Computational Fluid Dynamics Analysis of Surgical Approaches to Bilateral Vocal Fold Immobility

Abstract

Objectives Bilateral vocal fold immobility (BVFI) is a rare and life‐threatening condition in which both vocal folds are fixed, resulting in airway obstruction associated with life‐threatening respiratory compromise. Treatment of BVFI is largely surgical and remains an unsatisfactory compromise between voice, breathing, and swallowing. No comparisons between currently employed techniques currently exist. We sought to employ computational fluid dynamics (CFD) modeling to delineate the optimal surgical approach for BVFI. Methods Utilizing clinical computed tomography of BVFI subjects, coupled with image analytics employing CFD models and subject pulmonary function data, we compared the airflow features in the baseline pathologic states and changes seen between endoscopic cordotomy, endoscopic suture lateralization, and posterior cricoid expansion. Results CFD modeling demonstrated that the greatest airflow velocity occurs through the posterior glottis on inspiration and anterior glottis on expiration in both the normal condition and in BVFI. Glottic airflow velocity and resistance were significantly higher in the BVFI condition compared to normal. Geometric indices (cross‐sectional area of airway) were lower in posterior cricoid expansion surgery when compared to alternate surgical approaches. CFD measures (airflow velocity and resistance) improved with all surgical approaches but were superior with posterior cricoid expansion. Conclusion CFD modeling can provide discrete, quantitative assessment of the airflow through the laryngeal inlet, and offers insights into the pathophysiology and changes that occur after surgery for BVFI. Level of Evidence NA. Laryngoscope, 130:E57–E64, 2020

Analysis of the Effectiveness of Arytenoidectomy and Posterior Cordectomy with the Use of CFD Airflow Measurements in Patients with BVFP: A Retrospective Study

“…In Rios study, PCE allowed for a greater increase in the glottal area, as well as reduced airflow velocity and resistance; and the postoperatively achieved triangular shape (isosceles triangle) of the glottis may contribute to a more homogeneous distribution of airflow in the anterior-posterior axis, as pointed out by the authors. Further improvement of airflow resistance after additional glottic expansion was also observed in a BVFP patient with baseline glottal area of 50.4 mm 2 [ 5 ]. In our study, we took into account both pre- and postoperative measurements.…”

“…This is also a limitation of our study as all models assumed rigid airway walls. Rios et al [ 5 ] suggested a nonlinear relationship between the cross-sectional area and airflow velocity and resistance, as well as that there probably are “alteration points,” at which airflow parameters favorably increase.…”

“…Upper airway models, needed for CFD simulation, are created based on computed tomography (CT) or magnetic resonance imaging (MRI) scans and videolaryngoscopy pictures. Their use allows for the imaging of the mechanisms and effects of various pathologies, as well as the outcomes of potential therapeutic interventions within the upper respiratory tract (URT) [ 4 , 5 ]. This feature made the CFD method unique compared to other commonly used diagnostic techniques—it enabled researchers to observe changes in airflow parameters in conditions leading to glottic stenosis, such as vocal cord dysfunction (VCD), i.e., paradoxical vocal fold movement [ 6 ], subglottic stenosis [ 7 ], congenital glottic web [ 4 ], or BVFP [ 5 , 8 , 9 ].…”

Fluid dynamics of the upper airway in pediatric patients with severe laryngomalacia

“…The respiratory air ow can be in a laminar, transitional, or turbulent state, and turbulence simulations were performed on the subject model using the Reynolds-averaged Navier-Stokes (RANS) equation and the k-ω turbulence equation [7,14].…”

“…With the continuous advances in high-resolution imaging, and uid mechanics, computational uid dynamics (CFD) has been promoted for air ow studies in the airways, allowing for the visualization of air ow in the airways through distinctive pictures and the calculation of local ow variables such as volume ow, velocity, pressure, wall shear stress, and vortex motion [4]. CFD is often applied in the study of airway diseases, such as nasal diseases and obstructive sleep apnea hypoventilation syndrome [5,6], vocal cord dysfunction [4,7], and laryngotracheal stenosis [8]. Airway dynamics in infants and children have been less studied, and some studies have used unrealistic symmetric anatomical models to predict air ow dynamics [9,10], while a few reports have reconstructed realistic three-dimensional (3D) anatomical models of the airway from high-resolution computed tomography (CT) or magnetic resonance imaging (MRI) data for hydrodynamic studies of subglottic stenosis and tracheomalacia in pediatric patients [11][12][13].…”