Development of equine upper airway fluid mechanics model for Thoroughbred racehorses.
Authors: Rakesh V, Rakesh N G, Datta A K, Cheetham J, Pease A P
Journal: Equine veterinary journal
Summary
# Editorial Summary: Upper Airway Fluid Mechanics in Thoroughbreds Computational fluid dynamics modelling offers a non-invasive method to understand airway mechanics during exercise, and Rakesh and colleagues used CT imaging from a cadaver combined with pressure data from exercising horses to simulate realistic upper airway conditions. The model revealed critical differences between inspiratory and expiratory flow patterns: during inspiration, peak turbulence concentrates in the larynx whilst the rostral nasopharynx experiences the most negative wall pressure; during expiration, turbulence shifts to the rostral and mid-nasopharynx with maximum positive pressure at the caudal soft palate. Most significantly, the rostral nasopharyngeal floor encounters substantial collapsing pressure combined with high turbulent kinetic energy during inhalation—a combination that likely explains the high prevalence of dorsal displacement of the soft palate (DDSP) in racehorses and suggests a biomechanical vulnerability rather than purely functional obstruction. The finding that the rima glottidis is 7% larger than the trachea also indicates that horses may not require maximal arytenoid abduction for optimal performance, potentially reducing unnecessary muscular effort during maximal exercise. For practitioners managing performance horses, this work provides anatomical rationale for why certain individuals develop DDSP and supports targeted assessment of nasopharyngeal dynamics in horses with suspected upper airway compromise.
Read the full abstract on PubMed
Practical Takeaways
- •DDSP in racehorses may result from aerodynamic instability in the soft palate region during high-speed exercise rather than simple mechanical failure, suggesting treatment approaches should consider dynamic airway mechanics
- •The 7% larger cross-sectional area of the glottis compared to trachea indicates that maximal laryngeal opening may not be required for optimal performance, relevant when evaluating laryngeal function and surgical interventions
- •Understanding collapsible pressure zones in the upper airway helps target diagnostic imaging and endoscopic examination to high-risk regions during exercise simulation
Key Findings
- •CFD modeling of Thoroughbred upper airway during exercise identified the rostral nasopharynx floor as the region most susceptible to collapsing pressure during inspiration
- •The rima glottidis cross-sectional area is 7% greater than the trachea, suggesting maximal arytenoid abduction may not be necessary for optimal airflow
- •During inspiration, highest turbulence occurs in the larynx with most negative wall pressure at the rostral nasopharynx; during expiration, highest turbulence shifts to rostral and mid-nasopharynx
- •High turbulent kinetic energy combined with negative pressure in the rostral nasopharynx during inhalation may explain the high prevalence of DDSP in racehorses