scholarly journals Computational Fluid Dynamic Analysis of the Pharyngeal Airway after Bimaxillary Orthognathic Surgery in Patients with Mandibular Prognathism

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 152
Author(s):  
Puneet Wadhwa ◽  
Hyon-Seok Jang ◽  
Se-Hyun Park ◽  
Hyoung-Ho Kim ◽  
Eui-Seok Lee
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Pressure Drop ◽  
Orthognathic Surgery ◽  
Treatment Plan ◽  
Pressure Coefficient ◽  
Patient Specific ◽  
Mandibular Prognathism ◽  
Pharyngeal Airway ◽  
Bimaxillary Orthognathic Surgery

This study aimed to analyze pharyngeal airflow characteristics and their relationship with the skeletal movement of the maxilla and mandible after bimaxillary orthognathic surgery in patients with skeletal class III (mandibular prognathism) malocclusion. Cone-beam computed tomography (CBCT) was conducted before surgery (T0), immediately after surgery (T1), and at least six months after surgery (T2). Digital imaging and communications in medicine files were transferred to InVivo (Anatomage) software to measure the skeletal changes after surgery. The changes in the maxillary and mandibular position, tongue position, and hyoid bone position were analyzed. Patient-specific models were reconstructed using 3D-Doctor software. The models after converting to the stereolithography (STL) file for Ansys integrated computer engineering and manufacturing code for computational fluid dynamics (ICEM CFD), commercial software were used for calculating the geometry, pressure drop and adjusted pressure coefficient value. The total volume of the upper airway including nasal cavity was reduced by 23% immediately after surgery and recovered to 92.2% of the initial volume six months after surgery. The airflow computation analysis showed a decrease in the pressure drop values immediately after surgery and six months after surgery. The adjusted pressure coefficients were slightly different but the change was statistically insignificant. The airflow characteristics computed using the computational fluid dynamics were correlated to the surgical changes. The surgical changes can affect the aerodynamics of the pharyngeal airway. In clinical practice, this knowledge is useful for developing a suitable orthognathic surgery treatment plan.

scholarly journals Computational fluid dynamics for the assessment of upper airway changes in skeletal Class III patients treated with mandibular setback surgery

2016 ◽  
Vol 86 (6) ◽  
pp. 976-982 ◽  
Author(s):  
Darshit H. Shah ◽  
Ki Beom Kim ◽  
Mark W. McQuilling ◽  
Reza Movahed ◽  
Ankit H. Shah ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Pressure Drop ◽  
Negative Correlation ◽  
Significant Negative Correlation ◽  
Class Iii ◽  
Time Points ◽  
Pharyngeal Airway ◽  
Mandibular Setback ◽  
Mandibular Setback Surgery

ABSTRACT Objective: To analyze and compare pharyngeal airflow characteristics pre- and post–mandibular setback surgery in patients with Class III skeletal dysplasia using cone beam computed tomography (CBCT) and computational fluid dynamics (CFD). Materials and Methods: Records of 29 patients who had received orthodontic treatment along with mandibular setback surgery were obtained. CBCT scans were obtained at three time points: T1 (before surgery), T2 (average of 6 months after surgery), and T3 (average of 1 year after surgery). Digitized pharyngeal airway models were generated from these scans. CFD was used to simulate and characterize pharyngeal airflow. Results: Mean airway volume was significantly reduced from 35,490.324 mm3 at T1 to 24,387.369 mm3 at T2 and 25,069.459 mm3 at T3. Significant increase in mean negative pressure was noted from 3.110 Pa at T1 to 6.116 Pa at T2 and 6.295 Pa at T3. There was a statistically significant negative correlation between the change in airway volume and the change in pressure drop at both the T2 and T3 time points. There was a statistically significant negative correlation between the amount of mandibular setback and change in pressure drop at the T2 time point. Conclusions: Following mandibular setback surgery, pharyngeal airway volume was decreased and relative mean negative pressure was increased, implying an increased effort required from a patient for maintaining constant pharyngeal airflow. Thus, high-risk patients undergoing a large amount of mandibular setback surgery should be evaluated for obstructive sleep apnea and the proposed treatment plan be revised based on the risk for potential airway compromise.

Patient-specific computational fluid dynamics analysis of transcatheter aortic root replacement with chimney coronary grafts

2020 ◽  
Author(s):  
Michele Conti ◽  
Rodrigo M Romarowski ◽  
Anna Ferrarini ◽  
Matteo Stochino ◽  
Ferdinando Auricchio ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Pressure Drop ◽  
Aortic Root ◽  
Coronary Circulation ◽  
Ascending Aorta ◽  
Patient Specific ◽  
Coronary Perfusion ◽  
Computational Fluid Dynamics Analysis ◽  
The Impact

Abstract OBJECTIVES Transcatheter aortic root repair (TARR) consists of the simultaneous endovascular replacement of the aortic valve, the root and the proximal ascending aorta. The aim of the study is to set-up a computational model of TARR to explore the impact of the endovascular procedure on the coronary circulation supported by chimney grafts. METHODS Computed tomography of a patient with dilated ascending aorta was segmented to obtain a 3-dimensional representation of the proximal thoracic aorta, including aortic root and supra-aortic branches. Computed assisted design tools were used to modify the geometry to create the post-procedural TARR configuration featuring the main aortic endograft integrated with 2 chimney grafts for coronary circulation. Computational Fluid Dynamics simulations were run in both pre- and post-procedural configurations using a pulsatile inflow and lumped parameter models at the outflows to simulate peripheral aortic and coronary circulation. Differences in coronary flow and pressure along the cardiac cycle were evaluated. RESULTS After the virtual implant of the TARR device with coronary grafts, the flow became more organized and less recirculation was seen in the ascending aorta. Coronary perfusion was guaranteed with negligible flow differences between pre- and post-procedural configurations. However, despite being well perfused by chimney grafts, the procedure induces an increase of the pressure drop between the coronary ostia and the ascending aorta of 8 mmHg. CONCLUSIONS The proposed numerical simulations, in the specific case under investigation, suggest that the TARR technique maintains coronary perfusion through the chimney grafts. This study calls for experimental validation and further analyses of the impact of TARR on cardiac afterload, decrease of aortic compliance and local pressure drop induced by the coronary chimney grafts.

scholarly journals Application of Computational Fluid Dynamics Analysis after Bimaxillary Orthognathic Surgery

2020 ◽  
Vol 10 (5) ◽  
pp. 1676
Author(s):  
Jae Min Song ◽  
Heerim Seo ◽  
Na-Rae Choi ◽  
Eunseop Yeom ◽  
Yong-Deok Kim
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Orthognathic Surgery ◽  
Soft Tissues ◽  
Cfd Simulation ◽  
Computational Fluid Dynamics Analysis ◽  
Bimaxillary Orthognathic Surgery ◽  
Wall Shear

Bimaxillary orthognathic surgery is widely used to treat skeletal class III malocclusion. Changes in jaw position affect the shape of surrounding soft tissues. We used computational fluid dynamics (CFD) simulation to observe changes in airways observed in a patient who underwent bimaxillary orthognathic surgery. For CFD simulation, we performed cone beam computed tomography (CBCT) preoperatively (T0), 3 days postoperatively (T1), and 7 months postoperatively (T2). The values of velocity, pressure drop (ΔP), and wall shear stress all increased 7 months after surgery (Vmax 7.038 m/s to 12.054 m/s, ΔP −7.723 Pa to −53.739 Pa, WSSmax 4.214 Pa to 14.323 Pa). Locations where the velocity and pressure gradients are large included the velopharynx, oropharynx, and epiglottis, with narrow cross-sectional areas. Wall shear stress was also observed at these locations. The velopharynx, oropharynx, and epiglottis are structures most vulnerable to morphological changes, that is, they can easily become obstructed.

scholarly journals Morphological and Hemodynamic Changes during Cerebral Aneurysm Growth

2021 ◽  
Vol 11 (4) ◽  
pp. 520
Author(s):  
Emily R. Nordahl ◽  
Susheil Uthamaraj ◽  
Kendall D. Dennis ◽  
Alena Sejkorová ◽  
Aleš Hejčl ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Kinetic Energy ◽  
Swirling Flow ◽  
Morphological Changes ◽  
Cerebral Aneurysms ◽  
Patient Specific ◽  
Aneurysm Wall ◽  
Aneurysm Growth ◽  
Computational Fluid Dynamics Cfd

Computational fluid dynamics (CFD) has grown as a tool to help understand the hemodynamic properties related to the rupture of cerebral aneurysms. Few of these studies deal specifically with aneurysm growth and most only use a single time instance within the aneurysm growth history. The present retrospective study investigated four patient-specific aneurysms, once at initial diagnosis and then at follow-up, to analyze hemodynamic and morphological changes. Aneurysm geometries were segmented via the medical image processing software Mimics. The geometries were meshed and a computational fluid dynamics (CFD) analysis was performed using ANSYS. Results showed that major geometry bulk growth occurred in areas of low wall shear stress (WSS). Wall shape remodeling near neck impingement regions occurred in areas with large gradients of WSS and oscillatory shear index. This study found that growth occurred in areas where low WSS was accompanied by high velocity gradients between the aneurysm wall and large swirling flow structures. A new finding was that all cases showed an increase in kinetic energy from the first time point to the second, and this change in kinetic energy seems correlated to the change in aneurysm volume.

scholarly journals Porous Media Computational Fluid Dynamics and the Role of the First Coil in the Embolization of Ruptured Intracranial Aneurysms

2021 ◽  
Vol 10 (7) ◽  
pp. 1348
Author(s):  
Karol Wiśniewski ◽  
Bartłomiej Tomasik ◽  
Zbigniew Tyfa ◽  
Piotr Reorowicz ◽  
Ernest Bobeff ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Porous Media ◽  
Packing Density ◽  
Coil Embolization ◽  
Intracranial Aneurysms ◽  
Patient Specific ◽  
Computational Fluid Dynamics Analysis ◽  
Ruptured Intracranial Aneurysms ◽  
Statistical Results

Background: The objective of our project was to identify a late recanalization predictor in ruptured intracranial aneurysms treated with coil embolization. This goal was achieved by means of a statistical analysis followed by a computational fluid dynamics (CFD) with porous media modelling approach. Porous media CFD simulated the hemodynamics within the aneurysmal dome after coiling. Methods: Firstly, a retrospective single center analysis of 66 aneurysmal subarachnoid hemorrhage patients was conducted. The authors assessed morphometric parameters, packing density, first coil volume packing density (1st VPD) and recanalization rate on digital subtraction angiograms (DSA). The effectiveness of initial endovascular treatment was visually determined using the modified Raymond–Roy classification directly after the embolization and in a 6- and 12-month follow-up DSA. In the next step, a comparison between porous media CFD analyses and our statistical results was performed. A geometry used during numerical simulations based on a patient-specific anatomy, where the aneurysm dome was modelled as a separate, porous domain. To evaluate hemodynamic changes, CFD was utilized for a control case (without any porosity) and for a wide range of porosities that resembled 1–30% of VPD. Numerical analyses were performed in Ansys CFX solver. Results: A multivariate analysis showed that 1st VPD affected the late recanalization rate (p < 0.001). Its value was significantly greater in all patients without recanalization (p < 0.001). Receiver operating characteristic curves governed by the univariate analysis showed that the model for late recanalization prediction based on 1st VPD (AUC 0.94 (95%CI: 0.86–1.00) is the most important predictor of late recanalization (p < 0.001). A cut-off point of 10.56% (sensitivity—0.722; specificity—0.979) was confirmed as optimal in a computational fluid dynamics analysis. The CFD results indicate that pressure at the aneurysm wall and residual flow volume (blood volume with mean fluid velocity > 0.01 m/s) within the aneurysmal dome tended to asymptotically decrease when VPD exceeded 10%. Conclusions: High 1st VPD decreases the late recanalization rate in ruptured intracranial aneurysms treated with coil embolization (according to our statistical results > 10.56%). We present an easy intraoperatively calculable predictor which has the potential to be used in clinical practice as a tip to improve clinical outcomes.

scholarly journals Enhancement of cerebrovascular 4D flow MRI velocity fields using machine learning and computational fluid dynamics simulation data

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
David R. Rutkowski ◽  
Alejandro Roldán-Alzate ◽  
Kevin M. Johnson
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Velocity Fields ◽  
Dynamics Simulation ◽  
Patient Specific ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Phase ◽  
Flow Mri ◽  
Trained Network

AbstractBlood flow metrics obtained with four-dimensional (4D) flow phase contrast (PC) magnetic resonance imaging (MRI) can be of great value in clinical and experimental cerebrovascular analysis. However, limitations in both quantitative and qualitative analyses can result from errors inherent to PC MRI. One method that excels in creating low-error, physics-based, velocity fields is computational fluid dynamics (CFD). Augmentation of cerebral 4D flow MRI data with CFD-informed neural networks may provide a method to produce highly accurate physiological flow fields. In this preliminary study, the potential utility of such a method was demonstrated by using high resolution patient-specific CFD data to train a convolutional neural network, and then using the trained network to enhance MRI-derived velocity fields in cerebral blood vessel data sets. Through testing on simulated images, phantom data, and cerebrovascular 4D flow data from 20 patients, the trained network successfully de-noised flow images, decreased velocity error, and enhanced near-vessel-wall velocity quantification and visualization. Such image enhancement can improve experimental and clinical qualitative and quantitative cerebrovascular PC MRI analysis.

scholarly journals Evaluation of Active Heat Sinks Design under Forced Convection—Effect of Geometric and Boundary Parameters

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2041
Author(s):  
Eva C. Silva ◽  
Álvaro M. Sampaio ◽  
António J. Pontes
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Additive Manufacturing ◽  
Pressure Drop ◽  
Forced Convection ◽  
Thermal Performance ◽  
Heat Sinks ◽  
Trapezoidal Shape ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

This study shows the performance of heat sinks (HS) with different designs under forced convection, varying geometric and boundary parameters, via computational fluid dynamics simulations. Initially, a complete and detailed analysis of the thermal performance of various conventional HS designs was taken. Afterwards, HS designs were modified following some additive manufacturing approaches. The HS performance was compared by measuring their temperatures and pressure drop after 15 s. Smaller diameters/thicknesses and larger fins/pins spacing provided better results. For fins HS, the use of radial fins, with an inverted trapezoidal shape and with larger holes was advantageous. Regarding pins HS, the best option contemplated circular pins in combination with frontal holes in their structure. Additionally, lattice HS, only possible to be produced by additive manufacturing, was also studied. Lower temperatures were obtained with a hexagon unit cell. Lastly, a comparison between the best HS in each category showed a lower thermal resistance for lattice HS. Despite the increase of at least 38% in pressure drop, a consequence of its frontal area, the temperature was 26% and 56% lower when compared to conventional pins and fins HS, respectively, and 9% and 28% lower when compared to the best pins and best fins of this study.

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