure. Methods: We generate a spline from the centreline of an airway to measure the area and arclength at contiguous intervals. The tapering measurement is the gradient of the linear regression between area in log space and arclength. The reproducibility of the measure was assessed by analysing different radiation doses, voxel sizes and reconstruction kernel on single timepoint and longitudinal CT scans and by evaluating the effct of airway bifurcations. Results: Using 74 airways from 10 CT scans, we show a statistical difference, p = 3.4 × 10 −4 in tapering between healthy airways (n = 35) and those affected by bronchiectasis (n = 39). The difference between the mean of the two populations was 0.011mm −1 and the difference between the medians of the two populations was 0.006mm −1 . The tapering measurement retained a 95% confidence interval of ±0.005mm −1 in a simulated 25 mAs scan and retained a 95% confidence of ±0.005mm −1 on simulated CTs up to 1.5 times the original voxel size. Conclusion: We have established an estimate of the precision of the tapering measurement and estimated the effect on precision of simulated voxel size and CT scan dose. We recommend that the scanner calibration be undertaken with the phantoms as described, on the specific CT scanner, radiation dose and reconstruction algorithm that is to be used in any quantitative studies.Our code is available at https://github.com/quan14/AirwayTaperingInCT

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“…The airway tree model was built in SolidWorks (2012, SolidWorks corporation, Concord, MA.) based on the geometric features reported in earlier studies of pig airways [7,[25][26][27][28]. The resulting CAD model was 3D printed using a Desktop 3D printer (MBot3D, El Paso, TX, model: MBot Grid 2) at a print resolution of 0.2mm.…”

Section: Methodsmentioning

confidence: 99%

Pressure Loss and Sound Generated In a Miniature Pig Airway Tree Model

Azad¹

2017

JABB

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Background: Pulmonary auscultation is a common tool for diagnosing various respiratory diseases. Previous studies have documented many details of pulmonary sounds in humans. However, information on sound generation and pressure loss inside animal airways is scarce. Since the morphology of animal airways can be significantly different from human, the characteristics of pulmonary sounds and pressure loss inside animal airways can be different.Objective: The objective of this study is to investigate the sound and static pressure loss measured at the trachea of a miniature pig airway tree model based on the geometric details extracted from physical measurements.Methods: In the current study, static pressure loss and sound generation measured in the trachea was documented at different flow rates of a miniature pig airway tree. Results:Results showed that the static pressure and the amplitude of the recorded sound at the trachea increased as the flow rate increased. The dominant frequency was found to be around 1840-1870 Hz for flow rates of 0.2-0.55 lit/s. Conclusion:The results suggested that the dominant frequency of the measured sounds remained similar for flow rates from 0.20 to 0.55 lit/s. Further investigation is needed to study sound generation under different inlet flow and pulsatile flow conditions. A diaphragm pressure transducer (Model: DP 103, diaphragm: 8-06, Validyne Engineering, CA,) with full scale input of 0.35 cm of water, accuracy of 0.25% of full scale, and sensitivity of about 0.3 V/Pa was used to measure the static pressure at the trachea. The pressure transducer was calibrated using a hot wire anemometer (Model DT-8880, CEM, Shenzhen, China, range: 0.1~25 m/s, resolution: 0.01 m/s, accuracy: ±5% ± 0.1) and a pitot tube (Model: PAA-6-KL, United Sensor Corporation, NH) inside a wind tunnel that has uniform velocity distribution in the test section (except for a thin boundary layer). To calibrate the pressure transducer, the pitot tube was connected to the pressure transducer and placed inside a wind tunnel while the hot wire was placed at the same streamwise location (outside the boundary layer). The measured hot wire velocities at different flow rates were used to calibrate the pressure transducer. Sound was recorded using a probe mic (Model: ER-7C Probe Microphone Series B, Etymotic Research Inc., IL) with a sensitivity: 50mV/ Pascal. The static pressure and sound at the trachea were acquired using LabVIEW (Ver 2015, National Instruments, Austin, TX) with a data acquisition card (Model: NI 9215, National Instruments, Austin, TX, resolution: 0.305 mV). The flow rate was measured by placing the airway model inside a thin airbag of maximum volume of 6liters. The time needed to fill the maximum bag volume was recorded using a stopwatch (resolution: 0.01 second). Flow rate was then calculated using the recorded time and airbag volume. Keywords: ResultsHot wire velocities were plotted against the pressure transducer voltages at different flow rates inside the wind tunnel ( Figure 3). The velo...

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Geometric features of pig airways using computed tomography

Cited by 14 publications

References 36 publications

Surfactant delivery in rat lungs: Comparing 3D geometrical simulation model with experimental instillation

Surfactant delivery in rat lungs: Comparing 3D geometrical simulation model with experimental instillation

Reproducibility of an airway tapering measurement in computed tomography with application to bronchiectasis

Pressure Loss and Sound Generated In a Miniature Pig Airway Tree Model

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