Effects of continuous positive airway pressure on respiratory function in sedated foals.

This study examines how continuous positive airway pressure (CPAP), an air pressure therapy often used in humans, affects the respiratory function of sedated newborn horses (foals) with medically induced respiratory suppression. The research suggests that CPAP could be a more efficient method of respiratory support than oxygen insufflation (oxygen supply method), although it notes caution is needed when applying these findings to foals with actual respiratory diseases.

Introduction

• The study’s objective is to determine the effects of continuous positive airway pressure (CPAP) on the respiratory function in foals, specifically those with pharmacologically induced respiratory suppression.
• CPAP is a treatment commonly used in people suffering from sleep disorders such as sleep apnea. It works by continuously pumping a supply of air into the nasal passage to prevent the airway from collapsing.
• The study investigated whether this method could also be beneficial for managing respiratory issues in foals.

Methods

• This was a prospective randomized, cross-over study conducted at a university veterinary teaching hospital.
• There were 12 foals involved in the study that were born in consecutive seasons from a university teaching herd.
• The foals were administered xylazine and fentanyl, drugs that can induce respiratory suppression, and then monitored under two different support procedures: mask oxygen supplementation or CPAP. Each foal experienced both treatments with a period of ambient-air breathing in between, and the sequence of treatments was then reversed after 48 hours.

Results

• The results indicated that the injection of xylazine and fentanyl produced reliable respiratory suppression and recumbency (lying down) in the foals, both of which are reversible conditions.
• When CPAP was used as treatment, it led to similar increases in breathing oxygen as mask oxygen supplementation, but at a lower respiratory rate or breathing frequency. The foals also had increased oxygen extraction and improved elimination of carbon dioxide.
• Some increase in carbon dioxide pressure was observed during both CPAP and oxygen supplementation.
• During CPAP treatment, the expiration (breathing out) time increased and the peak expiratory flow (speed of air leaving the lungs) decreased.

Conclusion

• The findings suggest that CPAP could provide a more effective respiratory support compared to the conventional method of oxygen insufflation due to its effect on respiratory efficiency.
• This study’s applicability to foals suffering from clinical respiratory diseases should be interpreted with caution because the experiment used foals with pharmacologically induced respiratory problems.
• Further research is needed to better understand the reason and impact of the slight increase in carbon dioxide pressure observed during these studies.