Computational fluid dynamic analysis of bioprinted self-supporting perfused tissue models.
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ABSTRACT:
SUBMITTER: Sego TJ
PROVIDER: S-EPMC7015804 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BACKGROUND:Empty nose syndrome (ENS) remains highly controversial, with aggressive inferior turbinate reduction (ITR) or mucociliary dysfunction frequently implicated. However, the appropriate degree of ITR is highly debatable. METHODS:We applied individual computed tomography (CT)-based computational fluid dynamics (CFD) to 5 patients receiving relatively aggressive ITR but with no ENS symptoms, and compared them to 27 symptomatic ENS patients who all had histories of aggressive ITRs, and 42 healthy controls. Patients' surgical outcomes were confirmed with 22-item Sino-Nasal Outcome Test (SNOT-22) (ITR: 6.40 ± 4.56; ENS: 58.2 ± 15.9; healthy: 13.2 ± 14.9), Nasal Obstruction Symptom Evaluation (NOSE) scores (ITR: 4.00 ± 2.24; ENS: 69.4 ± 17.1; healthy: 11.9 ± 12.9), and Empty Nose Syndrome 6-Item Questionnaire (ENS6Q) (?11 for ENS). RESULTS:Both aggressive ITR without ENS symptoms and symptomatic ENS patients had significantly lower nasal resistance (ITR: 0.059 ± 0.020 Pa·s/mL; ENS: 0.052 ± 0.015 Pa·s/mL; healthy: 0.070 ± 0.021 Pa·s/mL) and higher cross-sectional areas surrounding the inferior turbinate (ITR: 0.94 ± 0.21 cm2 ; ENS: 1.19 ± 1.05 cm2 ; healthy: 0.42 ± 0.22 cm2 ) than healthy controls. The lack of significant differences among patient groups indicated similar degrees of surgeries between ITR with and without ENS symptom cohorts. However, symptomatic ENS patients have paradoxical significantly less airflow in the inferior meatus (ITR: 47.7% ± 23.6%; ENS: 25.8% ± 17.6%; healthy: 36.5 ± 15.9%; both p < 0.01), but higher airflow around the middle meatus (ITR: 49.7% ± 22.6%; ENS: 66.5% ± 18.3%; healthy: 49.9% ± 15.1%, p < 0.0001) than aggressive ITR without symptoms and controls. Aggressive ITR patients have increased inferior meatus airflow as expected (p < 0.05). This imbalanced airflow produced less inferior wall-shear-stress distribution among symptomatic ENS patients only (ITR: 42.45% ± 11.4%; ENS: 32.2% ± 12.6%; healthy: 49.7% ± 9.9%). ENS patients (n = 12) also had impaired nasal trigeminal function, as measured by menthol lateralization detection thresholds (ITR: 15.2 ± 1.2; ENS: 10.3 ± 3.9; healthy: 13.8 ± 3.09, both p < 0.0001). Surprisingly, aggressive ITR patients without ENS symptoms have better menthol lateralization detection thresholds (LDTs) than healthy controls. CONCLUSION:Although turbinate tissue loss is linked with ENS, the degree of ITR that might distinguish postoperative patient satisfaction in their nasal breathing vs development of ENS symptoms is unclear. Our results suggest that a combination of distorted nasal aerodynamics and loss of mucosal sensory function may potentially lead to ENS symptomology.
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Project description:In current research, the hydraulic performance prediction and optimization of an engine cooling water pump was conducted by computational fluid dynamic (CFD) analysis. Through CFD simulation, the pump head, shaft power and efficiency for the original pump at volume flow rate 25 L/min and impeller rotating speed 4231 r/min were 3.87 m, 66.7 W and 23.09% respectively. For improving hydraulic performance, an optimization study was carried out. After optimization, four potential optimized designs were put forward. The efficiency of the optimized design No.1 for engine cooling water pump was nearly 6% higher than that of the original pump model; and the head of the optimized design No.2 for engine cooling water pump was 9% higher than that of the original pump model. Under the condition of maintaining the pump head and considering comprehensive improvement effect, the optimized design No.3 was considered as the best design and selected as the test case for validating the optimum design. The hydraulic performance predictions for this optimum engine cooling water pump agreed well with experimental data at design condition with relative discrepancies of 2.9% and 5.5% for the pump head and pump efficiency, respectively. It proved that performance prediction calculation model and the automatic optimization model were effective. This research work can provide theoretical basis for the design, development and optimization of engine cooling water pump.
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Project description:OBJECTIVES/HYPOTHESIS:Current techniques for airway characterization include endoscopic or radiographic measurements that produce static, two-dimensional descriptions. As pathology can be multilevel, irregularly shaped, and dynamic, minimal luminal area (MLA) may not provide the most comprehensive description or diagnostic metric. Our aim was to examine the utilization of computational fluid dynamics (CFD) for the purpose of defining airway stenosis using an ovine model of tissue-engineered tracheal graft (TETG) implantation. STUDY DESIGN:Animal research model. METHODS:TETGs were implanted into sheep, and MLA was quantified with imaging and endoscopic measurements. Graft stenosis was managed with endoscopic dilation and stenting when indicated. Geometries of the TETG were reconstructed from three-dimensional fluoroscopic images. CFD simulations were used to calculate peak flow velocity (PFV) and peak wall shear stress (PWSS). These metrics were compared to values derived from a quantitative respiratory symptom score. RESULTS:Elevated PFV and PWSS derived from CFD modeling correlated with increased respiratory symptoms. Immediate pre- and postimplantation CFD metrics were similar, and implanted sheep were asymptomatic. Respiratory symptoms improved with stenting, which maintained graft architecture similar to dilation procedures. With stenting, baseline PFV (0.33 m/s) and PWSS (0.006 Pa) were sustained for the remainder of the study. MLA measurements collected via bronchoscopy were also correlated with respiratory symptoms. PFV and PWSS found via CFD were correlated (R2 = 0.92 and 0.99, respectively) with respiratory symptoms compared to MLA (R2 = 0.61). CONCLUSIONS:CFD is valid for informed interventions based on multilevel, complex airflow and airway characteristics. Furthermore, CFD may be used to evaluate TETG functionality. LEVEL OF EVIDENCE:NA. Laryngoscope, E272-E279, 2018.
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