Effect of nasal occlusion on tracheal and pharyngeal pressures in horses.
OBJECTIVE
To compare tracheal and pharyngeal inspiratory and expiratory pressures achieved during 60 seconds of nasal occlusion in standing horses with pressures achieved in horses during intense exercise.


METHODS
5 Standardbreds.


METHODS
Tracheal and pharyngeal inspiratory and expiratory pressures were obtained from 5 horses during 60 seconds of nasal occlusion and compared with tracheal and pharyngeal pressures achieved during incremental treadmill exercise tests in which horses ran at 50, 75, and 100% of the speed that resulted in maximal heart rate (HRmax).


RESULTS
Significant difference was not detected between peak tracheal inspiratory pressure during nasal occlusion and peak tracheal inspiratory pressure at HRmax Peak pharyngeal inspiratory pressure was 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
During upper airway endoscopy in standing horses, 60-second nasal occlusion induced tracheal and pharyngeal inspiratory pressures that equaled or exceeded pressures achieved during high-intensity exercise.


CONCLUSIONS
Nasal occlusion is useful to simulate upper airway pressures achieved during high-intensity exercise.
Holcombe
S J
SJ
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Tansing 48824-1314, USA.
Derksen
F J
FJ
Stick
J A
JA
Robinson
N E
NE
Boehler
D A
DA
D000818:Animals; D005260:Female; D006736:Horses / Q000502:physiology*; D001239:Inhalation; D008297:Male; D009666:Nose / Q000502:physiology*; D009919:Orchiectomy; D010614:Pharynx / Q000502:physiology*; D005082:Physical Exertion; D011312:Pressure; D012119:Respiration; D014132:Trachea / Q000502:physiology*