Computational Fluid Dynamic Modeling Reveals Nonlinear Airway Stress during Trachea Development.

Normative trachea dimensions and aerodynamic information during development was collected to establish clinical benchmarks and showed that airway development seems to outpace respiratory demands. Infants and toddlers' trachea exhibit higher aerodynamic stress that significantly decreases by teenage years. This implies large airway pathology in younger children may have a more substantial clinical impact.

The Application of Computational Fluid Dynamics in the Evaluation of Laryngotracheal Pathology.

OBJECTIVES: Laryngotracheal stenosis and obstruction can be challenging to manage. Traditional assessment tools are limited in clinical correlation. Three-dimensional computational fluid dynamics (CFD) modeling is a novel technique used to analyze airflow dynamics. The objective of this study was to apply CFD to the human upper airway to explore its utility. METHODS: CFD models were constructed on an adult patient with an obstructive tracheal lesion before and after intervention and on an adult with normal airway anatomy, using computed tomographic imaging obtained retrospectively. Key airflow metrics were calculated. RESULTS: CFD provided detailed airway geometry. The normal airway had a peak flow velocity of 3.12 m/s, wall shear stress of 0.30 Pa, and resistance of 0.02 Pa/mL/s. The pathologic patient showed an elevated peak flow velocity of 12.25 m/s, wall shear stress of 3.90 Pa, and resistance of 0.22 Pa/mL/s. This was reflected clinically with dyspnea, stridor, and obstructive impairment via pulmonary function testing. Following treatment, peak flow velocity corrected to 3.95 m/s, wall shear stress to 0.72Pa, and resistance to 0.01 Pa/mL/s. Cross-sectional area improved to 190 mm2 from a minimum of 53 mm2 at the same segment. Stridor and dyspnea resolved. CONCLUSIONS: CFD metrics were calculated on the normal, diseased, and posttreatment upper airway. Variations were reflected in clinical symptoms. These methods could model surgical outcomes and anticipate disease severity.

Endoscopic Endonasal Landmarks to the Greater Palatine Canal: A Radiographic Study.

Background The palatine neurovascular bundle is at risk during endoscopic surgery. Injury may result in significant blood loss and anesthesia of the ipsilateral hard palate. Nonetheless, its endoscopic anatomy has not been described previously. This article strives to establish landmarks to identify the greater palatine canal; thus, avoiding injury to its contents. Methodology This study comprised 50 deidentified computed tomographic angiograms using landmarks that are immediately visible during endoscopic medial maxillectomy to calculate: the angle of the greater palatine canal to the vertical, the distance from the anteroinferior aspect of the greater palatine canal to the orifice of the nasolacrimal duct, the distance from the anteroinferior aspect of the greater palatine canal to the posterolateral free edge of the hard palate, and the distance from the anterior aspect of the greater palatine canal as it enters the hard palate to the posterior wall of the maxillary sinus. Results The mean angle of the greater palatine canal to the vertical was 23.01 degrees. The mean distance from the anteroinferior aspect of the greater palatine canal to the nasolacrimal duct was 31.52 mm. The mean distance from the anterior aspect of the greater palatine canal to the posterolateral free edge of the hard palate was 7.71 mm and the mean distance from the anterior aspect of the greater palatine canal to the posterior wall of the maxillary sinus was 7.07 mm. Conclusion Accessible anatomical landmarks help ascertain the location of the greater palatine canal intraoperatively; thus, avoiding injury to its contents.

Radiographic Analysis of the Vidian Canal and Its Utility in Petrous Internal Carotid Artery Localization.

BACKGROUND: Endoscopic endonasal surgery of the skull base requires expert knowledge of the anatomy and a systematic approach. The vidian canal is regarded as a reliable landmark to localize the petrous internal carotid artery (pICA) near the second genu, which can be used for orientation in deep skull base approaches. There is controversy about the relationship between the vidian canal and the pICA. OBJECTIVE: To further establish the vertical relationship between the vidian canal and the pICA to aid in surgical approaches to the skull base. METHODS: We utilized a collection of institutional review board-approved computed tomographic (CT) angiograms (CTAs). Fifty CTAs were studied bilaterally for 100 total sides. The vidian canal was visualized radiographically to determine whether it terminates below, at, or above the level of the pICA. RESULTS: Sixty-six of 100 vidian canals terminated inferior to the pICA (66%), which was the most common relationship observed. The average distance inferior to the pICA was 1.01 mm on the right, 1.18 mm on the left, and 1.09 mm of the total 66 sides. Less commonly, the vidian canal terminated at the level of the pICA canal in 34 sides (34%). The vidian canal was not observed to terminate superior to the pICA in any of the 50 CTAs studied. CONCLUSION: The vidian canal terminates inferior to the pICA most commonly, but often terminates at the level of the pICA. Careful drilling clockwise inferior to superior around the vidian canal should allow for safe pICA localization in most cases.