Effect of aerosolized albuterol sulfate on resting energy expenditure determined by use of open-flow indirect calorimetry in horses with recurrent airway obstruction.

This study examined the effects of aerosolized albuterol sulfate on the resting energy expenditure (calories burned while at rest) of horses with a chronic respiratory condition called recurrent airway obstruction. The research demonstrated that after using albuterol, the horses experienced decreased resistance in their respiratory system and lower resting energy expenditure.

Methodology

• The researchers used open-flow indirect calorimetry (a method of measuring metabolic rates based on heat produced by the body) and forced oscillometry (a technique for assessing lung function) to gather measurements related to respiratory resistance and resting energy expenditure.
• The study involved three phases. The first phase involved monitoring the respiratory system resistance (RRS) in five healthy horses before and after sedation with xylazine. The second phase involved measuring the resting energy expenditure (REE) in four healthy horses both 20 to 25 minutes after xylazine sedation and again 35 to 40 minutes post-sedation.
• In the third phase, both indirect calorimetry and forced oscillometry were performed on eight horses with recurrent airway obstruction (RAO) after sedation with xylazine. These measures were repeated after the administration of albuterol sulfate.

Findings

• In the initial phase, the study found that RRS significantly decreased five and ten minutes after sedation. In the second phase, the diminishing effect of the sedation did not significantly impact REE.
• In the third phase, there was a significant fall in both respiratory resistance and resting energy expenditure of horses after albuterol administration.

Conclusion

• The study validates that forced oscillometry and indirect calorimetry can obtain repeatable measurements of respiratory resistance and energy expenditure in sedated horses respectively.
• The results indicate that albuterol administration leads to bronchodilation (widening of the bronchial tubes), and lower energy expenditure, implying that the increased energy demands seen in horses with recurrent airway obstruction may have been due to increased effort in breathing.