EFFECT OF NASAL OCCLUSION ON TRACHEAL AND PHARYNGEAL PRESSURES IN HORSES

Objective-To compare tracheal acid pharyngeal inspiratory and expirato ry pressures achieved during 60 seconds of nasal occlusion in standing horses with pressures achieved in horses during intense exercise. Ani mals-5 Standardbreds. Procedure-Tracheal and pharyngeal inspiratory an d expiratory pressures were obtained from 5 horses during 60 seconds o f nasal occlusion and compared with tracheal and pharyngeal pressures achieved during incremental treadmill exercise tests in which horses r an at 50, 75, and 100% of the speed that resulted in maximal heart rat e (HR(max)). Results-Significant difference was not detected between p eak tracheal inspiratory pressure during nasal occlusion and peak trac heal inspiratory pressure at HR(max). Peak pharyngeal inspiratory pres sure was significantly more negative, and peak tracheal and peak phary ngeal expiratory pressures were significantly more positive during 50 seconds of nasal occlusion than those observed in horses running at HR (max). Conclusion-During upper airway endoscopy in standing horses, 60 -second nasal occlusion induced tracheal and pharyngeal inspiratory pr essures that equaled or exceeded pressures achieved during high-intens ity exercise. Clinical Relevance-Nasal occlusion is useful to simulate upper airway pressures achieved during high-intensity exercise.