Effect of a mask and pneumotachograph on tracheal and nasopharyngeal pressures, respiratory frequency, and ventilation in horses.

This research investigates how a mask and pneumotachograph affect ventilation, respiratory frequency, and tracheal and nasopharyngeal pressures in running horses. The findings indicate that the mask and pneumotachograph significantly alter upper airway pressures, respiratory rate and ventilation in horses.

Methodology

• The study involved six Standardbred horses that performed run tests on a treadmill at three different speed levels: 50, 75, and 100 percent of their maximum oxygen-consuming speed. These tests were conducted both with and without the use of a mask and pneumotachograph.
• Several measurements were taken during these tests, including tracheal and pharyngeal inspiratory and expiratory pressures, respiratory frequency, and arterial blood gases. The techniques used for these measurements involved transnasal tracheal and pharyngeal side-hole catheters connected to differential pressure transducers.
• Blood samples were collected from the carotid artery and analysed with a blood gas analyser to measure PAO2, PaCO2, and pH.

Results

• The outcome of these tests indicated that when the horses were wearing a mask, all metrics were affected. Horses’ tracheal and pharyngeal inspiratory pressures were significantly more negative, while expiratory pressures were more positive.
• The respiratory frequency was significantly lower at all speed levels when running with a mask.
• Additionally, wearing a mask during exercise resulted in a higher PaCO2 and lower arterial pH and PaO2; highlighting that the use of the mask impacts the gas exchange process. All of which were statistically significant with a p-value less than 0.05.

Conclusion

• The findings of this study suggest that the use of a mask and pneumotachograph significantly alters upper airway pressures, respiratory frequency, and ventilation in horses running at various speeds on a treadmill.
• This highlights the need for careful consideration when using these tools in equine respiratory studies or treatment, as they may affect the animal’s natural respiration process.