Effect of nasal occlusion on tracheal and pharyngeal pressures in horses.

This research explores how nasal occlusion affects pressures in the trachea and pharynx of horses, comparing conditions during a 60-second nose block with those during intense physical exercise.

Objective and Methods

• The goal of the research was to study and compare the variations in tracheal and pharyngeal inspiratory (breathing in) and expiratory (breathing out) pressures in horses under two conditions – during a 60-second nasal occlusion (nose block) and intense exercise.
• The experimental population consisted of 5 standardbred horses.
• The research methodologies used were to measure the pressures in horses’ trachea and pharynx under a 60-second nasal block and during intensive treadmill exercise tests conducted at various speeds that led to different heart rates (50%, 75% and 100% of the maximum heart rate).

Findings

• The study found that there was no significant difference between peak tracheal inspiratory pressure during nasal occlusion and peak tracheal inspiratory pressure at the maximum heart rate (HRmax).
• Interestingly, peak pharyngeal inspiratory pressure was found to be significantly more negative, and peak tracheal and peak pharyngeal expiratory pressures were significantly more positive during 60 seconds of nasal occlusion than those observed in horses running at HRmax.

Conclusions

• While conducting an upper airway endoscopy in standing horses, nasal occlusion for 60-seconds was seen to create tracheal and pharyngeal inspiratory pressures that were equal to or exceeded pressures achieved during high-intensity exercise.
• The findings suggest that nasal occlusion can be effectively used to simulate the upper airway pressures that horses experience during high-intensity exercise. This can be particularly useful in understanding the horse’s respiratory performance under strenuous conditions while it is stationary.