Michelle Tucker ^1* David Wilson ² Donald Bergstrom ³ James Carmalt ²

• ¹ Department of Veterinary Clinical Sciences, Purdue University, West Lafayette, United States
• ² Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
• ³ Department of Mechanical Engineering, College of Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada

Computational fluid dynamics (CFD) is gaining momentum as a useful mechanism for analyzing obstructive disorders and surgeries in the human field and warrants further development for application in equine surgery. While improvements in procedures continue to be made, there is still a lot that is unknown about the specific influence that different surgeries have on obstructive airway disorders. The objective of this study was to apply CFD analysis to an equine head inhalation model replicating recurrent laryngeal neuropathy (RLN) and four surgical procedures.CFD was hypothesized to corroborate the order of the different trials based on impedance and to provide a numerically similar impedance value to the experimental results. Additionally, it was hypothesized that CFD would provide insights into the changes in the air flow associated with each procedure on a finite scale.An equine cadaver head underwent airflow testing and computed tomographic (CT) scans replicating the disease state, RLN, a laryngoplasty, combined laryngoplasty and corniculectomy, corniculectomy, and partial arytenoidectomy. Pressure at the pharynx and trachea were recorded along with the airflow for each trial.The CFD and experimental model resulted in the partial arytenoidectomy having the lowest impedance in this case. While this procedure did have the largest rima glottis area, the remaining procedural order was not dictated by rima glottis area. Recurrent laryngeal neuropathy and the combined laryngoplasty with corniculectomy showed negative pressure concentration on the luminal surface of the left arytenoid cartilage, which indicates a greater collapsing force on the tissues in this region. Narrowing within the caudal larynx in the region of the saccules showed increased negative pressure and higher velocities in the procedures with greater impedance while the partial arytenoidectomy had more uniform pressure and velocity. While this specific experimental head model contradicts previous flow studies, the CFD model reflected the experimental findings for procedure of least impedance and provided some insights as to why these discrepancies occurred for this particular case.